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

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 mu g 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 mu g 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 mu g 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 (r(2) = 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. Published by Elsevier Inc.