Original Contribution Comparison of noninvasive cardiac output measurements using the Nexfin monitoring device and the esophageal Doppler ☆ Guo Chen MD, PhD (Visiting Scholar, Attending) a,b , Lingzhong Meng MD (Assistant Clinical Professor) a , Brenton Alexander BS (Junior Specialist) c , Nam Phuong Tran BS (Medical Student) c , Zeev N. Kain MD, MBA (Professor and Chair) a , Maxime Cannesson MD, PhD (Associate Professor) a, ⁎ a Department of Anesthesiology & Perioperative Care, University of California, Irvine, CA 92868, USA b Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610041, P. R. China c School of Medicine, University of California, Irvine, CA 92868, USA Received 16 February 2011; revised 4 August 2011; accepted 10 August 2011 Keywords: Cardiac output; Esophageal Doppler; Nexfin; Phenylephrine 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 (CO ED ) and Nexfin (CO NXF ) 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 CO ED and CO NXF were 4.7 ± 1.8 L/min and 5.6 ± 2.0 L/min, respectively. There was a significant relationship between CO ED and CO NXF (r 2 = 0.82; P b 0.001). The agreement between CO ED and CO NXF was 0.88 ± 0.86 L/min (Bland Altman). The mean percent error (Critchley and Critchley) of CO NXF versus CO ED was 37%. Trending analysis found a 94% concordance between changes in CO ED and CO NXF after phenylephrine administration. ☆ Supported by departmental funding only. ⁎ Correspondence: Maxime Cannesson, MD, PhD, Department of Anesthesiology & Perioperative Care, University of California, Irvine, 101 The City Drive South, Bldg. 53, Rt. 81A, Rm. 227, Orange, CA 92868, USA. E-mail address: maxime_cannesson@hotmail.com (M. Cannesson). 0952-8180/$ – see front matter. Published by Elsevier Inc. doi:10.1016/j.jclinane.2011.08.014 Journal of Clinical Anesthesia (2012) 24, 275–283