The purpose of this study was to determine the relationship between obstructive sleep apnea (OSA) and cardiovascular disorders in a large Japanese population, and to assess the efficacy of continuous positive airway pressure (CPAP) in the treatment of OSA-associated arrhythmias. The study population comprised 1394 Japanese subjects (1086 men and 308 women) who were divided into four groups on the basis of polysomnography (PSG) analysis as follows: the no sleep apnea (N-SA) group (n = 44, apnea-hypopnea index [AHI] < 5), the mild OSA (Mi-OSA) group (n = 197, 5 < AHI < 15), the moderate OSA (Mo) group (n = 368, 15 < AHI < 30), and severe OSA (SOSA) group (n = 785, AHI < 30). The following baseline characteristics were significantly associated with OSA: age (P < 0.001), gender (P < 0.001), body mass index (P < 0.001), hypertension (P < 0.001), diabetes (P = 0.009), and hyperlipidemia (P = 0.013). In the OSA group, PSG revealed the predominance of paroxysmal atrial fibrillation (PAF) (P = 0.051), premature atrial complex short run (P < 0.005), premature ventricular complex (PVC, P = 0.004), sinus bradycardia (P = 0.036), and sinus pause (arrest >2 s, P < 0.001) during the PSG recording. A total of 316 patients from the group underwent CPAP titration and were then re-evaluated. Continuous positive airway pressure therapy significantly reduced the occurrences of PAF (P < 0.001), PVC (P = 0.016), sinus bradycardia (P = 0.001), and sinus pause (P = 0.004). The results of this study demonstrate a significant relationship between OSA and several cardiac disorders, and also demonstrate the efficacy of CPAP in preventing OSA-associated arrhythmias in a large population of Japanese patients.

Chest computed tomography (CT) and pulmonary function tests are usually used for the evaluation of emphysema. We performed the present study to evaluate more accurately the relationship between the degree of morphological change and the functional abnormality in emphysema. We used a helical CT apparatus to obtain the CT images both at full inspiration and full expiration. We classed the degree of emphysema into 5 grades (0-4) by visual observation on CT image obtained at the two levels, upper and lower fields, on each side. We assigned each of these grades a visual score. We also calculated the average ratio of CT numbers of each of the lung fields at full expiration to that at full inspiration for each level. We designated this the E/I ratio. We then examined the relationship between the findings acquired by each of these two methods and pulmonary function test results. The visual score showed correlations with FEV1(% predicted) (-0.592, p < 0.0001), RV/TLC(%)(0.425, p < 0.025), and DL(CO)/VA(% predicted)(-0.538, p < 0.0001). The E/I ratio showed correlations with FEV1(% predicted) (-0.620, p < 0.0001), RV/TLC(%)(0.661, p < 0.0001), and DL(CO)/VA(% predicted) (-0.299, p < 0.05). Compared with the E/I ratio, the visual score showed much higher correlation with DL(CO)/VA(% predicted), but the E/I ratio showed stronger correlation with RV/TLC(%) than did the visual score. The visual score may reflect the degree of emphysema, whereas the E/I ratio reflects the air trapping. These findings suggest that the helical CT is useful in the evaluation of emphysematous changes and that the E/I ratio reflects the air trapping.

This study evaluated small airway dysfunction and emphysematous destruction of lung parenchyma in cigarette smokers, using chest expiratory highresolution computed tomography (HRCT) and pulmonary function tests (PFT).The degree of emphysematous destruction was classified by visual scoring (VS) and the average HRCT number at full expiration/full inspiration (E/I ratio) calculated in 63 male smokers and 10 male nonsmokers (group A). The Brinkman smoking index (BI), defined as cigarettes . day -1 6 yrs, was estimated. Sixty-three smokers were divided into three groups by PFT: group B1 (n=7), with normal PFT; group B2 (n=21), with diffusing capacity of the lung for carbon monoxide (DL,CO) $80% predicted, forced expiratory volume in one second (FEV1) <80% pred and/or residual volume (RV) >120% pred; and group B3 (n=35), with DL,CO <80% pred, FEV1 <80% pred and/or RV >120% pred.Heavy smokers (BI $600) (n=48) showed a significant increase in emphysema by both VS and E/I. E/I was significantly elevated in both group B2 (meanSD 0.950.05) and B3 (0.960.06) compared with group B1 (0.890.03). VS could not differentiate group B2 (3.95.0) from B1 (1.11.6).These findings suggest that the expiration/inspiration ratio reflects hyperinflation and airway obstruction, regardless of the functional characteristics of emphysema, in cigarette smokers. Eur Respir J 1999; 13: 252±256.

Objective The prevalence of complex sleep apnea syndrome (CompSAS)

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