Device intended for use in a therapeutic system for respiratory care with a liquid

Abstract: In respiratory care with liquids, the patient (2) is connected to a liquid apparatus (6) and a ventilator (10) for supplying and removing a treatment liquid and a breathing gas respectively to/from the patient (2). The exchange of gases between the breathing gas and the treatment liquid is improved with a device according to the invention. In one embodiment, the device consists of a breathing gas generator (12) which generates different frequencies to cause the breathing gas and treatment liquid to oscillate at appropriate frequencies. In an alternative embodiment, the device consists of a vibrator unit (22) which is applied to the chest to cause the treatment liquid to oscillate. In a third embodiment, the device consists of a magnetic field generator (26) for generating a magnetic field across the lungs and setting electrically conductive components in the treatment liquid in motion.

Description: The present invention relates to a device intended for use in a therapeutic system for respiratory care with a liquid according to the preamble of patent claim 1. Treatment with liquid has proved to be effective, especially for severely ill or injured patients or in cases of pulmonary immaturity. In treatment with liquid, the damaged parts of lungs are filled with a special treatment liquid, usually a perfluorocarbonate. The liquid spreads to the alveoli and keeps them distended. Oxygen, for example, is highly soluble in the liquid, and gas is exchanged between the blood system and liquid in the alveoli. A breathing gas can simultaneously be supplied to the parts of the lungs (including the entire respiratory system, i.e. bronchi and other airways), in order to add fresh oxygen to the liquid and remove carbon dioxide. One such treatment system is described in WO 93/09833. Since the area of contact between the treatment liquid and breathing gas can be relatively small, especially on occasions in which a relatively large volume of liquid is employed, improving the exchange of gas between the treatment liquid and the breathing gas would be desirable. One objective of the invention is to achieve a device for use in liquid ventilation systems in order to improve gas exchange between the treatment liquid and the breathing gas. This objective is achieved in accordance with the invention by a device devised as set forth in the characterizing part of patent claim 1. Advantageous improvements and embodiments are set forth in the dependent claims to patent claim 1. When the treatment liquid and/or breathing gas is/are made to oscillate, gas exchange conditions are improved in both the liquid/gas as well as in the liquid-gas interface area. The device is described in greater detail, referring to the figure, wherein FIG. 1 shows one embodiment of the device in a liquid treatment system connected to a patient. FIG. 1 shows a patient 2 on a treatment couch 4. The patient 2 is connected to a liquid apparatus 6 by a liquid tube 8. The liquid apparatus 6 contains a treatment liquid, such as a solution of perfluorocarbon, which can be delivered to the patient's 2 lungs via the liquid tube 8. The patient's 2 lungs can accordingly be wholly or partially filled with the treatment liquid. A ventilator 10, equipped with a breathing gas generator 12, is also connected to the patient 2. A breathing gas can be fed to and evacuated from the patient 2 via an inspiratory tube 14 and an expiratory tube 16. The inspiratory tube 14 and expiratory tube 16 are connected to a patient tube 18, usually a tracheal tube. The breathing gas reaches the parts of the lung which are not filled with liquid. Between the treatment liquid in the lungs and the patient's 2 blood system there is an exchange of gases in which, primarily, oxygen diffuses into the blood system, and carbon dioxide diffuses into the treatment liquid. The carbon dioxide is subsequently carried by the treatment liquid to the treatment liquid-breathing gas interface. Gas exchange, in which carbon dioxide transfers to the breathing gas for evacuation from the patient 2, also takes place here, and oxygen in the breathing gas dissolves in the treatment liquid and is carried by same to the alveoli for delivery to the bloodstream. Gas transport would be very slow if diffusion were the only mechanism for the transportation of gases in treatment liquid. A plurality of embodiments of a device for accelerating or improving gas exchange are described below. A first embodiment of the device is achieved when the breathing gas generator 12 is devised to generate at least two breathing gas frequencies. One frequency is selected to maximize gas exchange in the breathing gas. This causes the rapid removal of carbon dioxide and rapid delivery of oxygen at the interface between the treatment liquid and breathing gas. In this way, a maximum difference in partial pressures is maintained between the two gases in the treatment liquid and breathing gas respectively. A big difference in partial pressure increases diffusion. The second frequency is selected to make the treatment liquid oscillate at an appropriate frequency. The transport of gas in the treatment liquid will then increase. The two frequencies can either be generated as superimposed frequencies for simultaneous action on the breathing gas and treatment liquid or be generated as alternating frequencies for sequential action on the breathing gas and treatment liquid. A plurality of frequencies can also be used to increase the effect of gas exchange. An alternate way of inducing the treatment liquid to oscillate at an appropriate frequency is illustrated in the figure by a second embodiment of the device. A vibrator unit 22 is placed at an appropriate position on the patient's 2 chest. The vibrator unit 22 is regulated by a control unit 24 connected to the liquid treatment system via the ventilator 10. Vibrations from the vibrator unit 22 are transmitted to the treatment liquid in the lungs and cause it to oscillate. This accordingly creates a stirring effect which accelerates gas transport in the treatment liquid. Another alternative way of inducing oscillations in the treatment liquid is shown in the figure, with a third embodiment of the device. A magnetic field generator 26 is placed under the patient 2. The magnetic field generator 26 generates a varying magnetic field across the patient's 2 lungs. The treatment liquid contains, or can be supplied with, conductive components which are acted on by the magnetic field and cause a stirring effect in the treatment liquid. Both the second and third embodiments of the device can be used with the first embodiment, i.e. with utilization of a plurality of frequencies in the generation of the breathing gas.

Claims: A device intended for use in a therapeutic system for respiratory care with a liquid, said therapeutic system comprising a liquid apparatus (6) for at least partially filling a lung with a special treatment liquid (30) and a ventilator (10) for supplying a breathing gas to the parts of the lung which are not filled with treatment liquid (30), whereby gas exchange occurs in an interface area between the breathing gas and treatment liquid (30), characterized in that the device comprises means (12; 22, 24; 26) for making the treatment liquid (30) oscillate to cause a stirring effect in the treatment liquid, thereby increasing the speed of gas transport through the treatment liquid (30) and increasing gas exchange between the breathing gas and treatment liquid (30). The device according to claim 1, characterized in that the device includes a breathing gas generator (12) for generating a flow of breathing gas with at least two oscillation frequencies, whereby the first frequency is tailored to the breathing gas to ensure maximum gas exchange therein, and the second frequency is tailored to the treatment liquid (30) and makes it oscillate, thereby increasing the speed of gas transport through the treatment. liquid (30). The device according to claim 2, characterized in that the breathing gas generator (12) is designed to generate a flow of breathing gas with superimposed oscillation frequencies. The device according to claim 2, characterized in that the breathing gas generator (12) is devised to generate a flow of breathing gas with alternating oscillation frequencies. The device according to any of claims 1-4, characterized in that the device comprises a vibrator unit (22, 24), devised for application to the chest to make the treatment liquid (30) oscillate at a frequency which increases the transport of gases through the treatment liquid (30). The device according to any of claims 1-4, characterized in that the treatment liquid (30) includes at least one conductive component, and the device includes a magnetic field generator (26) which is arranged to generate a variable magnetic field across the patient's lungs.

Inventors: HOEGNELID KURT, HOEGNELID, KURT, Högnelid, Kurt
Applicants: SIEMENS ELEMA AB, SIEMENS-ELEMA AB
Application year: 1997
Main classification: A61M16
IPC codes: A61M16, A61H23