Liu Xinqiang, Wen Miaoyun, Ding Hongguang, Chen Shenglong, Li Ya, Li Xusheng, Zeng Hongke
Department of Emergency and Critical Care Medicine, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Guangzhou 510080, Guangdong, China. Corresponding author: Zeng Hongke, Email:
Zhonghua Wei Zhong Bing Ji Jiu Yi Xue. 2020 May;32(5):564-569. doi: 10.3760/cma.j.cn121430-20200122-00099.
To investigate the effect of hypercapnia at admission on the clinical prognosis and the severity of infection in patients with severe community-acquired pneumonia (SCAP).
The clinical data of 219 SCAP patients admitted to the department of emergency and critical care medicine of Guangdong Provincial People's Hospital from December 2017 to November 2019 were retrospectively analyzed. Based on the partial pressure of arterial carbon dioxide (PaCO) within 1 day after admission, the patients were divided into hypocapnia group [HO group, PaCO < 35 mmHg (1 mmHg = 0.133 kPa)], normal carbonation group (NC group, PaCO 35-45 mmHg) and hypercapnia group (HC group, PaCO > 45 mmHg). The clinical parameters of patients, such as gender, age, underlying diseases, white blood cell (WBC), procalcitonin (PCT), C-reactive protein (CRP), interleukin-6 (IL-6), pH value and lactate (Lac) within 1 day after admission were reviewed. The oxygenation index (PaO/FiO), pneumonia severity index (PSI) score and acute physiology and chronic health evaluation II (APACHE II) score were evaluated. The change tendencies of each index on day 1, day 3, and day 5 after admission were observed subsequently. Meanwhile, the rate of invasive mechanical ventilation (IMV), length of hospital stays and 28-day mortality among three groups were compared. Kaplan-Meier survival analysis was performed to assess the 28-day cumulative survival rate of patients with SCAP among three groups. Multivariate Logistic regression analysis was used to screen the risk factors of IMV and 28-day death in patients with SCAP.
Compared with the HO group (n = 68) and NC group (n = 72), the HC group (n = 79) had higher proportion of preexisting comorbid chronic obstructive pulmonary disease (COPD) and PSI score, lower PCT, CRP, IL-6, and pH values. Compared with the HO group and NC group, there were smaller improvement trends on the levels of WBC, PCT, CRP, IL-6, PaO/FiO and Lac at day 3 and day 5 as compared with day 1 in the HC group. On the 5th day after admission, the levels of WBC, PCT, CRP, IL-6, and Lac in the HC group were significantly higher than those in the HO group and NC group [WBC (×10/L): 18.33±1.44 vs. 10.89±2.37, 11.15±1.74; PCT (μg/L): 5.04±1.18 vs. 3.46±0.87, 3.58±0.83; CRP (mg/L): 78.43±7.17 vs. 54.24±4.97, 57.93±5.39; IL-6 (ng/L): 75.35±11.92 vs. 60.11±10.27, 57.88±12.34; Lac (mmol/L): 4.36±1.24 vs. 0.78±0.39, 0.86±0.64; all P < 0.01], and the lowest in PaO/FiO was found in the HC group as compared with the HO and NC groups (mmHg: 171.31±6.73 vs. 226.68±7.36, 225.93±6.92, both P < 0.01). Compared with the HO group and NC group, the HC group had highest proportion of IMV (29.1% vs. 22.1%, 22.2%, both P < 0.01) and 28-day mortality (26.6% vs. 13.2%, 13.9%, both P < 0.01). Even when the patients with COPD were excluded from the analysis, the differences persisted among the groups. Kaplan-Meier survival analysis suggested that HC group had a higher 28-day cumulative survival rate as compared with the HO and NC groups (Log-Rank test: χ = 4.976, P = 0.026; χ = 4.629, P = 0.031). Multivariate Logistic regression analysis showed that IL-6, PSI score and hypercapnia within 1 day and PCT on the 5th day after admission were the independent risk factors of requiring IMV and 28-day death in patients with SCAP [odds ratio (OR) were 0.325, 1.229, 1.396, 1.313, respectively, all P < 0.01]. Even when patients with COPD were excluded from the analysis, the above results had not been changed.
Hypercapnia at admission was associated with higher proportion of IMV and 28-day mortality in patients with SCAP, which may be related to its early suppression of inflammation and then increment of infection.
探讨入院时高碳酸血症对重症社区获得性肺炎（SCAP）患者临床预后及感染严重程度的影响。
回顾性分析2017年12月至2019年11月在广东省人民医院急诊与重症医学科收治的219例SCAP患者的临床资料。根据入院后1天内动脉血二氧化碳分压（PaCO₂），将患者分为低碳酸血症组[HO组，PaCO₂<35 mmHg（1 mmHg = 0.133 kPa）]、正常碳酸血症组（NC组，PaCO₂ 35 - 45 mmHg）和高碳酸血症组（HC组，PaCO₂>45 mmHg）。回顾患者入院后1天内的临床参数，如性别、年龄、基础疾病、白细胞（WBC）、降钙素原（PCT）、C反应蛋白（CRP）、白细胞介素-6（IL-6）、pH值和乳酸（Lac）。评估氧合指数（PaO₂/FiO₂）、肺炎严重程度指数（PSI）评分和急性生理与慢性健康状况评估II（APACHE II）评分。随后观察入院后第1天、第3天和第5天各指标的变化趋势。同时，比较三组患者有创机械通气（IMV）率、住院时间和28天死亡率。采用Kaplan-Meier生存分析评估三组SCAP患者的28天累积生存率。采用多因素Logistic回归分析筛选SCAP患者IMV和28天死亡的危险因素。
与HO组（n = 68）和NC组（n = 72）相比，HC组（n = 79）既往合并慢性阻塞性肺疾病（COPD）的比例和PSI评分更高，PCT、CRP、IL-6和pH值更低。与HO组和NC组相比，HC组在第3天和第5天WBC、PCT、CRP、IL-6、PaO₂/FiO₂和Lac水平较第1天的改善趋势更小。入院后第5天，HC组WBC、PCT、CRP、IL-6和Lac水平显著高于HO组和NC组[WBC（×10⁹/L）：18.33±1.44 vs. 10.89±2.37，11.15±1.74；PCT（μg/L）：5.04±1.18 vs. 3.46±0.87，3.58±0.83；CRP（mg/L）：78.43±7.17 vs. 54.24±4.97，57.93±5.39；IL-6（ng/L）：75.35±11.92 vs. 60.11±10.27，57.88±12.34；Lac（mmol/L）：4.36±1.24 vs. 0.78±0.39，0.86±0.64；均P < 0.01]，且HC组PaO₂/FiO₂低于HO组和NC组（mmHg：171.31±6.73 vs. 226.68±7.36，225.93±6.92，均P < 0.01）。与HO组和NC组相比，HC组IMV比例最高（29.1% vs. 22.1%，22.2%，均P < 0.01），28天死亡率最高（26.6% vs. 13.2%，13.9%，均P < 0.01）。即使在分析中排除COPD患者，各组间差异仍然存在。Kaplan-Meier生存分析表明，HC组28天累积生存率高于HO组和NC组（Log-Rank检验：χ² = 4.976，P = 0.026；χ² = 4.629，P = 0.031）。多因素Logistic回归分析显示，IL-6、PSI评分、入院后1天内高碳酸血症及入院后第5天PCT是SCAP患者需要IMV和28天死亡的独立危险因素[比值比（OR）分别为0.３25、1.229、1.396、1.313，均P < 0.01]。即使在分析中排除COPD患者，上述结果仍未改变。
入院时高碳酸血症与SCAP患者较高的IMV比例和28天死亡率相关，这可能与其早期抑制炎症进而加重感染有关。
