Anesthesia machine
The anesthesia machine , which is part of the anesthesia workstation , takes over the respiratory function ( ventilation ) during an operation , since general anesthesia (anesthesia) often eliminates the need to breathe . However, depending on the operation and the anesthetic drugs used, general anesthesia with spontaneous breathing is also possible, i.e. the patient breathes completely himself, albeit through the ventilation tube or with assisted ventilation. In the latter case, the patient “triggers” the ventilator , that is, he specifies the time of each breath through his effort to inhale, and the ventilator then assists the patient in inhaling.
The anesthetist sets a mixture of oxygen and either compressed air or nitrous oxide and the inhalation anesthetic used (e.g. isoflurane , sevoflurane or desflurane ) on the device . This is chemically polyhalogenated ether, present at room temperature in liquid form, but are volatile (volatile) and by means of a so-called. Vapors evaporated and then mixed in vapor form of the breathing air in a precisely defined concentration. Depending on the patient, the operation and the preferences of the anesthetist, nitrous oxide-free anesthesia are sometimes also performed.
Haemodynamic monitoring ( EKG , blood pressure , oxygen saturation ) is coupled to the anesthesia machine . The amount of air released, the airway pressure, the gas concentrations and the end-tidal (exhaled) can be measured on the anesthesia machine . A monitoring unit integrated in the device issues an alarm as soon as a measured value reaches a critical limit.
In the anesthesia machine, the breathing gas mixture is usually guided in a so-called circle section . This was invented in 1902 by Bernhard Dräger and Otto Roth and has been used essentially unchanged to this day and only expanded with modern monitoring and precise metering devices. Here, the air exhaled by the patient is fed back into the anesthesia machine, a calcium absorber removes the carbon dioxide from the air and the gas mixture is enriched with a certain amount of fresh gas. The gas mixture is then returned to the patient.
Modern anesthesia machines are built in such a way that they continue to function for a long time even in the event of a power failure or failure of the hospital's gas supply. Accumulators and a system that generates compressed air from the room air as well as pressure bottles with oxygen and, if necessary, nitrous oxide are installed for this purpose.
literature
- Rogan Schmidt-Rimpler: The development of Dräger anesthesia technology (1902–1918) in an international comparison. Lübeck 2008
