Fat accumulation, leptin, and hypercapnia in obstructive sleep apnea-hypopnea syndrome
Department of Respirology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuou-ku, Chiba 260-8670, Japan. Chest
(Impact Factor: 7.48).
02/2005; 127(2):543-9. DOI: 10.1378/chest.127.2.543
Obesity and visceral fat accumulation (VFA) are risk factors for the development of obstructive sleep apnea-hypopnea syndrome (OSAHS), and a subgroup of OSAHS patients acquire hypoventilation. Circulating leptin, an adipocyte-derived signaling factor, increases in accordance with body mass index (BMI); under experimental conditions, leptin selectively decreases visceral adiposity and it is also a respiratory stimulant.
To investigate whether the location of body fat deposits, ie, the distribution of VFA and subcutaneous fat accumulation (SFA), contributes to hypoventilation and whether circulating levels of leptin are involved in the pathogenesis of hypoventilation, which is often observed in OSAHS.
We assessed VFA and SFA by abdominal CT scan, and measured lung function and circulating levels of leptin in 106 eucapnic and 79 hypercapnic male patients with OSAHS.
In the whole study group, circulating leptin levels correlated with BMI (r = 0.56), VFA (r = 0.24), and SFA (r = 0.47), but not with Po(2) or sleep mean arterial oxygen saturation (Sao(2)). BMI, percentage of predicted vital capacity, FEV(1)/FVC ratio, apnea-hypopnea index, sleep mean Sao(2), VFA, and SFA were not significantly different between two groups. Circulating leptin levels were higher in the hypercapnic group than in the eucapnic group. Logistic regression analysis indicated that serum leptin was the only predictor for the presence of hypercapnia (beta = 0.21, p < 0.01).
These results suggest that the location of body fat deposits may not contribute to the pathogenesis of hypoventilation, and circulating leptin may fail to maintain alveolar ventilation in hypercapnic patients with OSAHS.
Available from: Mahmoud I Mahmoud
- "When we compared the anthropometric data of patients with SHVS and those without, there were no significant differences between the two groups. Shimura et al.reported that leptin level was the only variable predictive of hypoventilation in Japanese men with OSA; whereas BMI, measures of OSA severity and visceral or subcutaneous fat measurements were not predictive of hypercapnia. Systemic comorbidities are known to be higher in patients with SRBDs. "
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ABSTRACT: PURPOSE: To assess the prevalence of SRBDs in acutely ill patients admitted to respiratory ICU and identify patients' characteristics that aid in predicting SRBDs in such population
METHODS: 72 patients were subjected to clinical apnea score (CAS) and classified into 2 groups: group I (n=21) patients with low clinical probability for SRBDs and group II (n=51) patients with high probability. We then compared the 2 groups according to their demographic data, anthropometric measures, clinical diagnosis, daytime gasometry (ABGs), APACHE score, mortality rate, length of ICU stay, and mode of assisted ventilation. 39 patients from group II were subjected to overnight sleep study.
RESULTS: Mean age, hypertension, diabetes mellitus, BMI, neck circumference, waist/hip ratio, occurrence of type 2 respiratory failure and use of BiPAP were statistically significantly higher in patients with SRBDs than in patients without SRBDs. All patients with high clinical suspicion objectively demonstrated AHI>5/hour on polysomnography. They included 10.2% (n=4) with mild OSAHS, 25.6% (n=10) with moderate OSAHS and 64.1% (n=25) with severe OSAHS. Sleep efficiency was decreased, stage 1 was increased, and several types of arrhythmias were detected. 82% of patients with SRBDs suffered from sleep related hypoventilation (SHV) in addition to OSAHS. Serum bicarbonate was the sole parameter that was statistically significantly higher in patient with SRBDs and SHV compared to patients without SHV.
CONCLUSIONS: SRBDs is a very common medical condition but yet underrecognized in ICU setting. CAS has a high clinical predictive value for detection of OSAHS. ABGs cannot predict presence or absence of SRBDs in the ICU setting. Anthropometric data have significant importance in directing the awareness towards SRBDs. Patients with SRBDs are complicated with many co morbidities such as hypertension, diabetes mellitus, hyperuricemia, dyslipidemia and cardiac arrhythmia. Patients in ICU have decreased sleep efficiency. Treating patients with SRBDs with positive pressure will significantly decrease the frequency of readmission to ICU. Serum bicarbonate is the sole parameter of significantly high clinical predictive value for presence of concomitant SHV in patients with OSAHS. AHI has linear relationship with neck circumference thus considered a good predictor to the presenceof OSAHS.
CLINICAL IMPLICATIONS: SRBDs is highly prevalent among patients admitted with respiratory failure. Physicians need to be aware of this common prevalnce for proper management.
Available from: del Campo F Felix
- "Several studies have shown increased levels of leptin in OSAS (Phillips et al., 2000; Tokuda et al., 2008), suggesting its role in the disease (Ip et al., 2000). The mechanisms underlying the relation between leptin and OSAS are very diverse, and may involve overnight changes in apnea levels (Patel et al., 2004; Sanner et al., 2004), sleep hypoxemia (Tatsumi et al., 2005), and hypercapnia (Shimura et al., 2005). "
Available from: Mehmet Karadag
- "It was suggested that sleep hypoxemia may be the main determinant of circulating leptin levels. Shimura et al. demonstrated that circulating leptin levels correlated with BMI, VFA, and SFA, but not with PaO2 or sleep mean arterial oxygen saturation. They reported that leptin levels were higher in the hypercapnic group than in the eucapnic group. "
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ABSTRACT: The aim of this study was to investigate the relationship among plasma leptin, ghrelin, adiponectin, resistin levels, and obstructive sleep apnea syndrome (OSAS).
Fifty-five consecutive newly diagnosed OSAS patients and 15 age-matched nonapneic controls were enrolled in this study. After sleep study between 8:00 AM and 9:00 AM on the morning, venous blood was obtained in the fasting state to measure ghrelin and adipokines.
Serum ghrelin levels of OSAS group were significantly (P < 0.05) higher than those of the control group. No significant difference was noted in the levels of leptin, adiponectin, and resistin in OSAS group when compared to controls. There was a significant positive correlation between ghrelin and apnea-hypopnea index (AHI) (r = 0.237, P < 0.05) or the Epworth sleepiness scale (ESS) (r = 0.28, P < 0.05). There was also a significant positive correlation between leptin and body mass index (r = 0.592, P < 0.0001). No significant correlation was observed between leptin, adiponectin, resistin, and any polysomnographic parameters.
Our findings demonstrated that serum ghrelin levels were higher in OSAS patients than those of control group and correlated with AHI and ESS. Further studies are needed to clarify the complex relation among OSAS, obesity, adipokines, and ghrelin.
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