Cardiac output measurements via echocardiography versus thermodilution: A systematic review and meta-analysis

Echocardiography, as a noninvasive hemodynamic evaluation technique, is frequently used in critically ill patients. Different opinions exist regarding whether it can be interchanged with traditional invasive means, such as the pulmonary artery catheter thermodilution (TD) technique. This systematic review aimed to analyze the consistency and interchangeability of cardiac output measurements by ultrasound (US) and TD. Five electronic databases were searched for studies including clinical trials conducted up to June 2019 in which patients’ cardiac output was measured by ultrasound techniques (echocardiography) and TD. The methodological quality of the included studies was evaluated by two independent reviewers who used the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2), which was tailored according to our systematic review in Review Manager 5.3. A total of 68 studies with 1996 patients were identified as eligible. Meta-analysis and subgroup analysis were used to compare the cardiac output (CO) measured using the different types of echocardiography and different sites of Doppler use with TD. No significant differences were found between US and TD (random effects model: mean difference [MD], -0.14; 95% confidence interval, -0.30 to 0.02; P = 0.08). No significant differences were observed in the subgroup analyses using different types of echocardiography and different sites except for ascending aorta (AA) (random effects model: mean difference [MD], -0.37; 95% confidence interval, -0.74 to -0.01; P = 0.05) of Doppler use. The median of bias and limits of agreement were -0.12 and ±0.94 L/min, respectively; the median of correlation coefficient was 0.827 (range, 0.140–0.998). Although the difference in CO between echocardiography by different types or sites and TD was not entirely consistent, the overall effect of meta-analysis showed that no significant differences were observed between US and TD. The techniques may be interchangeable under certain conditions.超声心动图（echocardiography）作为一种无创血流动力学评估技术，在重症患者中应用十分广泛。目前学界对于其能否与传统有创手段（如肺动脉导管热稀释法（TD））互换使用尚存争议。本系统综述旨在分析超声（US）与热稀释法测得的心输出量（CO）的一致性及互换性。我们检索了5个电子数据库，纳入截至2019年6月开展的、采用超声技术（超声心动图）与热稀释法测量患者心输出量（CO）的临床试验研究。由2名独立评价者采用依据本系统综述调整后的诊断准确性研究质量评价工具-2（QUADAS-2），使用Review Manager 5.3软件对纳入研究的方法学质量进行评估。最终共纳入68项研究，涉及1996名患者。我们采用Meta分析与亚组分析，对比不同类型超声心动图及不同多普勒检测位点测得的心输出量（CO）与热稀释法的结果差异。结果显示，超声与热稀释法整体无显著差异（随机效应模型：均数差[MD] = -0.14；95%置信区间：-0.30至0.02；P = 0.08）。在不同类型超声心动图及不同多普勒检测位点的亚组分析中，仅升主动脉（AA）亚组存在显著差异（随机效应模型：均数差[MD] = -0.37；95%置信区间：-0.74至-0.01；P = 0.05）。偏倚及一致性界限的中位数分别为-0.12 L/min与±0.94 L/min；相关系数的中位数为0.827（范围：0.140~0.998）。尽管不同类型或检测位点的超声心动图与热稀释法测得的心输出量（CO）差异并非完全一致，但Meta分析的整体效应显示，超声与热稀释法并无显著差异。二者在特定条件下可互换使用。