Thome Ulrich H, Ambalavanan Namasivayam
Division of Neonatology, University Hospital for Children and Adolescents, 04103 Leipzig, Germany.
Semin Fetal Neonatal Med. 2009 Feb;14(1):21-7. doi: 10.1016/j.siny.2008.08.005. Epub 2008 Oct 29.
Lung injury in ventilated premature infants occurs primarily through the mechanism of volutrauma, often due to the combination of high tidal volumes in association with a high end-inspiratory volume and occasionally end-expiratory alveolar collapse. Tolerating a higher level of arterial partial pressure of carbon dioxide (PaCO2) is considered as 'permissive hypercapnia' and when combined with the use of low tidal volumes may reduce volutrauma and lead to improved pulmonary outcomes. Permissive hypercapnia may also protect against hypocapnia-induced brain hypoperfusion and subsequent periventricular leukomalacia. However, extreme hypercapnia may be associated with an increased risk of intracranial hemorrhage. It may therefore be important to avoid large fluctuations in PaCO2 values. Recent randomized clinical trials in preterm infants have demonstrated that mild permissive hypercapnia is safe, but clinical benefits are modest. The optimal PaCO2 goal in clinical practice has not been determined, and the available evidence does not currently support a general recommendation for permissive hypercapnia in preterm infants.
机械通气的早产儿发生肺损伤主要是通过容积伤机制，这通常是由于高潮气量与高吸气末容积相结合，偶尔还会出现呼气末肺泡萎陷。耐受较高水平的动脉血二氧化碳分压（PaCO2）被认为是“允许性高碳酸血症”，当与低潮气量联合使用时，可能会减少容积伤并改善肺部预后。允许性高碳酸血症还可能预防低碳酸血症引起的脑灌注不足及随后的脑室周围白质软化。然而，极度高碳酸血症可能与颅内出血风险增加有关。因此，避免PaCO2值大幅波动可能很重要。近期针对早产儿的随机临床试验表明，轻度允许性高碳酸血症是安全的，但临床益处不大。临床实践中的最佳PaCO2目标尚未确定，现有证据目前也不支持对早产儿常规推荐允许性高碳酸血症。
