Article

Oximetry as an Accurate Tool for Identifying Moderate to Severe Sleep Apnea in Patients With Acute Stroke

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Abstract

Study objectives: Sleep-disordered breathing (SDB) is highly prevalent in patients with acute stroke. SDB is often underdiagnosed and associated with neurological deterioration and stroke recurrence. Polysomnography or home sleep apnea testing (HSAT) is typically used as the diagnostic modality; however, it may not be feasible to use regularly in patients with acute stroke. We investigated the predictive performance of pulse oximetry, a simpler alternative, to identify SDB. Methods: The records of 254 patients, who were admitted to Boston Medical Center for acute stroke and underwent HSAT, were retrospectively reviewed. Oxygen desaturation index (ODI) from pulse oximetry channel were compared to respiratory event index (REI) obtained from HSAT devices. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ODI were calculated, and different ODI cutoff values to predict SDB were proposed. Results: ODI had a strong correlation (r = .902) and agreement with REI. ODI was accurate in predicting SDB at different REI thresholds (REI ≥ 5, REI ≥ 15, and REI ≥ 30 events/h) with the area under the curve (AUC) of .965, .974, and .951, respectively. An ODI ≥ 5 events/h rules in the presence of SDB (specificity 91.7%, PPV 96.3%). An ODI ≥ 15 events/h rules in moderate to severe SDB (specificity 96.4%, PPV 95%) and an ODI < 5 events/h rules out moderate to severe SDB (sensitivity 100%, NPV 100%). Conclusions: Nocturnal pulse oximetry has a high diagnostic accuracy in predicting moderate to severe SDB in patients with acute stroke. Oximetry can be a simple modality to rapidly recognize patients with more severe SDB and facilitate the referral to the confirmation sleep study.

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... These variations may come, in part, from different study designs. Some studies have compared oximetry data obtained as a part of PSG recordings to apnea events analyzed from the same PSG recordings [14][15][16][17][18][19]. Others have compared oximetry data with data from simultaneous PSG [20][21][22]. ...
... Previous studies compared AHI and ODI from the same recordings, with correlation coefficients reported to range between 0.745 and 0.97 [14][15][16][17][18][19]. Some studies compared simultaneously performed oximetry and PSG, with correlation coefficients reported to be 0.617−0.95 ...
... First, the oximetry ODI was not measured simultaneously with PSG/OCST. Comparisons of ODI and AHI/REI from the same recordings showed the best correlation [14][15][16][17][18][19] (Figure 5), followed by simultaneous recording by different devices [20,21,25]. The correlation was worst when comparing ODI and AHI/REI from different devices on different nights [23,24] (Figures 2a and 6). ...
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A large epidemiological study using oximetry to analyze obstructive sleep apnea (OSA) and metabolic comorbidities was performed in Japan; however, reliability and validity of oximetry in the Japanese population remains poorly understood. In this study, oximetry data from the epidemiological study were compared with data from clinically performed polysomnography (PSG) and out-of-center sleep testing (OCST) in epidemiological study participants who later attended our outpatient units. The oxygen desaturation index (ODI) from oximetry showed a moderate positive relationship (correlation coefficient r = 0.561, p < 0.001) with apnea/hypopnea data from PSG/OCST. The area under the receiver operating characteristic curve showed moderate accuracy of this method in the detection of moderate-to-severe or severe OSA. However, the optimal ODI thresholds to detect moderate-to-severe OSA and severe OSA were the same (ODI > 20.1). Oximetry may be a useful tool for screening moderate-to-severe or severe sleep apnea. However, it may be difficult to set an appropriate threshold to distinguish between moderate and severe sleep apnea by oximetry alone.
... The HR, SpO 2 , and flex for each participant were sampled at a frequency of 1 Hz. This frequency was selected because (i) several previous works have adopted it, following [42][43][44], (ii) the HSAT device measures the parameters with a sampling frequency of 1 Hz, enabling fair comparisons of the performance metrics with HSAT, and, (iii) although an ideal sample frequency has yet to be established [44], Nigro et al. [45] observed that a minimum data sampling rate of 0.25 Hz can adequately avoid loss of oximetry resolution through sleep tests. However, we considered a sampling frequency four times greater than that suggested by [45]. ...
... The HR, SpO 2 , and flex for each participant were sampled at a frequency of 1 Hz. This frequency was selected because (i) several previous works have adopted it, following [42][43][44], (ii) the HSAT device measures the parameters with a sampling frequency of 1 Hz, enabling fair comparisons of the performance metrics with HSAT, and, (iii) although an ideal sample frequency has yet to be established [44], Nigro et al. [45] observed that a minimum data sampling rate of 0.25 Hz can adequately avoid loss of oximetry resolution through sleep tests. However, we considered a sampling frequency four times greater than that suggested by [45]. ...
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Sleep apnea (SA) is a common respiratory disorder, especially among obese people. It is caused by either the relaxation of the upper respiratory tract muscles or the failure of the neural signal to reach the muscles responsible for breathing, both of which interrupt the patient’s sleep–wake cycles. The traditional method for diagnosing this disorder, based on polysomnography, is complicated, vexing, expensive, time-consuming, and requires both sleep centers and specialized staff capable of connecting electrodes to the patient’s body. This paper proposes an SA prediction system based on merging five soft computing algorithms, specifically, combining the multi-verse optimizer (MVO) with an artificial neural network (ANN) to leverage measurements from heart rate, SpO2, and chest movement sensors. The most substantial novelty of this research is the hybridization of MVO and ANN (MVO-ANN), which improves the …
... The HR, SpO 2 , and flex for each participant were sampled at a frequency of 1 Hz. This frequency was selected because (i) several previous works have adopted it, following [42][43][44], (ii) the HSAT device measures the parameters with a sampling frequency of 1 Hz, enabling fair comparisons of the performance metrics with HSAT, and, (iii) although an ideal sample frequency has yet to be established [44], Nigro et al. [45] observed that a minimum data sampling rate of 0.25 Hz can adequately avoid loss of oximetry resolution through sleep tests. However, we considered a sampling frequency four times greater than that suggested by [45]. ...
... The HR, SpO 2 , and flex for each participant were sampled at a frequency of 1 Hz. This frequency was selected because (i) several previous works have adopted it, following [42][43][44], (ii) the HSAT device measures the parameters with a sampling frequency of 1 Hz, enabling fair comparisons of the performance metrics with HSAT, and, (iii) although an ideal sample frequency has yet to be established [44], Nigro et al. [45] observed that a minimum data sampling rate of 0.25 Hz can adequately avoid loss of oximetry resolution through sleep tests. However, we considered a sampling frequency four times greater than that suggested by [45]. ...
Article
Abstract Sleep apnea (SA) is a common respiratory disorder, especially among obese people. It is caused by either the relaxation of the upper respiratory tract muscles or the failure of the neural signal to reach the muscles responsible for breathing, both of which interrupt the patient’s sleep–wake cycles. The traditional method for diagnosing this disorder, based on polysomnography, is complicated, vexing, expensive, time-consuming, and requires both sleep centers and specialized staff capable of connecting electrodes to the patient’s body. This paper proposes an SA prediction system based on merging five soft computing algorithms, specifically, combining the multi-verse optimizer (MVO) with an artificial neural network (ANN) to leverage measurements from heart rate, SpO2, and chest movement sensors. The most substantial novelty of this research is the hybridization of MVO and ANN (MVO-ANN), which improves the ANN performance by selecting the best learning rate and number of neurons in hidden ANN layers. This enables highly accurate prediction of sleep apnea events. This work’s experimental results reveal that the MVO-ANN performs better than other algorithms, with mean absolute errors of 0.042, 0.202, and 0.166 for training, testing, and validation of the ANN. In addition, the SA prediction system achieved an accuracy of 98.67%, a sensitivity of 96.71%, and a specificity of 99.24%. These results provide good evidence that the proposed method can reliably predict respiratory events in people suffering from SA. Keywords Artificial neural network � Heart rate � Prediction � SpO2 � Sleep apnea � Soft computing algorithm
... The HR, SpO 2 , and flex for each participant were sampled at a frequency of 1 Hz. This frequency was selected because (i) several previous works have adopted it, following [42][43][44], (ii) the HSAT device measures the parameters with a sampling frequency of 1 Hz, enabling fair comparisons of the performance metrics with HSAT, and, (iii) although an ideal sample frequency has yet to be established [44], Nigro et al. [45] observed that a minimum data sampling rate of 0.25 Hz can adequately avoid loss of oximetry resolution through sleep tests. However, we considered a sampling frequency four times greater than that suggested by [45]. ...
... The HR, SpO 2 , and flex for each participant were sampled at a frequency of 1 Hz. This frequency was selected because (i) several previous works have adopted it, following [42][43][44], (ii) the HSAT device measures the parameters with a sampling frequency of 1 Hz, enabling fair comparisons of the performance metrics with HSAT, and, (iii) although an ideal sample frequency has yet to be established [44], Nigro et al. [45] observed that a minimum data sampling rate of 0.25 Hz can adequately avoid loss of oximetry resolution through sleep tests. However, we considered a sampling frequency four times greater than that suggested by [45]. ...
Article
Full-text available
Sleep apnea (SA) is a common respiratory disorder, especially among obese people. It is caused by either the relaxation of the upper respiratory tract muscles or the failure of the neural signal to reach the muscles responsible for breathing, both of which interrupt the patient’s sleep–wake cycles. The traditional method for diagnosing this disorder, based on polysomnography, is complicated, vexing, expensive, time-consuming, and requires both sleep centers and specialized staff capable of connecting electrodes to the patient’s body. This paper proposes an SA prediction system based on merging five soft computing algorithms, specifically, combining the multi-verse optimizer (MVO) with an artificial neural network (ANN) to leverage measurements from heart rate, SpO2, and chest movement sensors. The most substantial novelty of this research is the hybridization of MVO and ANN (MVO-ANN), which improves the ANN performance by selecting the best learning rate and number of neurons in hidden ANN layers. This enables highly accurate prediction of sleep apnea events. This work’s experimental results reveal that the MVO-ANN performs better than other algorithms, with mean absolute errors of 0.042, 0.202, and 0.166 for training, testing, and validation of the ANN. In addition, the SA prediction system achieved an accuracy of 98.67%, a sensitivity of 96.71%, and a specificity of 99.24%. These results provide good evidence that the proposed method can reliably predict respiratory events in people suffering from SA.
... Again, the importance of the above findings is the ability to triage patients based on severity risk classification of sleep-disordered breathing at screening and not necessarily based on the ODI/AHI. Our findings are similar to a recent study performed in hospitalized patients at an urban medical center with acute stroke and found a high concordance between PM and HRPO [32]. Finally, our earlier work demonstrated hospitalized patients who screened positive for SDB using HRPO had the diagnosis confirmed with polysomnography conducted post discharge, and that this inpatient screening protocol with an expedited outpatient diagnosis and treatment plan led to reduced readmission rates particularly in those patients with CHF and COPD [17][18][19][20][21]. ...
... Second, there is minimal research validating these questionnaires in patients with significant cardiopulmonary disease. The research that has been completed suggests these instruments underperform compared to larger studies in healthier populations [32][33][34][35]. This is important given that cardiopulmonary illness is a common reason for hospital admission. ...
Article
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Purpose High-resolution pulse oximetry (HRPO) may offer a low-cost and simple screening option for sleep-disordered breathing (SDB) that could be vitally important in rural areas with limited healthcare resources and specialty care. Our team hypothesized that application of this technology to a broad cohort of rural dwelling hospitalized individuals would demonstrate congruence similar to previous urban studies comparing HRPO to portable sleep monitors. Methods This retrospective study was conducted at West Virginia University Hospital and compared indices obtained from HRPO with those obtained from a type III portable sleep monitor (PM) on the same night. Results A total of 365 individuals underwent evaluation. The mean oxygen desaturation index (18.8 ± 19.3 events/h) from the HRPO was slightly higher than the mean respiratory event index (16.0 ± 18.1 events/h, p ≤ 0.001) from the PM. ROC curves were developed for thresholds of apnea severity predicted by the screening program. The AUC values for all three thresholds exceeded 0.92 and for a respiratory event index (REI) of ≥ 30 was 0.965. Indices from the PM and HRPO demonstrated agreement in those individuals with screening suggestive of moderate to severe disease. Conclusion This study demonstrates that use of HRPO in screening for SDB in hospitalized patients from rural communities is as accurate as PM and may serve as a simple cost-effective tool to address sleep health disparities in these regions with significant health inequity. Our data extend previous findings by applying HRPO to a larger hospitalized cohort with highly prevalent cardiopulmonary disease.
... The number of apnea and hypopnea events per hour of monitoring during a certain period was described as the respiratory event index (REI). The REI is used as a surrogate for the apnea-hypopnea index (AHI) because it measures time spent monitoring rather than total sleep time [16]. ...
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Objective This study aimed to evaluate the effect of sacubitril-valsartan (SV) on central apneas (CA) and obstructive apneas (OA) in patients with heart failure with reduced ejection fraction (HFrEF). Methods In patients with HFrEF, SV initiation was titrated to the highest tolerable dosage. Patients were evaluated with portable apnea monitoring, echocardiography, and cardiopulmonary exercise testing at baseline and 3 months later. Results Of a total of 18 patients, 9 (50%) had OA, 7 (39%) had CA, and 2 (11%) had normal breathing. SV therapy was related to a reduction in NT-pro BNP and an improvement in LV function after 3 months. Portable apnea monitoring revealed a significant decrease of the respiratory event index (REI) after treatment with SV (20 ± 23 events/h to 7 ± 7 events/h, p = 0.003). When subgrouping according to type of apneas, REI, and time spent below 90% saturation (T90) decreased in patients with CA and OA (all p < 0.05). Conclusion In this prospective study, SV treatment for 3 months in patients with CA and OA is associated with a significant decrease in REI.
... Indeed, nocturnal oxygen desaturation, measured via OXI, is capable of detecting previously undiagnosed sleep disordered breathing in patients referred for surgery (12) and those with heart failure (13). Subsequent studies reported abnormal OXI identified disordered sleep (14) and predicts the incidence of atrial fibrillation (15) in stroke patients. Additionally, data from the Taiwan Bus Driver Cohort Study found more frequent desaturation during sleep predicted future cardiovascular disease, after adjusting for risk factors, in a sample of over 1,000 subjects (16). ...
Article
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Background: Ambulatory overnight oximetry (OXI) has emerged as a cost-effective initial test for sleep disordered breathing. Obesity is closely associated with obstructive sleep apnea (OSA); however, whether body mass index (BMI) or waist-to-hip ratio (WHR) predicts abnormal overnight OXI remains unknown. Methods: We performed a retrospective cross-sectional study of 393 men seen in the Executive Health Program at Mayo Clinic in Rochester, Minnesota who underwent ambulatory overnight OXI ordered by preventive medicine physicians between January 1, 2004 through December 31, 2010. We compared participant/spouse-reported symptoms (sleepiness, snoring), physician indications for OXI (obesity, fatigue), Epworth Sleepiness Scale scores, anthropomorphic measurements (WHR, BMI), and comorbid medical conditions (hypertension, diabetes) with OXI results. Results: 295 of the 393 men who completed OXI had abnormal results. During multivariate analysis, the strongest independent predictor of abnormal OXI for men was WHR (≥1.0, OR = 5.59) followed by BMI (≥30.0 kg/m ² , OR = 2.75), age (≥55 yrs, OR = 2.06), and the presence of snoring (OR = 1.91, P < 0.05 for all). A strong association was observed between WHR and abnormal OXI in obese (BMI ≥ 30.0 kg/m ² , OR = 6.28) and non-obese (BMI < 29.9 kg/m ² , OR = 6.42, P < 0.01 for both) men. Furthermore, 88 men with abnormal OXI underwent polysomnography with 91% being subsequently diagnosed with OSA. Conclusions: In ambulatory, predominantly middle-aged men undergoing preventive services evaluation many physician indications for OXI were not predictors of abnormal results; however, WHR strongly predicted abnormal OXI in obese and non-obese men. As such, we suggest middle-aged men who snore and have a WHR ≥1.0 should be directly referred to a sleep clinic for polysomnography.
... Overnight home oximetry has been proposed as a simple diagnostic test for SDB due to its high accessibility, reliability, accuracy, portability, and low cost [13]. It has been used to reliably detect SDB in paediatric populations [14], adult patients with COPD [15], and stroke [16], and to predict CPAP initiation in general community patients [17]. Australian studies have shown that home oximetry screening supervised by trained registered nurses is not inferior to that of trained physicians for the management of severe OSA in patients without SMI [18]. ...
Article
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Background To describe the diagnosis and management pathway of sleep-disordered breathing (SDB) in a sample of patients with severe mental illness (SMI), and to assess the feasibility and patient acceptability of overnight oximetry as a first-step screening method for detecting severe SDB in this population. Methods The study was a retrospective audit of patients with SMI seen at a Collaborative Centre for Cardiometabolic Health in Psychosis service who were invited for overnight oximetry between November 2015 and May 2018. The adjusted oxygen desaturation index (ODI) was calculated using 4% desaturation criteria. Results were discussed with a sleep specialist and categorized into a 4-level risk probability tool for SDB. Results Of 91 adults consenting for overnight oximetry, 90 collected some oximetry data, though 11 of these 90 patients collected technically unsatisfactory oximetry. Thus 79/90 patients (88%) collected adequate oximetry data for at least one night. The oximetry traces suggested likely minimal obstructive sleep apnea (OSA) in 41 cases, moderate to severe OSA in 25 patients, severe OSA in 9 patients and possible obesity hypoventilation syndrome (OHS) in 4 cases. Full polysomnography was recommended for 39 patients but only one-third underwent testing. Nineteen patients were reviewed by a sleep specialist. Of the 10 patients who initiated CPAP, four were considered adherent to treatment. Conclusion Home oximetry may be a pragmatic option for SDB screening in patients with SMI but reliable full diagnostic and management pathways need to be developed.
... 7 Oximetry is another less expensive and easier alternative that is widely available. 8,9 However, attaching a device to the finger during sleep is uncomfortable and may limit natural position change during sleep; moreover, the device is removed on waking up, which limits its use in multiday, continuous recordings. ...
Article
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Study objectives: People with obstructive sleep apnea (OSA) remain undiagnosed owing to lack of easy and comfortable screening tools. Through this study, we aimed to compare the diagnostic accuracy of chest wall motion and cyclic variation of heart rate (CVHR) in detecting OSA by using a single-lead electrocardiogram (ECG) patch with a 3-axis accelerometer. Methods: In total, 119 snoring patients simultaneously underwent polysomnography (PSG) with a single-lead ECG patch. Signals of chest wall motion and CVHR from the single-lead ECG patch were collected. The chest effort index (CEI) was calculated using the chest wall motion recorded by a 3-axis accelerometer in the device. The ability of CEI and CVHR indices in diagnosing moderate-to-severe OSA (apnea hypopnea index ≥ 15) was compared using the area under the curve (AUC) by using the DeLong test. Results: CVHR detected moderate-to-severe OSA with 52.9% sensitivity and 94.1% specificity (AUC: 0.76, 95% confidence interval [CI]: 0.67-0.84, optimal cutoff: 21.2 events/h). By contrast, CEI identified moderate-to-severe OSA with 80% sensitivity and 79.4% specificity (AUC: 0.87, 95% CI: 0.80-0.94, optimal cutoff: 7.1 events/h). CEI significantly outperformed CVHR with regard to the discrimination ability for moderate-to-severe OSA (delta AUC: 0.11, 95% CI: 0.009-0.21, P = 0.032). For determining severe OSA, the performance of discrimination ability was greater (AUC = 0.90, 95% CI: 0.85-0.95) when combining these two signals. Conclusions: Both CEI and CVHR recorded from a patch-type device with ECG and a 3-axis accelerometer can be used to detect moderate-to-severe OSA. Thus, incorporation of CEI is helpful in the detection of sleep apnea by using a single-lead ECG with a 3-axis accelerometer.
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Background OSA is an independent risk factor for several systemic diseases. Compared with mild OSA, patients with moderate-to-severe OSA have more severe impairment in the function of all organs of the body. Due to the current limited medical condition, not every patient can be diagnosed and treated in time. To enable timely screening of patients with moderate-to-severe OSA, we selected easily accessible variables to establish a risk prediction model. Method We collected 492 patients who had polysomnography (PSG), and divided them into the disease-free mild OSA group (control group), and the moderate-to-severe OSA group according to the PSG results. Variables entering the model were identified by random forest plots, univariate analysis, multicollinearity test, and binary logistic regression method. Nomogram were created based on the binary logistic results, and the area under the ROC curve was used to evaluate the discriminative properties of the nomogram model. Bootstrap method was used to internally validate the nomogram model, and calibration curves were plotted after 1,000 replicate sampling of the original data, and the accuracy of the model was evaluated using the Hosmer-Lemeshow goodness-of-fit test. Finally, we performed decision curve analysis (DCA) of nomogram model, STOP-Bang questionnaire (SBQ), and NoSAS score to assess clinical utility. Results There are 6 variables entering the final prediction model, namely BMI, Hypertension, Morning dry mouth, Suffocating awake at night, Witnessed apnea, and ESS total score. The AUC of this prediction model was 0.976 (95% CI: 0.962–0.990). Hosmer-Lemeshow goodness-of-fit test χ ² = 3.3222 ( P = 0.1899 > 0.05), and the calibration curve was in general agreement with the ideal curve. The model has good consistency in predicting the actual occurrence of moderate-to-severe risk, and has good prediction accuracy. The DCA shows that the net benefit of the nomogram model is higher than that of SBQ and NoSAS, with has good clinical utility. Conclusion The prediction model obtained in this study has good predictive power for moderate-to-severe OSA and is superior to other prediction models and questionnaires. It can be applied to the community population for screening and to the clinic for prioritization of treatment.
Article
Aim: This study aimed to determine whether 1-night screening of oxygen desaturation in women with uncomplicated pregnancy about 1 month before the due date is useful to predict late-onset gestational hypertension (GH) after 37 weeks of gestation. Methods: We recruited 102 women with uncomplicated pregnancy between 34 and 36 weeks of gestation. These women then completed the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and Berlin Questionnaire for obstructive sleep apnea, and recorded their oxygen saturation (SpO2 ) and physical acceleration profiles during nocturnal sleep for 1 night at home using a portable pulse oximeter and actigraph, respectively. Thereafter, their blood pressure was monitored weekly until delivery. Results: Pulse oximetry data between 34 and 36 weeks of gestation revealed that three women had an oxygen desaturation index (ODI) ≥5.0 and seven had a minimum SpO2 < 90%. During follow-up until delivery, two women with an ODI ≥5.0 and a minimum SaO2 <90% developed GH at 37 weeks of gestation. Among clinical measures at recruitment, body mass index (BMI) and pulse oximetry measures appeared available for the prediction of GH. The positive predictive values (95% confidence intervals) of the criteria using these measures were 0.67 (0.26-0.67) for ODI ≥5.0, 0.29 (0.10-0.35) for minimum SpO2 <90%, and 0.07 (0.02-0.07) for BMI ≥25.0. Conclusion: For the prediction of late-onset GH after 37 weeks of gestation, pulse oximetry measures about 1 month before the due date are particularly useful because of their high positive predictive values.
Article
Background Sleep-disordered breathing (SDB) is present in more than 70% of stroke patients. Despite its association with increased morbidity, mortality, and reduced functional outcomes, targeted assessment of SDB in stroke patients, remain controversial. Polysomnography ("gold standard" examination) is a technically demanding and costly test with limited availability. The use of screening questionnaires is limited due to low specificity and sensitivity. Pulse oximetry seems to be a sensible alternative. Our study aimed to assess the feasibility and predictive value of routine pulse oximetric screening for assessment of SDB in patients with acute stroke. Methods Patients with acute stroke were enrolled in an open, prospective study. A single-night pulse oximetric assessment was used for SDB screening. Subsequently, polysomnography was performed to confirm SDB. Moderate-to-severe SDB was defined as apnea-hypopnea index ≥ 15. Results Out of 420 enrolled patients, refusal to undergo examination was reported in 4 and non-cooperation during the investigation in 21 subjects. The area under the curve in a receiver operating curve to predict moderate-to-severe SDB by desaturation index (DI) was 0.86 (95% CI: 0.76-0.97), and optimal DI cut-off by Youden index was 15.3. Positive pulse oximetric screening (DI≥15.3) had 90.5% sensitivity and 75% specificity to predict moderate-to-severe SDB. Conclusions Our results suggest a good adherence of acute stroke patients to the pulse oximetric screening. Pulse oximetry represents a simple, cost-effective, and sensitive examination that might be used in stroke patients as an appropriate tool for further selection for targeted diagnostic and therapeutic processes of SDB in the sleep laboratory.
Article
Background Screening for obstructive sleep apnea (OSA) in both inpatient and outpatient settings to pursue diagnostic testing is becoming increasingly relevant, particularly given the estimates of 85-90% of patients with OSA remaining undiagnosed. Albeit many questionnaires are available for OSA screening, the STOP-BANG questionnaire is becoming increasingly used due to ease of use and positive performance characteristics. The utility of nocturnal oximetry, in conjunction with standard questionnaire-based strategies to enhance OSA screening in adults, has yet to be systematically examined. Research Objectives To evaluate the utility of nocturnal oximetry measures combined with the standard STOP-BANG questionnaire as a screening strategy for OSA in the hospital setting and outpatient clinics. Study Design and Methods: We conducted a retrospective cohort study. We reviewed the electronic medical records of 130 patients who were referred to Sanford sleep center from both inpatient and outpatient settings over one year (August 1st, 2016 to August 1st, 2017). Nocturnal oximetry was conducted at home (in the outpatient group) and in the medical wards (in the inpatient group), and the following measures were obtained: Oxygen Desaturation Index (ODIPOx), mean SaO2POx and time spent below 88% SaO2 (T88Pox). Apnea-hypopnea index (AHI), mean SaO2PSG, and T88PSG from overnight polysomnography (PSG) and STOP-BANG score. Results Based upon likelihood ratio testing comparing discriminative ability, a model of (ODIPox + STOPBANG) was superior and more accurate than STOP-BANG alone in detecting mild OSA in the overall sample (AUC=0.644 [0.549-0.739], p=0.003) and inpatient sample (AUC=0.710 [0.582-0.839], p=0.001). This approach was also more accurate in detecting severe OSA in full sample (AUC=0.839 [0.763-0.914], p< 0.0001), inpatient sample (AUC=0.825 [0.711-0.939], p< 0.0001) and outpatient sample (AUC=0.827 [0.699-0.955], p < 0.0001). The ODIPox alone was more accurate than STOP-BANG alone in detecting mild OSA in the overall sample (AUC=0.620 [0.524-0.717], p=0.014) and inpatient sample (AUC=0.704 [0.574-0.835], p=0.002) and severe OSA in full sample (AUC=0.839 [0.764-0.915], p< 0.0001), inpatient sample (AUC=0.827 [0.714-0.940], p< 0.0001) and outpatient sample (AUC=0.861 [0.771-0.950], p < 0.0001). Conclusion The use of nocturnal oximetry measures (ODIPOx) improved the accuracy of standard OSA screening with the STOP-BANG questionnaire as a screening tool in severe OSA in both inpatient and outpatient settings. Clinical Implication Obstructive sleep apnea is a common sleep disorder that impacts many co-morbidities in different age groups. Enhancing affordable screening methods for OSA can facilitate early diagnosis and treatment and subsequently ameliorate morbidity and mortality related to sleep-disordered breathing.
Article
Purpose of review: Stroke and sleep apnea are highly prevalent conditions with a physiologically plausible bidirectional relationship. This review addresses prestroke sleep apnea, wake-up stroke and sleep apnea, and poststroke sleep apnea, with an attempt to highlight research published in the last 18 months. Recent findings: Sleep apnea is highly prevalent poststroke. Poststroke sleep apnea is associated with worse poststroke functional and cognitive outcomes and a higher risk of recurrent stroke. Physiologic tests are needed to diagnose sleep apnea in poststroke patients as sleep apnea questionnaires do not perform well in this population. The role of CPAP in poststroke management is not yet well established. Summary: Sleep apnea is a well established independent risk factor for stroke that confers an approximately two-fold increased risk of incident stroke. Sleep apnea is highly prevalent poststroke and is associated with worse outcomes after stroke. Sleep apnea is an attractive target for research addressing secondary stroke prevention and recovery.
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Introduction Meta-analyses report that more than 50% of patients who had a stroke suffer from moderate to severe sleep apnoea (SA), with adherence rates to positive airway pressure (PAP) therapy of only 30%. The primary objective of this study is to determine whether PAP adherence in patients who had a stroke with obstructive sleep apnoea (OSA) can be improved by a PAP training strategy during inhospital rehabilitation combined with a telemedicine monitoring system after discharge. Further objectives are (1) to compare the validity of a non-attended level-III polygraphy with that of a level-II polysomnography (PSG) in the diagnosis of SA, (2) to compare the validity of an apnoea-hypopnoea index (AHI) yielded by the PAP device with that obtained during PSG, (3) to determine changes in nocturnal systolic blood pressure (BP) due to PAP therapy with the pulse transit time (PTT) method and (4) to assess the impact of telemonitored PAP therapy on neurorehabilitation outcome parameters. Methods and analyses Single-blind, monocentre, randomised controlled trial. It includes 55 patients who had a subacute stroke, aged 19–70 years, with moderate to severe OSA, who have undergone successful PAP training and titration at the neurorehabilitation unit. Patients are randomised to either a standard care group or a telemedicine group. PAP adherence, sleep and respiratory variables, subjective and objective sleep quality, systolic BP (PTT method) of the two groups are compared after 3 months and 1 year as well as cognitive and motor neurorehabilitation outcome parameters, quality of life and PAP satisfaction. Additionally, intranight AHI/total sleep time versus AHI/time in bed and night-to-night variability of the AHI are assessed. Ethics and dissemination Before screening, all participants will be provided with oral and written information. The study will be disseminated by peer-reviewed publications and conference presentations. Trial registration number NCT02748681; Pre-results.
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Introduction: Sleep-disordered breathing (SDB) is highly prevalent in hospitalized patients with congestive heart failure (CHF) and the condition is diagnosed and treated in only a minority of these patients. Portable monitoring (PM) is a screening option, but due to costs and the expertise required, many hospitals may find it impractical to implement. We sought to test the utility of an alternative approach for screening hospitalized CHF patients for SDB, high-resolution pulse oximetry (HRPO). Methods: We conducted a prospective controlled trial of 125 consecutive patients admitted to the hospital with CHF. Simultaneous PM and HRPO for a single night was performed. All but one patient were monitored on breathing room air. The HRPO-derived ODI (oxygen desaturation index) was compared with PM-derived respiratory event index (REI) using both receiver operator characteristic (ROC) curve analysis and a Bland-Altman plot. Results: Of 105 consecutive CHF patients with analyzable data, 61 (58%) were males with mean age of 64.9 ± 15.1 years and mean body mass index of 30.3 ± 8.3 kg/m2. Of the 105 patients, 10 (9.5%) had predominantly central sleep apnea (central events > 50% of the total events), although central events were noted in 42 (40%) of the patients. The ROC analysis showed an area under the curve of 0.89 for REI > 5 events/h. The Bland-Altman plot showed acceptable agreement with 95% limits of agreement between -28.5 to 33.7 events/h and little bias. Conclusions: We conclude that high-resolution pulse oximetry is a simple and cost-effective screening tool for SDB in CHF patients admitted to the hospital. Such screening approaches may be valuable for large-scale implementation and for the optimal design of interventional trials.
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Study objectives: The aim of this study was to compare the oxygen desaturation index (ODI) generated by two different sleep software systems. Methods: Participants undergoing diagnostic polysomnography for suspected obstructive sleep apnea underwent simultaneous oximetry recording using the ResMedApneaLink Plus device (AL) and Compumedics Profusion PSG3 system (Comp). The ODI was calculated by the algorithms in the respective software of each system. To determine if differences were due to algorithm or recording devices, the Comp software was also used to generate ODI values using oximetry data from the AL. Results: In 106 participants, there was good correlation but poor agreement in the ODI generated by the two systems. AL ODI values tended to be higher than Comp ODI values, but with significant variability. For ODI4%, bias was 4.4 events/h (95% limits of agreement -5.8 to 14.6 events/h). There was excellent correlation and agreement when the same oximetry raw data was analyzed by both systems. For ODI4%, bias was 0.03 events/h (95% limits of agreement -2.7 to 2.8 events/h). Similar results were evident when the ODI3% was used. Conclusions: There is a clinically significant difference in ODI values generated by the two systems, likely due to device signal processing, rather than difference in ODI calculation algorithms.
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Introduction: This guideline establishes clinical practice recommendations for the diagnosis of obstructive sleep apnea (OSA) in adults and is intended for use in conjunction with other American Academy of Sleep Medicine (AASM) guidelines on the evaluation and treatment of sleep-disordered breathing in adults. Methods: The AASM commissioned a task force of experts in sleep medicine. A systematic review was conducted to identify studies, and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process was used to assess the evidence. The task force developed recommendations and assigned strengths based on the quality of evidence, the balance of benefits and harms, patient values and preferences, and resource use. In addition, the task force adopted foundational recommendations from prior guidelines as "good practice statements," that establish the basis for appropriate and effective diagnosis of OSA. The AASM Board of Directors approved the final recommendations. Recommendations: The recommendations can be found in the published guideline.
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Background Obstructive sleep apnea is associated with an increased risk of cardiovascular events; whether treatment with continuous positive airway pressure (CPAP) prevents major cardiovascular events is uncertain. Methods After a 1-week run-in period during which the participants used sham CPAP, we randomly assigned 2717 eligible adults between 45 and 75 years of age who had moderate-to-severe obstructive sleep apnea and coronary or cerebrovascular disease to receive CPAP treatment plus usual care (CPAP group) or usual care alone (usual-care group). The primary composite end point was death from cardiovascular causes, myocardial infarction, stroke, or hospitalization for unstable angina, heart failure, or transient ischemic attack. Secondary end points included other cardiovascular outcomes, health-related quality of life, snoring symptoms, daytime sleepiness, and mood. Results Most of the participants were men who had moderate-to-severe obstructive sleep apnea and minimal sleepiness. In the CPAP group, the mean duration of adherence to CPAP therapy was 3.3 hours per night, and the mean apnea–hypopnea index (the number of apnea or hypopnea events per hour of recording) decreased from 29.0 events per hour at baseline to 3.7 events per hour during follow-up. After a mean follow-up of 3.7 years, a primary end-point event had occurred in 229 participants in the CPAP group (17.0%) and in 207 participants in the usual-care group (15.4%) (hazard ratio with CPAP, 1.10; 95% confidence interval, 0.91 to 1.32; P=0.34). No significant effect on any individual or other composite cardiovascular end point was observed. CPAP significantly reduced snoring and daytime sleepiness and improved health-related quality of life and mood. Conclusions Therapy with CPAP plus usual care, as compared with usual care alone, did not prevent cardiovascular events in patients with moderate-to-severe obstructive sleep apnea and established cardiovascular disease. (Funded by the National Health and Medical Research Council of Australia and others; SAVE ClinicalTrials.gov number, NCT00738179; Australian New Zealand Clinical Trials Registry number, ACTRN12608000409370.)
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Introduction: Prompt diagnosis of obstructive sleep apnea (OSA) after acute ischemic stroke (AIS) is critical for optimal clinical outcomes, but in-laboratory conventional polysomnograms (PSG) are not routinely practical. Though portable out-of-center type III cardiopulmonary sleep studies (out-of-center cardiopulmonary sleep testing [OCST]) are widely available, these studies have not been validated in patients who have recently suffered from AIS. We hypothesized that OCST in patients with AIS would yield similar results when compared to conventional PSG. Methods: Patients with AIS had simultaneous type III OCST and PSG studies performed within 72 hours from symptom onset. The accuracy of OCST was compared to PSG using: chi-square tests, receiver operatory characteristic curves, Bland-Altman plot, paired Student's t-test/Wilcoxon signed-rank test, and calculation of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: Twenty-one out of 23 subjects with AIS (age 61±9.4 years; 52% male; 58% African-American) successfully completed both studies (9% technical failure). Nearly all (95%) had Mallampati IV posterior oropharynx; the mean neck circumference was 16.8±1.6 in. and the mean body mass index (BMI) was 30±7 kg/m(2). The apnea hypopnea index (AHI) provided by OCST was similar to that provided by PSG (19.8±18.0 vs 22.0±22.7, respectively; P=0.49). On identifying subjects by OCST with an AHI ≥5 on PSG, OCST had the following parameters: sensitivity 100%, specificity 85.7%, PPV 93%, and NPV 100%. On identifying subjects with an AHI ≥15 on PSG, OCST parameters were as follows: sensitivity 100%, specificity 83.3%, PPV 81.8%, and NPV 100%. Bland-Altman plotting showed an overall diagnostic agreement between OCST and PSG modalities for an AHI cutoff >5, despite fine-grained differences in estimated AHIs. Conclusion: Compared with PSG, OCST provides similar diagnostic information when run simultaneously in AIS patients. OCST is a reliable screening tool for early diagnosis of OSA in AIS patients.
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Objectives In its guidelines on the use of portable monitors to diagnose obstructive sleep apnoea, the American Academy of Sleep Medicine endorses home polygraphy with type III devices recording at a minimum airflow the respiratory effort and pulse oximetry, but advises against simple pulse oximetry. However, oximetry is widely available and simple to use in the home. This study was designed to compare the ability of the oxygen desaturation index (ODI) based on oximetry alone with a stand-alone pulse oximeter (SPO) and from the oximetry channel of the ApneaLink Plus (ALP), with the respiratory disturbance index (RDI) based on four channels from the ALP to predict the apnoea–hypopnoea index (AHI) from laboratory polysomnography. Design Cross-sectional diagnostic accuracy study. Setting Sleep medicine practice of a multispecialty clinic. Participants Patients referred for laboratory polysomnography with suspected sleep apnoea. We enrolled 135 participants with 123 attempting the home sleep testing and 73 having at least 4 hours of satisfactory data from SPO and ALP. Interventions Participants had home testing performed simultaneously with both a SPO and an ALP. The 2 oximeter probes were worn on different fingers of the same hand. The ODI for the SPO was calculated using Profox software (ODISOX). For the ALP, RDI and ODI were calculated using both technician scoring (RDIMAN and ODIMAN) and the ALP computer scoring (RDIRAW and ODIRAW). Results The receiver–operator characteristic areas under the curve for AHI ≥5 were RDIMAN 0.88 (95% confidence limits 0.81–0.96), RDIRAW 0.86 (0.76–0.94), ODIMAN 0.86 (0.77–0.95), ODIRAW 0.84 (0.75–0.93) and ODISOX 0.83 (0.73–0.93). Conclusions We conclude that the RDI and the ODI, measured at home on the same night, give similar predictions of the laboratory AHI, measured on a different night. The differences between the two methods are small compared with the reported night-to-night variation of the AHI.
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To determine the impact of averaging window-length on the "desaturation" indexes (DIs) obtained via overnight pulse oximetry (SpO2) at high altitude. Overnight SpO2 data were collected during a 10-day sojourn at high altitude. SpO2 was obtained using a commercial wrist-worn finger oximeter whose firmware was modified to store unaveraged beat-to-beat data. Simple moving averages of window lengths spanning 2 to 20 cardiac beats were retrospectively applied to beat-to-beat SpO2 datasets. After SpO2 artifacts were removed, the following DIs were then calculated for each of the averaged datasets: oxygen desaturation index (ODI); total sleep time with SpO2 <80% (TST<80), and the lowest SpO2 observed during sleep (SpO2 low). South Base Camp, Mt. Everest (5,364 m elevation). Five healthy, adult males (35±5 yr; 180±1 cm; 85±4 kg). Interventions: N/A. 49 datasets were obtained from the 5 participants, totalling 239 hours of data. For all window lengths ≥2 beats, ODI and TST<80 were lower, and SpO2 low was higher than those values obtained from the beat-to-beat SpO2 time series data (P < 0.05). Our findings indicate that increasing oximeter averaging window length progressively underestimates the frequency and magnitude of sleep disordered breathing events at high altitude, as indirectly assessed via the DIs. © 2014 Associated Professional Sleep Societies, LLC.
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. To assess the diagnostic ability of WristOx 3100 using its three different recording settings in patients with suspected obstructive sleep apnea syndrome (OSAS). . All participants (135) performed the oximetry (three oximeters WristOx 3100) and polysomnography (PSG) simultaneously in the sleep laboratory. Both recordings were interpreted blindly. Each oximeter was set to one of three different recording settings (memory capabilities 0.25, 0.5, and 1 Hz). The software (nVision 5.1) calculated the adjusted O desaturation index-mean number of O desaturation per hour of analyzed recording ≥2, 3, and 4% (ADI2, 3, and 4). The ADI2, 3, and 4 cutoff points that better discriminated between subjects with or without OSAS arose from the receiver-operator characteristics (ROCs) curve analysis. OSAS was defined as a respiratory disturbance index (RDI) ≥ 5. . 101 patients were included (77 men, mean age 52, median RDI 22.6, median BMI 27.4 kg/m). The area under the ROCs curves (AUC-ROCs) of ADI2, 3, and 4 with different data storage rates were similar (AUC-ROCs with data storage rates of 0.25/0.5/1 Hz: ADI2: 0.958/0.948/0.965, ADI3: 0.961/0.95/0.966, and ADI4: 0.957/0.949/0.963, NS). . The ability of WristOx 3100 to detect patients with OSAS was not affected by the data storage rate of the oxygen saturation signal. Both memory capacity of 0.25, 0.5, or 1 Hz showed a similar performance for the diagnosis of OSAS.
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To address the growing burden of disease and long waiting lists for sleep services, a simplified two-stage model was developed and validated for identifying obstructive sleep apnoea (OSA) in primary care using a screening questionnaire followed by home sleep monitoring. 157 patients aged 25-70&emsp14;years attending their primary care physician for any reason at six primary care clinics in rural and metropolitan regions of South Australia participated. The first 79 patients formed the development group and the next 78 patients the validation group. A screening questionnaire was developed from factors identified from sleep surveys, demographic and anthropometric data to be predictive of moderate to severe OSA. Receiver operating characteristic (ROC) curve analysis was used to validate the two-channel ApneaLink device against full polysomnography. The diagnostic accuracy of the overall two-stage model was then evaluated. Snoring, waist circumference, witnessed apnoeas and age were predictive of OSA and incorporated into a screening questionnaire (ROC area under curve (AUC) 0.84, 95% CI 0.75 to 0.94, p<0.001). ApneaLink oximetry with a 3% dip rate was highly predictive of OSA (AUC 0.96, 95% CI 0.91 to 1.0, p<0.001). The two-stage diagnostic model showed a sensitivity of 0.97 (95% CI 0.81 to 1.00) and specificity of 0.87 (95% CI 0.74 to 0.95) in the development group, and a sensitivity of 0.88 (95% CI 0.60 to 0.98) and specificity of 0.82 (95% CI 0.70 to 0.90) in the validation group. A two-stage model of screening questionnaire followed by home oximetry can accurately identify patients with OSA in primary care and has the potential to expedite care for patients with this common sleep disorder.
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The aim of the present study was to assess the impact of nasal continuous positive airway pressure (nCPAP) in ischaemic stroke patients followed for 2 yrs. Stroke patients with an apnoea-hypopnoea index ≥ 20 events·h⁻¹ were randomised to early nCPAP (n = 71; 3-6 days after stroke onset) or conventional treatment (n = 69). The Barthel Index, Canadian Scale, Rankin Scale and Short Form-36 were measured at baseline, and at 1, 3, 12 and 24 months. The percentage of patients with neurological improvement 1 month after stroke was significantly higher in the nCPAP group (Rankin scale 90.9 versus 56.3% (p < 0.01); Canadian scale 88.2 versus 72.7% (p < 0.05)). The mean time until the appearance of cardiovascular events was longer in the nCPAP group (14.9 versus 7.9 months; p = 0.044), although cardiovascular event-free survival after 24 months was similar in both groups. The cardiovascular mortality rate was 0% in the nCPAP group and 4.3% in the control group (p = 0.161). Early use of nCPAP seems to accelerate neurological recovery and to delay the appearance of cardiovascular events, although an improvement in patients' survival or quality of life was not shown.
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Obstructive sleep apnea syndrome (OSA) is a frequent clinical picture. It is characterized by repetitive respiratory arrest with a consecutive decrease in arterial oxygen saturation (SaO(2)). In clinical practice, the number of desaturations per hour, oxygen desaturation index (ODI), is used as an important diagnostic criterion. Medical literature, however, mentions different threshold values that are defined as pathological. By means of systematic comparative measurements, the study presented here will examine to what extent the diagnosis and the quantification of OSA severity are affected by the device-specific measurement technique, thus impacting the predictive value of nighttime pulse oximetry in outpatient OSA screening. Different pulse oximeters commonly used in clinical practice were analyzed comparatively regarding technical parameters, temporal dynamics and the reproducibility of measuring results. The measurements were executed simultaneously and time synchronized in a reference group of five test subjects (four males, one female, average age 33.0 +/- 9.4 years), in a group of five patients (all males, average age 51.8 +/- 18.4 years) and using a simulator (pulse oximeter simulator index 2). All devices underestimate the simulator's predetermined oxygen desaturation of 10%. The dispersion of values is high. The device-specific characteristics have a significant influence on the collected data. The fundamental weakness of the systems lies in the reproducibility of measuring results (this only seems adequate at a signal resolution in steps of 0.1%) as well as the differing temporal dynamics. In the synchronous use of different systems on patients for the purpose of a direct comparison of devices, the dispersion of values is serious, reaching a fluctuation range of up to factor 1.42. In measuring dynamic events (apneas), different pulse oximeters do not record identical values. This is due to the different internal signal processing of the devices. Without prior knowledge of the pulse oximeter used and the chosen device settings, meaningful interpretation of the measured desaturations is, therefore, ambiguous. Accordingly, different devices require different threshold values in determining the ODI. Standardized technical parameters and the standardization of signal processing are imperative for outpatient screening of sleep-related breathing disorders (SRBD) via pulse oximetry.
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To determine the frequency of sleep disordered breathing (SDB) in ischemic and hemorrhagic stroke and transient ischemic attack (TIA) patients by meta-analysis. A systematic literature search using Medline, EMBASE and CINAHL and a manual review of references through December 2008 was conducted using specific search terms. The frequency of SDB stratified by apnea hypopnea index (AHI) was extracted by the author. Weighted averages using a random-effects model are reported with 95% confidence intervals. Twenty-nine articles evaluating patients with autoCPAP, limited-channel sleep study, or full polysomnography were included in this study. In meta-analysis of 2,343 ischemic or hemorrhagic stroke and TIA patients, the frequency of SDB with AHI > 5 was 72% and with AHI > 20 was 38%. Only 7% of the SDB was primarily central apnea. There was no significant difference in SDB prevalence by event type, timing after stroke, or type of monitoring. Males had a higher percentage of SDB (AHI > 10) than females (65% compared to 48% p = 0.001). Patients with recurrent strokes had a higher percentage of SDB (AHI > 10) than initial strokes (74% compared to 57% p = 0.013). Patients with unknown etiology of stroke had a higher and cardioembolic etiology a lower percentage of SDB than other etiologies. SDB is very common in stroke patients irrespective of type of stroke or timing after stroke and is typically obstructive in nature. Since clinical history alone does not identify many patients with SDB, sleep studies should be considered in all stroke and TIA patients.
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To comprehensively evaluate the ability and reliability of the representative previously proposed oxyhemoglobin indexes derived automatically for predicting the severity of obstructive sleep apnea hypopnea syndrome (OSAHS). Patients with a diagnosis of OSAHS by standard polysomnography were recruited from China Medical University Hospital Centre. There were 257 patients in the learning set and 279 patients in the validation set. The presence of OSAHS was defined as apnea-hypopnea index (AHI) > 5/h. Three kinds of oxyhemoglobin indexes, including the oxyhemoglobin desaturation index (ODI), time-domain index, and frequency-domain index, were used. Degrees of severity were AHI > 15/h and AHI > 30/h, representing moderate and severe OSAHS. A total of 28 oxyhemoglobin indexes were tested in our study. Among the three kinds of indexes, ODI had a better diagnostic performance than the time-domain and frequency-domain indexes, with the results coincident in the validation set and learning set. For predicting the severity of OSAHS with AHI > 15/h or > 30/h, the ODI clinically had the higher correlation with AHI than time-domain and frequency-domain indexes, with sensitivity/specificity achieving 84.0%/84.3% in AHI > 15/h and 87.8%/96.6% in AHI > 30/h, respectively. Based on the smaller SEE of the AHI, the ODI had a significantly smaller SEE than the time-domain and frequency-domain indexes. The ODI index provided a high level of diagnostic sensitivity and specificity at different degrees of OSAHS severity.
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To investigate the prevalence and behavior of sleep-related breathing disorders (SRBDs) associated with a first-ever stroke or transient ischemic attack (TIA), we prospectively studied 161 consecutive patients admitted to our stroke unit. Complete neurological assessment was performed to determine parenchymatous and vascular localization of the neurological lesion. Stroke subtype was categorized as TIA, ischemic (IS), or hemorrhagic (HS). A portable respiratory recording (PRR) study was performed within 48-72 h after admission (acute phase), and subsequently after 3 mo (stable phase). During the acute phase, 116 patients (71.4%) had an apnea-hypopnea index (AHI) > 10 events/h and 45 (28%) had an AHI > 30. No relationships were found between sleep-related respiratory events and the topographical parenchymatous location of the neurological lesion or vascular involvement. Cheyne-Stokes breathing (CSB) was observed in 42 cases (26.1%). There were no significant differences in SRBD according to the stroke subtype except for the central apnea index (CAI). During the stable phase a second PRR was performed in 86 patients: 53 of 86 had an AHI > 10 and 17 of 86 had an AHI > 30. The AHI and CAI were significantly lower than those in the acute phase (16.9 +/- 13.8 versus 22.4 +/- 17.3 and 3.3 +/- 7.6 versus 6.2 +/- 10.2, respectively) (p < 0.05) while the obstructive apnea index (OAI) remained unchanged. CSB was observed in 6 of 86 patients. The prevalence of SRBD in patients with first-ever stroke or TIA is higher than expected from the available epidemiological data in our country. No correlation was found between neurological location and the presence or type of SRBD. Obstructive events seem to be a condition prior to the neurological disease whereas central events and CSB could be its consequence.
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Pulse oximetry is a well-established tool routinely used in many settings of modern medicine to determine a patient's arterial oxygen saturation and heart rate. The decreasing size of pulse oximeters over recent years has broadened their spectrum of use. For diagnosis and treatment of sleep-disordered breathing, overnight pulse oximetry helps determine the severity of disease and is used as an economical means to detect sleep apnea. In this article, we outline the clinical utility and economical benefit of overnight pulse oximetry in sleep and breathing disorders in adults and highlight the controversies regarding its limitations as presented in published studies.
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Previous studies have suggested that the obstructive sleep apnea syndrome may be an important risk factor for stroke. It has not been determined, however, whether the syndrome is independently related to the risk of stroke or death from any cause after adjustment for other risk factors, including hypertension. In this observational cohort study, consecutive patients underwent polysomnography, and subsequent events (strokes and deaths) were verified. The diagnosis of the obstructive sleep apnea syndrome was based on an apnea-hypopnea index of 5 or higher (five or more events per hour); patients with an apnea-hypopnea index of less than 5 served as the comparison group. Proportional-hazards analysis was used to determine the independent effect of the obstructive sleep apnea syndrome on the composite outcome of stroke or death from any cause. Among 1022 enrolled patients, 697 (68 percent) had the obstructive sleep apnea syndrome. At baseline, the mean apnea-hypopnea index in the patients with the syndrome was 35, as compared with a mean apnea-hypopnea index of 2 in the comparison group. In an unadjusted analysis, the obstructive sleep apnea syndrome was associated with stroke or death from any cause (hazard ratio, 2.24; 95 percent confidence interval, 1.30 to 3.86; P=0.004). After adjustment for age, sex, race, smoking status, alcohol-consumption status, body-mass index, and the presence or absence of diabetes mellitus, hyperlipidemia, atrial fibrillation, and hypertension, the obstructive sleep apnea syndrome retained a statistically significant association with stroke or death (hazard ratio, 1.97; 95 percent confidence interval, 1.12 to 3.48; P=0.01). In a trend analysis, increased severity of sleep apnea at baseline was associated with an increased risk of the development of the composite end point (P=0.005). The obstructive sleep apnea syndrome significantly increases the risk of stroke or death from any cause, and the increase is independent of other risk factors, including hypertension.
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Study objectives: Obstructive sleep apnea (OSA) is an independent risk factor for stroke. The objective of this study was to assess the effect of continuous positive airway pressure (CPAP) treatment on prevention of new vascular events among patients with stroke and OSA. Methods: Consecutive conscious patients presenting with first imaging-confirmed arterial stroke were included, 6 weeks or more after ictus. All patients underwent clinical and polysomnography (PSG) testing. Patients with an apnea-hypopnea index (AHI) of > 15 events/h were randomized to posttitration nightly CPAP treatment and non-CPAP (received best medical treatment) groups. On follow-up at 3, 6, and 12 months from randomization, evaluation was carried out for any new vascular events as the primary outcome measure, and for clinical stroke outcomes (using the Barthel Index and modified Rankin scale) and neuropsychological parameters as the secondary outcome measures. Results: Among the 679 patients with stroke who were screened, 116 reported for PSG, 83 had AHI > 15 events/h, and 70 (34 in CPAP and 36 in non-CPAP) were randomized. Thirteen patients could not be randomized because of a lack of CPAP devices. Four patients crossed over from the CPAP to the non-CPAP group. Age (mean age 53.41 ± 9.85 in CPAP versus 52.69 ± 13.23 years in non-CPAP,P= .81) and sex distribution (24 males in CPAP versus 33 males in non-CPAP,P= .79) were similar in both groups. At 12-month follow-up, there was 1 vascular event (3.33%) in the CPAP group and 6 events (15%) in the non-CPAP group (P= .23). Modified Rankin scale score improvement by ≥ 1 at 12-month follow-up was found in significantly more patients in the CPAP group than in the non-CPAP group (53% versus 27%). Conclusions: These findings suggest significantly better stroke outcomes and statistically nonsignificant favorable outcomes in terms of recurrence of vascular events for patients with stroke and OSA who use CPAP treatment. Clinical trial registration: Registry: Clinical Trials Registry - India, CTRI Registration No: CTRI/2016/07.007104, Title: Sleep Disordered Breathing in stroke patients: Effect of treatment trial, URL: http://ctri.nic.in/Clinicaltrials/showallp.php?mid1=8682&EncHid=&userName=sleep%20disordered%20breathing.
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There is increasing awareness and interest in the complex and extensive inter-relationships between sleep disorders and neurological disorders. This review focuses on the clinical interactions between obstructive sleep apnoea and stroke, headaches, epilepsy, cognition and idiopathic Parkinson's disease. We highlight to the neurologist the importance of taking a sleep history and considering the diagnosis and treatment of obstructive sleep apnoea.
Article
Objectives: Obstructive sleep apnea (OSA) predicts poor functional outcome after stroke and increases the risk for recurrent stroke. Less is known about continuous positive airway pressure (CPAP) treatment on stroke recovery. Methods: In a pilot randomized, double-blind, sham-controlled trial, adult stroke rehabilitation patients were assigned to auto-titrating or sham CPAP without diagnostic testing for OSA. Change in Functional Independence Measure (FIM), a measure of disability, was assessed between rehabilitation admission and discharge. Results: Over 18 months, 40 patients were enrolled and 10 withdrew from the study: 7 from active and 3 from sham CPAP (p > 0.10). For the remaining 30 patients, median duration of CPAP use was 14 days. Average CPAP use was 3.7 h/night, with at least 4 h nightly use among 15 patients. Adherence was not influenced by treatment assignment or stroke severity. In intention-to-treat analyses (n = 40), the median change in FIM favored active-CPAP over sham but did not reach statistical significance (34 versus 26, p = 0.25), except for the cognitive component (6 versus 2.5, p = 0.04). The on-treatment analyses (n = 30) yielded similar results (total FIM: 32 versus 26, p = 0.11; cognitive FIM: 6 versus 2, p = 0.06). Conclusion: A sham-controlled CPAP trial among stroke rehabilitation patients was feasible in terms of recruitment, treatment without diagnostic testing and adequate blinding-though was limited by study retention and CPAP adherence. Despite these limitations, a trend towards a benefit of CPAP on recovery was evident. Tolerance and adherence must be improved before the full benefits of CPAP on recovery can be assessed in larger trials.
Article
Background: Reducing the need for diagnostic sleep studies for obstructive sleep apnea (OSA) would reduce direct and opportunity costs while expediting time to treatment for this common and morbid disorder. We sought to determine if an established sleep apnea screening questionnaire (STOP-BANG) and wrist-worn overnight oximetry data could provide high positive predictive value for the presence of OSA. Methods: We conducted a prospective observational study of consecutive unattended sleep study patients at a single facility. Patients were referred for sleep testing after chart review by a sleep physician. We assessed area under the receiver-operating characteristic curve (ROC AUC) and positive predictive value (PPV) of STOP-BANG score and oxygen desaturation index (ODI) for a respiratory disturbance index (RDI) ≥15/h. Results: Among 234 test patients, 65 % had an RDI ≥15/h. STOP-BANG had poor ability to discriminate these patients (ROC AUC 0.62). ODI added significant diagnostic information to the STOP-BANG score, increasing the ROC AUC to 0.86. Having the ODI, the STOP-BANG score no longer contributed significant diagnostic information, and the ODI alone discriminated as well as the combination (ROC AUC 0.86). Forty nine percent had an ODI ≥7/h, which had PPV of 92 % (95 % confidence interval (CI), 86 to 96 %). In the validation sample of 1,196 consecutive patients, ODI ≥ 7/h had a PPV of 97 % (95 % CI, 95 to 97 %). Conclusions: Among patients with a high prevalence of OSA, high ODI is common and its presence has high PPV for OSA. These data suggest that overnight oximetry prior to sleep testing could significantly reduce the number of patients requiring sleep studies, thereby reducing costs and time to treatment.
Article
To assess the presence of right-to-left shunting (RLS) in patients with obstructive sleep apnea (OSA), and compare clinical characteristics and parameters of the sleep studies of patients with and without RLS. The most common cause of RLS is due to intermittent flow through a patent foramen ovale (PFO). PFO occurs more frequently in patients with OSA and may be involved in the exacerbation of OSA. Patients with an abnormal polysomnogram seen at UCLA-Santa Monica Sleep Medicine Clinic were enrolled. A diagnosis of RLS was made using a transcranial Doppler (TCD) bubble study. Gender and age-matched controls were drawn from patients referred for cardiac catheterization who underwent a TCD. The frequency of RLS in OSA patients and the controls was evaluated. Clinical characteristics and polysomnogram parameters were compared between OSA patients with and without a RLS. A total of 100 OSA patients and 200 controls participated in the study. The prevalence of RLS was higher in patients with OSA compared to the control group (42% versus 19%; p < 0.0001). Patients with OSA and a RLS had a lower apnea-hypopnea index (AHI), less obstructive apnea, and fewer hypopnea episodes than patients with OSA without a RLS. The baseline and nadir SpO2 were similar in both groups and did not correlate with the level of RLS assessed by TCD. The degree of desaturation for a given respiratory disturbance, as measured by oxygen desaturation index (ODI)/ AHI ratio, was higher in OSA patients with RLS versus OSA patients without RLS (0.85±0.07 versus 0.68±0.04; p < 0.0001). RLS, most commonly due to a PFO, occurs 2.2 times more frequently in OSA patients compared to a control population that was matched for age and gender. The severity of sleep apnea is not greater in OSA patients who have a PFO. However, patients with OSA and a PFO are more likely to become symptomatic at a younger age with an equivalent decrease in nocturnal SpO2, and have greater arterial desaturation in proportion to the frequency of respiratory disturbances. Copyright © 2015 American Academy of Sleep Medicine. All rights reserved.
Article
The main purpose of the present analysis is to assess the influence of introducing early nasal continuous positive airway pressure (nCPAP) treatment on cardiovascular recurrences and mortality in patients with a first-ever ischaemic stroke and moderate-severe obstructive sleep apnea (OSA) with an apnea-hypopnea index (AHI) ≥20 events h(-1) during a 5-year follow-up. Patients received conventional treatment for stroke and were assigned randomly to the nCPAP group (n = 71) or the control group (n = 69). Cardiovascular events and mortality were registered for all patients. Survival and cardiovascular event-free survival analysis were performed after 5-year follow-up using the Kaplan-Meier test. Patients in the nCPAP group had significantly higher cardiovascular survival than the control group (100 versus 89.9%, log-rank test 5.887; P = 0.015) However, and also despite a positive tendency, there were no significant differences in the cardiovascular event-free survival at 68 months between the nCPAP and control groups (89.5 versus 75.4%, log-rank test 3.565; P = 0.059). Early nCPAP therapy has a positive effect on long-term survival in ischaemic stroke patients and moderate-severe OSA.
Article
The primary objective was to systematically review the literature on how sleep disordered breathing (SDB) affects recurrence and death among stroke or transient ischemic attack (TIA) patients. A secondary objective was to evaluate how treatment of SDB with continuous positive airway pressure (CPAP) affects the risk of recurrence and death in these patients. Adults (18+) with a stroke or TIA diagnosis were eligible for inclusion. Case groups consisted of patients with a sleep disorder. The outcomes of interest were all-cause mortality, recurrent vascular events, and case fatality. Ten articles covering 1,203 stroke and TIA patients were included in the review. The results generally support a dose-response relationship between severity of SDB and risk of recurrent events and all-cause mortality in stroke and TIA patients. Three small-scale articles with substantial risk of bias evaluated the effects of CPAP therapy, and the results are inconclusive. Data on case fatality is too sparse to be conclusive. Existing studies provide sufficient data to establish obstructive SDB as a negative predictor of all-cause mortality and recurrent vascular events following stroke or TIA. The ability of CPAP treatment to lower the risk of serious adverse outcomes after stroke remains controversial because of substantial risk of bias identified in most of the eligible studies addressing this relation. Additional studies are needed. Birkbak J; Clark AJ; Rod NH. The effect of sleep disordered breathing on the outcome of stroke and transient ischemic attack: a systematic review. J Clin Sleep Med 2014;10(1):103-108.
Article
Sleep-disordered breathing is a common disorder with a range of harmful sequelae. Obesity is a strong causal factor for sleep-disordered breathing, and because of the ongoing obesity epidemic, previous estimates of sleep-disordered breathing prevalence require updating. We estimated the prevalence of sleep-disordered breathing in the United States for the periods of 1988-1994 and 2007-2010 using data from the Wisconsin Sleep Cohort Study, an ongoing community-based study that was established in 1988 with participants randomly selected from an employed population of Wisconsin adults. A total of 1,520 participants who were 30-70 years of age had baseline polysomnography studies to assess the presence of sleep-disordered breathing. Participants were invited for repeat studies at 4-year intervals. The prevalence of sleep-disordered breathing was modeled as a function of age, sex, and body mass index, and estimates were extrapolated to US body mass index distributions estimated using data from the National Health and Nutrition Examination Survey. The current prevalence estimates of moderate to severe sleep-disordered breathing (apnea-hypopnea index, measured as events/hour, ≥15) are 10% (95% confidence interval (CI): 7, 12) among 30-49-year-old men; 17% (95% CI: 15, 21) among 50-70-year-old men; 3% (95% CI: 2, 4) among 30-49-year-old women; and 9% (95% CI: 7, 11) among 50-70 year-old women. These estimated prevalence rates represent substantial increases over the last 2 decades (relative increases of between 14% and 55% depending on the subgroup).
Article
Background: The relationship between obstructive sleep apnea (OSA) and cardiovascular events remains unclear. We conducted a systematic review to determine the incident risk of cardiovascular events among patients with OSA. Methods and results: We searched MEDLINE and EMBASE in January 2011 for prospective studies that followed up patients with OSA for incident ischemic heart disease, stroke, and cardiovascular mortality. Outcomes data were pooled using random effects meta-analysis and heterogeneity assessed with the I(2) statistic. Regression analysis was performed to evaluate the effects of different gradations of OSA severity based on apnea-hypopnea index. We identified 9 relevant studies from 1731 citations. OSA was associated with incident stroke in a meta-analysis of 5 studies (8435 participants), odds ratio (OR) 2.24; 95% confidence interval (CI), 1.57-3.19; I(2)=7%. A significant association was seen in studies that were predominantly on men; OR, 2.87; 95% CI, 1.91-4.31, whereas data on women were sparse. In the overall analysis of 6 studies (8785 participants), OSA was nonsignificantly associated with ischemic heart disease (OR, 1.56; 95% CI, 0.83-2.91), with significant findings in the 5 studies that recruited mainly men (OR, 1.92; 95% CI, 1.06-3.48). Substantial heterogeneity was noted (I(2)=74%). OSA was linked to cardiovascular death in 2 studies involving 2446 participants (OR, 2.09; 95% CI, 1.20-3.65, I(2)=0%). Regression analysis showed greater likelihood of stroke or cardiovascular events with increasing apnea-hypopnea index values. Conclusions: OSA appears to be associated with stroke, but the relationship with ischemic heart disease and cardiovascular mortality needs further research.
Article
Sleep apnea syndrome (SAS) is a common sleep disorder in stroke patients and is associated with decreased recovery and increased risk of recurrent stroke and mortality. The standard diagnostic test for SAS is poly(somno)graphy, but this is often not feasible in stroke rehabilitation settings. This study investigated the diagnostic value of nocturnal oximetry for screening SAS in stroke rehabilitation. Fifty-six stroke patients underwent nocturnal polygraphy and oximetry. Sensitivity, specificity, and positive and negative predictive values for the oxygen desaturation index were calculated. Patient and sleep characteristics were used to develop a predictive model of apnea-hypopnea index. Forty-six percent of the stroke patients had SAS. The majority of SAS patients was male, older, and had a higher body mass index than patients without SAS. Sensitivity, specificity, and positive and negative predictive values for the oxygen desaturation index ≥15 were, respectively, 77%, 100%, 100%, and 83%. Oxygen desaturation index predicted 87% of the variance in the apnea-hypopnea index. Patient characteristics did not add significantly to the prediction model. Nocturnal oximetry is an accurate diagnostic screening instrument for the detection of SAS in stroke patients.
Article
Background: Polysomnography (PSG) is currently the standard diagnostic procedure for sleep apnoea. This study evaluates the diagnostic accuracy of a portable recording device, ApneaLink (AL; ResMed, Poway, CA, USA) for detection of sleep apnoea in comparisons against PSG. Methods: The AL device is a three-channel screening tool that measures airflow through a nasal pressure transducer, oximetry and pulse, providing an apnoea–hypopnoea index (AHI) based on recording time. Nocturnal PSG (Alice 4; Healthdyne, Atlanta, GA, USA), with airflow measured by a nasal pressure transducer (ProTech PTAF2; ProTech, Woodinville, WA, USA) and AL recordings were carried out simultaneously in consecutive patients with suspected obstructive sleep apnoea syndrome (OSAS). The PSG recordings were analysed manually by a blinded investigator. The oxygen desaturation index of AL was also compared against the AHI based on PSG. Results: Fifty consecutive subjects with symptoms of OSAS were recruited with mean age of 50 years and body mass index of 27.9 kg/m2. The AHI obtained by the AL device correlated closely to that obtained by PSG (Pearson correlation, r= 0.978, P < 0.001), whereas the correlation between PSG AHI and oxygen desaturation index by AL was also strong (r= 0.895, P < 0.001). Comparison of AHI based on the AL against the PSG demonstrated high sensitivity and specificity at AHI ≥10/h (sensitivity 0.977 and specificity 1.0) and at AHI ≥20/h (sensitivity 0.969 and specificity 1.0). Conclusion: The AL portable monitoring device is highly sensitive and specific in quantifying the apnoea–hypopnoea index when compared against hospital based polysomnography in patients with suspected OSAS. The simple device may be useful for screening and diagnostic purpose when access to PSG is limited.
Article
Continuous positive airway pressure (CPAP) is the first-line treatment for patients with symptomatic obstructive sleep apnea (OSA). However, its indication for all patients with sleep-disordered breathing, regardless of daytime symptoms, is unclear. To evaluate the effect of CPAP treatment on the incidence of hypertension or cardiovascular events in a cohort of nonsleepy patients with OSA. Multicenter, parallel-group, randomized controlled trial in 14 teaching hospitals in Spain. Between May 2004 and May 2006, 725 consecutive patients were enrolled who had an apnea-hypopnea index of 20 h(-1) or greater and an Epworth Sleepiness Scale score of 10 or less (scores range from 0-24, with values <10 suggesting no daytime sleepiness). Exclusion criteria were previous cardiovascular event, physical or psychological incapacity, chronic disease, or drug or alcohol addiction. Follow-up ended in May 2009. Patients were allocated to receive CPAP treatment or no active intervention. All participants received dietary counseling and sleep hygiene advice. Incidence of either systemic hypertension (taking antihypertensive medication or blood pressure greater than 140/90 mm Hg) or cardiovascular event (nonfatal myocardial infarction, nonfatal stroke, transient ischemic attack, hospitalization for unstable angina or arrhythmia, heart failure, or cardiovascular death). Seven hundred twenty-three patients underwent follow-up for a median of 4 (interquartile range, 2.7-4.4) years (1 patient from each group did not receive allocated treatment); 357 in the CPAP group and 366 in the control group were included in the analysis. In the CPAP group there were 68 patients with new hypertension and 28 cardiovascular events (17 unstable angina or arrhythmia, 3 nonfatal stroke, 3 heart failure, 2 nonfatal myocardial infarction, 2 transient ischemic attack, 1 cardiovascular death). In the control group there were 79 patients with new hypertension and 31 cardiovascular events (11 unstable angina or arrhythmia, 8 nonfatal myocardial infarction, 5 transient ischemic attack, 5 heart failure, 2 nonfatal stroke). The hypertension or cardiovascular event incidence density rate was 9.20 per 100 person-years (95% CI, 7.36-11.04) in the CPAP group and 11.02 per 100 person-years (95% CI, 8.96-13.08) in the control group. The incidence density ratio was 0.83 (95% CI, 0.63-1.1; P = .20). In patients with OSA without daytime sleepiness, the prescription of CPAP compared with usual care did not result in a statistically significant reduction in the incidence of hypertension or cardiovascular events. However, the study may have had limited power to detect a significant difference. clinicaltrials.gov Identifier: NCT00127348.
Article
It is impractical to perform polysomnography (PSG) in all surgical patients suspected of having sleep disordered breathing (SDB). We investigated the role of nocturnal oximetry in diagnosing SDB in surgical patients. All patients 18 years and older who visited the preoperative clinics for scheduled inpatient surgery were approached for study participation. Patients expected to have abnormal electroencephalographic findings were excluded. All patients underwent an overnight PSG at home with a portable device and a pulse oximeter. The PSG recordings were scored by a certified sleep technologist. The oximetry recordings were processed electronically. Four hundred seventy-five patients completed the study: 217 males and 258 females, aged 60 ± 11 years, and body mass index 31 ± 7 kg/m(2). The apnea-hypopnea index (AHI), the average number of episodes of apnea and hypopnea per hour of sleep, was 9.1 (2.8 to 21.4) [median (interquartile range)] and 64% patients had AHI >5. There was a significant correlation between oxygen desaturation index (ODI, hourly average number of desaturation episodes) and cumulative time percentage with SpO(2) <90% (CT90) from nocturnal oximetry, with the parameters measuring sleep breathing disorders from PSG. Compared to CT90, ODI had a stronger correlation and was a better predictor for AHI. The area under receiver operator characteristics curve for ODI to predict AHI >5, AHI >15, and AHI >30 was 0.908 (CI: 0.880 to 0.936), 0.931 (CI: 0.090 to 0.952), and 0.958 (CI: 0.937 to 0.979), respectively. The cutoff value based on the maximal accuracy for ODI to predict AHI >5, AHI >15, and AHI >30 was ODI >5, ODI >15, and ODI >30. The accuracy was 86% (CI: 83%-88%), 86% (CI: 83%-89%), and 94% (CI: 92%-96%), respectively. The ODI >10 demonstrated a sensitivity of 93% and a specificity of 75% to detect moderate and severe SDB. ODI from a high-resolution nocturnal oximeter is a sensitive and specific tool to detect undiagnosed SDB in surgical patients.
Article
Sleep apnea (SA) is common in stroke patients and is associated with poor functional outcome. Therefore, we studied the clinical value of the Berlin Questionnaire (BQ), a subjective screening method to detect stroke patients with SA in a neurorehabilitation care unit, and compared it with respirographic sleep studies. Another aim was to explore the association of SA with functional status in the subacute phase after stroke. Sixty-eight stroke patients were subjected to respirographic sleep studies to determine their apnea-hypopnea index (AHI). Subjective evaluation was performed by means of the BQ. Functional outcome was assessed by the Barthel Index (BI). Sensitivity and specificity of the BQ for detecting SA in stroke patients were calculated. Respirographic sleep studies showed a high prevalence of moderate and severe sleep apnea in 56% of stroke patients. Sensitivity and specificity of the BQ for SA (AHI ≯ 15) were 0.69 and 0.15, respectively. The area under the receiver operating characteristics (ROC) curve for detection of SA was 0.58. The AHI correlated significantly with the BI (r = -0.57, P ≤ .001). As the BQ demonstrated low diagnostic utility in stroke rehabilitation, screening for SA should not be based solely on clinical interviews. SA is linked to poor functional status in the subacute phase post stroke.
Article
Obstructive sleep apnoea (OSA) is a risk factor for stroke, but little is known about the effect of OSA and continuous positive airway pressure (CPAP) on the incidence of long-term, nonfatal cardiovascular events (CVE) in stroke patients. A prospective observational study was made in 223 patients consecutively admitted for stroke. A sleep study was performed on 166 of them. 31 had an apnoea/hypopnoea index (AHI) <10 events · h(-1); 39 had an AHI between 10 and 19 events · h(-1) and 96 had an AHI ≥ 20 events · h(-1). CPAP treatment was offered when AHI was ≥ 20 events · h(-1). Patients were followed up for 7 yrs and incident CVE data were recorded. The mean ± SD age of the subjects was 73.3 ± 11 yrs; mean AHI was 26 ± 16.7 events · h(-1). Patients with moderate-to-severe OSA who could not tolerate CPAP (AHI ≥ 20 events · h(-1); n = 68) showed an increased adjusted incidence of nonfatal CVE, especially new ischaemic strokes (hazard ratio 2.87, 95% CI 1.11-7.71; p = 0.03), compared with patients with moderate-to-severe OSA who tolerated CPAP (n = 28), patients with mild disease (AHI 10-19 events · h(-1); n = 36) and patients without OSA (AHI <10 events · h(-1); n = 31). Our results suggest that the presence of moderate-to-severe OSA is associated with an increased long-term incidence of nonfatal CVE in stroke patients and that CPAP reduces the excess of incidence seen in these patients.
Article
The association between obstructive sleep apnea (OSA) and atrial fibrillation (AF) is strong and is now well established. However, studies on the role of OSA on AF recurrence after catheter ablation have yielded conflicting results. The aim of the present study was to investigate the role of OSA on AF recurrence after catheter-based pulmonary vein isolation. We performed a data search on the PubMed, Web of Science, and the Cochrane databases for studies published by August 2010. In addition, we manually searched the conference proceedings of the European Society of Cardiology, American College of Cardiology, and American Heart Association for related abstracts. After the initial search returned 402 reports, we identified 6 studies with a total of 3,995 patients that met our inclusion criteria. Overall, patients with OSA have a 25% greater risk of AF recurrence after catheter ablation than those without OSA (risk ratio 1.25, 95% confidence interval 1.08 to 1.45, p = 0.003). Subgroup analysis showed that OSA diagnosed using polysomnography is a strong predictor of AF recurrence (risk ratio 1.40, 95% confidence interval 1.16 to 1.68, p = 0.0004) but not when OSA was diagnosed using the Berlin questionnaire (risk ratio 1.07, 95% confidence interval 0.91 to 1.27, p = 0.39). In conclusion, patients with OSA have significantly greater AF recurrence rates after pulmonary vein isolation. In addition to other factors, a diagnosis of OSA merits special consideration when evaluating patients for catheter-based AF ablation.
Article
Given the high prevalence of sleep-disordered breathing (SDB) in stroke and its importance as a vascular risk factor, a clinical instrument to assess its incidence would be useful. Acute stroke patients (n=121) were stratified into high- and low-risk groups for SDB using a modified Berlin Questionnaire (BQ) administered to the informants who were living with the patient. After a minimum of 4 weeks from stroke onset, patients who were fit underwent overnight polysomnography (PSG). On stratifying risk of obstructive sleep apnea (OSA) in these patients based on the BQ, 53% belonged to the high-risk group and 47% belonged to the low-risk group. There was poor correlation between the clinical questionnaire results and PSG findings, with sensitivity of 66.7%, specificity of 55.6%, a positive predictive value of 63.4%, and a negative predictive value of 58.8%.
Article
OSA is a common condition associated with cardiovascular (CV) morbidity. It remains underdiagnosed globally in part due to the limited availability and technical requirements of polysomnography (PSG). The aim of this study was to test the accuracy of two simple methods for diagnosing OSA. Consecutive subjects identified from a community register with high CV risk were invited to complete the Berlin Sleep Questionnaire and undergo simultaneous, home, overnight PSG and ApneaLink device oximetry and nasal pressure recordings. The relative accuracies of the Berlin Questionnaire, oximetry and nasal pressure results in diagnosing PSG-defined moderate-severe OSA were assessed. Of 257 eligible high CV risk subjects enrolled, 190 completed sleep studies and 143 subjects' studies were of sufficient quality to include in final analyses. Moderate-severe OSA was confirmed in 43% of subjects. The Berlin Questionnaire had low overall diagnostic accuracy in this population. However, ApneaLink recordings of oximetry and nasal pressure areas had high diagnostic utility with areas under the receiver operating characteristic curves of 0.933 and 0.933, respectively. At optimal diagnostic thresholds, oximetry and nasal pressure measurements had similar sensitivity (84% vs 86%) and specificity (84% vs 85%). Technical failure was lower for oximetry than nasal pressure (5.8% vs 18.9% of tests). In patients with high CV risk overnight single-channel oximetry and nasal pressure measurements may provide high diagnostic accuracy and offer an accessible alternative to full PSG.
Article
Early deterioration can occur after acute stroke for a variety of reasons. We describe a hemodynamic steal and associated neurological deterioration, the reversed Robin Hood syndrome (RRHS). We aimed to investigate the frequency and factors associated with RRHS. Consecutive patients with acute cerebral ischemia underwent serial National Institutes of Health Stroke Scale and bilateral transcranial Doppler monitoring with breathholding. Steal magnitude (%) was calculated from transient mean flow velocity reduction in the affected arteries at the time of velocity increase in normal vessels. Excessive sleepiness and likelihood of sleep apnea were evaluated by the Epworth Sleepiness Scale and Berlin Questionnaire. Among 153 patients (age, 61+/-14 years; 48% women; 21% transient ischemic attack) admitted within 48 hours from symptom onset, 21 (14%) had steal phenomenon (median steal magnitude, 20%; interquartile range, 11%; range, 6% to 45%), and 11 (7%) had RRHS. RRHS was most frequent in patients with proximal arterial occlusions (17% versus 1%; P<0.001). The following factors were independently (P<0.05) associated with RRHS (multivariate logistic regression model): male gender, younger age, persisting arterial occlusions, and excessive sleepiness (P<0.001). A 1-point increase in the Epworth Sleepiness Scale was independently related to an increased likelihood of RRHS of 36% (95% CI, 7% to 73%). RRHS and hemodynamic steal can be found in 7% and 14%, respectively, of consecutive patients with stroke without other known causes for deterioration. Patients with persisting arterial occlusions and excessive sleepiness can be particularly vulnerable to the steal.
Article
Obstructive sleep apnea (OSA) is an independent risk factor for stroke, but little is known about the role of continuous positive airway pressure (CPAP) on mortality in patients with stroke. To analyze the independent impact of long-term CPAP treatment on mortality in patients with ischemic stroke. Prospective observational study in 166 patients with ischemic stroke. Sleep study was performed in all of them and CPAP treatment was offered in the case of moderate to severe cases. Patients were followed-up for 5 years to analyze the risk of mortality. Of 223 patients consecutively admitted for stroke, a sleep study was performed on 166 of them (2 mo after the acute event). Thirty-one had an apnea-hypopnea index (AHI) of less than 10; 39 had an AHI between 10 and 19, and 96 had an AHI of 20 or greater. CPAP treatment was offered when AHI was 20 or greater. Patients were followed up in our outpatient clinic at 1, 3, and 6 months, and for every 6 months thereafter for 5 years (prospective observational study). Mortality data were recorded from our computer database and official death certificates. The mean age of subjects was 73.3 +/- 11 years (59% males), and the mean AHI was 26 (for all patients with a predominance of obstructive events). Patients with an AHI of 20 or greater who did not tolerate CPAP (n = 68) showed an increase adjusted risk of mortality (hazards ratio [HR], 2.69; 95% confidence interval [CI], 1.32-5.61) compared with patients with an AHI of less than 20 (n = 70), and an increased adjusted risk of mortality (HR, 1.58; 95% CI, 1.01-2.49; P = 0.04) compared with patients with moderate to severe OSA who tolerated CPAP (n = 28). There were no differences in mortality among patients without OSA, patients with mild disease, and patients who tolerated CPAP. Our results suggest that long-term CPAP treatment in moderate to severe OSA and ischemic stroke is associated with a reduction in excess risk of mortality.
Article
Sleep-disordered breathing (SDB) is more prevalent in stroke patients than age- and sex-matched controls, but the relationship between SDB and functional outcome of stroke patients is unclear. The aim of our study was to determine the prevalence of SDB in ischemic stroke and its influence on functional outcome at 3 and 6 months after stroke onset. In a prospective study, 60 patients were selected by polysomnography (PSG). The apnea-hypopnea index (AHI) was determined 6.5+/-3.2 days after stroke onset. Neurologic severity at admission was assessed by the Scandinavian Stroke Scale (SSS) and outcome by the Barthel Index (BI). Patients were evaluated on admission, 3 and 6 months after stroke onset. Among the 60 patients, 39 (65%) patients had SDB (AHI5); of these, 30 patients (50%) had AHI15 and 18 (30%)>30. On Logistic regression analysis, the BI at 3 months was independently predicted by SSS (OR=0.74, 95% CI [0.62-0.88], P=0.001) and AHI (OR=1.09, 95% CI [1.02-1.17], P<0.05). At 6 months, the BI was predicted only by SSS (OR=0.83, 95% CI [0.74-0.92], P=0.001). SDB is common in patients during acute phase after stroke onset. SDB appears to be associated with a worse functional outcome during the early recovery period following stroke, increasing the likelihood of dependency.
Article
The effect of sleep apnea on mortality and cardiovascular morbidity is mainly unknown. We aimed to study whether sleep apnea is related to stroke, death, or myocardial infarction in patients with symptomatic coronary artery disease. A total of 392 men and women with coronary artery disease referred for coronary angiography were examined by use of overnight sleep apnea recordings. Sleep apnea, defined as an apnea-hypopnea index >or=5, was recorded in 54% of the patients. All patients were followed up prospectively for 10 years, and no one was lost to follow-up. Stroke occurred in 47 (12%) of 392 patients during follow-up. Sleep apnea was associated with an increased risk of stroke, with an adjusted hazard ratio of 2.89 (95% confidence interval 1.37 to 6.09, P=0.005), independent of age, body mass index, left ventricular function, diabetes mellitus, gender, intervention, hypertension, atrial fibrillation, a previous stroke or transient ischemic attack, and smoking. Patients with an apnea-hypopnea index of 5 to 15 and patients with an apnea-hypopnea index >or=15 had a 2.44 (95% confidence interval 1.08 to 5.52) and 3.56 (95% confidence interval 1.56 to 8.16) times increased risk of stroke, respectively, than patients without sleep apnea, independent of confounders (P for trend=0.011). Death and myocardial infarction were not related to sleep apnea. Intervention in the form of coronary artery bypass grafting or percutaneous coronary intervention was related to a longer survival but did not affect the incidence of stroke. Sleep apnea is significantly associated with the risk of stroke among patients with coronary artery disease who are being evaluated for coronary intervention.
Article
s: To compare the relative usefulness of the different indexes derived from pulse oximetry in the diagnosis of obstructive sleep apnea (OSA), and to determine if a combination of these indexes improves the prediction of the apnea-hypopnea index (AHI) measured by polysomnography. Prediction model developed from 224 patients, validated prospectively in 101 patients from the same center (group 1) and in 191 patients from a different sleep center (group 2). Two independent sleep clinics run by university sleep specialists. Patients who underwent polysomnography for suspicion of OSA. The following indexes were calculated from pulse oximetry recordings performed simultaneously during polysomnography: (1) Delta index, the average of the absolute differences of oxygen saturation between successive 12-s intervals; (2) desaturation events per hour to 2%, 3%, and 4% levels; and (3) cumulative time spent below 90%, 88%, 86%, 84%, 82%, and 80% saturation. The best predictor was the Delta index, although desaturation events provided similar levels of diagnostic accuracy. An aggregation of multivariate models using combination of indexes reduced the prediction error (r(2) = 0.70) significantly (p < 0.05) compared to using the Delta index alone (r(2) = 0.60). The proportion of subjects from the validation groups within 95% confidence interval (CI) of the derivation group was 90% (95% CI, 83 to 95%) and 91% (95% CI, 86 to 95%) for groups 1 and 2, respectively. The overall likelihood ratios for the aggregated model in all patient groups were 4.2 (95% CI, 3.3 to 15.3), 3.4 (95% CI, 2.7 to 4.3), 3.0 (95% CI, 2.2 to 4.1), and 6.7 (95% CI, 4.9 to 9.2) for normal (AHI < 5/h), mild (AHI 5 to < 15/h), moderate (AHI 15 to < 30/h), and severe (AHI > or = 30/h) disease, respectively. The Delta index and oxygen desaturation indexes provided similar levels of diagnostic accuracy. The combination of indexes improved the precision of the predicted AHI and may offer a potentially simpler alternative to polysomnography.
Article
The concept of sleep apnea as a risk factor for primary stroke derives mainly from evidence implicating sleep-disordered breathing (SDB) in the causation or aggravation of systemic hypertension and heart disease. Evidence of an association between SDB and sustained systemic hypertension is available from several large studies, though the exact mechanism involved is unknown. Another study found a 37% increase in risk of developing cardiovascular disease among middle-aged men attending a sleep clinic. The same study also found that treatment of SDB reduced the cardiovascular risk. Other mechanisms less well studied linking SDB with cerebrovascular risk include reduction in cerebral blood flow, altered cerebral autoregulation, impaired endothelial function, and accelerated proinflammatory states.
Article
Objectives: Nocturnal pulse oximetry is a widely used alternative to polysomnography (PSG) in screening for obstructive sleep apnea (OSA) syndrome. Several oximetric indexes have been derived from nocturnal blood oxygen saturation (SaO2). However, they suffer from several limitations. The present study is focused on the usefulness of nonlinear methods in deriving new measures from oximetry signals to improve the diagnostic accuracy of classical oximetric indexes. Specifically, we assessed the validity of central tendency measure (CTM) as a screening test for OSA in patients clinically suspected of suffering from this disease. Materials and methods: We studied 187 subjects suspected of suffering from OSA referred to the sleep unit. A nocturnal pulse oximetry study was applied simultaneously to a conventional PSG. Three different index groups were compared. The first one was composed by classical indexes provided by our oximeter: oxygen desaturation indexes (ODIs) and cumulative time spent below a saturation of 90% (CT90). The second one was formed by indexes derived from a nonlinear method previously studied by our group: approximate entropy (ApEn). The last one was composed by indexes derived from a CTM analysis. Results: For a radius in the scatter plot equal to 1, CTM values corresponding to OSA positive patients (0.30+/-0.20, mean+/-S.D.) were significantly lower (p<0.001) than those values from OSA negative subjects (0.71+/-0.18, mean+/-S.D.). CTM was significantly correlated with classical indexes and indexes from ApEn analysis. CTM provided the highest correlation with the apnea-hipopnea index AHI (r=-0.74, p<0.0001). Moreover, it reached the best results from the receiver operating characteristics (ROC) curve analysis, with 90.1% sensitivity, 82.9% specificity, 88.5% positive predictive value, 85.1% negative predictive value, 87.2% accuracy and an area under the ROC curve of 0.924. Finally, the AHI derived from the quadratic regression curve for the CTM showed better agreement with the AHI from PSG than classical and ApEn derived indexes. Conclusion: The results suggest that CTM could improve the diagnostic ability of SaO2 signals recorded from portable monitoring. CTM could be a useful tool for physicians in the diagnosis of OSA syndrome.
Spectral Analysis of Overnight Pulse Oximetry Recordings in Sleep Studies
  • B Schultheiß
  • A Jozefiak-Wesolowska
  • N Böhning
  • E Schmittendorf
Schultheiß B, Jozefiak-Wesolowska A, Böhning N, Schmittendorf E. Spectral Analysis of Overnight Pulse Oximetry Recordings in Sleep Studies. In: Vander Sloten J, Verdonck P, Nyssen M, Haueisen J, eds. 4th European Conference of the International Federation for Medical and Biological Engineering. IFMBE Proceedings, vol 22. Berlin, Heidelberg: Springer; 2009.
The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications. Version 2.5
  • R B Berry
  • C L Albertario
  • S M Harding
Berry RB, Albertario CL, Harding SM, et al.; for the American Academy of Sleep Medicine. The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications. Version 2.5. Darien, IL: American Academy of Sleep Medicine; 2018.