2001 OPEN FORUM Abstracts
Performance ofHeated Humidifiers at Pediatric Ventilatory Settings
T. Nishida,MD , M Nishimura, MD, PhD; Y. Fujuno, MD, PhD; A Uchiyama, MD, PhD; andT. Mashima, MD, PhD Intensive Care Unit, Osaka University Hospital, Japan
Infant ventilators usually maintaina continluous flow. This improves trigger performance dramatically, howeversome ventilators use a very low continuous flow. It takes a long time for inspiratorygas to travel from the humidifier chamber to the patient's airway. It may thereforebe difficult to consistently maintain the humidity (H) and temperature (T) ofdelivered inspiratory gas with a heated humidifier (HH). At pediatric ventilatorysettings with a low continuous flow, we compared the performances of differentHHs.
Methods: Using a pediatricmodel lung, we compared the performances of commercially available HHs-MR730with MR 290, Fisher and Paykel (F&P); Conchathern IV, Hudson RCI (CVI; andHummax II, Metran (HH). A sensor to monitor T andH (Moiscope, MEra) was placedbetween the Y-piece and inspiratory limb of the vnetalator circuit. A Servo300 ventilator was connected to the pediatric model lung (test lung CPI, Drager)via a pediatric ventilator circuit. Ventilator settings were peak inspiratorypressure 20cmH2O; PEEP 5cmH2O; respiratory rate 30 breaths/min; continuous flow0.51 pm. Each HH was set to maintain the airway-opening temperature at 32°Cand 37°C.
Results: The table showsT, relative H (RH), and absolute H (AH) at the airway opening, F&P and CIVfailed to achieve the set T, although they maintained 100 RH. In HH, T was unstablealthough it maintained mean T close to the set T.
|HH||31.6±1.9 (29.6 34.7)||91.8 ±0.4 (91.0 92.2)||30.5 ± 3.0||36.7 ± 1.7 (34.7 39.1)||100 ±0||43.3 ± 3.7|
|F&P||30.1 ± 0.0 (30.1)||100 ± 0||30.6 ± 0.0||33.9 ± 0.1 (33.6 34.2)||100 ±0||37.4 ± 0.2|
|CIV||25.4 ± 0.0 (25.4)||100 ± 0||23.6 ± 0.0||0.12 ± 0.04||100 ±0||25.5 ± 0.0|
Data shown are mean ±SD. Numbers in parenthesis indicate range.
Conclusion: The HHs reportedhere failed to maintain the airway opeing T at the set point or T varied greatlyunder pediatric ventilatory settings with a low continuous flow.