The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts

PERFORMANCE OF HEAT AND MOISTURE EXCHANGERS AND OTHER HUMIDIFYING DEVICES FOR TRACHEOSTOMIZED PATIENTS WITH SPONTANEOUS BREATHING: A BENCH STUDY.

Yusuke Chikata, Jun Oto, Mutsuo Onodera, Masaji Nishimura; Emergency and Critical Care Medicine, The University of Tokushima Graduate School, Tokushima, Japan

Background: Heat and moisture exchanger (HME) is popular as a humidifying device for mechanically ventilated patients. It is also applied for tracheostomized patients with spontaneous breathing (SB), however its performance remains to be clarified. The aims of this bench study were to investigate effects of SB parameters and supplemental oxygen on performance of the HMEs and to compare them with other humidifying devices. Method: We assessed humidification performance of 11 HMEs. In addition, an oxygen mask with nebulizer heater and high flow continuous positive airway pressure (CPAP) system for tracheostomized patients. SB was simulated with a mechanical ventilator (Puritan-Bennett 840, Covidien, Carlsbad, CA), a model lung (TTL model 1601, Michigan Instruments, Grand Rapids, MI) and a servo-controlled heated humidifier (MR730, Fisher&Paykel, Auckland, NZ). Tidal volume (VT) were 300, 500 and 700 mL and respiratory rate of 10 and 20 breaths/min. High flow CPAP system was set at 15, 30 and 45 L/min. Eight of HMEs and high flow CPAP system had a port to deliver oxygen, and measurements were repeated with 3 L/min of dry oxygen. We measured absolute humidity (AH) of the inspired gas by using a hygrometer after stabilization of at least one hour. Results: A figure shows AH values among the devices and effects of supplemental oxygen. AH varied among the tested HMEs, and 4 of 11 HMEs maintained AH higher than 30 mg/L. AH with the high flow CPAP system and oxygen mask with nebulizer heater was 37.7±2.8 mg/L and, 31.9±2.2 mg/L, respectively. Supplemental oxygen of 3 L/min decreased AH, and AH was not maintained above 30 mg/L with any HMEs. As VT increased, AH decreased in all devices. Conclusions: There were significant differences in humidification performance among HMEs for tracheostomized patients with SB. With supplemental oxygen, AH decreased below the level of AARC guideline values. Caution is advised, when supplemental oxygen is applyed to HMEs in tracheostomized patients with SB. Sponsored Research - None