The Science Journal of the American Association for Respiratory Care

1999 OPEN FORUM Abstracts

RANDOMIZED, CONTROLLED, CLINICAL TRIAL OF AN INNOVATIVE SELF-HEATED HUMIDIFIER.

Shirley D. Broach, RRT, Charles G. Durbin, Jr., MD University of Virginia Health Systems, Charlottesville, Virginia 22908

INTRODUCTION: Inadequate humidity of inspired gases through an artificial airway adversely affects patient outcomes from retained secretions and damage to lung mucosa. The passive HME/HCH has replaced water-filled heated humidifiers in many clinical settings. Recently, a self-contained chemically heated, active HME/HCH has been developed. The ThermaxÒ Super HCH with Filter (T), available through 3CI/Critical Care Concepts Inc., combines soda sorb with standard HME material, and from the chemical reaction with exhaled carbon dioxide produces heat, increasing the delivered water content. We compared a passive HME/HCH (GibeckÒ Humid Vent 2S manufactured by Louis Gibeck AB of Sweden) (G) to the T in a prospective, randomized trial.

Methods: The Human Investigation Committee permitted the study without informed consent since we were comparing FDA approved products. Patients undergoing first time, non-emergency, coronary artery bypass surgery, having good ventricular function, were randomly assigned either a standard HME/HCH or the T HME/HCH at the completion of surgery. We hypothesized that the T would increase core temperature more quickly and that this would improve coagulation and hasten extubation. Blood loss, time to extubation, body temperature, dynamic airway pressures and flows, and number of HME change outs were recorded until extubation. Quality and quantity of secretions were noted. Initial rate of temperature rise and added resistance of the humidifier at extubation was calculated. 24 patients in the G group and 22 patients in the T group completed the study. Continuous values were compared using T tests.

Results:

HME/HCH Initial Temp Rise Blood Loss Time to Extubation Added Resistance
GibeckÒ 0.0699 °C/hr* 382 ml 8.54 hr 0.0899 cmH2O×sec×L-1
ThermaxÒ 0.269 °C/hr* 429 ml 10.12 hr 0.0956 cmH2O×sec×L-1
*p=0.0027

Only the rate of rise of body temperature was different between the groups. No device needed changing due to accumulation of secretions.

Conclusions: The ThermaxÒ increased these hypothermic patients' core temperature three times more quickly than a standard, passive HME/HCH. Extubation time and bleeding are influenced by many factors, not just core temperature. This preliminary study suggests that the ThermaxÒ device may be useful in hypothermic patients. Further investigation is needed to define other benefits. Secretions were not significant in any of these patients.

OF-99-006

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