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A randomized, controlled, clinical trial of a chemically-reactive heated humidifier
1University of Virginia Health Systems, Box 800688, Charlottesville VA 22908-0688, USA. sdb2@virginia.edu
Background:
Inspired gases can be warmed and humidified in a variety of ways. The effect of a chemically-reactive heated heat and moisture exchanger/hygroscopic condenser humidifier (HME/HCH) on secretions, rate of core body warming, blood loss, and time to extubation was studied in hypothermic post-cardiac surgery patients.
Methods:
Fifty patients with normal ventricular function, undergoing coronary bypass grafting, were randomized to receive either a conventional HME (Gibeck, Humid-Vent 1 [PN 11112], Hudson RCI, Temecula, California) or a chemically-heated HME (Thermax HCH Filter [PN 9302], Enternet Medical, Las Vegas, Nevada) following surgery or on arrival in the ICU. Effects on secretions, core temperature, postoperative bleeding, duration of intubation, and added resistance were measured. The Thermax weighs 67 g and adds 79 mL of dead space. The Humid-Vent 1 weighs 9.4 g and adds 10 mL of dead space.
Results:
There was no significant difference between the 2 devices in time to extubation, blood loss, or quality or quantity of secretions. Use of the Thermax device, however, resulted in a more rapid rise in body temperature (0.299 degrees C/h with the Thermax vs 0.073 degrees C/h with the Humid-Vent 1, p = 0.001) and more added resistance (0.0672 cm H(2)O/L/s with the Thermax vs 0.0123 cm H(2)O/L/s with the Humid-Vent 1, p = 0.00000172).
Conclusions:
The Thermax chemically-heated HME results in more rapid warming of mildly hypothermic patients following cardiopulmonary bypass than does a conventional passive HME.