Accuracy and trending of non-invasive oscillometric blood pressure monitoring at the wrist in obese patients

Abstract

BackgroundIn obese patients, non-invasive blood pressure monitoring in the arm is difficult due to the arm size and morphology. We compared the non-invasive oscillometric wrist blood pressure measurement with the arm and forearm in obese patients monitored with invasive radial blood pressure (reference standard). MethodsThis prospective observational study included adult obese patients scheduled for bariatric surgery. Non-invasive blood pressure was measured at the arm, upper forearm and wrist of one upper extremity, while invasive blood pressure was simultaneously measured through a radial arterial catheter in the contralateral upper extremity. The accuracy of non-invasive blood pressure reading at each site was evaluated for absolute and trending values using the Bland–Altman analysis and Spearman's correlation coefficient. ResultsIn 40 patients, 262, 259, and 263 pairs of non-invasive blood pressure readings were obtained from the arm, forearm, and wrist sites, respectively. As primary outcome, the correlation coefficient for systolic blood pressure was higher for the wrist (0.92, 95% confidence interval (CI) [0.9–0.94]) than for the arm (0.74, 95% CI [0.68–0.79]) and the forearm (0.71, 95% CI [0.64–0.76]) (P<0.05). The non-invasive systolic wrist blood pressure showed the least mean bias and the narrowest limits of agreement (−0.3±7.6mmHg) when compared with forearm (4.3±16) and arm measurements (14.2±13.6) (P<0.05). For trending values, the correlation coefficient was the highest at the wrist. ConclusionIn obese patients undergoing bariatric surgery, non-invasive blood pressure measured at the wrist showed the highest accuracy in comparison with the arm and forearm.