General anesthesia machines typically deliver a cocktail of gases to a patient to ensure sedation during surgery. Nitrous oxide (also known as laughing gas) and other gases are mixed with oxygen and delivered to the patient. The buffer area shown in the drawing below is where the combination of nitrous oxide and oxygen is mixed together. Here, the anesthesiologist needs to be aware of the mix of gases that is appropriate to the patient. At times, the combination needs to be adjusted depending on patient requirements.
To control the level of oxygen and nitrous oxide delivered to the buffering section of the anesthesia machine, it is necessary to measure the volume of each gas. In the drawing below, the FS4008 mass flow sensor is shown as a method to measure and monitor the various gas levels. The FS4008 comes in various flow ranges from 0-10 SLPM up to 0-50 SLPM. Available outputs include linear voltage or digital RS232 or RS485, allowing for the FS4008 to be easily integrated into a control system for the various gases. The flow channel diameter is 8 mm, and there are exchangeable mechanical connectors for ease of installation (BSPT thread and one-touch connectors).
At the delivery location of the gas mixture to the patient, another flow measurement point is needed. Here, the FS6022 mass flow sensor can play an important role in ensuring gases are delivered to the patient and then subsequently exhaled. Because the FS6022 has bi-directional measurement capability, it is ideal for use in the scavenging portion of the anesthesia machine, which expels the used gas from the patient's lungs. For details about the FS6022, you can also review our blog post: Mass Flow Sensors for Medical Ventilators.
In summary, measuring and monitoring mass flow of gases in anesthesia equipment is a critical part of patient comfort and surgery success. Not only is it important to measure the mix of anesthesia gases, it is also vital to measure delivery of the gases to the patient.
You can learn more about mass flow sensors here or download our mass flow product & pricing guide.