An evaluation of a new continuous blood pressure monitoring system in critically ill patients

Study Objective: To determine if the DxTek monitor, which is a device that measures blood pressure (BP) noninvasively and continuously by means of pul se velocity and wave shapes derived from the pulse oximeter optical plethys mograph and electrocardiogram is as accurate as an oscillometric cuff devic e when compared with intraarterial BP measurement. Design: Prospective, comparative study. Setting: University Medical Center. Patients: 28 intensive care unit patients. Interventions: Blood pressures were reported every minute by intraarterial catheters and DxTek and every 10 minutes by an oscillometric monitor for 2 to 5 hours. DxTek calibration was performed initially and when specified pa tient manipulations by caretakers were performed (on average, every 100 min utes). Comparisons with intraarterial pressure included: 1) DxTek calibrate d with arterial catheter pressure, 2) DxTek calibrated with oscillometric p ressure, and 3) oscillometric pressure. Measurements and Main Results: When comparing oscillometric pressure to int raarterial pressure, the averages of the mean differences (bias) were -4.0 mmHg for systolic (SBP) and < 1.5 mmHg for diastolic (DBP) and mean (MAP) p ressures. The averages of the standard deviation of the differences (precis ions) were 9.6, 6.4, and 6.3 mmHg, respectively. With the DxTek device cali brated to intraarterial pressure, comparison of the DxTek pressure to intra arterial pressure resulted in a bias <less than or equal to>0.5 mmHg for al l three pressures and an average precision of 10.1 mmHg for SBP, 6.0 mmHg f or DBP, and 6.7 mmHg for MAP. With the DxTek device calibrated to the oscil lometric pressure, the DxTek pressure compared to the intraarterial pressur e resulted in average biases of -5.1, -0.8, and -2.2 mmHg and average preci sions of 11.1, 7.7, and 8.1 mmHg for SBP, DBP and MAP, respectively. Conclusions: The DxTek monitor provides continuous, noninvasive BP measurem ents with an accuracy comparable to oscillometric devices. (C) 2000 by Else vier Science Inc.