Chest
Heat and Moisture Exchanger vs Heated Humidifier during Long-Term Mechanical Ventilation: A Prospective Randomized Study
Section snippets
Patients and Methods
All consecutive patients mechanically ventilated in our ICU from June 1988 to June 1989 were preincluded in this study at the onset of MV if their expected duration of MV was more than five days. They were then randomly assigned to MV either with HH or with HME. Only patients who underwent MV for at least five days were ultimately included for analysis. The duration of evaluation was limited to ten days.
In the HH group, the humidifier was either a Bennett Cascade II when a Servo 900 B
Study Population
Seventy-four patients entered the study and underwent randomization (Table 1 and 2). Eighteen of them were excluded because MV was stopped before the fifth day. In the remaining 56 patients, 26 were assigned to MV with HH and 30 with HME. In the HH group, a Cascade II Bennett humidifier was used in 21 patients and a Fisher Paykel humidifier in five. The two groups were similar in terms of diagnosis on admission in the ICU, age, sex, SAPS at the time of inclusion, duration of MV before
Discussion
Heat and moisture exchangers might replace the functions of the UAs by avoiding loss of heat and moisture during expiration and returning them to the inhaled gas. Their main advantages are high bacterial filtering capacity9 and simplification of the ventilator tubing. Therefore, the use of a HME should be generalized if an equivalent humidification of inspired gases could be demonstrated between HME and HH.
During the last decade, many HME proved to be effective by in vitro assays.3, 10, 11, 12,
Conclusion
Our results suggest that tracheal secretions during MV with periodic tracheal instillations become thicker with PALL BB 2215 HME than with HH. The number of patients is too small to state that these features are associated with a greater incidence of tube occlusion with HME. In view of the advantages of HME (reduction of nurses’ work and of financial cost) it seems reasonable to carry on their use in long-term MV, but it is advisable to replace them by HH when difficulty in suctioning occurs.
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Cited by (0)
Supported in part by a grant from the Institut G. Roussy (CRC 88D23).
Manuscript received November 5; revision accepted December 13.