Abstract: A gas mixing apparatus in the form of an anaesthesia apparatus includes a first path for oxygen, a second path for nitrous oxide and third path for carbon dioxide. The first path is divided for at least a part of its length into first and second by-pass passages 210, 212. A valve 214 in the first by-pass passage 210 is inter-connected with a valve 222 controlling the flow of a nitrous oxide through the second path and a valve 215 in the second by-pass passage 212 is interconnected with a valve 232 controlling the flow of carbon dioxide through the third path. The interconnecting means 250, 260 are so arranged that the opening of the valves 222, 232 associated with the second and third paths causes corresponding opening of the valves 214, 215 associated with the by-pass passages such that the total flow of oxygen through the apparatus will never fall below a predetermined minimum proportion by volume.

Abstract: A gas scavenger system is disclosed for use particularly with anesthetic administering equipment utilizing a demand valve for providing anesthetic gas to the patient. The gas scavenger system includes a collection manifold that collects the waste gases as they leave the normal exhaust ports of the demand valve. A flexible tubing means then carries those collected gases to a surge chamber prior to eventual discharge into a vacuum system. The surge chamber provides an interface between the vacuum system and the collection manifold and is connected to the vacuum system through a predetermined sized orifice which limits the flow to the vacuum system to a maximum known flow. The surge chamber normally allows continuous flow through the orifice to the vacuum system but is sized to accumulate an excess of flow from the collection manifold under abnormal conditions such as is occasioned when a patient coughs to allow time to remove the gases through the orifice and thus to prevent leakage to atmosphere.

Abstract: An ultrasonic flowmeter which measures gas velocity including a pair of ultrasonic transducers oppositely located around a conduit at a predetermined angle to the flow direction. Each transducer alternates between acting as a transmitter and a detector of ultrasonic frequencies, thus as one transducer transmits, the other receives. A measurement is made of the time of flight of the ultrasonic signal between the transmitter transducer and the receiver transducer and a microcomputer calculates the velocity of the gas by a known mathematical relationship utilizing the difference between the time of flight of the ultrasonic signals traveling upstream and those traveling downstream. The time of flight is determined by the phase shift or difference in phase angle between the signal at the transmitter transducer and the signal detected by the receiver transducer. To prevent ambiguity arising when the phase angle difference exceeds 360.degree.

Abstract: A gas switching device for use with a gas supply system in which two gases, for example, oxygen and air are supplied to a medical unit comprises a manifold 106 to which are attached two identical valve assemblies 108, 110. The manifold has a first inlet 1 and outlet 5 for the passage therethrough of the oxygen and a second inlet 2 and outlet 6 for the air. Each valve assembly 108, 110 includes a spool valve 122 movable from a first to a second position under the influence of the pressure of its associated gas. At least one valve assembly 110 has an inlet 18' communicating with a passageway 15 in the manifold which, in turn, communicates with the inlet 1 for the oxygen and an outlet 22 communicating with a further passageway 16 in the manifold which in turn communicates with the outlet 6 in the manifold for the air.

Abstract: An anaesthetic vaporizer of the by-pass type has a sump 7 with an outlet flow path comprising a first run 27 leading upwardly, a second run 30 leading downwardly and a third run 32 leading upwardly again. A duct 23 connects the lower end of the run 30 with the lower part of the sump and in normal operation is sealed by the sump liquid. However, if the vaporizer is displaced such that the liquid flows from the sump into runs 27 or 30 of the outlet flow path the liquid inevitably drains from the duct 23. A flow path for inflowing gas is thereby opened directly to the downstream end of the run 30, preventing the over-administration of vapor from the device and removing any danger of liquid anaesthetic being blown through the device from the runs 27 and 30.

Abstract: Processes for the preparation of certain halogenated aliphatic ethers are described, and in particular the preparation of 1,1,2-trifluoro-2-chloroethyl methyl ether, i.e., CH.sub.3 OCF.sub.2 CHFCl. This particular ether has many uses, and is a valuable material for use in the production of the inhalant anesthetic enflurane, 1,1,2-trifluoro-2-chloroethyl difluoromethyl ether, i.e., CF.sub.2 HOCF.sub.2 CHFCl, made and sold under the trademark ETHRANE by Airco, Inc., Montvale, New Jersey 07645.

Abstract: A thoracic drainage unit for removal of fluids from the thoracic cavity of a patient and/or to assist a patient in breathing comprises a collection chamber for receiving the fluids from the patient and an underwater seal located between the collection chamber and the patient. The underwater seal prevents pressure being applied to the thoracic cavity or backflow to that cavity. The water or other liquid for the seal is provided with the collection chamber as a complete unit ready for use. A collapsible bottle has a breakable neck that is readily broken by the user, whereupon the bottle is collapsed to force the liquid therein to create the liquid seal. A baffle is provided to prevent the liquid from reentering the bottle as it reexpands so that the precise needed volume of liquid is retained to create the seal.

Abstract: A gas flow unit such as a vaporizer mountable on a gas administration apparatus such as an anaesthesia machine in plug-in fashion includes an interlock system which prevents a valve for controlling the admission to the unit of gas from a supply provided by the apparatus from being operated before a locking mechanism has locked the unit to the anaesthesia machine.The interlock system also includes actuating means which when the unit is mounted on the anaesthesia machine, opens respective valve members in ports located on the anaestheia machine only when the control valve is moved to its operating position.In the case when two similar units are mounted side-by-side on the anaesthesia machine and intended for use as alternatives, the interlock system includes pins which when the control valve on one unit is moved to its operating position, extend outwardly from the unit to prevent the control valve on the other unit from being operated.

Abstract: Process for adjusting the halogen content of halogenated aliphatic ethers, by selective replacement of a halide substituent on the ether with a hydrogen. The process is particularly useful for the production of certain inhalant anesthetics.

Abstract: A device in the form of a flexible intravascular probe for use in analyzing absorbed blood gases includes a gas-permeable membrane 10 comprising two layers in intimate contact and supporting each other. The permeability of the second layer 6 is significantly less than that of the first 5, and provides the desired permeability of the membrane 10 as a whole. The first layer 5 provides the desired mechanical compatibility and other properties of the membrane 10.

Abstract: A counterbalance mechanism is disclosed for offsetting the normal gravitational forces exerted on a rotatable cylindrical hood for an incubator. The mechanism includes a specially shaped cam that is fixed with respect to the rotatable hood. A cam follower, mounted on a slide movable with the rotatable hood, is spring biased against the cam. As the rotatable hood is moved to various positions, the spring loading and cam profile coact to produce a counter-rotational force that is opposite and equal to the force of gravity acting upon the hood at any point in its rotation. One or more detents is provided in the cam at predetermined positions such that the cam follower can be positioned within one of the detents at one or more desired positions of hood rotation such that the hood may be held at that selected position.

Abstract: Methods for the dehalogenation of various haloethers are disclosed, comprising providing a haloether having the formula CX'.sub.3 -[CY.sub.2 ].sub.n -O-CZ.sub.2 -CX.sub.3 in which X', Y, Z and X are specifically disclosed combinations of hydrogen, fluorine chlorine and bromine such that the molecule includes at least one reducible group, but where both portions of any ethyl groups present are not reducible. Dehalogenation of these haloethers is carried out by contacting same with a hydrogen donor comprising an amine, preferably a primary or secondary amine or a primary, secondary or tertiary alkanol amine. The amine is preferably used in combination with a catalyst, such as a varivalent metal or a salt thereof, such as copper or a copper salt.

Abstract: An improved infant incubator is disclosed having a cylindrical shaped transparent hood which provide considerable accessibility to the infant. The cylindrically shaped hood consists of a plurality of sections rotatable about a central axis. The sections may be individually opened to give limited access to the infant or totally rotated to a position beneath the infant support structure such that access may be had from all sides of the incubator without obstructions. Heating of the incubator compartment is achieved by a unique means of circulating heated air through a double wall construction of the hood. The air is heated in a compartment beneath the infant and the warm air enters one of the hood sections and circulates through that section whereupon it is transferred serially to the next section and eventually can be received back into the heater compartment from the hood sections for recirculation. A fan and heater are located in the heater compartment for heating and circulating the air.

Abstract: A membrane and the method of making the same is disclosed for use with glucose analyzers to detect the level of glucose in liquid mediums such as whole blood. The membrane comprises a thin base wafer of a hydrophobic fluorocarbon material such as polytetrafluoroethylene (TEFLON). The wafer is initially etched by removing surface fluorides to produce a hydrophilic surface and is then contacted with a mixed reagent formed by combining in a volume ratio of about 1:1:1 about 4% paraformaldehyde in water, about 5% bovine serum albumin in water and about 10% glucose oxidase in water. The resultant membrane contains glucose oxidase covalently bonded to the surface of the base wafer.

Abstract: A device for use in vacuum suction systems for withdrawing fluids from a patient's body cavity, such as the stomach, wherein the device includes a chamber that is located in the flow stream of such fluids between the patient and the source of vacuum. At predetermined intervals, the device forces a quantity of the withdrawn fluid from the chamber, back into the suction tubing leading to the patient such that some of the fluid previously removed from the body cavity is forced backward toward such cavity under a positive pressure to dislodge any obstructions that may have occurred in the tubing or at the end of such tubing. In the preferred embodiment, the device is effectively self-contained and needs no source of positive pressure or electricity for its operation and is readily and fully operable from present commercial intermittent suction systems without revamping or otherwise modifying existing systems.

Abstract: A vaporizer interlock system is disclosed which is used in an anesthesia machine having two calibrated vaporizers for providing an anesthetic to a patient and further having a selector valve with three positions, two extreme positions where one of the two vaporizers is being utilized and a middle position where neither vaporizer is used. The system prevents opening of either vaporizer when the selector valve is in the middle position. Also, when the selector valve is moved to one of its extreme positions selecting one of the vaporizers, the other vaporizer is prevented from being moved from its "off" position. The "on" vaporizer must thereafter be placed in its "off" position before the selector valve can be returned to its middle position. In addition, a quick disconnect means is shown for quickly attaching and detaching the vaporizers from the anesthesia machine.

Abstract: An antidisconnect device is provided to prevent the inadvertent separation of medical fittings or connectors normally provided on the external end of a patient connected medical device such as an endotracheal or tracheostomy tube. The antidisconnect device basically comprises an annular ring having an internal diameter adapted to slip in close engagement over the normal outside diameter of the medical tubing. When assembled, the medical tubing is forced onto the tapered endotracheal tube connector thus distorting and enlarging the outside diameter of the medical tubing to a diameter larger than the internal diameter of the antidisconnect device. The antidisconnect device can then be moved toward the endotracheal tube tapered connector and can be forcefully held in position against the expanded diameter of the medical tubing. A strap extends from the annular ring to encircle any fitting or connector extending from the medical tubing to the patient and the distal end of the strap is affixed to the annular ring.

Abstract: An anesthesia machine is disclosed wherein flowmeters used to denote flow of O.sub.2 and other gases are in the form of precalibrated modules. The modules each contain a flowtube, float and scale and are precalibrated and the modules sealed to prevent tampering or affecting the calibration. The flowmeter modules are thus readily inserted into or removed from the anesthesia machine by a single plug-in maneuver to a common manifold without further calibration or leak testing. A key index system prevents the mislocation of any particular flowmeter module in a machine.The flowmeter module has a lower manifold at its bottom where all plug-in connections are located. A flowtube containing the float extends upwardly from the manifold and has an easily visible scale for accurate readings. Internal tubing within the flowmeter module returns gas from the flowtube back to the outlet connection in the lower manifold.

Abstract: A system is disclosed for detecting the position of the pointer of a gauge. The system includes a stationary light source which is positioned adjacent the pointer. A lens receives the light from the light source and redirects the light in at least one elongated light beam directed toward the pointer. In the preferred embodiment, the light source is located along the pointer's axis of rotation and the lens bends the light rays 90.degree. to form at least one arcuate light beam. A plurality of elongated light beams can be used and variations of different shapes of light beams can readily be used by so designing the lens means. A light sensitive detector is positionable in the gauge itself and is movable along a guided path on the opposite side of the pointer than is the light source. The guided path generally follows the particular shape of light beams that is directed toward the needle.

Abstract: A manifold is described for use with anesthesia breathing circuits and which is adapted to receive exhaust anesthetic gases from the anesthesia breathing circuit for disposal thereof. The manifold is connectible to a vacuum system for such disposal and includes a needle valve which may be set to establish a desired flow of exhaust anesthetic gas to the vacuum system. Because the pressures (either positive or negative) within the manifold will also have an effect on pressures within the anesthesia breathing circuit from which the exhaust anesthetic gas is received, it is necessary to control the pressure inside the manifold within certain predetermined limits. Relief valves are thus provided and which relieve the pressure within the manifold at certain predetermined positive and negative limits. The relief valves are so arranged that both may be opened manually by a common member which is accessible exterior of the manifold and can readily be displaced by personnel.