The Science Journal of the American Association for Respiratory Care

2004 OPEN FORUM Abstracts


IN-VITRO COMPARISON OF INDIRECT VERSUS DIRECT HEATED HUMIDITY DELIVERY DEVICES



Authors Lisa Cracchiolo, RRT, Peggy Reed-Watts, MS, RRT, Marin Kollef, MD, FACP, FCCP, Cheryl Hoerr, BS, RRT, CPFT, Barnes-Jewish Hospital, St. Louis, MO.

Objective
To compare the relative effectiveness of direct versus indirect heated humidity delivery devices.

Design
In-vitro study utilizing indirect heated humidity versus direct heated humidity. The in-direct heated humidity set-up consisted of an Airlife nebulizer, donut heater attached to an Airlife nebulizer cap, and 1000 ml sterile water bottle. The direct heated humidity set-up consisted of a Fisher & Paykel Air Entrainer device (P/N RT008) attached to a Fisher & Paykel MR730 heater with a 1,500 ml continuous feed sterile water bag. Both the direct and in-direct heated humidification systems included 36" of corrugated tubing from the output device to a condensate collection bag and 72" of corrugated tubing from the collection bag to an adult trach mask. The indirect system included an Airlife Temperature Sensor (P/N 001956) placed between the corrugated tubing and trach mask. The direct system included a Fisher-Paykel temperature probe (P/N MR561) inserted into an Airlife U/Adapt-It Straight Adapter (P/N 004084) and placed proximal to the trach mask. The simulated patient consisted of a large Kerlix gauze roll (11.4 cm X 3.7 m) placed inside an open plastic Ziploc bag (9" X 13"). The trach mask from each system was placed inside the Ziploc bag approximately 3" from the Kerlix gauze.

Method
Both humidification systems were simultaneously activated and allowed to run for one hour. The study was repeated ten times at each of three FiO2 settings (.28, .40, and .90). The Kerlix gauze roll was placed inside the Ziploc bag and weighed prior to and at the end of each trial. There was no statistical difference in dry weights prior to the study. A statistically significant difference was noted for both devices at the completion of the test. However, the net weight gain at each FiO2 was significantly greater with the direct system than with the indirect system.



*Comparison of wet weight for Fisher-Paykel versus Doughnut

Conclusion The direct heated humidification system (Fisher-Paykel) provides superior airway humidification for trached patients requiring heated humidity. Based on these results Respiratory Care Services at Barnes-Jewish Hospital is changing its humidification system for tracheostomy patients to the Fisher-Paykel MR730.