Analysis of physician ability in the measurement of pulsus paradoxus by sphygmomanometry

Context: Measurement of pulsus paradoxus (PP) is one of several measures pr eviously advocated in the National Heart, Lung, and Blood Institute asthma management guidelines: a pulsus of > 12 mm Hg warranted hospital admission. It is one of only a few measures that is not effort dependent and therefor e important in the evaluation of patients with asthma. Objective: Determination of physician accuracy in measuring PP. Design: A model of induced PP in a trained healthy subject without respirat ory disease was constructed with a fixed inspiratory resistance with measur ement of inspiratory air pressure and beat-to-beat BP noninvasively, Setting: Laboratory. Participants: Attending physicians from emergency medicine and critical car e disciplines who served as consecutive examiners of the trained reference subject generating known PP. Interventions: A total of 19 attending physicians were assessed for ability in measuring PP by sphygmomanometry and by palpation. The reference subjec t generated 4 degrees of PP sequentially, with each examiner blinded to the value of negative inspiratory pressure and PP, Examiners first assessed PP qualitatively by palpation, followed by its measurement within 2 min. Main outcome measure: Proximity of physician-measured PP (PPm) to true PP ( PPt). Results: At inspiratory pressures of -10, -15, -20, and -25 mm Hg, PP t was 13.7, 16.2, 19.1, and 20.7 mm Hg, respectively (F = 14.8, p < 0.0001; analysis of variance [ANOVA]). At the same pressures, PPm was 13.1, 17.5, 17.7, and 18.0 mm Hg (p > 0.10; ANOVA). Linear regression of PPm against PP t for each examiner revealed a slope (SE) of 0.53 (0.23), and not a 1:1 rel ationship. Conclusions: Past and present guidelines do not account for the challenges in measuring PP, especially in tachypneic patients. Sphygmomanometric deter mination of PP should be augmented by new aids developed through technologi cal innovation.