PULSUS PARADOXUS - AN OBJECTIVE-MEASURE OF SEVERITY IN CROUP

We used a noninvasive monitor of arterial pressure to determine the ut ility of pulsus paradoxus (PP) as an objective severity measure in cro up. We performed a prospective, blinded comparison of PP in children w ith croup versus healthy control subjects, analysed the relationship b etween PP and Westley croup score (WCS), and observed the effect of ra cemic epinephrine (RE) on PP and WCS in a subgroup of patients with se vere croup. The PP and WCS were measured at presentation and in severe patients after treatment with RE. Mean PP was 6.1 +/- 1.8 (SD) mm Hg (n = 29) in control subjects compared with a mean of 17.8 +/- 11.2 (SD ) mm Hg (n = 28) in patients with croup (p < 0.00001). There was signi ficant concordance between baseline WCS and PP (Spearman's rho: 0.68; p = 0.0001). The mean decrease in PP after RE was 7.5 +/- 11.8 (SD) mm Hg (p = 0.05; n = 12). The magnitude of decrease in PP after RE has s ignificant concordance with the concurrent decrease in WCS (Spearman's rho: 0.73; p < 0.007). PP is elevated in children with croup, and the magnitude of elevation correlates with severity as measured by the WC S. PP may have utility as a research tool to objectively measure the s everity of upper airway obstruction in croup.