Comparison of oscillometric(OM) versus the vasotrac™(VT) non-invasive blood pressure (BP) system in the non-paralyzed intensive care patient population - An efficacy study

Introduction: The new Vasotrac™(Medwave Inc., St. Paul, MN) is an accurate BP monitor utilizing a wrist sensor for the continual display of radial arterial waveform, BP and heart rate¹. In this study we determined its efficacy in nonparalyzed intensive care unit(ICU) patients and compared it to the OM cuff system. Methods: Following IRB approval and informed consent, 16 nonparalyzed ICU patients were studied Exclusion criteria included absence of a radial pulse, arm to arm BP difference, quadriplegia, and coma. VT and OM setup times and its concurrent BP and cycle times were recorded every 15 minutes for 6 hours. Associated complications and problems were recorded. Data were analyzed using paired T-tests, Fisher's exact test, linear regression analysis. P<0.05 was considered significant. Results: No complications were recorded with either device. Setup times were not different between the VT and OM systems (89.9±46.0 Vs 75.7±53.3 sec, p>0.20) The VT provided readings more rapidly (23.6±26.8 Vs 50.4±62.5 sec, p<0.001). The number of readjustments required were not different (VT 19/390 Vs OM 12/390 readings; p>0.20). OM BP correlated significantly (p<0.0001) with VT BP (systolic r = 0.60;diastotic r = 0.50 and mean r = 0.62). There was good agreement between OM and VT BP with 95% of mean BP differences within 12.8 mm Hg (see histogram). Histogram: Frequency Vs MAP differences between the VT and OM system. Dotted line indicates 95% confidence interval. Mean = 4.5±12.8 mm Hg. (Figure Presented) Conclusions: The VT provided readings more rapidly than the OM method without increasing application time or the frequency of readjustments. Earlier studies have reported its accuracy similar to invasive radial arterial BP¹. In this study we found that even OM cuff BP agreed and correlated with VT BP. Because the VT can noninvasively provide frequent (every 12-15 beats) BP monitoring with an arterial waveform, it should be a useful monitor to deliver care to critically ill patients in the ICU.