单肺通气时低氧血症

我们推测这种发育不全导致非依赖性、非通气性肺分流增强，这是一种以前未报道的单肺通气低氧血症的潜在原因。

虽然肺发育不全估计仅发生在1:200000的人群中，但应考虑回顾常规获得的术前计算机断层扫描，以评估肺动脉大小差异作为单肺通气期间低氧血症的罕见潜在危险因素。

如果存在低氧血症风险增加的预期，应促使辅助治疗迅速升级（即呼气末正压；持续气道正压；双肺通气，考虑将胸腔镜技术转换为开胸手术）。体外膜肺氧合也是一个潜在的选择。

原文

Hypoxemia remains a well-described occurrence duringone-lung ventilation.1 We recently observed unexpected refractoryhypoxemia during one-lung ventilation in a previously healthy nonsmoking30-yr-old female undergoing left thoracotomy in the right lateral decubitusposition to facilitate complex descending aorta to left subclavian/carotidartery bypass grafting to treat upper limb and cerebral ischemia resulting fromTakayasu’sarteritis. Despite endotracheal suctioning, reconfirmation of optimal bronchialblocker positioning, optimizing the fraction of inspired oxygen, and using bothdependent lung positive end-expiratory pressure and nondependent lungcontinuous positive airway pressure,the Pao2 remained ~50 mmHg. No intracardiac shunt was seen on transesophagealechocardiography. Only intermittent two-lung ventilation temporarily corrected thehypoxemia. A postoperative computed tomography angiogram three-dimensionalreconstruction (panel A) was performed to evaluate the vascularreconstruction and showed a hypoplastic right pulmonary artery (10 mm diameter;panel B) compared to a normal left pulmonary artery (19 mm diameter; panel C). We speculate that this hypoplasia resulted in enhanced shunting to thenondependent, nonventilated lung; this is a previously unreported potentialcause for one-lung ventilation hypoxemia. Although pulmonary hypoplasia isestimated to occur in only 1:200,000 of the population, consideration should begiven to reviewing the routinely acquired preoperative computed tomography scanto assess for pulmonary artery size differential as a rare potential risk factorfor hypoxemia during one-lung ventilation. If present, anticipation of anincreased risk for hypoxemia should prompt rapid escalation of adjuncttherapies (i.e., positive end-expiratory pressure; continuous positive airway pressure;two-lung ventilation, with consideration to conversion of a thoracoscopictechnique to open thoracotomy). Extracorporeal membrane oxygenation is also a potentialoption.

这篇文章也提到了单肺通气时发生低氧血症的处理方法，主要有：

1、尽可能去除诱因或纠正导致低氧血症的因素，如清除气管内分泌物、调整导管位置等。

2、提高吸入氧浓度。

3、适当给予呼气末正压（PEEP），可从5cmH2O开始根据效果调整。

4、持续正压通气（CPAP）。

5、交替双肺通气。

6、改善心肺功能。

7、其他措施如肺通气侧肺吹入纯氧、膜肺氧合等。