Trial of BiPAP during Sleep in Chronic Respiratory Failure with hypercapnic

目的：部分慢性呼吸衰竭患者，尤其是高碳酸血症患者，出现严重的夜间氧减饱和。睡眠中的氧减饱和加重了患者的一般情况。氧减饱和的主要原因被认为是睡眠时换气不足。同时，压力支持呼吸机得到了改进，我们可以期待更好的耐受性的双水平气道正压(BiPAP)系统已经出现。因此，我们试图阐明夜间氧减饱和的病理生理机制、BiPAP的设置方式和BiPAP的最佳压力设置，以便在慢性呼吸衰竭合并夜间氧减饱和的患者中正确应用BiPAP。方法：对40例慢性呼吸衰竭患者采用脉搏血氧饱和度测定仪测量睡眠时氧减饱和度，并用笔记本电脑连续记录。在20名患者中，重复测量超过一次mo…。并将计算结果与各参数进行了比较，显示了一般情况。对部分出现夜间低氧的患者，除进行脉搏血氧饱和度测定外，还进行了多导睡眠监测和二氧化碳分压监测。分析睡眠阶段与夜间氧减饱和度、通气量或呼气末二氧化碳的关系。结果：许多日间PaO2>60torr的慢性呼吸衰竭患者出现夜间氧减饱和，部分患者出现非常严重的氧减饱和。大多数出现严重夜间减饱和的患者有因急性加重而反复入院的病史。REM期夜间氧减饱和度较非REM期严重。BiPAP能较好地预防夜间氧减饱和，即使在REM阶段也是如此。结论：预防夜间氧减饱和对慢性呼吸衰竭患者具有重要意义，满意的BiPAP可预防夜间氧减饱和。较少

Purpose : Some patients with chronic respiratory failure, especially patients with hypercapnia, show severe nocturnal oxygen desaturation. The oxygen desaturation during sleep aggravate the general condition of the patients. The main reason of the oxygen desaturation is believed to be the hypoventilation during sleep. Meanwhile, pressure support ventilator has been ameliorated and bilevel positive airway pressure (BiPAP) system, by which we can expect better tolerance, has become available. We, therefore, tried to elucidate the pathophysiology of nocturnal oxygen desaturation, way of setting of BiPAP and optimal setting of pressures for BiPAP,in order to apply BiPAP properly for patients of chronic respiratory failure with nocturnal oxygen desaturation.Methods : We measured oxygen desaturation during sleep using pulse oxymeter and recorded continuously using a notebook computer in 40 patients with chronic respiatory failure. In 20 patients, measurements were repeated for more than a mo … More nth and the results were compared with the various parameters showing general conditions. Some of the patients showing nocturnal hypoxia were examined using polysomnograph and capnograph in addition to pulse oxymeter. Relations of the sleep stage to the nocturnal oxygen desaturation, ventilation, or end-tidal CO2 were analyzed. BiPAP was applied during sleep to some of the patients with nocturnal oxygen desaturation.Results : Many patients of chronic respiratory failure with daytime PaO2 over 60 torr showed nocturnal oxygen desaturation and some of them were very severe desaturation. Most of the patients showing severe nocturnal desaturation had history of repeated admission for acute exacerbation. Nocturnal oxygen desaturation was worse in REM stage than in non-Rem stage. BiPAP satisfactory prevented nocturnal oxygen desaturation even in REM stage. Repeated trials were necessary to obtain optimal pressures for BiPAP.Conclusion : Prevention of nocturnal oxygen desaturation is important for the patients of chronic respiratory failure and BiPAP satisfactory prevents the nocturnal oxygen desaturation. Less