Comparison of Accuracy of Blood Pressure Measurement in Two-stage and One-stage Approach

The two-stage approach to measuring blood pressure has been widely accepted as the most accurate and reliable noninvasive method. But possible venous congestion induced with this method might result in inaccurate blood pressure reading. The aim of this study is comparison of two methods to determine most accurate approach. 52 patients in intensive care unit of open heart surgery was enrolled in this study. Study cases blood pressure was measured with mercury manometer and arm cuffs compatible with arm size, first by two-stage approach and at least after 3 minutes interval, using one-stage approach. Direct blood pressure consists of mean, systolic and diastolic blood pressure recorded immediately before noninvasive reading. Paired sample t test and Pearson correlation was used for data analysis. Mean bias for two two-stage approach was -4±7.49 (p<0.001) and for one-stage was -2.25±4.93 (p=0.002) in systolic pressure and in diastolic blood pressure the mean bias was 8.35±5.17 (p<0.001) for two-stage approach and 4.42±2.71 for one-stage approach (p<0.001). By contrast there was significant differences in accuracy of diastolic blood pressure reading of two methods (p<0.001). two-stage and one-stage approach tend to underestimate direct systolic blood pressure while there are no statistical difference between two methods. Both of methods tend to overestimate diastolic blood pressure, but one-stage approach is more accurate. So with considering one-stage approach is more accurate, it is recommended to use this method as noninvasive method.