PT - JOURNAL ARTICLE AU - Patrick F Allan AU - Michael J Hollingsworth AU - Gordon C Maniere AU - Anthony K Rakofsky AU - Kevin K Chung AU - Gregory A Naworol AU - John A Ward AU - Michelle Perello AU - Michael J Morris TI - Airway Humidification During High-Frequency Percussive Ventilation DP - 2009 Mar 01 TA - Respiratory Care PG - 350--358 VI - 54 IP - 3 4099 - http://rc.rcjournal.com/content/54/3/350.short 4100 - http://rc.rcjournal.com/content/54/3/350.full AB - BACKGROUND: We were concerned about the risk of inadequate humidification during highfrequency percussive ventilation (HFPV). METHODS: We studied 5 humidifiers during HFPV with a lung model, at bias gas flows of 10 L/min, 30 L/min, and 50 L/min, and compared the results to those from a comparator ventilator/humidifier setup and to the minimum temperature (30°C) and humidity (30 g/L) recommended by the American Association for Respiratory Care, at both regular room temperature and a high ambient temperature. Temperature was measured at the humidifier outflow point and at the artificial carina. Humidity was measured at the artificial carina. RESULTS: Of the 7 HFPV/humidifier combinations, 2 (the MR850 at a bias flow of 50 L/min, and the ConchaTherm Hi-Flow with VDR nebulizer) provided a carinal temperature equivalent to the comparator setup at room temperature, whereas one HFPV/humidifier combination (the ConchaTherm Hi-Flow with modified programming, at bias flows of 30 L/min and 50 L/min) provided a higher carinal temperature. At high ambient temperature, all of the setups delivered lower carinal temperature than the comparator setup. Only 2 setups (the ConchaTherm with modified programming at a bias flow of 50 L/min, and the ConchaTherm Hi-Flow with VDR nebulizer) provided carinal humidification equivalent to the comparator setup, without regard to ambient temperature; the other humidifiers were less effective. The ConchaTherm with modified programming, and the ConchaTherm with the VDR nebulizer provided the most consistent humidification. CONCLUSION: HFPV's distinctive gas-flow mechanism may impair gas heating and humidification, so all humidification systems should be tested with HFPV prior to clinical use.