Datasheet1_Impact of central venous pressure during the first 24 h and its time-course on the lactate levels and clinical outcomes of patients who underwent coronary artery bypass grafting.docx

PurposePrevious studies have revealed that elevated mean central venous pressure (CVP) was associated with poor prognosis in specific patient groups. But no study explored the impact of mean CVP on prognosis of patients who underwent coronary artery bypass grafting surgery (CABG). The purpose of this study was to investigate the impacts of elevated CVP and its time-course on clinical outcomes of patients who underwent CABG and potential mechanisms.
MethodsA retrospective cohort study was performed based on the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. We first identified the CVP during specific period with the most predictive value. Patients were categorized into the low-CVP and high-CVP group on the basis of the cut-off value. A propensity score matching was used to adjust covariates. The primary outcome was a 28-day mortality. The secondary outcomes were 1-year mortality and in-hospital mortality, the length of intensive care unit (ICU) stay and hospitalization, acute kidney injury incidence, use of vasopressors, duration of ventilation and oxygen index, and lactate levels and clearance. Patients in the high-CVP group were categorized into the “second day CVP ≤ 13.46 mmHg” group and the “second day CVP > 13.46 mmHg” group, respectively, and the clinical outcomes were the same as before.
ResultsA total of 6,255 patients who underwent CABG were picked from the MIMIC-IV database, of which 5,641 CABG patients were monitored by CVP measurement during the first 2 days after ICU admission and 206,016 CVP records were extracted from the database. The mean CVP during the first 24 h was the most correlative and statistically significant for the 28-day mortality. The risk of the 28-day mortality was increased in the high-CVP group [OR 3.45 (95% CI: 1.77–6.70; p < 0.001)]. Patients with elevated CVP levels had worse secondary outcomes. The maximum of lactate levels and lactate clearance were also poor in the high-CVP group. For patients in the high-CVP group during the first 24 h, whose mean CVP during the second day lowered to less than the cut-off value, had better clinical outcomes.
ConclusionsAn elevated mean CVP during the first 24 h was correlated with poor outcomes in patients who underwent CABG. The potential mechanisms may be influencing the lactate levels and lactate clearance through the impact on afterload of tissue perfusion. Patients whose mean CVP during the second day dropped to less than the cut-off value had favorable prognosis.

研究目的：既往研究已证实，升高的平均中心静脉压（central venous pressure, CVP）与特定患者群体的不良预后存在关联，但目前尚无研究探讨平均CVP对接受冠状动脉旁路移植术（coronary artery bypass grafting surgery, CABG）患者预后的影响。本研究旨在分析升高的CVP及其时间进程对CABG患者临床结局的影响，并探究其潜在机制。
研究方法：本研究基于重症监护医学信息数据库IV（Medical Information Mart for Intensive Care IV, MIMIC-IV）开展回顾性队列研究。首先筛选出具有最佳预测价值的特定时段内的CVP数据，以截断值为界将患者分为低CVP组与高CVP组；采用倾向得分匹配法对混杂变量进行校正。本研究的主要结局为28天死亡率，次要结局包括1年死亡率、住院死亡率、重症监护病房（intensive care unit, ICU）停留时长与住院时长、急性肾损伤发生率、血管活性药物使用情况、通气时长与氧合指数，以及乳酸水平与乳酸清除率。此外，将高CVP组患者进一步分为次日CVP≤13.46 mmHg亚组与次日CVP>13.46 mmHg亚组，其结局评价指标与前述一致。
研究结果：本研究从MIMIC-IV数据库中共筛选出6255例行CABG的患者，其中5641例患者在ICU入住后前2天接受了CVP监测，共提取得到206016条CVP记录。分析显示，入院后前24小时的平均CVP与28天死亡率相关性最强且具有统计学意义。高CVP组患者的28天死亡风险显著升高[OR=3.45，95%CI: 1.77~6.70；p<0.001]。CVP升高患者的次要结局均更差，高CVP组患者的乳酸峰值水平与乳酸清除率亦表现不佳。对于前24小时处于高CVP状态的患者，若其次日平均CVP降至截断值以下，则临床结局更佳。
研究结论：ICU入住后前24小时的平均CVP升高与CABG患者的不良临床结局相关，其潜在机制可能通过影响组织灌注后负荷，进而干预乳酸水平与乳酸清除率。若患者次日平均CVP降至截断值以下，则预后更佳。