Patient Monitor User Manual Monitoring AG
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17.3.2.1 Zeroing
The module purges and zeroes itself and does not need any interaction by the user. Waveforms
flatline and parameter box values blank from the screen during this cycle.
17.3.2.2 MAC Calculation
Standard MAC values
1 standard MAC is equal to the alveolar anesthetic concentration at one atmosphere (760 mmHg)
at which 50% of all patients no longer respond to noxious stimuli. The integrated MAC algorithm
is based on the MAC values shown in the following table. The values specified in the table apply
to a patient age of 40 years and are guiding values only.
For gas mixtures, the respective multiples for N
2
O and anesthetic agents are added according to
the following equation.
ONMAC
ONconc.exp.
Anesth.MAC
Anesth.conc.exp.
Anesth.MAC
Anesth.conc.exp.
MAC
2
standard
2
2standard
2
1standard
1
totalstandard,
++=
NOTE:
Age and other factors are not taken into account for standard MAC value calculation.
Age-corrected MAC values
The equation applies to patients older than 1 year.
MAC
age corrected
= standard MAC x 10
(–0.00269 x (age –40))
For gas mixtures, the respective multiples for N
2
O and anesthetic agents are added according to
the following equation.
ONMAC
ONconc.exp.
Anesth.MAC
Anesth.conc.exp.
Anesth.MAC
Anesth.conc.exp.
MAC
2
correctedage
2
2correctedage
2
1correctedage
1
totalcorrected,age
++=
CAUTION
1 Always set patient age correctly. Incorrect settings can lead to inappropriate MAC
values and therefore to inappropriate anesthetic gas delivery.
2 Age-based MAC values only apply if the patient’s age is ≥ 1 year. An aged-based
MAC of 1 year is used if the patient’s age is < 1 year.
3 If patient age is not entered, the default age-based MAC of 40 years is used.
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