Medical Intensive Care Unit and INSERM U1088, Amiens University Hospital, Amiens, France.
Medical-Surgical ICU, La Florida Dr. Eloisa Diaz Insunza Hospital, Santiago, Chile.
Crit Care. 2017 Jun 9;21(1):136. doi: 10.1186/s13054-017-1737-7.
Cardiac output (CO) monitoring is a valuable tool for the diagnosis and management of critically ill patients. In the critical care setting, few studies have evaluated the level of agreement between CO estimated by transthoracic echocardiography (CO-TTE) and that measured by the reference method, pulmonary artery catheter (CO-PAC). The objective of the present study was to evaluate the precision and accuracy of CO-TTE relative to CO-PAC and the ability of transthoracic echocardiography to track variations in CO, in critically ill mechanically ventilated patients.
Thirty-eight mechanically ventilated patients fitted with a PAC were included in a prospective observational study performed in a 16-bed university hospital ICU. CO-PAC was measured via intermittent thermodilution. Simultaneously, a second investigator used standard-view TTE to estimate CO-TTE as the product of stroke volume and the heart rate obtained during the measurement of the subaortic velocity time integral.
Sixty-four pairs of CO-PAC and CO-TTE measurements were compared. The two measurements were significantly correlated (r = 0.95; p < 0.0001). The median bias was 0.2 L/min, the limits of agreement (LOAs) were -1.3 and 1.8 L/min, and the percentage error was 25%. The precision was 8% for CO-PAC and 9% for CO-TTE. Twenty-six pairs of ΔCO measurements were compared. There was a significant correlation between ΔCO-PAC and ΔCO-TTE (r = 0.92; p < 0.0001). The median bias was -0.1 L/min and the LOAs were -1.3 and +1.2 L/min. With a 15% exclusion zone, the four-quadrant plot had a concordance rate of 94%. With a 0.5 L/min exclusion zone, the polar plot had a mean polar angle of 1.0° and a percentage error LOAs of -26.8 to 28.8°. The concordance rate was 100% between 30 and -30°. When using CO-TTE to detect an increase in ΔCO-PAC of more than 10%, the area under the receiving operating characteristic curve (95% CI) was 0.82 (0.62-0.94) (p < 0.001). A ΔCO-TTE of more than 8% yielded a sensitivity of 88% and specificity of 66% for detecting a ΔCO-PAC of more than 10%.
In critically ill mechanically ventilated patients, CO-TTE is an accurate and precise method for estimating CO. Furthermore, CO-TTE can accurately track variations in CO.
心输出量（CO）监测是诊断和治疗危重病患者的一种有价值的工具。在重症监护环境中，很少有研究评估经胸超声心动图（CO-TTE）估计的 CO 与参考方法（肺动脉导管（CO-PAC））测量的 CO 之间的一致性水平。本研究的目的是评估 CO-TTE 相对于 CO-PAC 的精密度和准确性，以及经胸超声心动图在机械通气的危重病患者中监测 CO 变化的能力。
对 38 例机械通气并安置 PAC 的患者进行前瞻性观察研究，该研究在一所拥有 16 张床位的大学医院 ICU 进行。CO-PAC 通过间歇热稀释法进行测量。同时，第二名研究人员使用标准视图 TTE 测量心输出量，将心输出量估计为亚主动脉速度时间积分测量期间获得的每搏量和心率的乘积。
比较了 64 对 CO-PAC 和 CO-TTE 测量值。两种测量值呈显著相关（r=0.95；p<0.0001）。中位偏倚为 0.2 L/min，一致性界限（LOA）为-1.3 和 1.8 L/min，百分比误差为 25%。CO-PAC 的精密度为 8%，CO-TTE 的精密度为 9%。比较了 26 对ΔCO 测量值。ΔCO-PAC 和 ΔCO-TTE 之间存在显著相关性（r=0.92；p<0.0001）。中位偏倚为-0.1 L/min，LOA 为-1.3 和+1.2 L/min。使用 15%排除区时，四象限图的符合率为 94%。使用 0.5 L/min 的排除区时，极坐标图的平均极角为 1.0°，百分比误差 LOA 为-26.8 至 28.8%。30 到-30 之间的符合率为 100%。当使用 CO-TTE 检测 CO-PAC 的 ΔCO 增加超过 10%时，接受者操作特征曲线下面积（95%CI）为 0.82（0.62-0.94）（p<0.001）。ΔCO-TTE 超过 8%可检测到 CO-PAC 的 ΔCO 增加超过 10%，其敏感性为 88%，特异性为 66%。
在机械通气的危重病患者中，CO-TTE 是一种准确且精确的 CO 估计方法。此外，CO-TTE 可以准确地跟踪 CO 的变化。
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