Disposable anti-fog airway adapter

Abstract

A disposable anti-fog airway adapter for use with a mainstream respiratory gas analyzer which provides a measurement of a patient's inhaled and exhaled gases. The airway adapter includes windows that are constructed of a thin, low heat capacity plastic that rapidly equilibrates to the temperature of the warm moist gases in the patient breathing circuit. In addition, the inside of the windows is also coated with an anti-fog surfactant either by laminating an anti-fog film with the window plastic prior to attaching the window to the airway adapter body or by first attaching the window to the airway adapter body and then applying the surfactant to the airway adapter after the window film is bonded in place so that the surfactant coats the entire inside of the adapter. The surfactant functions to increase the critical wetting tension of the surface it covers so that water on the window spreads into a uniform thin layer which does not absorb very much infrared energy and thus does not significantly reduce the signal strength. 'Instant on' operation is accomplished because no heater and the like is necessary to warm up the windows to maintain them at an elevated temperature to prevent fogging. Numerous techniques are also provided for adhering the windows to the airway adapter body so that a substantially airtight seal may be obtained.