[Comparison of invasive and non-invasive blood pressure in critically ill patients]

Objective: To investigate the difference of invasive and noninvasive blood pressure in systolic, diastolic and mean blood pressure (SBP, DBP and MAP) levels in critically ill patients. Methods: A total of 197 critically ill patients were enrolled in the intensive care unit of Peking Union Medical College Hospital in this prospective observative study. There were 113 males and 84 females with a mean age of (59±17) years. With Pearson correlation and Bland-Altman analysis, the difference and agreement of invasive and noninvasive blood pressure in SBP, DBP and MAP levels were investigated. Results: Invasive blood pressure monitoring was significantly correlated with noninvasive blood pressure (the correlation coefficients of SBP, DBP and MAP was 0.908, 0.861 and 0.888, respectively, all P<0.001). The mean bias and 95% confidence interval (CI) in SBP(invasive)-SBP(noninvasive), DBP(invasive)-DBP(noninvasive), MAP(invasive)-MAP(noninvasive) respectively was as following: SBP (14.5±11.9) mmHg (-8.8-37.8 mmHg); DBP (1.0±7.2) mmHg(-13.2-15.2 mmHg); MAP (10.5±8.3) mmHg (-5.9-26.8 mmHg). Moreover, there was a significant positive correlation between the bias of SBP(invasive)-SBP(noninvasive) and the value of SBP; when the SBP(invasive)≥143 mmHg was used to predict a value of bias≥20 mmHg, the sensitivity was 72.4% and specificity was 81.3%, and the area under the receiver operating characteristic curve was 0.808 (95% CI: 0.745-0.870). Conclusions: There is a good agreement between invasive and noninvasive blood pressure in critically ill patients, the bias of invasive-noninvasive blood pressure measurement is positively correlated to the value of blood pressure.