Humidification performance of 48 passive airway humidifiers: comparison with manufacturer data.
BACKGROUND
Heat and moisture exchangers (HMEs) are increasingly used in the ICU for gas conditioning during mechanical ventilation. Independent assessments of the humidification performance of HMEs are scarce. The aim of the present study was thus to assess the humidification performance of a large number of adult HMEs.


METHODS
We assessed 48 devices using a bench test apparatus that simulated real-life physiologic ventilation conditions. Thirty-two devices were described by the manufacturers as HMEs, and 16 were described as antibacterial filters. The test apparatus provided expiratory gases with an absolute humidity (AH) of 35 mg H(2)O/L. The AH of inspired gases was measured after steady state using the psychrometric method. We performed three hygrometric measurements for each device, measured their resistance, and compared our results with the manufacturer data.


RESULTS
Of the 32 HMEs tested, only 37.5% performed well (>or= 30 mg H(2)O/L), while 25% performed poorly (< 25 mg H(2)O/L). The mean difference (+/- SD) between our measurements and the manufacturer data was 3.0 +/- 2.7 mg H(2)O/L for devices described as HMEs (maximum, 8.9 mg H(2)O/L) [p = 0.0001], while the mean difference for 36% of the HMEs was > 4 mg H(2)O/L. The mean difference for the antibacterial filters was 0.2 +/- 1.4 mg H(2)O/L. The mean resistance of all the tested devices was 2.17 +/- 0.70 cm H(2)O/L/s.


CONCLUSIONS
Several HMEs performed poorly and should not be used as HMEs. The values determined by independent assessments may be lower than the manufacturer data. Describing a device as an HME does not guarantee that it provides adequate humidification. The performance of HMEs must be verified by independent assessment.
Lellouche
François
F
Service de Soins Intensifs de Chirurgie Cardiaque, Centre de Recherche Hôpital Laval, Université Laval, Québec City, QC, Canada. Electronic address: francois.lellouche@crhl.ulaval.ca.
Taillé
Solenne
S
Service de Réanimation Médicale, Assistance Publique-Hôpitaux de Paris, Centre Hospitalier Albert Chenevier-Henri-Mondor, Créteil, France.
Lefrançois
Frédéric
F
Service de Réanimation Médicale, Assistance Publique-Hôpitaux de Paris, Centre Hospitalier Albert Chenevier-Henri-Mondor, Créteil, France.
Deye
Nicolas
N
Service de Réanimation Médicale, Hôpital Lariboisière, Paris, France.
Maggiore
Salvatore Maurizio
SM
Istituto di Anestesiologia e Rianimazione-Università Cattolica Policlinico A. Gemelli, Rome, Italy.
Jouvet
Philippe
P
Service de Réanimation Médicale Pédiatrique, Hôpital Necker-Enfants Malades, Paris, France.
Ricard
Jean-Damien
JD
Service de Réanimation Médicale, Hôpital Louis Mourier, Hôpitaux de Paris, Colombes, Paris, France.
Fumagalli
Bruno
B
Pharmacie Centrale des Hôpitaux-Assistance Publique-Hôpitaux de Paris, Paris, France.
Brochard
Laurent
L
Service de Réanimation Médicale, Assistance Publique-Hôpitaux de Paris, Centre Hospitalier Albert Chenevier-Henri-Mondor, Créteil, France.
D000328:Adult; D003257:Consumer Product Safety; D004869:Equipment Safety; D006801:Humans; D006813:Humidity; D007362:Intensive Care Units; D008420:Manufactured Materials / Q000592:standards*; D012121:Respiration, Artificial / Q000295:instrumentation*; D012680:Sensitivity and Specificity; D013673:Technology Assessment, Biomedical; D012122:Ventilators, Mechanical