Mindray A5 Operating Instructions

A5/A3™ Operating Instructions 046-003777-00 8 - 3
AG and O2 Concentration Monitoring (Optional) Understand MAC Values
8.2 Understand MAC Values
Minimum alveolar concentration (hereinafter referred to as MAC) can be displayed on the screen
when the
anesthesia system is configured with an external AG module.
MAC is a basic index indicating the depth of inhaled anesthesia. The ISO 80601-2-55 defines MAC as
follows: alveolar concentration of an inhaled anesthetic agent that, in the absence of other anesthetic
agents and at equilibrium, prevents 50% of subjects from moving in response to a standard surgical
stimulus.
The following table lists 1 MAC of various inhaled anesthetic agents.
NOTE: The data shown in this table is from ISO 80601-2-55, which are
published by the U.S. Food and Drug Administration for a healthy 40-
year-old male patient.
NOTE: In actual applications, although the A5 accounts for patient age, the
effects of weight and other factors on the inhaled anesthetic agent
should be considered.
When one or more than one anesthetic agents are used, the formula for calculating MAC is:
Where, N stands for the number of all anesthetic agents (including N
2
O) which the AG module can
measure, EtAgent
i
for the concentration of end-tidal anesthetic agent and AgentVol
age
i for the 1MAC
value corresponding to the anesthetic agent after age correction.
The formula for calculating age correction of 1MAC is:
NOTE: The formula above is only suitable for patients who are older than one
year old. If the patient is less than one year old, the system will use one
year to do age correction.
For example, for a 60-year-old patient, if the AG module detects 0.9% Iso and 50% N
2
O in the patient
end-tidal mixed gas, the 1MAC of Iso is 1.01% and 1MAC of N
2
O is 92.7% of the 60-year-old patient
based on the above age correction formula. The MAC value is calculated as follows:
Anesthetic
agent
Des Iso Enf Sev Hal N
2
O
1 MAC 6.0% 1.15% 1.7% 2.1% 0.77% 105%*
* 1 MAC nitrous oxide can only be reached in a hyperbaric chamber.
TABLE 8-1 1 MAC of various inhaled anesthetic agents

−
=
=
1
0
N
i
age
i
iAgentVol
EtAgent
MAC
))40(00269.0(
40
10
−×−
×=
age
age
MACMAC
4.1
%7.92
%50
%01.1
%9.0
=+=MAC

Mindray A5 Specifications

General

Brand	Mindray
Model	A5
Category	Medical Equipment
Language	English