Bedside evaluation of efficient airway humidification during mechanical ventilation of the critically ill.
OBJECTIVE
To determine the correlation between simple rating of condensation seen in the flex-tube connecting the heating and humidifying device used with the endotracheal tube and hygrometric parameters (absolute and relative humidity and tracheal temperature) measured by psychrometry.


METHODS
Prospective randomized clinical trial.


METHODS
Medical ICU of Louis Mourier Hospital, Colombes, France, a university-affiliated teaching hospital.


METHODS
Forty-five consecutive mechanically ventilated critically ill patients.


METHODS
Patients undergoing mechanical ventilation were randomly assigned to receive humidification with one of the four heat and moisture exchangers (HMEs) tested or with a conventional heated humidifier.


METHODS
The hygrometric performances of four HMEs (BB2215, BB50, and BB100 from Pall Biomedical, Saint-Germaine-en-Laye, France; and Hygrobac-Dar from Mallinckrodt, Mirandola, Italy) and a heated humidifier (Fisher & Paykel; Auckland, New Zealand) were studied after 3 h and also after 48 h of use for the Hygrobac-Dar and correlated to a clinical visual inspection rating the amount of condensation in the flex-tube of the endotracheal tube.


RESULTS
A total of 95 measurements in 45 patients were performed. The best hygrometric parameters were obtained with the heated humidifier (p < 0.001). The Hygrobac-Dar yielded significantly higher values for both humidities and tracheal temperature than the other three HMEs (p < 0.001). The performance of Hygrobac-Dar was unchanged after 48 h of use. There was a significant correlation between the condensation seen in the flex-tube and the hygrometric parameters measured by psychrometry (absolute humidity, rho = 0.7; relative humidity, rho = 0.7; tracheal temperature, rho = 0.5, p < 0.0001).


CONCLUSIONS
In mechanically ventilated ICU patients, visual evaluation of the condensation in the flex-tube provides an estimation of the heating and humidifying efficacy of the heating and humidifying device used, thus allowing the clinician bedside monitoring of airway humidification.
Ricard
J D
JD
Service de Réanimation Médicale, Hôpital Louis Mourier (Assistance Publique-Hopitaux de Paris), Colombes, France.
Markowicz
P
P
Djedaini
K
K
Mier
L
L
Coste
F
F
Dreyfuss
D
D
D000208:Acute Disease; D001831:Body Temperature; D016638:Critical Illness; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D007362:Intensive Care Units; D007442:Intubation, Intratracheal; D008875:Middle Aged; D015588:Observer Variation; D019095:Point-of-Care Systems; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods* / Q000592:standards; D012131:Respiratory Insufficiency / Q000628:therapy*; D014132:Trachea / Q000502:physiology