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 low
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 (nitrox) in
an innovative pediatric porcine, independent lung, mechanical ventilation
model.

      Results:
      All of the lungs showed evidence of severe bronchospasm after
            methacholine challenge. Prospective definition of 'heliox response'
            was a 15% or greater improvement in lung function in the lung receiving heliox
            compared 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 responded
            to heliox therapy with respect to compliance and tidal volume (P
            < 0.03). After crossover from nitrox to heliox, eight out of eight lungs
            significantly improved with respect to tidal volume, resistance and compliance
            (P < 0.001). After crossover from heliox to nitrox all eight lungs
            showed a significant increase in resistance and a significant decrease in tidal
            volume (P < 0.001).


      Conclusions:
      In a pediatric porcine model of acute, severe methacholine-induced
            bronchospasm and independent lung mechanical ventilation, administration of
            heliox improves pulmonary mechanics, gas flow, and ventilation. Administration
            of heliox should be considered for support of pediatric patients with acute,
            severe bronchospasm requiring mechanical ventilation through small artificial
            airways.