INHALED HELIUM-OXYGEN REVISITED - EFFECT OF INHALED HELIUM-OXYGEN DURING THE TREATMENT OF STATUS-ASTHMATICUS IN CHILDREN

Objectives: To assess the effects of breathing a low-density gas mixtu re on dyspnea and the pulsus paradoxus in children with status asthmat icus. Design: In an urban academic tertiary referral center, 18 patien ts, aged 16 months to 16 years, who were being treated for status asth maticus with continuously inhaled p-agonist and intravenously administ ered methylprednisolone and had a pulsus paradoxus of greater than 15 mm Hg received either an 80%:20% helium-oxygen gas mixture (HELIOX pat ients) or room air (control patients) at 10 L/min by nonrebreathing fa ce mask in a double-blind, randomized, controlled trial. In all patien ts, baseline data, including pulsus paradoxus (determined by sphygmoma nometer or arterial catheter blood pressure readings), respiratory rat e, heart rate, investigator-scored dyspnea index, and oxygen saturatio n, were compared with values obtained 15 minutes during and after inte rvention. In a subset of patients, peak flows before and after breathi ng HELIOX or room air were measured. When clinically indicated, arteri al blood gases were obtained. Results: The pulsus paradoxus (in millim eters of mercury) fell significantly from an initial mean value of 23. 3 +/- 6.8 to 10.6 +/- 2.8 with HELIOX breathing (p < 0.001) and increa sed again to 18.5 +/- 7.3 after cessation of HELIOX. Peak flow increas ed 69.4% +/- 12.8% during HELIOX breathing (p < 0.05). The dyspnea ind ex decreased from an initial mean value of 5.7 +/- 1.3 to 1.9 +/- 1.7 with HELIOX breathing (p < 0.0002) and increased again to 4.0 +/- 0.5 after cessation of HELIOX breathing. In control patients, there was no significant difference in pulsus paradoxus or dyspnea index at any ti me during the study period. Mechanical ventilation was averted in thre e patients in whom dyspnea lessened dramatically during breathing of H ELIOX. Conclusion: During acute status asthmaticus, inhaled HELIOX sig nificantly lowered the pulsus paradoxus, increased peak flow, and less ened the dyspnea index. Moreover, HELIOX spared three patients a plann ed intubation and caused no apparent side effects. Thus HELIOX reduces the work of breathing and may forestall respiratory failure in childr en with status asthmaticus, thus preventing the need for mechanical ve ntilation.