Effect of humidified versus nonhumidified CPAP on inflammatory response and nasopharyngeal symptoms in healthy participants.

Introduction: Continuous positive airway pressure (CPAP) may induce nasal inflammation because of mucosal compression or dryness. This study examined the impact of humidified versus nonhumidified CPAP on nasal inflammation and upper airway symptoms.

Methods: Seventeen healthy male subjects with no previous or current history of nasal symptoms were recruited. All subjects underwent 3 hours of nonhumidified CPAP at 12.5 cmH₂O via nasal mask. Among the 17 studied subjects, seven returned to receive a humidified CPAP at 12.5 cmH₂O via nasal mask. The nasal wash leukocyte count was assessed at baseline and after each CPAP setting. The white blood cell (WBC) count and levels of WBCs that are mononuclear cells (including lymphocytes and monocytes) were monitored. A six-point nasal score was also assessed before and after the CPAP intervention.

Results: The nasal wash WBC count (10³/µL) and mononuclear cell level (10³/µL) at baseline, on 12.5 cmH₂O humidified CPAP, and on 12.5 cmH₂O nonhumidified CPAP were significantly different (p = 0.016; p = 0.003). Changes in nasopharyngeal symptoms occurred in 12 of 17 subjects (70.5%) in the nonhumidified group. Participants experienced at least one nasal symptom after application of nonhumidified CPAP at 12.5 cmH₂O.

Conclusion: The present investigation suggests that humidified CPAP was not associated with early nasal inflammation and there were fewer nasopharyngeal symptoms. Further study is required to confirm the results and evaluate the impact of adding heat to the humidified CPAP system.