Blood Pressure Measurement in Severely Obese Patients: Validation of the Forearm Approach in Different Arm Positions

Blood pressure measurement in severe obesity may be technically challenging as the cuff of the device may not fit adequately around the upper arm. The aim of the study was to assess the agreement between intra-arterial blood pressure values (gold standard) compared with forearm blood pressure measurements in severely obese patients in different arm positions.

Thirty-three severely obese patients and 21 controls participated in the study. Pairs of intra-arterial blood pressures were compared with simultaneous forearm blood pressure measurement using an oscillometric device in 4 positions: (i) supine, (ii) semi-fowler with the forearm resting at heart level, (iii) semi-fowler with the arm downward, and (iv) semi-fowler with the arm raised overhead. Degree of agreement between measurements was assessed.

Overall, correlations of systolic and diastolic blood pressure measurements between the gold standard and forearm blood pressure were 0.95 (n = 722; P < 0.001) and 0.89 (n = 482; P < 0.001), respectively. Systolic blood pressure measured using the forearm approach in the supine and the semi-fowler positions with arm downward showed the best agreement when compared with the gold standard (-4 ± 11 (P < 0.001) and 2 ± 14 mm Hg (P = 0.19), respectively). In the control group, better agreement was found between the supine and semi-fowler positions with the arm resting at heart level (1 ± 9 mm Hg (P = 0.29) and -3 ± 10 mm Hg (P = 0.01), respectively).

Forearm systolic blood pressure consistently agreed with the gold standard in the supine position. This method can be of use in clinical settings when upper-arm measurement is challenging in severe obesity.