Mindray DPM 1 Manuel de l'opérateur télécharger pdf (Page 207)

16-5

16.3 MAC

Minimum alveolar concentration (MAC) is the minimum concentration of the agent in the alveoli.

It is a basic index to indicate the depth of anesthesia. The standard ISO 21647 defines MAC as

this: alveolar concentration of an inhaled anesthetic agent that, in the absence of other anesthetic

agents and at equilibrium, prevents 50% of patients from moving in response to a standard

surgical stimulus.

Minimum alveolar concentration (MAC) values are listed below:

Agent Des Iso Enf Sev Hal N2O

1 MAC 7.3% 1.15% 1.7% 2.1% 0.77% 105%*

* indicates 1 MAC nitrous oxide can only be reached in hyperbaric chamber.

NOTE

z The MAC values shown in the table above are those published by the U.S. Food

and Drug Administration for a healthy 40-year-old adult male patient.

z In actual applications, the MAC value may be affected by age, weight and other

factors.

The formula to calculate the MAC value is as follows:

∑

−

AgentVol

EtAgent

MAC

Where N is the number of all agents (including N

O) that the AG module can measure, EtAgenti

is the concentration of each agent and AgentVoli is the concentration of each agent at 1 MAC.

For example, the AG module measures there are 4% of Des, 0.5% of Hal and 50% of N

O in the

patient’s end-tidal gas:

4.0% 0.5% 50%

1.67

7.3% 0.77% 105%

MAC =+ + =

NOTE

z The formula mentioned above is intended for adult patients only.

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Mindray DPM 1 Manuel de l'opérateur Page 207