Gas monitoring

A gas monitor enables continuous non-invasive sidestream monitoring of CO2 and anaesthetics concentration in inspired and expired gases. The Sedaconda ACD can be used together with any CE-marked gas monitor that complies with ISO 80601 2 55. The gas monitor must be able to measure concentrations of anaesthetic gases in FET (end expiratory) concentration, which represents the alveolar concentration. Sedana Medical offers the AMG-o6 gas monitor. Add link to gas monitor.

The minimal alveolar concentration (MAC) is the alveolar concentration of an inhaled anaesthetic at one atmosphere that prevents skeletal muscle movement in response to a noxious stimulus in 50% of patients. MAC represents a relative measure of the level of anaesthesia. It is a useful index of anaesthetic potency and can be used to compare inhaled anaesthetics. MAC corresponds to FET%, which is the end expiratory concentration of anaesthetic gases.

The highest gas concentration occurs at the start of the inspiration cycle when the recycled gas is mixed with the fresh gas from the Sedaconda ACD. However, this represents a short peak and the concentration decreases rapidly to its lowest point at the end of inspiration. Most monitors show a Fi value which is measured at the end of inspiration, thus showing a low value when using the Sedaconda ACD. The expiratory values are measured at the end of expiration, which gives the value of alveolar concentration.

Always refer to the gas analyser manual regarding which sampling line to use. Connecting the incorrect type or length of line may cause incorrect Fet/MAC readings from the gas analyser.