Abstract: Gas analyzers of the non-dispersive infrared radiation type which are designed to measure the concentration of one gas in a mixture of gases containing that gas. A novel, electrically modulated, stable, thick film infrared radiation emitter is employed to emit a beam of collimated, focused energy; and two electrically biased detectors are preferably used so that a ratioed, error eliminating output signal can be supplied to the failsafe, signal processing circuitry of the analyzer. The latter, and a conventional analog-to-digital convertor, supply information to a microcomputer which: (1) turns the infrared radiation emitter on and off; (2) controls a heater which keeps the infrared radiation detectors at a constant, precise temperature; and (3) controls displays of a variety of information concerning the gas being measured and the status of the gas analyzer. The microcomputer also accepts ambient temperature, barometric pressure, and other compensation factors.

Abstract: A patient's airway adapter is fitted into a patient's airway, which is a combined breathing air supply and exhaust gas fluid flow passageway. The housing of this patient's airway adapter connects directly to a standard tapered tracheostomy or endotracheal tube connection or standard tapered portions of other fittings, and in turn provides a standard tapered connection to a patient's airway. The main air and gas stream, respectively, going to and from a patient, continues to flow directly through the patient's airway adapter. Samples of the patient's gas are withdrawn through a smaller diameter sampling exhaust port in the housing. The sampled patient's gas, immediately upon leaving the main air and gas stream, passes from the interior of a hollow cylindrical hydrophobic liquid baffle, through the baffle, and then into the sampling cannula enroute to a monitor. This hydrophobic baffle is held in a sealed position within the surrounding housing.

Abstract: A water trap is connected to a cannula which has a substantially constant internal diameter and which communicates moisture laden patient exhalations therethrough to an analyzer. The trap includes a body having a recess adapted for receiving a water absorbing compound which has an aperture therethrough for communicating dried exhalations to the analyzer. A second recess in the body is adapted for receiving another water adsorbing compound which similarly has an aperture of same diameter. When the first compound becomes substantially saturated and thereby permits moisture laden exhalations to pass therethrough, then the second compound absorbs those exhalations and swells for thereby closing its aperture and preventing communication of moisture laden exhalations to the analyzer.