Abstract: The gas sample identification apparatus transmits at least one beam of light of predefined frequency band through a gas sample present in a gas sampling chamber. The presence and concentration of various agents in the gas sample are determined by a linear variable filter that selectively passes the light beam transmitted through the gas sample chamber to an array of detectors. The detectors are positioned to receive only a narrow passband component of the light beam. The output signals from the array of detectors is processed by a multivariate statistical processor to accurately identify both the presence and concentration of one or more agents contained in the gas sample.

Abstract: The disclosed gas analyzer (10) provides two separate folded optical paths (16 and 18) from a single source (12) to a single detector array (14) via a polychromatic filter (26). One optical path (16) passes through a sample gas chamber (24) containing a gas to be analyzed and the other path (18) passes through a reference chamber (30) containing a reference gas. On each optical path (16 or 18), radiation from the source (12) is collected by upstream optics (22 or 28) to form a converging beam (16b, c or 18b, c), thereby reducing or eliminating the need for collection optics at the detector array (14).

Abstract: A needle valve in which the needle is moved with respect to its valve seat. The distal end of the needle has a length of a constant, uniform diameter that allows the flow to reach a maximum flow and not change while that finite length is moving within the valve seat. This allows a less critical placement of a stop that prevents further movement of the needle away from its valve seat.

Abstract: The source (12) has a heater element (122) sandwiched between elongate emitter plates (124 and 126). In operation, the source (12) is operated at temperatures in excess of 900.degree. C. and, preferably, at least about 1200.degree. C. to provide radiation in the 7-10 micrometer wavelength range. In one embodiment, the source (12) is used in conjunction with an elongate detector array (14) in a gas analyzer (10) for analyzing respiratory and anesthetic gases. Spherical mirrors (36a, 36b) and flat mirrors (38a, 38b) are employed to image the source (12) on the detector array (14). A linear variable filter (26) allows for analysis of the radiation at multiple wavelengths using detector array (14).

Abstract: An anesthesia system is disclosed that prolongs the lifetime of an oxygen fuel cell be used to detect the concentration of oxygen in that anesthesia system. The system determines and provides a signal indicating the end of any particular operation using the anesthesia system and that signal is used to cut off all gas supplies with the exception of the fresh air supply which is then allowed to pass through the system to wash the various lines, including the conduit having the oxygen gas fuel cell thus preventing the typically high concentrations of oxygen used in a operation from remaining in the oxygen fuel cell for an unnecessary period of time. Furthermore, the gases in the anesthesia machine are eliminated along with their deleterious effects and replaced by fresh air from the normal supply of fresh air to the system.

Abstract: An optical alignment device comprised of two "H" shaped structures may be used to precisely position an optical element in two orthogonal directions. Each "H" shaped web structure includes two flanges extending from opposite ends of a center web having a centroidal flexure axis. The "H" shaped structures also each include an aperture extending through the flanges and the web. The center webs may be resiliently flexed, allowing the angle between the flanges of each "H" shaped structure to be adjusted by rotating screws fitted through one flange and threaded to the other. The "H" shaped structures are mounted together so that their flexure axes are orthogonally oriented with respect to each other and so that the apertures of each structure are aligned to form an optical path cavity.

Abstract: A system and method for estimating the NO.sub.2 concentration in the gas provided to a patient. The therapy of using nitric oxide to threat the lungs of a patient includes administering that gas along with a gas containing oxygen. Since the mixing of NO and oxygen cause a reaction leading to the formation of NO.sub.2 and which is toxic, the method and system determine the concentration of oxygen in the oxygen containing gas, the concentration of NO in the NO containing gas and the residence time between the time those gasses are mixed together to the time that mixture is administered to the patient. Those values are then used, preferably in a microprocessor to access a look up table in the memory of the processor, to thereby provide an estimation of the NO.sub.2 concentration of the gas administered to the patient.

Abstract: The thermal time of flight signal guard overcomes the leakage crosstalk problem encountered in prior art systems by eliminating the leakage currents in the flow transducer before they reach the temperature sensors. This is accomplished by the installation of a conductive strip into the fluid flow path, interposed between the temperature sensors and the heat source. The conductive strip intercepts any errant leakage currents that are generated by the heat source and carried by moisture which accumulates on the walls of the fluid flow path to the temperature sensor. The signals that pass through the fluid flow conduit past the conductive strip to the temperature sensors are the thermal tracer signals. Therefore, the temperature sensors operate in a leakage current free environment and the signals produced by the temperature sensors are devoid of leakage current noise.

Abstract: A breathing bag arm assembly that is affixed to a medical apparatus such as an anesthesia machine or component thereof. The breathing bag arm assembly comprises three moving parts, a base connector that rotatable attaches to the medical apparatus, a bent tube that is affixed to the base connector and can be rotated to a plurality of discrete locked positions with respect to the base connector and a port connector that is rotatable affixed to the other end of the bent tube. The port connector has a port for connecting to the flexible bag. By manipulation of the assembly, the clinician can locate the flexible bag in a variety of positions for convenient use, and retain the flexible bag in the desired position depending vertically downwardly. The overall assembly is readily disassembled and reassembled for cleaning or the like.

Abstract: An anesthetic vaporizer filler valve is disclosed that can be used in conjunction with anesthetic agent bottles currently commercially available and which have standard keying systems with rotating collars having lugs extending therefrom. The standard collar of such anesthetic agent bottles is keyed into the vaporizer filling valve. the vaporizer filler valve has an internal valve that must be opened in order to introduce the liquid anesthetic agent into the vaporizer sump. By means of a corresponding slot in the vaporizer filler valve that correspond with mating lugs of the standard anesthetic agent bottle, only a proper anesthetic agent bottle can engage and be screwed into the filler valve designed for that specific anesthetic agent.

Abstract: The apparatus of the present invention characterizes the operating characteristics of a medical monitoring probe in a more comprehensive and accurate manner than is heretofore known in the prior art. This apparatus not only identifies the present value of a plurality of operating characteristics of the optical components contained in the probe, but also computes the interrelationship therebetween to produce a composite probe indicia that substantially defines the net operating characteristics of the probe, including the interrelation of the various interactive and/or cumulative effects. This composite probe indicia represents either a number or a graphical representation of probe operating characteristics that can be used directly by the processor contained within the monitoring system to perform the required computations.

Abstract: A locking device is disclosed for attachment to an absorber used in an anesthesia system and which provides assurance that the bag to ventilator switch cannot be put in the ventilator position for those applications where a ventilator is not intended to be used, i.e. MRI applications. As a further feature, the locking device also physically prevents the ventilator input to the bag to ventilator switch from being occluded, either by a protective plastic shipping cap or by having tubing or other conduits connected thereto.

Abstract: A system is disclosed to prevent the build up of pressure within a patient circuit when an oxygen flush is activated in a ventilator powered anesthesia system. In the event the user activates the oxygen flush at a time that the ventilator is in the inhalation cycle providing a breath to the patient, a valve is automatically opened to vent the patient circuit to the atmosphere, thereby preventing that additional oxygen flow to the patient circuit from resulting in an undesirable pressure build up that could affect the lungs of the patient.

Abstract: This probe makes use of a simplified housing construction that significantly reduces the cost of the manufacture of the probe housing. The housing is implemented using two molded housing halves, which are pivotally connected together and which include an integral spring member. In addition, the housing includes a connector mounted thereon for enabling the probe to be disengaged from the cable and its associated connector that interconnects the probe with the medical monitoring equipment. As a further improvement, a notch is provided on the housing so that the conductors can be positioned to exit the probe in any direction to minimize the possibility of the conductors inadvertently pulling the probe loose from the patient's finger.

Abstract: A system is provided for detecting the breakthrough of CO.sub.2 into the inspiratory limb of a substantially closed circle patient breathing circuit having a CO.sub.2 absorber to remove CO.sub.2 from the continuously recirculating gases. The CO.sub.2 is detected by a gas analyzer located in the inspiratory limb of the patient breathing circuit. Upon detection of that CO.sub.2, the system increases the flow of fresh gas into the circle patient breathing circuit to a flow rate in excess of the minute volume of gas being delivered at that time to the patient. The increased flow of fresh gas basically prevents the further flow of CO.sub.2 from the expiratory limb into the inspiratory limb, thus preventing the CO.sub.2 from being inhaled by the patient.

Abstract: A Raman gas analysis system uses a half-wave plate to match the polarization of Raman scattered light emitted from a gas analysis cell to a preferred polarization orientation of a diffraction grating. The gas analysis system includes a plasma discharge tube for generating a polarized light beam; a gas analysis cell for containing a sample gas which produces Raman scattered light in response to being irradiated with the polarized light beam; an optical subsystem for collecting and providing the Raman scattered light with a preferred polarization orientation; a holographic diffraction grating for dispersing the Raman scattered light into component light signals; and an array detector for detecting the component light signals.

Abstract: An algorithm is disclosed that enables the display for a medical ventilator to automatically adjust its wave characteristics depending on the settings for that ventilator established by the clinician. As the respiratory rate, or rate at which the ventilator provides breaths to the patient, is changed by the user, the rate of sweep of the waveform generator displaying that data is also changed to insure that the data is displayed in the most relevant manner. As another parameter, as the pressure limit in the patient circuit is set by the clinician, the waveform vertical scale is adjusted to make sure the particular limit of pressure is displayed. As the pressure limit or the respiratory rate are changed in the ventilator by the clinician, the waveform of he data displayed also is automatically modified to make that data best presentable to the clinician.

Abstract: An improved system for the determining the collapse of a bellows within a canister as part of a ventilator system for delivering breaths to a patient via a patient circuit. The system measures the pressure in the bellows canister external of the bellows and measures the pressure within the interior of the bellow. A processor compares the pressures and determines when the pressure within the canister exceeds a predetermined offset in excess of the pressure within the interior of the bellows to conclude that the bellows is in a collapsed condition. In the preferred embodiment, the processor also uses, as input data, the flow delivered by the ventilator to the bellows canister to determine that offset value. When a bellows empty condition is determined, various actions can be taken, among them to signal an alarm and also to change various functions of the ventilator to prevent further difficulties in the overall system.

Abstract: An improved system for the control of PEEP in a medical ventilator system having a ventilator and a bellows contained within a bellows canister. A pop-off valve that normally vents excess pressure within the bellows to atmosphere is modified such that its exhaust is vented to a predetermined pressure above atmospheric pressure, such as the PEEP pressure. In the preferred embodiment, that predetermined pressure is the pressure within the ventilator drive gas conduit that transmits the gas from the ventilator to drive the bellows and the exhaust from the pop-off is effectively isolated from that drive gas conduit to avoid contaminating the gas within that drive gas conduit.

Abstract: A system of making a connection between the yoke of an anesthetic delivery apparatus and a gas cylinder for supplying a gas to that apparatus. The system includes an adaptor block that has a keying system, such as pegs, that keys the adapter block into a specific gas cylinder, such as by indentations. The adapter block has machine readable indicia and is affixed to the anaesthesia delivery apparatus such that the apparatus can read the indicia to determine the position of the adaptor block and thus identify the particular gas cylinder that is connected to the adapter block. By this system, a plurality of gas cylinders having differing gases can be used to supply a single inlet of an anesthetic delivery apparatus rather than have a separate inlet for each gas. In each instance, the particular gas thus provided is identified by the anaesthetic delivery apparatus to make the necessary adjustments to that apparatus to administer the gas to a patient.