Elsevier

Respiratory Medicine

Volume 101, Issue 9, September 2007, Pages 1874-1879
Respiratory Medicine

The effect of mouth leak and humidification during nasal non-invasive ventilation

https://doi.org/10.1016/j.rmed.2007.05.005Get rights and content
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Summary

Background

Poor mask fit and mouth leak are associated with nasal symptoms and poor sleep quality in patients receiving domiciliary non-invasive ventilation (NIV) through a nasal mask. Normal subjects receiving continuous positive airways pressure demonstrate increased nasal resistance following periods of mouth leak. This study explores the effect of mouth leak during pressure-targeted nasal NIV, and whether this results in increased nasal resistance and consequently a reduction in effective ventilatory support.

Methods

A randomised crossover study of 16 normal subjects was performed on separate days. Comparison was made of the effect of 5 min of mouth leak during daytime nasal NIV with and without heated humidification. Expired tidal volume (VT), nasal resistance (RN), and patient comfort were measured.

Results

Mean change (Δ) in VT and RN were significantly less following mouth leak with heated humidification compared to the without (ΔVT −36±65 ml vs. −88±50 ml, p<0.001; ΔRN +0.9±0.4 vs. +2.0±0.7 cmH2O l s−1, p<0.001). Baseline comfort was worse without humidification (5.3±0.4 vs. 6.2±0.4, p<0.01), and only deteriorated following mouth leak without humidification.

Conclusions

In normal subjects, heated humidification during nasal NIV attenuates the adverse effects of mouth leak on effective tidal volume, nasal resistance and improves overall comfort. Heated humidification should be considered as part of an approach to patients who are troubled with nasal symptoms, once leak has been minimised.

KEYWORDS

Respiratory impairment
Non-invasive ventilation
Airway resistance
Visual analogue scale

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