Department of Neurology, Puai Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
Wuhan Fourth Hospital, Wuhan, Hubei, China.
PLoS One. 2023 Oct 24;18(10):e0293256. doi: 10.1371/journal.pone.0293256. eCollection 2023.
The relationship between the levels of the first 24-h PaCO2 and the prognosis of sepsis-associated encephalopathy (SAE) remains unclear, and the first 24-h optimal target for PaCO2 is currently inconclusive. This study was performed to investigate the correlation between PaCO2 and all-cause mortality for SAE patients, establish a reference range of the initial 24-hour PaCO2 for clinicians in critical care, and explain the possible pathophysiological mechanisms of abnormal PaCO2 levels as a higher mortality risk factor for SAE.
The baseline information and clinical data of patients were extracted from the fourth edition Medical Information Mart for Intensive Care database (MIMIC-IV 2.0). Multivariate logistic regressions were performed to assess the relationship between PaCO2 and all-cause mortality of SAE. Additionally, restricted cubic splines, Kaplan-Meier Survival analyses, propensity score matching (PSM) analyses, and subgroup analyses were conducted.
A total of 5471 patients were included in our cohort. In the original and matched cohort, multivariate logistic regression analysis showed that normocapnia and mild hypercapnia may be associated with a more favorable prognosis of SAE patients, and survival analysis supported the findings. In addition, a U-shaped association emerged when examining the initial 24-hour PaCO2 levels in relation to 30-day, 60-day, and 90-day mortality using restricted cubic splines, with an average cut-off value of 36.3mmHg (P for nonlinearity<0.05). Below the cut-off value, higher PaCO2 was associated with lower all-cause mortality, while above the cut-off value, higher PaCO2 was associated with higher all-cause mortality. Subsequent subgroup analyses revealed similar results for the subcohort of GCS≤8 compared to the original cohort. Additionally, when examining the subcohort of GCS>8, a L-shaped relationship between PaCO2 and the three clinical endpoints emerged, in contrast to the previously observed U-shaped pattern. The findings from the subcohort of GCS>8 suggested that patients experiencing hypocapnia had a more unfavorable prognosis, which aligns with the results obtained from corresponding multivariate logistic regression analyses.
The retrospective study revealed the association between the first 24-h PaCO2 and all-cause mortality risk (30-day, 60-day, and 90-day) for patients with SAE in ICU. The range (35mmHg-50mmHg) of PaCO2 may be the optimal target for patients with SAE in clinical practice.
第 24 小时内 PaCO2 水平与脓毒症相关脑病（SAE）预后之间的关系尚不清楚，目前也不确定 PaCO2 的 24 小时最佳目标值。本研究旨在探讨 PaCO2 与 SAE 患者全因死亡率之间的相关性，为危重症患者建立初始 24 小时 PaCO2 的参考范围，并解释异常 PaCO2 水平作为 SAE 更高死亡率风险因素的可能病理生理机制。
从第四版医疗信息监护数据库（MIMIC-IV 2.0）中提取患者的基线信息和临床数据。使用多变量逻辑回归评估 PaCO2 与 SAE 全因死亡率之间的关系。此外，还进行了限制性立方样条、Kaplan-Meier 生存分析、倾向评分匹配（PSM）分析和亚组分析。
共纳入 5471 例患者。在原始和匹配队列中，多变量逻辑回归分析显示，正常碳酸血症和轻度高碳酸血症可能与 SAE 患者更有利的预后相关，生存分析也支持这一发现。此外，通过限制性立方样条分析，在第 24 小时 PaCO2 水平与 30 天、60 天和 90 天死亡率之间的关系时，呈现出 U 形关联，平均截断值为 36.3mmHg（P<0.05）。在截断值以下，较高的 PaCO2 与较低的全因死亡率相关，而在截断值以上，较高的 PaCO2 与较高的全因死亡率相关。随后的亚组分析显示，在 GCS≤8 的亚组中，结果与原始队列相似。此外，当检查 GCS>8 的亚组时，与之前观察到的 U 形模式相比，出现了 PaCO2 与三个临床终点之间的 L 形关系。来自 GCS>8 亚组的结果表明，发生低碳酸血症的患者预后更差，这与相应的多变量逻辑回归分析结果一致。
本回顾性研究揭示了 ICU 中 SAE 患者第 24 小时 PaCO2 与全因死亡率风险（30 天、60 天和 90 天）之间的关联。PaCO2 范围（35mmHg-50mmHg）可能是 SAE 患者临床实践中的最佳目标值。
