Endocrine Abstracts

Obesity is a major cause of chronic hypoventilation and/or obstructive sleep apnea syndrome (OSAS). Aim of this study was to evaluate the prevalence of pulmonary dysfunction and the relationship between OSAS and several clinical, functional and polysomnographics parameters in severely obese patients. 101 subjects (68 females and 33 males) aged 49.2±13.2 years (mean±S.D.), with BMI 46.8±6.5 Kg/m² were enrolled. Sleep quality and daytime sleepiness were assessed using the Epworth Sleepiness Scale (EPSS). Serum triglycerides, HDL-cholesterol, glucose, leptin, and thyroid hormones were measured. All patients underwent cardio-respiratory polygraphic sleep study and lung function tests. Arterial hypertension was present in 56.4% patients and type 2 diabetes in 30.7%. Snoring was referred by 91% patients, nocturnal awakening by 51% and apneas by 41%. Pathologic sleepiness was present in 61% patients. 70.3% patients had larger than normal neck circumference. Arterial gas analyses showed reduced PaO2 in 41% patients. An obstructive ventilatory pattern was found in 15% patients, a restrictive pattern in 10% and a mixed pattern in 3%. The expiratory reserve volume and functional residual capacity were significantly reduced in 50% patients. 14% patients had mild, 13% moderate, 13% severe and 21% very severe OSAS. Only 39% patients did not meet the diagnostic criteria for OSAS. A significant positive correlation was found between the apnea-hypopnoea index (AHI) and EPSS (P<0.005), waist/hip ratio (P<0.005), neck circumference (P<0.005) or PaCO2 (P<0.05). An inverse correlation was observed between AHI and PaO2, nocturnal mean or minimum oxygen saturation. No correlation was found between AHI and other respiratory functional, cardio-respiratory, metabolic or hormonal parameters.

In conclusion, our data indicate a high prevalence of respiratory dysfunction in severely obese patients, including diurnal hypoventilation and OSAS. We suggest that pulmonary function should be systematically screened in severely obese subjects even in the absence of overt manifestations of disease.