Cold Water in Cold Passover Humidifiers for CPAP Therapy
You should not use cold water in a cold passover humidifier for CPAP therapy, as heated humidification is specifically recommended by the American Academy of Sleep Medicine to reduce side effects and improve treatment adherence. 1
Why Heated Humidification is Recommended
The American Academy of Sleep Medicine clinical practice guidelines explicitly recommend using heated humidification with PAP devices to reduce common side effects including nasal dryness, oral dryness, throat irritation, hoarse voice, nasal congestion, and reduced smell. 1 While meta-analyses showed no clinically significant improvement in PAP adherence, sleepiness, or quality of life with humidification versus no humidification, the reduction in troublesome side effects supports its use. 1
Performance Differences: Cold vs. Heated Humidifiers
The evidence clearly demonstrates that heated humidifiers are vastly superior to cold passover humidifiers in delivering adequate moisture:
- Heated humidifiers achieve absolute humidity levels of 26-32 g/m³, compared to only 15-17 g/m³ with cold passover humidifiers—a difference of approximately 16-21 g/m³ more moisture delivered. 2
- Cold passover humidifiers provide minimal improvement over no humidification at all (only 5-7 g/m³ increase versus 16-21 g/m³ with heated units). 2
- Under typical European bedroom conditions, heated humidifiers demonstrate high humidification performance (23.2 ± 2.8 g/m³) compared to baseline without humidification (9.6 ± 3.0 g/m³). 3
Clinical Guideline Requirements
Heated humidification should be available for all patients undergoing PAP titration, according to American Academy of Sleep Medicine standards. 1 The addition of heated humidification is specifically indicated when patients complain of significant oral or nasal dryness, unless not tolerated by the patient. 1
When Heated Humidification is Particularly Critical
Higher PAP pressures make heated humidification even more essential:
- PAP devices deliver air at reduced relative humidity compared to ambient air, and increasing pressure further lowers the delivered relative humidity. 1, 4
- NPPV treatment frequently uses relatively high pressures and is associated with high intentional and unintentional leak, making heated humidification particularly important. 1
- Patients in particularly dry climates (American southwest or winter in cold climates) or those with significant nasal congestion or history of severe mucosal dryness should have humidification initiated at the start of titration. 1
Common Pitfall to Avoid
Do not assume that any humidification is adequate humidification. Cold passover humidifiers may give a false sense of addressing the problem while providing insufficient moisture to prevent upper airway symptoms. 2 The American Academy of Sleep Medicine guidelines recommend heated humidification specifically, not just any form of humidification. 1
Practical Implementation
Heated humidification with heated tubing should be standard practice to avoid "rain out" (condensation of water into the PAP circuit, face, and nose or mouth). 1 While this increases ongoing costs (purchasing distilled water, heated hoses) and maintenance requirements, the clinical benefits in reducing side effects justify these additional burdens. 1