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Volume 3 Supplement 2

19th International Symposium on Intensive Care and Emergency Medicine

A clinical evaluation of a new humidifier in long-term mechanical ventilation

The adequacy of humidification of heat and moisture exchangers (HMEs) during long-term mechanical ventilation is still controversial. Recently, an active HME (AHME) (Humid-Heat, Gibeck) has been developed. This AHME combines a HME with a unit which adds water and heat between the patient and the HME. The AHME automatically regulates the water and heat supply. The only user-set input for AHME is the minute ventilation (V'e) of the patient. We evaluated the AHME efficiency for humidification during long-term mechanical ventilation.


The AHME was used for 5 days on seven patients which were mechanically ventilated in different modes. On each day we measured the number of tracheal aspirations, the secretions characteristics, the condensate in the flex tube and in the water traps, the airway temperature, the number of changes of the V'e setting on AHME. A chest X-ray and a bronchoscopy were performed on days 1, 3 and 5. We scored the secretions characteristics and the condensate in the flex tube from 0 (insufficient) to 3 (excessive), the atelectasis at chest X-ray from 0 (absent) to 2 (evident), and the bronchial occlusions at bronchoscopy from 1 (absent) to 4 (complete).

Results and conclusion

AHME provided adequate humidification over the 5 days, as indicated by the secretions characteristics and by the absence of new atelectasis and of secretions accumulation in the bronchi. The temperature of inspired air was adequate. The value of V'e set on the AHME was changed on average twice (range: 0–8 times) per day, to maintain this setting close to the V'e of the patient. No water condensate was found in the water traps. The AHME is adequate for humidification in long-term mechanical ventilation, and eliminates the problem of condensation in the ventilator tubings. The humidification efficiency of AHME is not influenced by the mechanical ventilation mode, provided that the V'e setting of AHME is kept close to the V'e of the patient.

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Olivei, M., Via, G., Palo, A. et al. A clinical evaluation of a new humidifier in long-term mechanical ventilation. Crit Care 3 (Suppl 2), P016 (2000).

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