[Comparative clinical evaluation of 4 heat and moisture exchangers (HME) in general anesthesia].

Objective: To determine the efficiency, during general anaesthesia, of four commercially available HMEs, with particular attention to the change of performances due to the new modifications introduced by the manufacturers.
Design: Comparisons of the performances of each HMEs with psychometric method in terms of T degree C, RH (%), AH (mgH2O/1) of inhaled and expired gases.
Patients: A sample of 28 patients under general anesthesia longer than 150 minutes, undergone elective urological surgery. Patients with cardiological, respiratory and metabolic impairments have been excluded.
Measurements and Results: The measurements of T degree C, RH and AH have been performed with thermometric probes every minute. The collected data have been analyzed by Student's "t"-test for unpaired data.
Conclusions: The obtained data show that a good conditioning of the inhaled gases is possible, although only few HMEs satisfy the requirements indicated in the ISO and BSI standards.