Heliox improves pulmonary mechanics in a pediatric porcine model of induced severe bronchospasm and independent lung mechanical ventilation

Background: A helium-oxygen gas mixture (heliox) has low gas density and lo w turbulence and resistance through narrowed airways. The effects of heliox on pulmonary mechanics following severe methacholine-induced bronchospasm were investigated and compared to those of a nitrogen-oxygen gas mixture (n itrox) in an innovative pediatric porcine, independent lung, mechanical ven tilation model. Results: All of the lungs showed evidence of severe bronchospasm after meth acholine challenge. Prospective definition of `heliox response' was a 15% o r greater improvement in lung function in the lung receiving heliox compare d with the matched lung receiving nitrox. Seven out of 10 pigs responded to heliox therapy with respect to resistance and eight out of 10 pigs respond ed to heliox therapy with respect to compliance and tidal volume (P< 0.03). After crossover from nitrox to heliox, eight out of eight lungs significan tly improved with respect to tidal volume, resistance and compliance (P< 0. 001). After crossover from heliox to nitrox all eight lungs showed a signif icant increase in resistance and a significant decrease in tidal volume (P< 0.001). Conclusions: In a pediatric porcine model of acute, severe methacholine-ind uced bronchospasm and independent lung mechanical ventilation, administrati on of heliox improves pulmonary mechanics, gas flow, and ventilation. Admin istration of heliox should be considered for support of pediatric patients with acute, severe bronchospasm requiring mechanical ventilation through sm all artificial airways.