Bain环路对单肺通气时血气值及肺分流量的影响

Influence of Bain Circuit on the Blood Gas and Q ·s/ Q ·t during One lung Ventilation

目的与方法：选择２２例术前肺功能正常和轻度损害肺叶切除手术的病人，观察单肺通气（ＯＬＶ）期间术侧肺加用Ｂａｉｎ环路行持续气道正压通气（ＣＰＡＰ）对Ｑｓ／Ｑｔ和氧合的影响。结果与结论：不用Ｂａｉｎ环路的Ⅰ组病人，术侧肺完全萎缩，ＰａＯ２、ＰＶＯ２均明显降低，分别为双肺通气（ＴＬＶ）时的６３％和７４％（Ｐ＜０．０５），Ａ－ａＤＯ２和Ｑｓ／Ｑｔ升高，说明低氧血症与ＯＬＶ时严重肺内分流有关。而在术侧肺加用Ｂａｉｎ环路者（Ⅱ组）上述变化表现极其轻微（Ｐ＞０．０５），这是因为氧能以一定的压力和流速持续吹入术侧肺泡，使其扩张并进行气体交换，在纠正低氧血症和降低Ｑｓ／Ｑｔ方面，其效果非常明显，且操作简便易行。

Objective and Methods:22 adult patients scheduled for elective pulmonary resection, with normal or slightly abnormal pulmonary function, were studied to determine whether CPAP via Bain circuit on the lung of operative side nonventilated lung during one lung anesthesia would reduce intrapulmonary shunting ( Q ·s/ Q ·t) and improve arterial oxygen desaturation. Results: The significant differences were observed in PaO 2 and PvO 2, A aDO 2 and Q ·s/ Q ·t between the patients in whom oxygen was not insufflated (group Ⅰ) and those in whom oxygen was insufflated (group Ⅱ) via Bain circuit. Group Ⅰ, when the lung was deflated, had significantly lower PaO 2 and PvO 2 and higher A aDO 2 and Q ·s/ Q ·t. Conclusion:Hypoxemia is due to greatly increased venous admixture through the lung of operative side. Because oxygen could be unintermitently insufflated into the pulmonary alveoli through Bain circuit, gas exchange was completed on the site of expansive alveoli leading to the reduction of Q ·s/ Q ·t and hypoxemia.