title: Pulsus paradoxus: an objective measure of severity in croup.
abstract: We used a noninvasive monitor of arterial pressure to determine the utility of pulsus paradoxus (PP) as an objective severity measure in croup. We performed a prospective, blinded comparison of PP in children with croup versus healthy control subjects, analyzed the relationship between PP and Westley croup score (WCS), and observed the effect of racemic epinephrine (RE) on PP and WCS in a subgroup of patients with severe 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 significant 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 significant 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 WCS. PP may have utility as a research tool to objectively measure the severity of upper airway obstruction in croup.
authors.affiliation: Brown University, Department of Pediatrics, Center for Statistical Sciences, Providence, Rhode Island.
authors.forename: D W
authors.initials: DW
authors.lastname: Steele
authors.forename: K A
authors.initials: KA
authors.lastname: Santucci
authors.forename: R O
authors.initials: RO
authors.lastname: Wright
authors.forename: R
authors.initials: R
authors.lastname: Natarajan
authors.forename: K K
authors.initials: KK
authors.lastname: McQuillen
authors.forename: G D
authors.initials: GD
authors.lastname: Jay
mesh_terms: D000293:Adolescent; D001794:Blood Pressure; D001993:Bronchodilator Agents / Q000494:pharmacology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003440:Croup / Q000145:classification* / Q000188:drug therapy / Q000503:physiopathology*; D004837:Epinephrine / Q000494:pharmacology; D006801:Humans; D011446:Prospective Studies; D011674:Pulse; D064705:Racepinephrine; D015203:Reproducibility of Results; D012119:Respiration; D012720:Severity of Illness Index; D016037:Single-Blind Method; D018709:Statistics, Nonparametric; D013599:Systole
chemical_list: D001993:Bronchodilator Agents; D064705:Racepinephrine; D004837:Epinephrine