Blood Pressure Measurement in Obese Patients

Arm Circumference, Shape, and Length: How Interplaying Variables Affect Blood Pressure Measurement in Obese Persons

“…In an unpublished study, McFarlane compared blood pressure measurements obtained in the forearm and upper arm using extralong versus appropriately-sized cuffs in patients with BMIs of 36 to 40. 10 Blood pressure was overestimated with the extra long cuff. Additionally, forearm blood pressure was closer to values obtained with a properly sized cuff on the upper arm (vs measurements with extra long cuffs).…”

“…7,8,18 When assessing blood pressure at alternative locations, it is essential to recognize that blood pressure varies appreciably in different parts of the arterial system, with SBP increasing in more distal arteries and DBP decreasinig. 23 Thus, because measurements of blood pressure in the forearm generally yield overestimates of SBP, DBP, and mean arterial pressure (MAP) compared with the upper arm (reported variances, 2.3-27 mm Hg), 10,14,[19][20][21]24,25 it is important to decide what discrepancy is clinically acceptable. 10,14,20 As McFarlane 10 described, a difference of ±5 mm Hg (standard deviation ≤8 mm Hg) is the standard used by the International Standards Organization and manufacturers that test noninvasive devices for measuring blood pressure against mercury sphygmo manometers.…”

“…7 In conclusion, consistent use of methods for measuring blood pressure is imperative for accurate yields a false underestimate of blood pressure (range of error, 10-30 mm Hg). 9,10 These anatomic challenges and the many cuff choices are compounded by the potential lack of consistent use of a particular cuff size between clinicians, further reducing the reliability of blood pressure values that guide critical treatment decisions. As a result, the following PICO (population, intervention, control, and outcomes) question was chosen for this clinical review: What is the most accurate method of assessing blood pressure in obese persons?…”

“…12 To complicate matters more, obese patients of small stature may have short upper arms. 10 Thus, if cuffs that are too wide are used (bladders too large), arm length poses a problem. Although thigh cuffs may be the best fit for the arm circumference, the distal cuff end will be too long, extending past the elbow/antecubital fossa.…”

“…9 Such "undercuffing" leads to overestimates of systolic blood pressure (SBP) and diastolic blood pressure (DBP; range of error, 2.4-30 mm Hg), resulting in erroneous classification of patients as hypertensive, leading to unnecessary therapy. [8][9][10] A regular feature of the American Journal of Critical Care, Clinical Evidence Review unveils available scientific evidence to answer questions faced in contemporary clinical practice. It is intended to support, refute, or shed light on health care practices where little evidence exists.…”