Clinical diagnosis of sleep apnea based on single night of polysomnography vs. two nights of polysomnography

Sleep Research Unit, Toronto Western Research Institute, University Health Network, ON, Canada.
Sleep And Breathing (Impact Factor: 2.48). 08/2009; 13(3):221-6. DOI: 10.1007/s11325-008-0234-2
Source: PubMed


The purpose of this study was to investigate apnea-hypopnea index (AHI) across two polysomnographies (PSGs) to examine AHI variability and impact on clinical diagnosis.
Two-night PSGs of 193 sleep clinic patients were reviewed, and the AHI variability was analyzed. Anonymized records from five patients with significant night-to-night AHI variability were used in this study: the two-night PSGs from two patients were represented as four individual PSGs; the two-night PSG for two others were represented as being obtained from two different sleep clinics; the last patient's PSG was shown as a two-night study. Twenty-two sleep experts attending the Associated Professional Sleep Societies meeting were recruited to make diagnoses based on the PSGs. They were told that the PSGs were from seven patients: four with single-night PSG; two with two PSGs, each one from a different clinic; and one patient with a two-night PSG.
Twenty-one percent of the 193 sleep clinic patients had a nightly PSG AHI variability of greater than 5. Forty-eight percent of all patients had a significantly higher AHI on the first night, and 41% had a significantly higher AHI on the second night. Using an AHI > 15 diagnostic criteria, sleep apnea would have been undetected in 20% (n = 39) of patients due to low AHI on one night. Furthermore, 13% of all patients had a more severe sleep apnea classification based on the second night of PSG. For the seven cases, 27-36% of sleep experts failed to identify sleep apnea especially when presented with the PSG containing the lower AHI. Incidences of missed sleep apnea diagnoses were reduced to 15-18% when information from two PSGs was presented to the sleep experts.
Utilizing a large patient population, this study supports the significant night-to-night variability in PSG respiratory variables. Identification of sleep apnea in some patients is reduced when sleep experts are provided with only one PSG recording. The clinical implication is that about 13% of sleep clinic patients might benefit from a second night of PSG.

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Available from: Gilla Shapiro, Oct 15, 2014
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    • "What factors might have moderated the return of OSA in the present study? An apparent improvement in OSA might merely reflect the known inter-night variability of OSA, which may lead to misclassification at low ranges of AHI91011. This inherent variability is unlikely to account for the marked attenuation seen in severe OSA. "
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    ABSTRACT: Background: Obstructive Sleep Apnea (OSA) describes intermittent collapse of the airway during sleep, for which continuous positive airway pressure (CPAP) is often prescribed for treatment. Prior studies suggest that discontinuation of CPAP leads to a gradual, rather than immediate return of baseline severity of OSA. The objective of this study was to determine the extent of OSA recurrence during short intervals of CPAP depressurization during sleep. Methods: Nine obese (BMI = 40.4 ± 3.5) subjects with severe OSA (AHI = 88.9 ± 6.8) adherent to CPAP were studied during one night in the sleep laboratory. Nasal CPAP was delivered at therapeutic (11.1 ± 0.6 cm H20) or atmospheric pressure, in alternating fashion for 1-hour periods during the night. We compared sleep architecture and metrics of OSA during CPAP-on and CPAP-off periods. Results: 8/9 subjects tolerated CPAP withdrawal. The average AHI during CPAP-on and CPAP-off periods was 3.6 ± 0.6 and 15.8 ± 3.6 respectively (p<0.05). The average 3% ODI during CPAP-on and CPAP-off was 4.7 ± 2 and 20.4 ± 4.7 respectively (p<0.05). CPAP depressurization also induced more awake (p<0.05) and stage N1 (p<0.01) sleep, and less stage REM (p<0.05) with a trend towards decreased stage N3 (p = 0.064). Conclusion: Acute intermittent depressurization of CPAP during sleep led to deterioration of sleep architecture but only partial re-emergence of OSA. These observations suggest carryover effects of CPAP.
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    • "Obstructive sleep apnea-hypopnea syndrome (OSAHS) is the coexistence of excessive daytime sleepiness and obstructive sleep-disordered breathing. It is more prevalent than asthma and diabetes mellitus in adults (Ahmadi et al., 2009). OSAHS is associated with several cardiovascular diseases including arterial hypertension, acute myocardial infarction, and stroke, and increases cardiovascular mortality and morbidity (Yaggi et al., 2005). "
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    ABSTRACT: Published data on a possible association between the angiotensin-converting enzyme (ACE) gene I/D polymorphism and obstructive sleep apnea-hypopnea syndrome (OSAHS) occurrence and its severity risk are inconclusive. We performed a meta-analysis of case-control studies published in English or Chinese. Thirteen studies, totaling 1361 cases and 1373 controls, were investigated for association of the ACE I/D polymorphism with OSAHS. We also made a study of ACE I/D with OSAHS severity risk, including 879 mild/moderate OSAHS patients and 357 severe OSAHS patients. A random-effects model was used, irrespective of between-study heterogeneity. Study quality was assessed in duplicate. Overall, the ACE I/D polymorphism was not significantly associated with an increase in OSAHS risk [odds ratio (OR) = 1.21; 95% confidence interval (95%CI) = 0.88-1.65; P = 0.24]. In subgroup analysis by ethnicity, comparison of alleles I with D demonstrated a 58% (nonsignificantly) increased risk for OSAHS in Chinese (OR = 1.58; 95%CI = 0.92-2.70; P = 0.09). We also found that there was no significant association between ACE I/D and OSAHS severity risk. No publication biases were observed. This meta-analysis suggests that there is no significantly increased risk for OSAHS occurrence or severity associated with the ACE I/D polymorphism.
    Preview · Article · Jan 2013 · Genetics and molecular research: GMR
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    • "Obstructive sleep apnea syndrome (OSAS) is characterized by repetitive episodes of upper respiratory tract obstruction during sleep and frequent decrease in arterial oxygen saturation , and its prevalence in a community is determined to be 3.9% among men and 1.2% among women at ages of 20 to 100 years. It is reported to be a disease that is more prevalent than asthma and diabetes mellitus among adults (Ursava and Ege, 2003; Yavuz et al., 2008; Ahmadi et al., 2009). Among patients with OSAS, there is an increased incidence of various cardiovascular diseases including hypertension, stroke, acute myocardial infarct, and arrhythmia complications, and it has been shown to be related to cardiovascular mortality-morbidity rate (Barceló et al., 2001; Yaggi et al., 2005). "
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    ABSTRACT: Angiotensin-converting enzyme (ACE) is a vital enzyme in the renin-angiotensin-aldosterone system, and there are reports in the literature describing its role in the development of cardiovascular system diseases, with I/D polymorphism of the ACE gene. We examined the relationship between a patient group with obstructive sleep apnea syndrome (OSAS) and a control group in terms of I/D polymorphism of the ACE gene. We examined 64 patients, with 37 individuals serving as the control group. PCR was used to detect ACE I/D gene polymorphism. Genotype was determined according to the bands that formed on agarose gel electrophoresis. Among the 64 OSAS patients, 27 were identified with the ID genotype, 27 with the DD genotype and 10 with the II genotype; among the 37 control subjects, 19 were identified with the ID genotype, 11 with the DD genotype and 7 with the II genotype. When the case group and controls were compared in terms of ID, II and DD genotypes, no significant difference was observed. On the other hand, when the two groups were compared with respect to mean body mass index, the OSAS group was found to be significantly different from the control group (P = 0.009). We conclude that ACE I/D gene polymorphism is not a genetic risk factor for OSAS in Turkish patients.
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