A Comparison of Radial Artery Blood Pressure Determination Between the Vasotrac Device and Invasive Arterial Blood Pressure Monitoring in Adolescents Undergoing Scoliosis Surgery

Abstract

The Vasotrac device (Medwave, Arden Hills, MN) allows noninvasive measurement of arterial blood pressure (BP) and arterial waveform. We have previously demonstrated agreement between the Vasotrac and continuous intraarterial BP monitoring in children with a stable circulation after cardiac surgery in the cardiac intensive care unit. To assess this monitor during different physiologic conditions, we studied the Vasotrac in anesthetized adolescent children undergoing scoliosis surgery in the prone position, with or without controlled hypotension. Eleven children undergoing surgery for idiopathic scoliosis were enrolled in this study. The anesthetic consisted of primarily a nitrous oxide and narcotic technique with controlled hypotension obtained using IV labetalol. Data were analyzed using correlations, mean error, and Bland-Altman plots. Noninvasive BP measured by the Vasotrac correlated closely with intraarterial BP. Waveforms displayed by the two systems were qualitatively similar. Correlation between the two methods for systolic, diastolic and mean BP was r = 0.82, r = 0.83, and r = 0.90, respectively. We conclude that noninvasive BP measurement using the Vasotrac monitor enables near-continuous and reliable monitoring of BP during anesthesia in the prone position and pharmacologic-induced hypotension. The Vasotrac, a noninvasive arterial blood pressure monitor, performs well in the prone position in adolescent patients undergoing scoliosis surgery using a technique of mild-to-moderate induced hypotension.