Medical Application: Anesthesia Machines

What are Anesthesia Machines?

These are medical apparatuses for administering inhalation anesthetic gases and vapors and for controlling ventilation. Although there are many different models, all have the following features: a delivery system for medical gases, a mechanism to measure gas flow, vaporizers for volatilizing and combining the anesthetic agents with oxygen and carrier gases, a circuit for delivering the gas to the patient, monitoring equipment or gauges, a ventilator, and a scavenging system to collect and discharge excess gas.

How do they work?

Most modern Anesthesia Machines are essentially a ventilator that uses pressure to move air, oxygen, and nitrous oxide (anesthesia gas) into the lungs of the patient. This pressure is known as positive pressure.

You usually exhale (breathe out) the air on your own, but in some situations the ventilator portion of the machine may have to perform this function for the person. Therefore as shown in the below diagram another branch showing the path of nitrous oxide has been added to the overall anesthesia delivery system. The ventilator portion of the machine can be programmed to “breathe” a specific number of times over a certain time frame, usually minutes.

Download this application note to learn more about where exactly pressure sensors are used within anesthesia machines.