The Science Journal of the American Association for Respiratory Care

2011 OPEN FORUM Abstracts

WATER ACCUMULATION IN THE CIRCUIT DURING HEATED HUMIDIFIED NASAL CANNULA (HHNC) THERAPY USING TWO DIFFERENT HUMIDIFICATION SYSTEMS.

Rob Diblasi, David Crotwell, John W. Salyer; Respiratory Therapy, Seattle Children's Hospital and Research Institute, Seattle, WA

BACKGROUND: We recently began to migrate our HHNC delivery systems from Fisher-Paykel MR 730 humidification systems to MR 850 system. We received some sporadic and uncorroborated anecdotal reports that there was more "rain-out" with the MR 850 system. Thus we sought to compare the amount of water accumulation in HHNC circuits during simulated operation with both humidifier configurations. METHODS: We tested three each HHNC systems using both MR 730 & MR 850's. Both types of humidifier systems were operated simultaneously using Fisher-Paykel circuits. Room temperature was controlled at 65 degrees F. Proximal temperature was set at 37 degrees C and chamber to proximal gradient was set at - 3 (for the MR 730). The flow rates were set at 3 L/min and FIO2 of 30%. Each circuit was weighed dry prior to set up. Following a warm-up period of 20 minutes, each of the systems was run for 4 hours with an oscillating fan blowing continuously on the humidifiers and circuits to simulate difficult environmental conditions for the humidifiers. Following the 4-hour testing period, circuits were re-weighed. Volume of water accumulated was assessed by assuming that any difference in dry and wet weights was due to accumulation of fluid using the density of water (1 g = 1 mL). Mean (SD) values for accumulated water volume were calculated for each type of humidifier and tested for statistical significance (P < 0.05) using Students T-test. Results: Mean (SD) mL of water accumulated was: MR 730 = 11.2 (2.65) mL, MR 850 = 7.4 (6.0) mL. P = 0.14. Conclusions: We conclude that water accumulation was not statistically different between the two humidified nasal cannula systems. This finding highlights the difficulty with assessing the validity of anecdotal reports of equipment malfunction and demonstrates the need for product performance testing. Sponsored Research - None