PRESERVATION OF HUMIDITY AND HEAT OF RESPIRATORY GASES IN SPONTANEOUSLY BREATHING, TRACHEOSTOMIZED PATIENTS

Background: Ventilation with endotracheal intubation bypasses the uppe r airway and the normal heat and moisture exchanging process of inspir ed gases. A continuous loss of moisture and heat occurs and predispose s patients to serious airway damage. We therefore prospectively studie d one heated humidifier system, one cold humidifier system and one hea t and moisture exchanger in spontaneously breathing, tracheostomized i ntensive care unit patients to determine the ability to preserve patie nts' heat and water. Methods: Following a randomized order, 10 patient s were spontaneously ventilated for 24-h periods with the Nam 35(R) hu midifier (Europe Medical, France, a cold water humidifier), the heat a nd moisture exchanger Trach-Vent(R) (Gibeck, Sweden), and the Aerodyne (R) humidifer (Kendall, USA). in each patient, during the inspiration phase, the following measurements were performed: mean values of tempe rature and relative humidity of inspired gases. The absolute humidity was calculated. Values were obtained in each patients after 40 min and 24 h. Results: The Trach-Vent(R) filter and the Aerodyne(R) humidifie r had better humidification and thermic capacities than the Nam 35(R) humidifier (P<0.001). With the Nam 35(R) humidifier, no patient had te mperature of inspired gas >29 degrees C Concerning absolute humidity o f inspired gases, the Nam 35(R) humidifier achieved a lower performanc e than the other two tested systems (P<0.001). Conclusion: In spontane ously breathing, tracheostomized intensive care unit patients, the Tra ch-Vent(R) heat and moisture exchanger and the Aerodyne(R) heated syst em achieved satisfactorily preservation of heat and humidity of inspir ed gases.