Design
Prospective, masked assessment of the relationship between PP, peak expiratory flow rate, oxygen saturation, clinical scoring, and admission decisions.

Setting
An urban pediatric emergency department.

Patients
Children with acute asthma.

Interventions
Standardized treatment per National Heart, Lung, and Blood Institute guidelines.

Main Outcome Measures
Peak expiratory flow rate, oxygen saturation, pulmonary index score, and masked disposition decision.

Results
Significant positive correlations existed between PP and the pulmonary index score at the initial evaluation (r=0.44; P<.001) and after 30 minutes (r=0.51;

P<.001) and 60 minutes (r=0.45; P<.001). Significant negative correlations existed between PP and the percent predicted peak expiratory flow rate (r=–0.31; P=.01) and the oxygen saturation (r=–0.30; P=.02). The mean PP was significantly greater in patients who were admitted for further treatment at all time points (P=.003 or P=.002). At 30 minutes after presentation, a PP greater than 15 mm Hg predicted admission for further treatment or relapse; the sensitivity was 0.42, the specificity was 0.89, and the likelihood ratio was 3.86.

Conclusions
Our measurement technique for PP is a useful objective indicator of the severity of asthma. Pulsus paradoxus correlates with clinical score, peak expiratory flow rate, and oxygen saturation. Furthermore, an elevated PP is associated with the decision to admit a patient for further treatment. These results suggest that this technique may represent a useful research tool for the assessment of acute, severe asthma. Further development of the technology may allow for a clinical application.

Arch Pediatr Adolesc Med. 1996;150:914-918