The Science Journal of the American Association for Respiratory Care

2011 OPEN FORUM Abstracts

RELATIVE HUMIDITY OUTPUT AT DIFFERENT OXYGEN FLOWRATES USING SALTER HIGH FLOW CANNULA AND BUBBLE HUMIDIFIER.

John W. Newhart, Richard M. Ford; Resp Care, UCSD Medical Center, San Diego, CA John Newhart RRT RCP, Richard M. Ford BS RRT FAARC UC San Diego Medical Center.

Background: At our institution we have observed an increase in the utilization of high flow oxygen delivery systems. We sought an answer to the question, are bubble humidifiers'capable of adequately humidifying gas delivered to the patient at higher flows? We elected to bench test the Salter (Salter Labs Arvin, Ca) high flow cannula and bubble humidifier (HFBH) (REF7900) and measure relative humidity (RH) at flowrates of oxygen between 6 and 15LPM. Methods: We ran the HFBH and cannula at 6, 9, 12, and 15 LPM of oxygen from a wall outlet. The HF cannula was attached to the HFBH and the two nasal outlet tubes of the cannula were attached snugly to a nose model configured with two small holes and similar spacing as nasal openings. This fitting was closed at one end with a 6" corrugated open ended tube on the other. A hygrometer sensor was inserted into the open end of the tubing with the sensing portion just downstream of the cannula openings. The sensor would only be exposed to gas from the cannula. For each flow setting, the temperature and RH reading of the sensor and accompanying components were allowed adequate time to stabilize. Results: Oxygen flowrates with corresponding RH: 6 lpm/66%, 9 lpm/60%, 12 lpm/57%, 15 lpm/54%. Conclusion: Our results indicate that the HFBH is able to significantly improve the relative humidity of dry gas. In using such devices we determined that patients are more comfortable with less complaints of nasal drying. The clinician should however be aware that humidity deficits continue to exist with such devices and impact on patients should be assessed.
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