Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, Hubei, China.
ESC Heart Fail. 2023 Apr;10(2):1385-1400. doi: 10.1002/ehf2.14306. Epub 2023 Feb 6.
Acute heart failure (AHF) poses a major threat to hospitalized patients for its high mortality rate and serious complications. The aim of this study is to determine whether hypocapnia [defined as the partial pressure of arterial carbon dioxide (PaCO ) below 35 mmHg] on admission could be associated with in-hospital all-cause mortality in AHF.
A total of 676 patients treated in the coronary care unit for AHF were retrospectively analysed, and the study endpoint was in-hospital all-cause mortality. The 1:1 propensity score matching (PSM) analysis, Kaplan-Meier curve, and Cox regression model were used to explore the association between hypocapnia and in-hospital all-cause mortality in AHF. Receiver operating characteristic (ROC) curve and Delong's test were used to assess the performance of hypocapnia in predicting in-hospital all-cause mortality in AHF. The study cohort included 464 (68.6%) males and 212 (31.4%) females, and the median age was 66 years (interquartile range 56-74 years). Ninety-eight (14.5%) patients died during hospitalization and presented more hypocapnia than survivors (76.5% vs. 45.5%, P < 0.001). A 1:1 PSM was performed between hypocapnic and non-hypocapnic patients, with 264 individuals in each of the two groups after matching. Compared with non-hypocapnic patients, in-hospital mortality was significantly higher in hypocapnic patients both before (22.2% vs. 6.8%, P < 0.001) and after (20.8% vs. 8.7%, P < 0.001) PSM. Kaplan-Meier curve showed a significantly higher probability of in-hospital death in patients with hypocapnia before and after PSM (both P < 0.001 for the log-rank test). Multivariate Cox regression analysis showed that hypocapnia was an independent predictor of AHF mortality both before [hazard ratio (HR) 2.22; 95% confidence interval (CI) 1.23-3.98; P = 0.008] and after (HR 2.19; 95% CI 1.18-4.07; P = 0.013) PSM. Delong's test showed that the area under the ROC curve was improved after adding hypocapnia into the model (0.872, 95% CI 0.839-0.901 vs. 0.855, 95% CI 0.820-0.886, P = 0.028). PaCO was correlated with the estimated glomerular filtration rate (r = 0.20, P = 0.001), left ventricular ejection fraction (r = 0.13, P < 0.001), B-type natriuretic peptide (r = -0.28, P < 0.001), and lactate (r = -0.15, P < 0.001). Kaplan-Meier curve of PaCO tertiles and multivariate Cox regression analysis showed that the lowest PaCO tertile was associated with increased risk of in-hospital mortality in AHF (all P < 0.05).
Hypocapnia is an independent predictor of in-hospital mortality for AHF.
急性心力衰竭（AHF）具有较高的死亡率和严重的并发症，对住院患者构成重大威胁。本研究旨在确定入院时低碳酸血症[定义为动脉二氧化碳分压（PaCO ）低于 35mmHg]是否与 AHF 住院全因死亡率相关。
回顾性分析了在冠心病监护病房因 AHF 接受治疗的 676 例患者，研究终点为住院全因死亡率。采用 1:1 倾向评分匹配（PSM）分析、Kaplan-Meier 曲线和 Cox 回归模型探讨低碳酸血症与 AHF 住院全因死亡率之间的关系。接受者操作特征（ROC）曲线和 Delong 检验用于评估低碳酸血症预测 AHF 住院全因死亡率的性能。研究队列包括 464 名（68.6%）男性和 212 名（31.4%）女性，中位年龄为 66 岁（四分位距 56-74 岁）。98 例（14.5%）患者在住院期间死亡，与幸存者相比，低碳酸血症患者的低碳酸血症发生率更高（76.5%比 45.5%，P<0.001）。对低碳酸血症和非低碳酸血症患者进行了 1:1 PSM，匹配后每组各有 264 例患者。与非低碳酸血症患者相比，低碳酸血症患者的院内死亡率在匹配前后均显著升高（分别为 22.2%比 6.8%，P<0.001；20.8%比 8.7%，P<0.001）。Kaplan-Meier 曲线显示低碳酸血症患者在 PSM 前后的院内死亡概率明显更高（对数秩检验的 P 值均<0.001）。多变量 Cox 回归分析显示，低碳酸血症是 AHF 死亡率的独立预测因子，在匹配前（风险比 [HR] 2.22；95%置信区间 [CI] 1.23-3.98；P=0.008）和匹配后（HR 2.19；95%CI 1.18-4.07；P=0.013）均如此。Delong 检验显示，在模型中加入低碳酸血症后，ROC 曲线下面积得到改善（0.872，95%CI 0.839-0.901 比 0.855，95%CI 0.820-0.886，P=0.028）。PaCO 与估算肾小球滤过率（r=0.20，P=0.001）、左心室射血分数（r=0.13，P<0.001）、B 型利钠肽（r=-0.28，P<0.001）和乳酸（r=-0.15，P<0.001）呈正相关。PaCO 三分位组的 Kaplan-Meier 曲线和多变量 Cox 回归分析显示，最低 PaCO 三分位组与 AHF 住院死亡率增加相关（均 P<0.05）。
低碳酸血症是 AHF 住院死亡率的独立预测因子。
