Mask humidity during CPAP: influence of ambient temperature, heated humidification and heated tubing

Abstract

Purpose

Mucosal drying during continuous positive airway pressure (CPAP) therapy is problematic for many patients. This study assessed the influence of ambient relative humidity (rH) and air temperature (T) in winter and summer on mask humidity during CPAP, with and without mask leak, and with or without heated humidification ± heated tubing.

Methods

CPAP (8 and 12 cmH₂O) without humidification (no humidity [nH]), with heated humidification controlled by ambient temperature and humidity (heated humidity [HH]) and HH plus heated tubing climate line (CL), with and without leakage, were compared in 18 subjects with OSA during summer and winter.

Results

The absolute humidity (aH) and the T inside the mask during CPAP were significantly lower in winter versus summer under all applied conditions. Overall, absolute humidity differences between summer and winter were statistically significant in both HH and CL vs. nH (p < 0.05) in the presence and absence of mouth leak. There were no significant differences in aH between HH and CL. However, in-mask temperature during CL was higher (p < 0.05) and rH lower than during HH. In winter, CPAP with CL was more likely to keep rH constant at 80% than CPAP without humidification or with standard HH.

Conclusion

Clinically-relevant reductions in aH were documented during CPAP given under winter conditions. The addition of heated humidification, using a heated tube to avoid condensation is recommended to increase aH, which could be useful in CPAP users complaining of nose and throat symptoms.

Keywords:

• continuous positive airway pressure
• humidification
• temperature
• leakage

Acknowledgments

The study was supported by uncommitted fund from ResMed. ResMed had no influence on study design, data management and analysis.

Disclosure

G Nilius has received research funding from Fisher & Paykel Healthcare, Heinen und Löwenstein, and Weinmann; this has gone into department funds. H Woehrle and A Graml are employees of ResMed. KJ Franke, U Domanski, and M Schroeder have no financial or other potential conflicts of interest in this work.