Bradley T D, Rutherford R, Lue F, Moldofsky H, Grossman R F, Zamel N, Phillipson E A
Am Rev Respir Dis. 1986 Nov;134(5):920-4. doi: 10.1164/arrd.1986.134.5.920.
The mechanisms responsible for the development of chronic hypercapnia in patients with obstructive sleep apnea (OSA) are not well defined. Therefore, we tested the hypothesis that diffuse airway obstruction may be involved by studying 50 patients with a well-documented OSA syndrome. Seven patients had daytime hypercapnia with a mean PaCO2 of 51 +/- 2 (SEM) mm Hg, compared to a PaCO2 of 35 +/- 1 in the other 43 patients. There were no differences between the 2 groups in the number or duration of nocturnal obstructive events. In contrast, the hypercapnic patients were significantly heavier than the normocapnic patients (body weight, 189 +/- 11 versus 148 +/- 6% of ideal; p less than 0.005) and had evidence of diffuse airway obstruction, as indicated by an increased residual volume and a reduction in all expiratory flow rates. When the hypercapnic patients were compared with a weight-matched group of 9 normocapnic patients (body weight, 196 +/- 8% of ideal), there were still no differences in nocturnal obstructive events, but the differences in tests of airway mechanics persisted. Multiple regression analysis of PaCO2 against several anthropometric, respiratory physiologic, and polysomnographic variables revealed that only 2 variables (expiratory reserve volume and FEV1/FVC), both of which are influenced by airway mechanics, were significantly correlated with PaCO2 (multiple r = 0.78; p = 0.0001). The findings suggest that OSA alone does not produce daytime hypercapnia even in obese patients, and that the presence of diffuse airway obstruction is an important predisposing factor to the development of chronic CO2 retention in such patients.
阻塞性睡眠呼吸暂停（OSA）患者发生慢性高碳酸血症的机制尚未完全明确。因此，我们通过研究50例有充分记录的OSA综合征患者，来检验弥漫性气道阻塞可能与之相关的这一假设。7例患者出现日间高碳酸血症，平均动脉血二氧化碳分压（PaCO2）为51±2（标准误）mmHg，而其他43例患者的PaCO2为35±1 mmHg。两组患者夜间阻塞性事件的数量或持续时间并无差异。相比之下，高碳酸血症患者明显比正常碳酸血症患者体重更重（体重分别为理想体重的189±11%和148±6%；p<0.005），并且有弥漫性气道阻塞的证据，表现为残气量增加和所有呼气流量降低。当将高碳酸血症患者与9例体重匹配的正常碳酸血症患者（体重为理想体重的196±8%）进行比较时，夜间阻塞性事件仍无差异，但气道力学测试的差异依然存在。对PaCO2与多个身体测量、呼吸生理和多导睡眠图变量进行多元回归分析发现，只有两个受气道力学影响的变量（呼气储备量和第1秒用力呼气容积/用力肺活量）与PaCO2显著相关（多元相关系数r = 0.78；p = 0.0001）。这些发现表明，即使在肥胖患者中，单独的OSA也不会导致日间高碳酸血症，并且弥漫性气道阻塞的存在是此类患者发生慢性二氧化碳潴留的重要 predisposing 因素。 （注：predisposing 这个词在医学语境中可能有“易患的、 predisposing 因素指的是使个体更容易患病的因素，但直接翻译“predisposing”为中文不太准确，可根据上下文理解为“促成……的、诱发……的”等意思，这里保留英文是因为准确的中文表述较难在不影响原文整体意思下直接给出合适的词）
