[Impaired glucose metabolism in patients with obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To investigate the prevalence of impaired glucose-insulin metabolism in obstructive sleep apnea hypopnea syndrome (OSAHS); to examine the relation between severity of OSAHS and impaired glucose metabolism; and to evaluate the effectiveness of continuous positive airway pressure (CPAP) on impaired glucose metabolism. METHODS: A total of 214 patients who were free of diabetes at baseline underwent both nocturnal polysomnography (PSG), and 2-h oral glucose-tolerance test, insulin and hemoglobin A1c test. CPAP treatment for glucose-insulin metabolism (+) was given to OSAHS group after informed consent had been obtained. RESULTS: Eighty-eight patients and 17 patients with impaired glucose-insulin metabolism were found in OSAHS group and the control group respectively. Impaired glucose-insulin metabolism was present in 54.3% of OSAHS group and 32.7% of control group. Logistic regression analysis showed a significant positive correlation with OSAHS (AHI ≥ 10 times/h) and impaired glucose-insulin metabolism in all patients (OR = 2.440, 95%CI 1.201 - 4.958). Plasma glucose level changes had no significant differences between before and after CPAP treatment (P > 0.05). CONCLUSION: OSAHS is associated with a high frequency of impaired glucose metabolism. The relationship between OSAHS and impaired glucose metabolism is independent of obesity. Longest apnea time (LAT) and AHI are important contributors to impaired glucose metabolism in OSAHS patients. Short-term CPAP therapy has no significant improvement on glucose metabolism in patients with OSAHS.

[The relation between obstructive sleep apnea hypopnea syndrome and the severity of coronary atherosclerosis in coronary artery disease].

OBJECTIVE: To investigate the relation between obstructive sleep apnea hypopnea syndrome (OSAHS) and the Gensini score, which is given to define the severity of coronary atherosclerosis, based on coronary angiograms findings, in patients with coronary artery disease. METHODS: We examined the apnea hypopnea index (AHI) using polysomnography (PSG) in 231 consecutive patients with coronary artery disease (ejection fraction, > 40%) that was diagnosed by coronary angiography, 160 patients with angina pectoris and 71 patients with myocardial infarction. The Gensini score was calculated for each patient from the coronary arteriogram. The patients were classified into the following four groups according to the AHI, serious group: AHI > 40 events per hour, 44 patients; moderate group: 20 events per hour < AHI < or = 40 events per hour, 67 patients; mild group: 10 events per hour < or = AHI < or = 20 events per hour, 57 patients; OSAHS (-) group: AHI < 10 events per hour, 63 patients. Then the groups were examined for the relation between the AHI and the Gensini score. RESULTS: Of the total number of patients, 72. 72% (168/231) had an AHI of more than ten per hour. The prevalence of multivessel disease ( > or = 3 vessels) was 75.00% (33/44)in serious group, 61.12% (41/67)in moderate group, 38.60% (22/57) in mild group, and 30.16% (19/63) in OSAHS(-) group. The Gensini score was significantly higher in serious group than the other three groups. The Gensini score was higher in moderate group than mild group and OSAHS (-) group, and the Gensini score in mild group was higher than that in OSAHS (-) group. The Gensini score showed a significant positive correlation with the AHI (r = 0.561, P < 0.001) in all patients. Multiple regression analysis showed that AHI was the most significant, independent determinant of the Gensini score among the coronary risk factors tested, and that it explained 31.4% of the variances. CONCLUSION: These findings suggest that AHI which is used to assess the severity of OSAHS is an important contributor to coronary atherosclerosis in the patients with cardiovascular disease, and the patients with more serious OSAHS would have more serious and complex coronary artery lesions.

[The changes of respiratory mechanics in patients with obstructive sleep apnea-hypopnea syndrome during sleep].

OBJECTIVE: To study the changes of respiratory mechanics in patients with obstructive sleep apnea hypopnea syndrome (OSAHS) during sleep. METHODS: Eighty-one consecutive subjects, 70 males and 11 females, mean age (43.9 +/- 12.6), were recruited in this study. The respiratory mechanics during sleep were studied by using the side stream spirmeter (SSS) technique. All subjects underwent respiratory mechanics monitoring with Novametrix Medical Systems (connected with full face mask) during nocturnal polysomnographic (PSG) study. Then by the apnea-hypopnea index (AHI), the subjects were divided into the OSAHS group (AHI >or= 15/h) and the control group (AHI < 15/h). RESULTS: Fifty-four subjects were confirmed to have OSAHS [AHI = (57.6 +/- 24.9) h] by PSG, and 27 as the control group [AHI = (4.4 +/- 4.1) h]. In the OSAHS group, inspiratory tidal volume/expiratory tidal volume (V TI/V TE) was 1.37 +/- 0.18 during the first respiratory cycle after apnea, which was significantly greater than that (0.99 +/- 0.04) during wakefulness. The mean V TI/V TE (0.86 +/- 0.09) during the 5 respiratory cycles and that (0.72 +/- 0.19) of the last respiratory cycle before the next apnea decreased significantly. These indicated that the functional residual capacity (FRC) and upper airway size were reduced gradually before apnea. Compared with the measurements before sleep, V TI [(463 +/- 122) ml vs (554 +/- 134) ml], V TE [(466 +/- 127) ml vs (565 +/- 147) ml], and expired minute volume [(6.4 +/- 1.6) L/min vs (8.3 +/- 1.9) L/min] were decreased significantly during light sleep without apnea. Tidal breath flow-volume loop showed that in the OSAHS group, the inspiratory resistance increased in 54 patients (100%), the expiratory resistance increased in 52 (96.3%), and both of them increased in 52 (96.3%). CONCLUSIONS: OSAHS patients exhaled more air than inhaled gradually before apnea onset, and then this change was compensated by inhaling more air than exhaled in the first respiratory cycle following apnea. These resulted in decreases in FRC and upper airway size, which may play an important role in the pathophsiological mechanisms of sleep apnea. The tidal volume decrease suggested that the breathing drive was reduced in light sleep of OSAHS. In addition, a rise of both inspiratory and expiratory resistance was evident in a majority of patients with OSAHS.

[Pharyngeal size and collapsibility in patients with obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To study the pharyngeal cross-sectional area and collapsibility among the patients with obstructive sleep apnea hypopnea syndrome (OSAHS), simple snorers, and normal persons. METHODS: 171 patients with OSAHS, 44 with mild, 51 with moderate, and 56 with severe OSAHS, 47 simple snorers, and 47 healthy subjects underwent upper airway cross-sectional area measurement using acoustic pharyngometer at the conditions of functional residual capacity (FRC) and residual volume (RV) in the upright sitting position. RESULTS: When the lung volume decreased from the condition of FRC to the condition of RV the pharyngeal cross-sectional area decreased from 2.63 cm(2) +/- 0.42 cm(2) to 1.96 cm(2) +/- 0.35 cm(2) for the simple snorers, 2.70 cm(2) +/- 0.44 cm(2) to 1.78 cm(2) +/- 0.39 cm(2) for the mild OSAHS patients, from 2.62 cm(2) +/- 0.52 cm(2) to 1.79 cm(2) +/- 0.37 cm(2) for the moderate OSAHS patients, and from 2.57 cm(2) +/- 0.46 cm(2) to 1.75 cm(2) +/- 0.40 cm(2) for the severe OSAHS patients, all with higher decrease rates (33.93% +/- 11.81%, 31.13% +/- 10.76%, and 31.31% +/- 13.44%) than that of the normal persons (25.07% +/- 10.39%), smaller than that for the normal persons (21.11% +/- 8.19%, from 3.05 cm(2) +/- 0.6 cm(2) to 2.38 cm(2) +/- 0. 47 cm(2), all P < 0.05). The change ratios of the 3 OSAHS groups were significantly higher than that of the simple snorer group (all P < 0.01). This indicated that the pharynges of OSAHS patients were more collapsible. CONCLUSION: Snorers with or without apnea have smaller pharyngeal cross-sectional area than nonsnorers. The collapsibility of the upper airway is greater in both OSHAS patients and simple snorers than in healthy subjects.