Effect of the anthropometric characteristics of the arm on blood pressure measurement in the obese
Year: 2017
Type: article
Abstract: BACKGROUND The type of cuff that should be used for blood pressure measurement in the obese is still the subject of debate. The problem is even more controversial in people with morbid obesity due to the pronounced tronco-conical shape of the upper arm. OBJECTIVES In this study we investigated the effect of the shape of the cuff on blood pressure measurement in obese subjects with arm circumference > 42 cm by comparing the blood pressure readings obtained with a cylindrical and a tronco-conical cuff with the same width. MATERIAL AND METHODOS We enrolled 33 obese subjects (mean BMI, 45 ± 5 kg/m2) with arm circumference between 42 and 50 cm (mean 44.8 ± 2.7 cm ). In each subject, body weight and height, upper arm length, proximal, medial and distal circumference, biceps and triceps skinfold, and blood pressure at enrolment were measured. From the proximal and distal arm circumference and the arm length the slant angle (in degrees) of the truncated cone was calculated. Two cuffs and bladders of different shape (cylindrical and conical) of proper fit were built following the recommendations of the American Heart Association. The tronco-conical cuff had a 85.5° slant angle (bladder had proximal and distal length, respectively, of 45 and 35 cm). Sequential same-arm measurements were performed in triplicate by two observers using the two cuffs in a random order. The obese subjects (group 2) were compared with a group of individuals with normal upper arm circumference (< 32 cm, group 1). In group 2, the pressure transmitted to the arm surface under the centre of the two cuffs was also measured using a paper thin sensor. RESULTS The blood pressure differences between the two cuffs were negligible in group 1. In contrast, in the obese subjects of Group 2 the systolic blood pressure (SBP) and diastolic blood pressure (DBP) differences were 4.8±4.0 and 3.0±4.3 mmHg, respectively, and were significantly greater than in the control group (SBP, p< 0.001 and DBP, p=0.01, after adjustment for age an sex). These differences remained significant also after adjustment for BP at enrolment (p< 0.001/0.01). Among the obese participants, in a multivariable linear regression that included sex, age, height, upper arm length and systolic blood pressure, upper arm slant angle was an independent predictor of the between-cuff SBP difference (p=0.003). A close correlation was found between SBP at enrolment and the measurement error with the cylindrical cuff (r=0.55, p<0.001). In the subjects of the top SBP quintile (SBP≥150 mmHg), the between-cuff SBP difference was particularly elevated, being 9.1±5.1 mmHg. Measurement of BP under the cuffs with the pressure sensor revealed that there was a loss of pressure under the cylindrical cuff which was proportional to the BP applied, with a mean difference of -10.2 ± 5.2 mmHg. CONCLUSIONS In people with morbid obesity, the upper arm has a pronunced tronco-conical shape and cylindrical cuffs may overestimate the true pressure especially in people with high SBP. Tronco-conical cuffs should be used for blood pressure measurement in individuals with very large arms.
Author: Elisabetta Benetti
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2906409941