Comparison of noninvasive cardiac output measurements using the Nexfin monitoring device and the esophageal Doppler

Abstract Study Objective To evaluate the validity of cardiac output (CO) measurements obtained using the Nexfin device in comparison to those obtained with the esophageal Doppler in steady-state conditions and after phenylephrine administration. Design Prospective observational study. Setting Operating room of a North American academic medical center. Patients 25 ASA physical status 1, 2, and 3 patients referred for abdominal or orthopedic surgeries. Interventions After endotracheal intubation, patients who presented with a 20% or greater decrease in mean arterial pressure (MAP) received an intravenous (IV) bolus of 100 μg of phenylephrine. If MAP was still 20% lower than the patient's baseline level at least 10 minutes after the first vasopressor treatment, a second bolus of 100 μg of phenylephrine was given. Measurements CO was measured simultaneously by esophageal Doppler (COED ) and Nexfin (CONXF ) at baseline and when blood pressure peaked after an IV 100 μg phenylephrine bolus. Comparisons were then made between the two devices to evaluate the ability of the Nexfin device to track changes in CO. Main Results 66 pairs of data were obtained. Mean COED and CONXF were 4.7 ± 1.8 L/min and 5.6 ± 2.0 L/min, respectively. There was a significant relationship between COED and CONXF (r2 = 0.82; P < 0.001). The agreement between COED and CONXF was 0.88 ± 0.86 L/min (Bland Altman). The mean percent error (Critchley and Critchley) of CONXF versus COED was 37%. Trending analysis found a 94% concordance between changes in COED and CONXF after phenylephrine administration. Conclusions Intraoperative CO measurement using the Nexfin device has a strong correlation with CO measured by esophageal Doppler.