A humidification system for CPAP therapy in obstructive sleep apnea--evaluation of the effectiveness in changing climatic environmental conditions

Abstract

Upper airway dryness is a frequent side-effect of nasal continuous positive airway pressure (nCPAP) therapy in obstructive sleep apnoea syndrome (OSA). In this situation, heated humidification is often used. Therefore, the present study aimed to investigate the humidification performance--defined as the maximum achievable humidity in the tube system of the CPAP device--of a heated humidifier (HH) offered as CPAP accessories, as a function of ambient air conditions (humidity and temperature). In 30 patients (22 male, 8 female, mean age 56.4 +/- 11.7 years) with OSA undergoing CPAP treatment, temperature (T) and relative humidity (RH) in the CPAP tube system were measured, with and without the HH Somnowave, until a steady state was achieved. At the same time, ambient T and RH in the examination room were recorded. T and RH were used to calculate the absolute humidity (AH). The conditions of the examination room during the examination nights were as follows: T = 21.9 +/- 2.8 degrees C (15.2-26.9), RH 46.5 +/- 11.9% (21.7-69.1) and AH 9.2 +/- 3.2 g/m3 (3.7-16.7). The steady state AH without HH was 9.6 +/- 3.0 g/m3 (4.1-15.4), that with HH (humidification performance) 23.2 +/- 2.8 g/m3 (19.1-29.9) (p < 0.001). Under the ambient conditions of humidity and temperature, commonly found in European bedrooms, the HH demonstrate a high humidification performance. Thus, it would appear that the HH is suitable for the treatment of dry upper airways under nCPAP therapy.