The validity of trans-esophageal Doppler ultrasonography as a measure of cardiac output in critically ill adults.

Abstract

To determine the validity of the esophageal Doppler monitor (EDM) and echo-esophageal Doppler (Echo-ED) in measuring cardiac output in the critically ill. Systematic search of relevant international literature and data synthesis. Literature search (1989-2003) using Ovid interface to Medline, Embase and Cochrane databases aimed at finding studies comparing EDM or Echo-ED cardiac output with that derived from simultaneous pulmonary artery thermodilution (PAC(TD)) with Bland Altman measures of validity. Critically ill adults in operating departments or intensive care units. Summary validity measures synthesized from Bland Altman analyses included pooled median bias and the median percentage of clinical agreement (PCA) derived from the limits of agreement. Eleven validation papers for EDM (21 studies) involving 314 patients and 2,400 paired measurements. The pooled median bias for PAC(TD) versus EDM was 0.19 l/min (range -0.69 to 2.00 l/min) for cardiac output (16 studies), and 0.6% (range 0-2.3%) for changes in cardiac output (5 studies). The pooled median percentage of clinical agreement for PAC(TD) versus EDM was 52% (interquartile range 42-69%) for cardiac output and 86% (interquartile range 55-93%) for changes in cardiac output. These differences in PCA were significant ( p=0.03 Mann-Whitney) for bolus PAC(TD) as the clinical "gold standard". We found an insufficient number of studies (2 papers) to assess the validity of Echo-ED. The esophageal Doppler monitor has high validity (no bias and high clinical agreement with pulmonary artery thermodilution) for monitoring changes in cardiac output.