- Heliox is a mixture of helium and oxygen
- Helium is an inert gas with a significantly lower density (and specific gravity) than room air (1.42g/L for O2 vs 0.17g/L for He)
MECHANISM OF ACTION
- by substituting helium for nitrogen -> reduction in density of the gas -> reduction in Reynolds number -> more laminar flow
-> reduces airflow resistance, work of breathing and dynamic hyperinflation
- gas administered via a mask with a reservoir bag or via endotracheal tube
- supplied at 137 bar as either Heliox (79% He, 21% O2) in white cylinders with white/brown shoulders or as 100% helium in brown cylinders (size C, D, E and G cylinders (410, 1400, 3500 and 7300L nominal capacity respectively)
- can be used as the driving gas for nebulisation
- helium:oxygen mix of 80:20 or 70:30, which are 1.8 and 1.6 times less dense than pure oxygen, respectively.
- lower airways disorders – e.g. severe asthma, severe COPD, bronchiolitis, bronchiectasis, lung cancer
- extrathoracic or tracheal obstruction – e.g. croup, epiglottitis, foreign body, tumour, tracheal stenosis, tracheomalacia
- FRC assessment (helium dilution technique)
- decompression sickness
- expensive (10x the cost of oxygen)
- lack of availability
- can’t use on those with a high FiO2 (>0.4)
- ventilators require recalibration for FiO2 and TV – interferes with valve function
- requires heated humidified circuits as helium conducts heat 6x faster than nitrogen
- alteration of vocal pitch
- may reduce the efficiency of coughing
- near instantaneous onset an offset
- eliminated within a few breaths
- anecdotal evidence of avoiding need for intubation in upper airway obstruction
- little evidence of benefit in lower airways obstructive lung disease – the common theme is that heliox is a temporising measure but is not a treatment
References and Links
Journal articles and textbooks
- Fink JB. Opportunities and risks of using heliox in your clinical practice. Respir Care. 2006 Jun;51(6):651-60. PMID: 16723042.
- Gentile MA. Inhaled medical gases: more to breathe than oxygen. Respir Care. 2011 Sep;56(9):1341-57; discussion 1357-9. PMID: 21944684.
- Hess DR, Fink JB, Venkataraman ST, Kim IK, Myers TR, Tano BD. The history and physics of heliox. Respir Care. 2006 Jun;51(6):608-12. PMID: 16723037
- Kim IK, Saville AL, Sikes KL, Corcoran TE. Heliox-driven albuterol nebulization for asthma exacerbations: an overview. Respir Care. 2006 Jun;51(6):613-8. PMID: 16723038.
- McGarvey JM, Pollack CV. Heliox in airway management. Emerg Med Clin North Am. 2008 Nov;26(4):905-20, viii. Review. PMID: 19059090.
- Reuben AD, Harris AR. Heliox for asthma in the emergency department: a review of the literature. Emerg Med J. 2004 Mar;21(2):131-5. PMC1726290.
- Vorwerk C, Coats T. Heliox for croup in children. Cochrane Database Syst Rev. 2010 Feb 17;(2):CD006822. PMID: 20166089.
- Wigmore T, Stachowski E. A review of the use of heliox in the critically ill. Crit Care Resusc. 2006 Mar;8(1):64-72. PMID: 16536724.