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.

Abstract: A system and method for determining the concentration of an analyte such as oxygen in an unknown gas sample. A Vertical Cavity Surface Emitting Laser (VCSEL) is used as a variable wavelength light source which is "swept" through a wavelength range by varying the drive signal applied thereto. Quantitative spectroscopic analysis of the unknown gas sample is performed without the requirement of feedback circuitry for tuning the light source to the characteristic frequency of an analyte. Instead, the VCSEL is repeatedly "swept" through a range of frequencies determined by the drive signal, and the absorption is measured by the detector. The absorption lines do not always occur at the same place but instead move along around during the sweep based on the temperature and baseline current. The absorption at a particular wavelength may be determined by overlaying the drive signal and its timing information over the detected absorption signal.

Abstract: An side stream infrared gas analyzer for detecting the concentration of a gaseous component of a substantially gaseous flow stream such as the expired air of a patient under anesthesia. The infrared gas analyzer comprises an infrared energy detector, a sample cell, and an infrared energy source which are designed to be small and to consume relatively little electrical power. The infrared energy detector converts the received incident radiation into at least one electrical signal representative of the received incident radiation and is preferably mounted directly onto a printed circuit board containing signal processing circuitry which processes the electrical detection signals provided by the infrared energy detector. The infrared energy detector also has a first infrared transmissive window on a detection side thereof through which the incident radiation passes for detection.