Portable anaesthetic machine and emergency kit

Abstract: A portable anaesthetic machine (2) is described. Dispensing a liquid anaesthetic to a patient is sometimes desirable and may be hard to achieve, especially with portable equipment. This problem is resolved with the present invention in that the portable anaesthetic machine (2) comprises a gas flow generator (4) for generating a flow of gas at an adjustable pressure and/or flow rate, an inspiratory line (6) and an expiratory line (8). The gas flow generator (4), inspiratory line (6) and expiratory line (8) constitute the gas flow pathways for the respirator (2). Finally, a membrane (10) is arranged in the gas flow pathways and made of a self-sealing material, whereby the membrane (10) can be punctured by a syringe needle (12A) for dispensing the liquid anaesthetic into the gas flow pathways an optional number of times.

Description: The present invention relates to a portable anaesthetic machine according to claim 1. The present invention also relates to a portable anaesthetic emergency kit according to claim 8. Many different respirators are available for specific uses in the treatment of patients. Anaesthetic machines, which are generally stationary because of their size, like the KION anaesthetic machine from Siemens-Elema AB, Solna, are used to anaesthetise patients prior to surgery. Intensive care often utilises multifunction ventilators, capable of operating in a plurality of modes, such as the Servo Ventilator 300, Siemens-Elema AB. Simpler ventilators are employed for subacute care and the care of patients in their homes. Completely portable ventilators are being developed, as described in the Swedish patent application 9703290-8. Special emergency equipment for life-saving and emergency treatment at accident sites are also available. In particular, portable equipment has limitations in its ability to administer additives, in particular anaesthetics to the patient. Many substances, which could be advantageously administered via the lungs, must either be injected, with all the associated risks found at an accident site, or the medication or substance must be administered with a separate inhaler, which means that the respiratory assistance will be interrupted. One object of the invention is to achieve a portable anaesthetic machine with which the administration of an anaesthetic to a patient connected to the machine can be performed in a safe and reliable fashion with no need to interrupt respiratory assistance. Another object of the invention is to achieve a portable anaesthetic emergency kit for inhalation anaesthesia. Such an emergency kit would be of tremendous benefit in the rapid treatment of or surgery on acutely injured patients. A portable anaesthetic machine according to the first objective is achieved in accordance with the invention in that the portable anaesthetic machine comprises the features according to claim 1. Advantageous refinements and embodiments will be evident from the dependent claims to claim 1. Membranes, which can be punctured with a syringe needle tip and then self-seal when the needle is withdrawn, are known from e.g. implantable insulin pumps. A reservoir in these insulin pumps is replenished with insulin by inserting a syringe needle through the skin of the patient, through a membrane on the implanted insulin pump and into the pump's reservoir. The contents of the syringe are then discharged, into the reservoir and the syringe needle is withdrawn. The membrane self-seals to prevent any insulin from leaking out into body tissues. These membranes have also been used in the ventilator area for administering drugs to a patient. In US patent 5,181,508 a connector for connection between a respirator and a patient. The connector comprises a membrane through which drugs can be administered. In the corresponding manner, an anaesthetic liquid can be injected into the respirator's gas flow pathways in order to dispense the anaesthetic liquid for inspiration. The membrane is advantageously arranged near the gas flow generator for maximal vaporisation/atomisation of the anaesthetic liquid before it reach the lungs. The portable anaesthetic machine can advantageously have a closed breathing system, whereby the membrane can be arranged, in principle, anywhere in the gas flow pathways. To increase usefulness, it would be advantageous if the portable anaesthetic machine were devised with a provision for delivering an additive gas into the gas flow pathways. It would be particularly advantageous if the additive gas were oxygen or nitrous oxide. It would also be advantageous if a gas analyser for analysing the gas in the gas flow pathways were integrated into the respirator. The second objective is achieved in accordance with the invention in that the portable anaesthetic emergency kit is devised according to claim 8. Advantageous refinements and designs will be evident from the dependent claims to claim 8. In principle, the portable anaesthetic emergency kit consists of a portable anaesthetic machine according to the invention augmented with a dispensing means to permit the dispensing of liquid anaesthetic. The dispensing means can consist of a syringe, pre-filled with a specific amount of an anaesthetic, or even of a syringe and a plurality of different bottled anaesthetics. The choice of dispensing means depends on the intended placement of the portable anaesthetic machine. The former version is preferable for certain emergency uses. The invention is described below in greater detail, referring to the figures, in which FIG. 1 shows a first embodiment of a portable anaesthetic machine and dispensing means according to the invention; and FIG. 2 shows a second embodiment of a portable anaesthetic machine and dispensing means according to the invention. The portable anaesthetic emergency kit in the figure comprises a portable anaesthetic machine 2 with a gas flow generator 4. The gas flow generator 4 can advantageously consist of a turbine, fan, pump or similar generator in order to generate a specific pressure for and flow of ambient air (the air intake is not shown in the figure). The breathing gas is sent from the gas flow generator 4 to an inspiratory line 6 for carrying breathing gas to a patient (not shown). Gas expired by the patient is returned to the gas flow generator 4 via an expiratory line 8. A membrane 10, through which a liquid anaesthetic is injected with a syringe 12A (or some other suitable dispensing means), is arranged at the gas flow generator 4. When the liquid anaesthetic is injected into the gas flow generator 4, it vaporises and is carried with breathing gas to the patient. The liquid anaesthetic is contained in bottles 12B, 12C from which the user of the portable anaesthetic equipment can fill the syringe 12A with an appropriate anaesthetic and dispense it through the membrane 10. Since the gas flow pathways, consisting of the gas flow generator 4, the inspiratory line 6 and the expiratory line 8, are a closed system, safe and accurate dispensing of anaesthetic injected into the flow pathways is achieved. A carbon dioxide absorber 14 is located in the expiratory line 8 to absorb a sufficiently large part of the expired carbon dioxide and keep excessive concentrations of carbon dioxide from reaching the patient. The anaesthetic machine 2 is controlled by a control unit 16 that can receive reference values from a user interface (not shown) for setting respiratory parameters. The control unit 16 mainly controls the gas flow generator 4 and also controls the dispensing of an additive gas from a gas cylinder 18 into the inspiratory line 6 via a dispensing line 20. The additive gas consists appropriately of oxygen or a mixture of oxygen and nitrous oxide. The control unit 16 can control the respirator 2 on the basis of the gas concentrations measured by a gas analyser 22. The gas analyser 22 can collect gas samples for analysis via a gas sampling line 24. If the gas analyser 22 consists of an analyser which pumps relatively large amounts of gas, gas samples should be returned to the breathing gas in the circle system. The gas samples can be appropriately returned to the gas flow generator 4. If the gas analyser 22 requires relatively small volumes (compared to the total volume in the closed system), these volumes can instead be discharged into atmosphere. However, the advantage of re-using gas samples is that discharge of anaesthetic into atmosphere is minimised. This is particularly important when the respirator is used in environments with limited air change rates, e.g. in aircraft. There is also minimum impact on the operator. Since the respirator 2 in the figure is devised so the expiratory line 8 is connected to the inspiratory line 6, an expiratory valve 26 is arranged at the connection point. Another embodiment is shown in FIG. 2. Components or devices which are identical to those in the previous embodiment have been assigned the same designations. The anaesthetic machine 28 comprises a first gas connector 30A and a second gas connector 30B for connection of gas under pressure to the anaesthetic machine 28. Each gas is dispensed with an exact flow and pressure in a first gas regulator 32A and a second gas regulator 32B. The gases are mixed into a breathing gas and carried in an inspiratory line 34 to a patient (not shown) for inspiration. A membrane 10 is also arranged in the inspiratory line 34 into which an anaesthetic liquid is injected by a syringe 12A or the like. Expired gas is returned in an expiratory line 36 to the anaesthetic machine 28 for transport to an exhaust unit. A control unit 38 controls all the functions in the anaesthetic machine 28, especially the gas regulators 32A, 32B and an expiratory valve 40. The gauges 42, 44 for flow and/or pressure supply the control unit 38 with information on current values. Combinations of the illustrated embodiments are possible where appropriate. For example, the membrane 10 can be located in the mixing chamber after the gas regulators 32A, 32B in the anaesthetic machine 28 in FIG. 2. A gas analyser can also be used in the respirator 28. Recirculation into a circle system can also be used with the anaesthetic machine 28. It should then be combined with a carbon dioxide absorber.

Claims: A portable anaesthetic machine (2; 28), comprising a gas flow generator (4; 32A, 32B) for generating a flow of breathing gas at an adjustable pressure and/or flow rate, an inspiratory line (6; 34) connected to the gas flow generator (4; 32A, 32B) and to an expiratory line (8; 36), the gas flow generator (4; 32A, 32B), inspiratory line (6; 34) and the expiratory line (8; 36) constituting gas flow pathways for the breathing gas in the machine (2; 28), and a membrane (10), arranged in the gas flow pathways and made of a self-sealing material through which a specific amount of a liquid anaesthetic can be dispensed into the breathing gas in the gas flow pathways an optional number of times. The portable anaesthetic machine according to claim 1, characterised in that the membrane (10) is arranged at the gas flow generator (4; 32A, 32B). The portable anaesthetic machine according to claim 1 or 2, characterised in that the expiratory line (8; 36) is connected to the gas flow generator (4; 32A, 32B) to form a circle system of gas flow pathways, and a carbon dioxide absorber (14) is arranged in the gas flow pathways. The portable anaesthetic machine according to any of the preceding claims, characterised in that the gas flow generator (4) consists of a turbine or a fan. The portable anaesthetic machine according to any of the preceding claims, characterised in that a gas cylinder (18) containing an additive gas is arranged to dispense the additive gas into the gas flow pathways. The portable anaesthetic machine according to claim 5, characterised in that the additive gas is oxygen and/or nitrous oxide. The portable anaesthetic machine according to any of the preceding claims, characterised in that a gas analyser (22) is arranged to analyse at least one component gas in the gas flowing in the gas flow pathways. A portable anaesthetic emergency kit, comprising a portable anaesthetic machine according to any of the preceding claims in combination with a dispensing means (12A, 12B) for dispensing a specific amount of a liquid anaesthetic through the membrane (10). The portable anaesthetic machine according to claim 8, characterised in that the dispensing means comprises at least one bottle (12B, 12C) holding a liquid anaesthetic, preferably one of the anaesthetics halothane, isoflurane and enflurane, and a syringe (12A). The portable anaesthetic machine according to claim 8, characterised in that the dispensing means consists of at least one syringe (12A) filled with a predetermined dose of a liquid anaesthetic, preferably one of the anaesthetics halothane, isoflurane and enflurane.

Inventors: PSAROS GEORGIOS, PSAROS, GEORGIOS
Applicants: MAQUET CRITICAL CARE AB
Application year: 1998
Main classification: A61M16
IPC codes: A61M16, A61M39