Can transthoracic echocardiography be used to predict fluid responsiveness in the critically ill patient? A systematic review

Abstract

Introduction. We systematically evaluated the use of transthoracic echocardiography in the assessment of dynamic markers of preload to predict fluid responsiveness in the critically ill adult patient. Methods. Studies in the critically ill using transthoracic echocardiography (TTE) to predict a response in stroke volume or cardiac output to a fluid load were selected. Selection was limited to English language and adult patients. Studies on patients with an open thorax or abdomen were excluded. Results. The predictive power of diagnostic accuracy of inferior vena cava diameter and transaortic Doppler signal changes with the respiratory cycle or passive leg raising in mechanically ventilated patients was strong throughout the articles reviewed. Limitations of the technique relate to patient tolerance of the procedure, adequacy of acoustic windows, and operator skill. Conclusions. Transthoracic echocardiographic techniques accurately predict fluid responsiveness in critically ill patients. Discriminative power is not affected by the technique selected.

Figure 1

The physiological explanation for the changes in stroke volume and IVC diameter caused by mechanical ventilation. RV right ventricle, LV left ventricle, SV_max⁡ and SV_min⁡ maximum and minimum stroke volume, RAP right atrial pressure, IAP intraabdominal pressure, IVC D _max⁡ and IVC_min⁡ maximum and minimum inferior vena cava diameter during the cycle. ^aThe pulmonary transit time represents the time taken for blood to travel through the pulmonary circulation. ^bSV is the product of the velocity-time integral (area under the Doppler signal curve) and the diameter of the vessel at the point the reading was taken.

Figure 2

Citation filtering process.

Figure 3

The stages of the two different methods of passive leg raising. CO cardiac output, SV stroke volume. ^aMeasurements at this stage were not taken in one study (Maizel).