| Sumario: | BACKGROUND: The value of heliox (helium-oxygen mixture) for patients with severe air-flow obstruction is uncertain. The purpose of this study was to determine whether heliox could reduce the degree of hyperinflation and hypercapnia in mechanically ventilated patients with severe airflow obstruction. METHODS: This was a single-center, prospective observational study conducted in a medical ICU of an academic medical center. We assessed the impact of heliox (65-70% helium, 30-35% oxygen) on airway pressures and arterial blood gases of 13 subjects undergoing mechanical ventilation for severe asthma (n = 8) or exacerbation of COPD (n = 5). RESULTS: As compared with ventilation with air-O2, heliox resulted in a reduction in peak airway pressure (54.1 ± 12.6 cm H2O vs 47.9 ± 10.8 cm H2O, P < .001) and PaCO2 (64.3 ± 14.9 mm Hg vs 62.3 ± 15.1mmHg, P = .01). In contrast, there was no change in plateau pressure (25.3±5.5 cm H2O vs 25.8 ± 5.6 cm H2O, P = .14) or total PEEP (13.4 ± 3.8 cm H2O vs 13.3 ± 4.1 cm H2O, P = .79) in response to heliox. CONCLUSIONS: In mechanically ventilated subjects with severe air-flow obstruction, administration of heliox had no effect on indices of dynamic hyperinflation (plateau pressure and total PEEP) and resulted in only a small reduction in PaCO2.
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