Blood Pressure Difference Between Arms

Singer and Hollander¹ describe an approximately 50% prevalence in systolic or diastolic interarm blood pressure (BP) difference of more than 10 mm Hg. Although their assertion that BP ought be measured in both arms is beyond argument, their results are better explained by differences between measurements than between arms. An alert reaction to BP measurement has been well described,² and the question of how to measure BP was recently reviewed by Reeves,³ who was quoted by Singer and Hollander but whose recommendations were somewhat overlooked. The finding of slightly higher BP in the right arm is consistent with this possibility, ie, the difference between measurements, as the right arm is more frequently approached first. Even the "almost simultaneous measurements" may overlook the difference, as these alert reactions abate immediately on cuff deflation (see Figure 2 in Mejia et al⁴). Emergency department BP determinations are notoriously exaggerated,