Helium - useful for more than making your voice sound funny

Todd Fraser on 18-02-2012

A couple of recent papers have focused on the use of Helium-Oxygen mixture in respiratory failure, particularly in infants on nasal CPAP for bronchiolitis, both papers finding it useful. I'm a bit perplexed by the physiology involved here. The pathology associated with bronchiolitis, smoking related lung disease and asthma is largely small airways where flows are very slow. The purported benefit of helix is that it reduces turbulent flow by having a reduced density and hence viscosity, which allows improvements in flow. I'm not entirely clear how this occurs at small airway level. Nonetheless, it appears to work. Perhaps it has a benefit in the highly stressed patient by reducing work of breathing at higher airway levels. One concern I've always had is taking a patient with hypoxia and borderline respiratory function and giving them no more than 30% oxygen (because you need high percentages of helium to have any effect at all) seems to be flirting with disaster. Being no expert in the area, I wondered what experience others have had.

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Alex McKenzie wrote 02-19-2012 03:23:31 pm
I must admit I've not used it much.

I do remember hearing someone talk about problems with using it in conjunction with a ventilator, because the different density gas buggered up the flow-meters' accuracy. I don't think its as easy as just changing the gas...

LEWIS CAMPBELL wrote 03-07-2012 12:57:08 pm
The viscosity is higher than airmix. In air breathing, turbulent flows at the very high flow rates of respiratory distress reach into the millimetre sized airways in any case and inertance (the bit we always ignore because it's so tiny) starts to become real. With HOX's higher viscosity its flow becomes turbulent more easily (hence further into the respiratory tree) and mixes gas better, while its tiny density is easier to move around so makes mass transport in larger airways easier. As diffusion is facilitated by disruption of airflow laminae and is the main gas transport mechanism at work in these airways the overall gas transport is improved.

veerendra jagarlamudi wrote 07-09-2012 09:32:52 am
heliox is 70-30 helium oxygen mix and that is added to oxygen in place of air, so u can give 50% oxygen and 50% helix with good effect and get > 50% fio2.