Department of Anesthesiology and Reanimation, University of Health Sciences, İzmir Bozyaka Training and Research Hospital, İzmir-Türkiye.
Department of Neurology, University of Health Sciences, İzmir Bozyaka Training and Research Hospital, İzmir-Türkiye.
Ulus Travma Acil Cerrahi Derg. 2024 Feb;30(2):90-96. doi: 10.14744/tjtes.2024.37309.
In critically ill patients, especially those with septic shock, fluid management can be a challenging aspect of clinical care. One of the primary steps in treating patients with hemodynamic instability is optimizing intravascular volume. The Passive Leg Raising (PLR) maneuver is a reliable test for assessing fluid responsiveness, as demonstrated by numerous studies and meta-analyses. However, its use requires the measurement of cardiac output, which is often complex and may necessitate clinician experience and specialized equipment. End-Tidal Carbon Dioxide (ETCO2) measurement is relatively easy and is generally stable under steady metabolic conditions. It depends on the body's CO2 production, diffusion of CO2 from the lungs into the bloodstream, and cardiac output. If the other two parameters (metabolic conditions and minute ventilation) are constant, ETCO2 can provide information about cardiac output. The aim of the present study is to investigate the sensitivity of ETCO2 measurement in demonstrating fluid responsiveness.
All patients diagnosed with septic shock and meeting the inclusion criteria were subjected to a passive leg raising test, and cardiac outputs were measured by echocardiography. An increase in cardiac output of 15% or more was considered indicative of the fluid responder group, while patients with an increase below 15% or no increase were classified as the non-responder group. Patients' intensive care unit admission diagnoses, initial laboratory parameters, tidal volume, minute volume before and after the PLR maneuver, mean and systolic blood pressure, heart rate, Pulse Pressure Variation (PPV) values, and ETCO2 values were recorded.
Before and after the ETCO2 test, there was no statistically significant difference between the two groups. However, the change in ETCO2 (ΔETCO2) was significantly higher in the responder group. In the non-responder group, ΔETCO2 was 2.57% (0.81), whereas it was 5.71% (2.83) in the responder group (p<0.001). Receiver Operating Characteristic (ROC) analysis was performed for ΔETCO2, baseline Stroke Volume Variation (SVV), ΔSVV, baseline Heart Rate (HR), ΔHR, baseline PPV, and ΔPPV to predict fluid responsiveness. ΔETCO2 predicted fluid responsiveness with a sensitivity of 85% and a specificity of 86% when it was 4% or higher. When ΔETCO2 was 5% or higher, it predicted fluid responsiveness with a specificity of 99.3% and a sensitivity of 75.5%, with an Area Under the Curve (AUC) of 0.89 (95% confidence interval, 0.828-0.961).
This study demonstrates that in septic patients, ETCO2 during the PLR test can indicate fluid responsiveness with high sensitivity and specificity and can be used as an alternative to cardiac output measurement.
在危重症患者中，尤其是合并感染性休克的患者，液体管理是临床治疗中极具挑战性的方面之一。治疗血流动力学不稳定患者的首要步骤之一是优化血管内容量。被动抬腿试验（PLR）是评估液体反应性的可靠试验，许多研究和荟萃分析已经证实了这一点。然而，其应用需要测量心输出量，而心输出量的测量往往较为复杂，并且可能需要临床医生的经验和专门设备。呼气末二氧化碳（ETCO2）的测量相对简单，在稳定代谢条件下通常较为稳定。它取决于机体的 CO2 产生、CO2 从肺部扩散到血液中以及心输出量。如果其他两个参数（代谢条件和分钟通气量）保持不变，ETCO2 可以提供心输出量的信息。本研究旨在探讨 ETCO2 测量在显示液体反应性方面的敏感性。
所有诊断为感染性休克且符合纳入标准的患者均接受被动抬腿试验，并通过超声心动图测量心输出量。心输出量增加 15%或以上被认为是液体反应者组，而心输出量增加低于 15%或无增加的患者被归类为非反应者组。记录患者的重症监护病房入院诊断、初始实验室参数、PLR 前和后的潮气量、分钟通气量、平均和收缩压、心率、脉压变异（PPV）值和 ETCO2 值。
在 ETCO2 试验前后，两组之间没有统计学上的显著差异。然而，反应者组的 ETCO2 变化（ΔETCO2）明显更高。在非反应者组中，ΔETCO2 为 2.57%（0.81），而在反应者组中为 5.71%（2.83）（p<0.001）。对 ΔETCO2、基线每搏量变异（SVV）、ΔSVV、基线心率（HR）、ΔHR、基线 PPV 和 ΔPPV 进行了接收者操作特征（ROC）分析，以预测液体反应性。当 ΔETCO2 为 4%或更高时，其预测液体反应性的敏感性为 85%，特异性为 86%。当 ΔETCO2 为 5%或更高时，其预测液体反应性的特异性为 99.3%，敏感性为 75.5%，曲线下面积（AUC）为 0.89（95%置信区间，0.828-0.961）。
本研究表明，在感染性休克患者中，PLR 期间的 ETCO2 可以以较高的敏感性和特异性指示液体反应性，并且可以作为心输出量测量的替代方法。
