A new noninvasive method to measure blood pressure: Results of a multicenter trial

Background: Blood pressure (BP) monitoring with arterial waveform display requires an arterial cannula. We evaluated a new noninvasive device, Vasotrac (Medwave, Arden Hills, MN) that provides BP measurements approximately every 12-15 beats and displays pulse rate and a calibrated arterial waveform for each BP measurement. Methods: Surgical and critically ill patients (n = 80) served as subjects for the study. BPs, pulse waveforms, and pulse rates measured via a radial artery catheter were compared with those obtained by the Vasotrac from the opposite radial artery. Data were analyzed to determine agreement between the two systems of measurement. Results: Blood pressure measured noninvasively by the Vasotrac demonstrated excellent correlation (P < 0.01) with BP measured via a radial arterial catheter (systolic r² = 0.93; diastolic r² = 0.89; mean r² = 0.95). Differences in BP measured by the Vasotrac versus the radial arterial catheter were small. The mean ± SD bias and precision were as follows: systolic BP 0.02 ± 5.4 mmHg and 3.9 ± 3.7 mmHg; diastolic BP -0.39 ± 3.9 mmHg and 2.7 ± 2.8 mmHg; mean BP -0.21 ± 3.0 mm Hg and 2.1 ± 2.2 mmHg compared with radial artery measurements. The Vasotrac pulse rates were almost identical to those measured directly (r² = 0.95). The Vasotrac BP waveform resembled those directly obtained radial artery pulsatile waveforms Conclusions: In surgical and critically ill patients, the Vasotrac measured BP, pulse rate, and displayed radial artery waveform, which was similar to direct radial arterial measurements. It should be a suitable device to measure BP frequently in a noninvasive fashion.