Helium in the adult critical care setting

J-L Diehl,C Faisy,L Lecourt,A Mercat,V Peigne,E Guérot

doi:10.1186/2110-5820-1-24

Abstract

Helium is a low-density inert gas whose physical properties are very different from those of nitrogen and oxygen. Such properties could be clinically useful in the adult critical care setting, especially in patients with upper to more distal airway obstruction requiring moderate to intermediate levels of FiO2. However, despite decades of utilization and reporting, it is still difficult to give any firm clinical recommendation in this setting. Numerous case reports are available in the context of upper airway obstruction of different origins, but there is a lack of controlled studies for this indication. One study reported a helium-induced beneficial effect on surrogates of work of breathing after extubation in non-COPD patients, possibly in relation to laryngeal consequences of tracheal intubation. Physiological benefits of helium-oxygen breathing have been demonstrated in the context of acute severe asthma, but there is a lack of large controlled studies demonstrating an effect on pertinent clinical endpoints, except for a study reported only as an abstract, which mentioned a reduction in the intubation rate in helium-treated patients. Finally, there are a number of physiological studies in the context of COLD-COPD patients demonstrating a beneficial effect, mainly by a reduction in the resistive inspiratory work of breathing but also by a reduction in hyperinflation. Reduction of hypercapnia was mainly observed in spontaneously breathing and noninvasively ventilated helium-treated patients but not in intubated patients during controlled ventilation, suggesting that the decrease in PaCO2 was mainly in relation to a diminution in CO2 production, related to the diminution in work of breathing and not an improved alveolar ventilation. Moreover, there is little evidence that helium-oxygen could improve parameters of heterogeneity in such patients. Two RCTs were unable to demonstrate a reduction in the intubation rate in such setting, but they were likely underpowered. An adequately powered international multicentric study is ongoing and will help to determinate the exact place of the helium-oxygen mixture in the future. The place of the mixture during the weaning period will deserve further evaluation.

Highlights

Helium is an inert gas whose physical properties are very different from those of nitrogen and oxygen
The purpose of this review was to detail part of these clinical uses, focusing mainly on obstructive respiratory diseases in the adult critical care setting, and excluding pediatric studies and studies solely centered on helium-driven nebulization
Jaber et al extended these data in a comparable setting while studying ten COPD patients at two different levels of pressure support during noninvasive ventilation [17]

Summary

Introduction

Helium is an inert gas whose physical properties are very different from those of nitrogen and oxygen. Jaber et al extended these data in a comparable setting while studying ten COPD patients at two different levels of pressure support during noninvasive ventilation [17] They mainly reported a helium-oxygen-associated diminution in the inspiratory work of breathing compared with air-oxygen periods. Use of helium during invasive ventilation Tassaux et al performed a study in 23 decompensated intubated COPD patients that compared two periods of air-oxygen ventilation to one period of helium-oxygen ventilation; all other parameters remained unchanged [20] They mainly found helium-associated significant reductions in Pmax, static intrinsic PEEP (staticPEEPi), and trapped volume. These results emphasized the need to search for predictors useful to identify responders to helium-oxygen breathing, because the physiological response could be variable for a patient to another, with possibility of detrimental effects

Conclusions and perspectives

Findings

Barach AL