Abstract: A method of determining the mixed venous PCO.sub.2 (PvCO.sub.2) is disclosed, the method comprising the steps of:(a) measuring the PCO.sub.2 of the gases inhaled and exhaled by the patient under controlled conditions without rebreathing;(b) causing the patient to inhale a test gas containing at least a small concentration of CO.sub.2 and continuing to measure the PCO.sub.2 of the inspired and expired gases, the patient taking at least two breaths without rebreathing;(c) determining the PCO.sub.2 of the inspired gases (P.sub.I CO.sub.2) and the end tidal PCO.sub.2 of expired gased (PECO.sub.2);(d) determining the differences between the end tidal PCO.sub.2 and inspired PCO.sub.2 under control and test conditions, and relating it to the inspired PCO.sub.2 used in the determination of the difference. This relationship can be used to calculate the mixed venous PCO.sub.2.

Abstract: A method of determining the mixed venous PCO.sub.2 (PvCO.sub.2) is disclosed, the method comprising the steps of:(a) measuring the PCO.sub.2 of the gases inhaled and exhaled by the patient under controlled conditions without rebreathing;(b) causing the patient to inhale a test gas containing at least a small concentration of CO.sub.2 and continuing to measure the PCO.sub.2 of the inspired and expired gases, the patient taking at least two breaths without rebreathing;(c) determining the PCO.sub.2 of the inspried gases (P.sub.I CO.sub.2) and the end tidal PCO.sub.2 of expired gases (PECO.sub.2);(d) determing the differences between the end tidal PCO.sub.2 and inspired PCO.sub.2 under control and test conditions, and relating it to the inspired PCO.sub.2 used in the determination of the difference. This relationship can be used to calculate the mixed venous PCO.sub.2.

Abstract: A method of determining the mixed venous PCO.sub.2 (PvCO.sub.2) is disclosed, the method comprising the steps of: (a) measuring the PCO.sub.2 of the gases inhaled and exhaled by the patient under controlled conditions without rebreathing; (b) causing the patient to inhale a test gas containing at least a small concentration of CO.sub.2 and continuing to measure the PCO.sub.2 of the inspired and expired gases, the patient taking at least two breaths without rebreathing; (c) determining the PCO.sub.2 of the inspired gases (P.sub.I CO.sub.2) and the end tidal PCO.sub.2 of expired gases (PECO.sub.2); (d) determing the differences between the end tidal PCO.sub.2 and inspired PCO.sub.2 under control and test conditions, and relating it to the inspired PCO.sub.2 used in the determination of the difference. This relationship can be used to calculate the mixed venous PCO.sub.2.

Abstract: A mouthpiece through which a person may breathe has a sealing flange for introduction into the mouth. The sealing flange has an upper portion for lying against the hard palate and a lower portion for fitting between the lower lip and the anterior surface about the lower teeth and gums. The juxtaposition in the mouth of the upper portion against the hard palate and the lower portion seated in the lower vestibule portion of the mouth results in the sealing flange forming an effective seal and the sealing flange being comfortably held in place in the mouth even when the mouth is open to the extent of the normal relaxed muscle tone of the mouth. To facilitate the seal when the mouthpiece is introduced into the mouth, a tooth tray is provided. Another aspect of the invention permits the mouthpiece to envelop the nostrils such that when the mouthpiece is in place all inspired and expired air must pass through the mouthpiece.

Abstract: A heating element comprising a plurality of ceramic components strung together on a heating wire to form a flexible structure, adjacent ceramic components comprising integrally formed mating projections and depressions. The element comprises ceramic components of a type each having a body defining two generally parallel passages therethrough, both passages terminating at one end in a depression, one passage terminating at the other end in a depression and the other passage terminating at the other end in a projection.

Abstract: A heating element comprising a plurality of ceramic components strung together on a heating wire to form a flexible structure, adjacent ceramic components comprising integrally formed mating projections and depressions.

Abstract: An endotracheal tube introducer comprising a rigid hollow mouth piece of greater diameter than the endotracheal tube being inserted thereinto, and an elongated member secured to and extending longitudinally away from the mouth piece, the elongated member comprising at least one guide rib extending longitudinally along the length of the elongated member away from the mouth piece and relatively thin pliable film pleated longitudinally and secured to the at least one guide rib and forming with the at least one guide rib, when the film is unpleated, an enclosed tubular structure for guiding the endotracheal tube into the trachea.