Determination of airway humidification in high-frequency oscillatory ventilation using an artificial neonatal lung model. Comparison of a heated humidifier and a heat and moisture exchanger.
OBJECTIVE
Thus far only few data are available on airway humidification during high-frequency oscillatory ventilation (HFOV). Therefore, we studied the performance and efficiency of a heated humidifier (HH) and a heat and moisture exchanger (HME) in HFOV using an artificial lung model.


METHODS
Experiments were performed with a pediatric high-frequency oscillatory ventilator. The artificial lung contained a sponge saturated with water to simulate evaporation and was placed in an incubator heated to 37 degrees C to prevent condensation. The airway humidity was measured using a capacitive humidity sensor. The water loss of the lung model was determined gravimetrically.


RESULTS
The water loss of the lung model varied between 2.14 and 3.1 g/h during active humidification; it was 2.85 g/h with passive humidification and 7.56 g/h without humidification. The humidity at the tube connector varied between 34. 2 and 42.5 mg/l, depending on the temperature of the HH and the ventilator setting during active humidification, and between 37 and 39.9 mg/l with passive humidification.


CONCLUSIONS
In general, HH and HME are suitable devices for airway humidification in HFOV. The performance of the ventilator was not significantly influenced by the mode of humidification. However, the adequacy of humidification and safety of the HME remains to be demonstrated in clinical practice.
Schiffmann
H
H
Department of Pediatrics, University of Göttingen, Robert-Koch-Strasse 40, D-37 073 Göttingen, Germany. schiffi@med.uni- goettingen.de
Singer
S
S
Singer
D
D
von Richthofen
E
E
Rathgeber
J
J
Züchner
K
K
D001187:Artificial Organs / Q000706:statistics & numerical data; D004867:Equipment Design / Q000706:statistics & numerical data; D006612:High-Frequency Ventilation / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D007231:Infant, Newborn; D008168:Lung; D011312:Pressure; D013696:Temperature; D014160:Transducers, Pressure