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DE-102024133027-A1 - Anesthesia system and method for controlling gas quantities in an anesthesia system

DE102024133027A1DE 102024133027 A1DE102024133027 A1DE 102024133027A1DE-102024133027-A1

Abstract

A method for controlling gas quantities during the dosing and supply of oxygen to an anesthesia system is described. In a sequence of steps (101, 102, 103) a check is carried out to determine whether there is a reason (11) to reduce the amount of oxygen supplied in the breathing gas and, depending on the result of the check, a limitation of the supply of oxygen is carried out.

Inventors

  • Andreas KATER
  • Björn Bargstädt

Assignees

  • Drägerwerk AG & Co. KGaA

Dates

Publication Date
20260513
Application Date
20241112

Claims (10)

  1. Method for controlling gas quantities during the dosing and supply of quantities of oxygen in a piping system (38) by means of a mixing unit (1) for mixing and dosing a gas mixture of at least two gas components, wherein: • in a first step (101) a check is carried out to see if there is a reason (11) to reduce the quantity of oxygen currently supplied in the piping system (38) or in the breathing gas; • in a second step (102), if there is a reason to reduce the quantity of oxygen currently supplied in the piping system (38), an output signal (550) is generated which indicates this reason and is provided to a mixing unit (1) for mixing and dosing a gas mixture; • so that in a third step (103) a limitation (76) of the supply of quantities of oxygen to the piping system (38) is effected.
  2. Procedure according to Claim 1 , whereby the limitation of the supply of oxygen quantities is achieved by reducing the amount of oxygen.
  3. Procedure according to Claim 2 , wherein the limitation of the supply of oxygen quantities is geared towards falling below a predetermined lower threshold value of an oxygen concentration.
  4. Procedure according to Claim 2 , wherein the limitation of the supply of quantities of oxygen is designed by means of an error band around an absolute limit or around a relative limit of an inspiratory oxygen fraction ( FiO2 ) or an inspiratory oxygen concentration.
  5. Procedure according to Claim 3 or after Claim 4 , whereby a physiological limiting situation is taken into account when defining the predetermined lower threshold.
  6. Procedure according to one of the Claims 3 until 5 , whereby a patient category or patient type is included in the design of the predetermined lower threshold or the absolute or relative limit value based on the physiological limit situation.
  7. Procedure according to one of the Claims 3 until 6 , whereby hysteresis is taken into account when limiting the supply of quantities of oxygen by aligning with the predetermined lower threshold of an oxygen concentration or with the absolute or relative limit of an oxygen concentration.
  8. Procedure according to Claim 2 , whereby the limitation of the supply of oxygen quantities is achieved by reducing the amount of oxygen for a predetermined period of time.
  9. Device (100) for carrying out the method according to one of the preceding claims, wherein the device (100) comprises at least the following components: • a control unit (20) • a sensor (30) for gas analysis • a mixing unit (5) for mixing and dosing a gas mixture of at least two gas components • a line system (38) formed from hoses for a fluidic connection with a patient (50), wherein the control unit (20) is configured with the unit (1) for mixing and dosing for carrying out the method steps (101, 102, 103).
  10. Device (100) according to Claim 9 , wherein the device (100) comprises at least one of the following further components: • a respiratory gas drive (4) • a manual resuscitation bag BB (80), • an output unit • a dosing unit (2) for dosing volatile anesthetic agents • an input interface for receiving input signals or user interactions • an output interface for providing output signals, wherein the device (100) forms an anesthesia system for performing anesthesia on a patient (50).

Description

The present invention relates to a method for controlling gas volumes during the dosing and supply of oxygen to an anesthesia system, as well as to an anesthesia system itself. Anesthesia systems are used for the safe administration of inhalation anesthesia. Modern anesthesia systems have a closed or semi-closed breathing system, often also referred to as a closed-loop system, in which the majority of the breathing gas does not leave the device. The exhaled carbon dioxide is absorbed by soda lime, and fresh gas is added back to the exhaled gas when it is recirculated. This method has the advantage that the substances used for anesthesia (general anesthetics) can be used efficiently. Various types of anesthesia machines with a radial blower (blower, radial compressor, blower) are used in the US5875783 A described. The US5875783 A This shows a circular system that can be designed with a radial fan. For an understanding of the function and advantages of the circular system according to the state of the art, as described in the DE19714644 C2 As described, this application should be based on the character description of the 6 the DE19714644 C2 The functions of the closed-loop system are described. During inhalation, a radial blower draws an anesthetic gas, a mixture of oxygen, air, nitrous oxide, and vaporized anesthetic, from a fresh gas line. Buffered breathing gas is also drawn from a manual resuscitation bag. If the pressure level in the patient's lungs is lower than the pressure level at the radial blower, this breathing gas passes through a carbon dioxide absorber and an inspiratory check valve, then through breathing tubes, a patient connector (patient Y-piece), and an airway access device (breathing mask, endotracheal tube, tracheostomy) to and into the patient. As soon as the pressure reverses, i.e., as soon as the pressure level in the patient's lungs is higher than the pressure level at the radial blower, the gas flows from the patient back into the manual resuscitation bag through an expiratory check valve. When administering gases, gas mixtures containing oxygen, and anesthetic gases, it is necessary to implement resource-efficient gas management during anesthesia to avoid wasting valuable oxygen resources and for climate protection reasons, given the climate-damaging effects of anesthetic gases such as desflurane, isoflurane, enflurane, sevoflurane, and halothane. Whenever oxygen or anesthetic gas concentrations change during anesthesia, the question arises as to how quickly the gas change must take effect at the patient's bedside. If the operator initiates an infusion of 100% oxygen—for example, before intubating the patient—this can occur without any significant delay, provided the anesthesia machine's oxygen flush function is used. In this process, the gas mixture previously present in the anesthesia machine's tubing system is flushed into the anesthetic gas delivery system, resulting in an immediate high concentration of oxygen in both the tubing and the breathing gas mixture supplied to the patient. However, high concentrations of oxygen over a prolonged period can pose health risks to patients, a phenomenon known as "oxygen toxicity." For example, prolonged exposure to a high inspiratory oxygen fraction ( FiO2 ) can lead to damage to the alveoli, a condition called pulmonary oxygen toxicosis. Long-term consequences can include pulmonary edema or pulmonary fibrosis. These can manifest as effects on the nervous system, such as dizziness or nausea. Particularly in newborns, oxygen concentrations above 60% can lead to irreversible eye damage. Therefore, during the administration of anesthesia, various situations with high concentrations of oxygen can arise, which the user - usually a specialist in anesthesiology or intensive care medicine - would like to reduce as quickly as possible in the further course of time for the aforementioned therapeutic and/or physiological considerations. In a conventional, state-of-the-art, closed-loop anesthesia system, reducing the target oxygen level typically results in the newly set lower target oxygen level being adjusted by setting the minimum oxygen concentration of the medical air (if applicable) to 21% for the fresh gas mixture (FG) consisting of medical air (air), oxygen, possibly nitrous oxide, and anesthetic agent. This is achieved by increasing the quantity of the fresh gas mixture (FG) and thus, through a "washout" from the closed-loop system into the anesthetic gas delivery system (NGF), reducing the actual oxygen level. This is achieved in the breathing gas mixture for the patient. During the period with the increased amount of fresh gas (FG), increased amounts of anesthetic are simultaneously removed from the recirculating system by means of "washout" to maintain a constant concentration of anesthetic agents in the breathing gas mixture for the patient. Based on the state of the art, the tasks are to develop a method for controlling gas quantities i