Influence of patent ductus arteriosus and ventilators on electrical velocimetry for measuring cardiac output in very-low/low birth weight infants.

Abstract

We evaluated electrical velocimetry, a noninvasive method for continuous cardiac output measurement, in very-low and low birth weight infants and the influence of patent ductus arteriosus (PDA) and ventilators on this method. This prospective study compared 81 pairs of simultaneous cardiac output measurements by electrical velocimetry and transthoracic echocardiography in 28 patients. Data were compared by correlation, Bland-Altman analysis and two-way analysis of variance. The two methods exhibited a high correlation (r=0.859, P<0.0001). The bias (mean difference of the methods) and percent error (100 × 1.96 × s.d./mean cardiac output) were -6 ml min(-1) and 29.2%, respectively. PDA significantly affected the bias (P=0.0004), but ventilators did not (P=0.14). Hemodynamically significant PDA had a larger bias (-36 ml min(-1)) and higher percent error (38.6%). Although influenced by PDA, electrical velocimetry was generally interchangeable with transthoracic echocardiography even using ventilators.