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 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 < 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.

CONCLUSIONS

Intraoperative CO measurement using the Nexfin device has a strong correlation with CO measured by esophageal Doppler.