Lack of Benefit of Heliox During Mechanical Ventilation of Subjects With Severe Air-Flow Obstruction

Abstract

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-O 2 , heliox resulted in a reduction in peak airway pressure (54.1 ؎ 12.6 cm H 2 O vs 47.9 ؎ 10.8 cm H 2 O, P < .001) and P aCO 2 (64.3 ؎ 14.9 mm Hg vs 62.3 ؉ 15.1 mm Hg, P ‫؍‬ .01). In contrast, there was no change in plateau pressure (25.3 ؎ 5.5 cm H 2 O vs 25.8 ؎ 5.6 cm H 2 O, P ‫؍‬ .14) or total PEEP (13.4 ؎ 3.8 cm H 2 O vs 13.3 ؎ 4.1 cm H 2 O, 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 P aCO 2 .

A randomized single‐center controlled trial of synchronized intermittent mandatory ventilation with heliox in newborn infants with meconium aspiration syndrome

“…The main cause of MAS is fetal excretion of meconium polluting amniotic fluid, followed by inhalation of meconium into the respiratory tract causing mechanical obstruction, which narrows the airway and increases resistance. Helium, which has a low density and high viscosity and mobility due to its physical properties contributing to smaller resistance, is useful in the treatment of MAS to significantly increase ventilation per minute and the expiratory flow, reduce power consumption due to breathing, accelerate the dispersion of oxygen and CO 2 , and improve lung compliance 28–32 . SIMV produces more synchronization and fewer cardiovascular complications in the treatment of MAS 33,34 .…”

Helium: Is the Sky the Limit?

“…Shortening inspiratory and expiratory times favors turbulence, which reduces expiratory flow and inspiratory and expiratory volumes, and also worsens hyperinflation (dynamic hyperinflation). Unlike the physiology described by Leatherman et al, 4 in the presence of turbulent flow, as seen with exercise, heliox improves respiratory mechanics. Therefore, heliox has clinical benefit when used in the out-patient treatment of obstructive lung disease as a part of pulmonary rehabilitation.…”

“…However, by utilizing hyperpolarized helium, MRI images are improved, enabling clinicians to gain valuable information about oxygenation and to display airway obstruction and changes over time in patients with obstructive lung disease. 16 Despite the lack of positive findings regarding indices of hyperinflation in the population of intubated subjects with COPD and asthma studied by Leatherman et al, 4 heliox appears to have many potential clinical benefits, and medical applications for helium continue to evolve. Unfortunately, comparatively few studies on heliox have been published, with many of these being observational in nature.…”

Implementing a Respiratory Therapist-Driven Continuous Albuterol Weaning Protocol in the Pediatric ICU

“…Criticisms of heliox include lack of high-quality evidence and high cost. [15][16][17][18] However, there are some studies that show it could be beneficial, 19,20 so it is possible that this could have contributed to the shorter duration of continuous albuterol treatment in their study. 14 One strength of our protocol is that the rate of adverse events did not change.…”