Continuous, noninvasive measurement of pulsus paradoxus in patients with acute asthma
R. O. Wright, D. W. Steele, K. A. Santucci, R. Natarajan and G. D. Jay
Department of Pediatrics, Brown University School of Medicine, Providence, RI, USA.
OBJECTIVE: To evaluate a continuous, noninvasive measurement technique for
pulsus paradoxus (PP) as an objective asthma severity indicator. 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.
