Department of Emergency Medicine, Cooper University Hospital and Cooper Medical School of Rowan University, Camden, NJ, USA.
Department of Emergency Medicine, Cooper University Hospital and Cooper Medical School of Rowan University, Camden, NJ, USA; Department of Medicine, Division of Critical Care Medicine (ST), Cooper University Hospital and Cooper Medical School of Rowan University, Camden, NJ, USA.
Resuscitation. 2015 Jun;91:32-41. doi: 10.1016/j.resuscitation.2015.03.015. Epub 2015 Mar 28.
Partial pressure of arterial carbon dioxide (PaCO2) is a major regulator of cerebral blood flow (CBF). Derangements in PaCO2 have been thought to worsen clinical outcomes after many forms of cerebral injury by altering CBF. Our aim was to systematically analyze the biomedical literature to determine the effects of PaCO2 derangements on clinical outcomes after cerebral injury.
We performed a search of Cochrane Library, PUBMED, CINHAL, conference proceedings, and other sources using a comprehensive strategy. Study inclusion criteria were (1) human subjects; (2) cerebral injury; (3) mechanical ventilation post-injury; (4) measurement of PaCO2; and (5) comparison of a clinical outcome measure (e.g. mortality) between different PaCO2 exposures. We performed a qualitative analysis to collate and summarize effects of PaCO2 derangements according to the recommended methodology from the Cochrane Handbook.
Seventeen studies involving different etiologies of cerebral injury (six traumatic brain injury, six post-cardiac arrest syndrome, two cerebral vascular accident, three neonatal ischemic encephalopathy) met all inclusion and no exclusion criteria. Three randomized control trials were identified and only one was considered a high quality study as per the Cochrane criteria for assessing risk of bias. In 13/17 (76%) studies examining hypocapnia, and 7/10 (70%) studies examining hypercapnia, the exposed group (hypercapnia or hypocapnia) was associated with poor clinical outcome.
The majority of studies in this report found exposure to hypocapnia and hypercapnia after cerebral injury to be associated with poor clinical outcome. However, the optimal PaCO2 range associated with good clinical outcome remains unclear.
动脉血二氧化碳分压（PaCO2）是脑血流（CBF）的主要调节因子。通过改变 CBF，PaCO2 的紊乱被认为会使多种形式的脑损伤后的临床结果恶化。我们的目的是系统地分析生物医学文献，以确定 PaCO2 紊乱对脑损伤后临床结果的影响。
我们使用综合策略对 Cochrane 图书馆、PUBMED、CINHAL、会议记录和其他来源进行了搜索。研究纳入标准为：（1）人类受试者；（2）脑损伤；（3）损伤后机械通气；（4）PaCO2 测量；（5）不同 PaCO2 暴露之间临床结果测量（例如死亡率）的比较。我们根据 Cochrane 手册推荐的方法进行了定性分析，以整理和总结 PaCO2 紊乱的影响。
有 17 项研究涉及不同病因的脑损伤（6 项创伤性脑损伤、6 项心搏骤停后综合征、2 项脑血管意外、3 项新生儿缺血性脑病）符合所有纳入标准，没有排除标准。确定了 3 项随机对照试验，只有 1 项根据 Cochrane 评估偏倚风险的标准被认为是高质量研究。在 17 项研究中（76%）检查低碳酸血症，以及在 10 项研究中（70%）检查高碳酸血症，暴露组（高碳酸血症或低碳酸血症）与不良临床结果相关。
本报告中的大多数研究发现，脑损伤后暴露于低碳酸血症和高碳酸血症与不良临床结果相关。然而，与良好临床结果相关的最佳 PaCO2 范围仍不清楚。
