Helium-oxygen therapy for pediatric acute severe asthma requiring mechanical ventilation

Abstract

Objective: To illustrate the use of helium-oxygen gas mixtures as therapy for pediatric patients with acute severe asthma requiring conventional mechanical ventilation. Design: Retrospective review. Setting: Tertiary care children's teaching hospital. Patients: All mechanically ventilated patients with severe asthma admitted to the pediatric intensive care unit from August 1994 to October 2000. Interventions: Within 24 hrs of intubation or admission, patients were stabilized on volume ventilation, bronchodilator therapy, corticosteroids, and antibiotics when indicated. Hypercapnia was permitted while maintaining arterial blood gas pH ≥7.25. A helium-oxygen gas mixture then was begun with helium flow set at 5-7 L/min, and oxygen flow was titrated to maintain desired oxygen saturation. Only sedated, chemically paralyzed patients with adequate pre-helium-oxygen and post-helium-oxygen measurements were statistically analyzed. Measurements and Main Results: Twenty-eight mechanically ventilated patients with severe asthma placed on helium-oxygen gas mixtures were identified who met study entry criteria. Mean patient age was 8.8 yrs (range, 1.1-14.6). Before helium-oxygen therapy began, mean peak inspiratory pressure was 40.5 ± 4.2 cm H2O, mean arterial blood gas pH was 7.26 ± 0.05, and mean CO2 partial pressure was 58.2 ± 8.5 torr. After patients were placed on helium-oxygen therapy, there was a significant decrease in mean peak inspiratory pressure to 35.3 ± 3.0 cm H2O. Mean pH increased significantly to 7.32 ± 0.06, and mean partial pressure CO2 decreased significantly to 50.5 ± 7.4 torr. Initial mean inspired helium was 57 ± 4% (range, 32-74). Mechanical ventilation days ranged from 1 to 23 days (mean, 5.0). Hospital stay ranged from 4 to 29 days (mean, 10.1), with an average pediatric intensive care unit stay of 6.9 days (range, 2-24). There were two incidences of pneumothorax. Conclusions: In the pediatric patient with severe asthma requiring conventional mechanical ventilation, helium-oxygen administration appears to be a safe therapy and may assist in lowering peak inspiratory pressure and improving blood gas pH and partial pressure CO2. Copyright © 2003 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies.