Abstract: A capnoscope assembly for measuring carbon dioxide (CO2) concentration, and an associated method. The assembly includes a detection unit, an indicator holder, a processing unit, and a calibration member. The processing unit adjusts light parameters such that a camera detects a predetermined calibration colour. A colorimetric indicator is arranged to be used in the indicator holder. The colour of the colorimetric indicator surface is measured when illuminated by emitted light being generated by using determined calibrated control signal values, when no CO2 is present. The measured colour is stored as a zero CO2 colour value. A CO2 concentration relationship is determined based upon the measured zero CO2 colour value. The processing unit applies the CO2 concentration relationship during CO2 concentration measurements provided that the determined calibrated control signal values are applied when emitting light.

Abstract: A breath analyzing and training assembly for detecting CO2 concentration in the breathing gas of a user, includes a selective colorimetric CO2 detector having a detector surface which rapidly and reversibly changes color with CO2 concentration, when exposed thereto, and an adapter including: a docking part for receiving a mobile unit including an image capturing element, a display, and a processing element, the docking part configured to position the image capturing element in a fixed relation to the colorimetric detector, such that the image capturing element captures images of the detector surface; a detector holding part for receiving the colorimetric detector; a conduit for leading breathing gas to and from the user such that part thereof passes the detector surface; wherein the processing element measures CO2 concentration changes in the breathing gas by identifying color changes of images of the detector surface captured by the image capturing element.

Abstract: A manual resuscitator assembly for measuring the carbon dioxide (CO2) concentration in breathing gas of a person being ventilated, includes: a selective colorimetric CO2 detector having a detector surface adapted to change color rapidly and reversibly with CO2 concentration, a detector holding part for receiving and attaching the colorimetric detector, a manual resuscitator including a bi-directional gas conduit between an expiratory and an inspiratory part of a breathing circuit, the conduit configured such that a clinically predetermined fraction of breathing gas enters the holding part and contacts the surface during ventilation, a docking part for receiving and attaching a mobile unit, including image capturing, processing and a display elements, the processing element adapted to execute an application program to measure CO2 concentration changes in the breathing gas by identifying changes in the optical property of the detector surface captured by the image capturing element.

Abstract: A breath analyzing and training assembly for detecting CO2 concentration in the breathing gas of a user, includes a selective colorimetric CO2 detector having a detector surface which rapidly and reversibly changes color with CO2 concentration, when exposed thereto, and an adapter including: a docking part for receiving a mobile unit including an image capturing element, a display, and a processing element, the docking part configured to position the image capturing element in a fixed relation to the colorimetric detector, such that the image capturing element captures images of the detector surface; a detector holding part for receiving the colorimetric detector; a conduit for leading breathing gas to and from the user such that part thereof passes the detector surface; wherein the processing element measures CO2 concentration changes in the breathing gas by identifying color changes of images of the detector surface captured by the image capturing element.

Abstract: A device for detecting breathing of a subject, includes a colorimetric CO2 detector. A method for determining whether a subject is breathing and a method for verifying proper placement of an endotracheal tube when using a resuscitation bag are also described.

Abstract: A method and apparatus for determining a pulmonary function parameter, EVG, indicative of a living subject's effective lung volume, namely the lung volume in which gas exchange between respiratory air and pulmonary blood takes place efficiently. The apparatus carries out the steps of the method: (1) determining for a first breath during normal steady state breathing of the subject the end-tidal carbon dioxide or oxygen concentration Pet1 and the average rate of flow Va1, over the duration T1 of the breath, of expired carbon dioxide or oxygen, (2) determining for a second breath comprising a breath-hold period the end-tidal carbon dioxide or oxygen concentration Pet2 and the average rate of flow Va2, over the duration T2 of the breath, of expired carbon dioxide or oxygen, and (3) determining EVG as a quantity proportional to the ratio of the difference between said average flow rates Va1 and Va2 to the difference between said end-tidal concentrations Pet2 and Pet1.

Abstract: A method of increasing the shelf life of a reversible calorimetric device for indicating carbon dioxide is disclosed, which method comprises placing said device together with at least one non-toxic pH-lowering gas in a gas-tight wrapping or casing. A package is also disclosed which is prepared by means of said method. The invention also relates to the use of a non-toxic pH-lowering gas for increasing the shelf life of a device of the above mentioned type.

Abstract: A device for indicating the presence of CO.sub.2 in a patient's inhaled air comprises a CO.sub.2 detector including an indicator element (14) which undergoes a reversible color change in response to exposure thereof to air containing CO.sub.2 in concentrations of the same order of magnitude as the CO.sub.2 concentration of air exhaled by a human being, and also comprises a heat-moisture exchanger (12) including a housing (13) with a first connecting port (15) adapted to be connected to the trachea of a patient, and a second connecting port (15) adapted for connection to a ventilator or an anesthetic machine, for example. In a flow-through passage (P) extending between the connecting ports (15, 16) there is mounted an element (18) for the regenerative exchange of heat and moisture between, on the one hand, air flowing through the flow-through passage (P) in one direction and, on the other hand, air flowing through the flow-through passage (P) in the opposite direction.

Abstract: Apparatus for examining pulmonary function parameters of a patient comprises a rebreathing system (1-6) adapted to be connected with the patient and including a variable-volume reservoir (1), a carbon dioxide absorber (19) in an inhalation conduit (3) and valve means (24) for selectively switching the carbon dioxide absorber (19) on and off. A carbon dioxide meter (25) is controllable to selectively measure the carbon dioxide content of respiratory gas being exhaled and of exhaled respiratory gas collected in the reservoir (1). Volume monitoring devices (17,18) monitory the volume variations of the reservoir (1). A computing unit (30) computes the pulmonary blood flow and other pulmonary function parameters using carbon dioxide concentration parameters measured by the carbon dioxide meter (25) and ventilatory rate parameters are measured by the monitoring devices (17,18).

Abstract: A device for determining the depth of anaesthesia of a patient, the device including an optical measuring means (1) for measuring on a part (2) of the patient an optical parameter such as transmission or reflection, which is influenced by the circulation of the blood through this part of the patient's body, and to produce an electric signal which varies in accord with this parameter. This signal is related to the periodic variations in the blood-pressure of the patient and thus has a frequency which coincides with the heart frequency of the patient and a maximum amplitude and a minimum amplitude which are related respectively to the systolic and diastolic blood-pressure of the patient. The signal is applied to signal processing circuits (3) which determine the variation in the period of the signal (.DELTA.(R-R)) and the variation in its maximum amplitude (.DELTA.P.sub.max) or minimum amplitude (.DELTA.P.sub.min) or in the difference between its maximum and minimum amplitudes (.DELTA.(P.sub.max -P.sub.

Abstract: Apparatus for measuring the oxygen uptake of a person connected to a respirator (23) includes a closed container (1) of variable volume. The container (1) can be connected to the respiratory passages of the person, via an inspiration line (2) and an expiration line (3), so that the person can inspire from and expire to the container (1). One of the lines incorporates a carbon dioxide absorber (19) for removing carbon dioxide from the respiratory gas. Means (17,18) are provided for monitoring the volume of the container (1), and controllable means (8,9,10) are found for supplying pure oxygen gas to the container (1). The oxygen-gas supply means (8,9,10) are so controlled by the means (17,18) monitoring the volume of the bellows (1) that the volume of the bellows at a given predetermined point in the breathing cycle of the person connected to the apparatus is held substantially unchanged. Means are also provided for determining the amount of oxygen gas supplied to the container (1) herewith.

Abstract: Apparatus for determining the proportion of a given gas component in a gas mixture, comprising a piezoelectric crystal provided with a surface layer containing a substance capable of selectively and reversibly adsorbing said gas component, and being so arranged that the gas mixture can be brought into contact with said surface layer. The crystal is incorporated in an oscillator circuit which produces an output signal representing the oscillating frequency of the crystal, and therewith the proportion of the given gas component in the gas mixture. For compensating the temperature dependency of the surface-layer adsorption of the relevant gas component, a thermistor (R.sub.T) is arranged to be influenced by the same temperature variations as the piezoelectric crystal. Further, the output signal (S) of the oscillator circuit is connected to the input of an amplifying circuit, which incorporates the thermistor (R.sub.

Abstract: A method and means is disclosed for carrying out the calibration of a gas monitor. The calibration is effected by providing a calibration gas containing a precise amount of the constituent that is measured by the gas monitor. That calibration gas is introduced into the gas monitor and passes therethrough in a closed system such that leakage of calibration gas to the surrounding environment at the inlet to the gas monitor and from the outlet of the monitor is prevented. The calibration gas is further stalled in the gas sensor chamber of the gas monitor for the operator to make necessary adjustments to the gas monitor at no flow conditions of the calibration gas.

Abstract: An anesthetic apparatus for administering a gaseous anesthetic comprises a breathing mask which is connected to the inspiration pipe and the expiration pipe of the apparatus and used for connecting the apparatus to the airways of a patient. To prevent harmful gaseous anesthetic from being released to the surroundings when the mask is temporarily lifted from the patient's face during anesthesia in order to check the condition of the patient, the apparatus is provided with a gas suction device which can be connected to the mask through a controllable valve. The gas suction device may be continuously operated or may be started automatically when the valve is opened. A signal emitter for generating control signals and applying these to the valve is arranged on, or in the vicinity of the mask in a manner such that it can either be activated manually by the anesthetist, or is activated automatically when the mask is lifted from the patient's face, at which time it generates a control signal for opening the valve.

Abstract: A device for connecting a respirator or an anesthesia machine to a patient comprises a hose (1) which is flexible along substantially its whole length, and one end (1a) of which is formed in a manner to enable it to be connected, in gas-tight fashion, to an endotracheal tube or the like, and the other end (1b) of which is formed in a manner to enable it to be connected, in gas-tight fashion, to the Y-piece of the respirator or anesthesia machine. Incorporated in the part of the hose (1) located nearest the aforementioned other end (1b) is a flexible heat and moisture exchanger body (2) which fills substantially the whole of the cross-sectional through-flow area of the hose (1) and which is substantially uniformly permeable to a gas flow. The heat and moisture exchanger body (2) advantageously comprises a homogenous felted material impregnated with a hygroscopic substance and an anti-bacteria agent. The hose (1) together with the heat and moisture exchanger body (2) incorporated therein form a disposable unit.

Abstract: For the purpose of measuring the concentration of one or more given components of the breathing gas of a patient there is removed a small part of the breathing gas at a location immediately in front of the mouth of the patient. The withdrawn gas is passed to a measuring instrument sensitive to the component or components of interest through a line which comprises, at least in part, a thin tube of a fluorosulfonyl polymer, and the outer surface of which is in free contact with the ambient air. In this way, the temperature and relative humidity of the breathing gas supplied to the measuring instrument are brought into agreement with the temperature and relative humidity of the ambient air.

Abstract: For the purpose of carrying out an MMV-treatment (Mandatory Minute Volume) by means of a lung ventilator which includes a breathing-gas source from which a patient connected to the ventilator is able to breath spontaneously through an inspiratory line, and a ventilator unit which can be activated by means of a control signal so as to deliver to the patient through the inspiratory line a mandatory breath of determinable tidal volume from the breathing-gas source, the flow of breathing gas through the inspiratory line is continuously sensed by means of a flow meter. In a control unit there is generated a signal which is representative of the continuous integral of the difference between a reference signal and the flow signal from the flow meter. The value of the integrated difference signal is compared with a given limit value. Each time the value of the integrated difference signal reaches the limit value, the ventilator unit is activated to deliver to the patient a mandatory breath of given tidal volume.

Abstract: In the illustrated embodiment, the moisture reservoir comprises a tube of gas-permeable, hygroscopic material. The exhalation flow path is into a blind axial bore of a spool like member having a series of transverse notches or cuts at the top and bottom which provide interspaces leading from the bore to the tube which covers the notches at their periphery. The notches leave integral fins or lamellae with large surface area exposed to the in-flow of dry respiration gas radially through the tube wall and into the interspaces which provide further reservoirs for moisture and warmth.

Abstract: An illustrative embodiment shows infrared radiation divided into two beams which impinge on respective detectors via respective stationary filters, so as to provide measures of two constituents of a mixture of gases used for mixed anaesthesia. The same angled mirrors which provide the measurement beams may also be reflective on their sides toward the infrared source to provide reference beams to the filters and detectors such that the detectors may alternately sense the measurement and reference beams with the aid of beam interrupters.