GE CARESCAPE, User Manual

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Airway gases
The MAC values correspond to those of healthy adults of about 40 years old, and
cannot be applied to children or elderly patients. Age and some other individual
factors influencing the effect of volatile agents are not taken into account.
The other calculation method, MACage, takes the patient's age into account. The age
range is 0 to 150 years. The calculation uses 0 if age is less than 0, and 100 if age is
more than 100. In addition, MACage calculations include the atmospheric pressure
and the patient’s (highest measured) temperature values. If no patient temperature is
measured, 37°C is used instead. For volatile agents this calculation method means
about 6.7% decrease of MAC value with each increasing decade of life. MACage is
calculated if it is enabled in the care unit settings and the patient’s age is given on the
monitor. If no age is given, MAC is calculated despite the care unit setting.
References used for MAC and MACage values
The alveolar concentrations of traditional (MAC) and age dependent (MACage) values
are based on the following references:
●
References for anesthetic agent MAC values:
￭
Mapleson W.W.: Effect of age on MAC in humans: a meta-analysis. Br. J. of
Anaesthesia 1996; 76: 179-185
￭
Rampil I.J.; Zwass M.; Lockhart S.; Eger E.I. II; Johnson B.H.; Yasuda N.; Weiskopf
R.B.: MAC of I653 in surgical patients, Anesthesiology. Tram-Rac71 (3A):A269,
September 1989
￭
Scheller M.S., Partridge B.L., Saidman L.J.: MAC of sevoflurane in humans and
the New Zealand white rabbit. Anesthesiology 1987; 67: A373
￭
ISO21647:2004 + C1:2005, Medical electrical equipment - Particular
requirements for the basic safety and essential performance of respiratory
gas monitors.
●
References for MACage calculations:
￭
Eger, E.I. II.: Age, minimum alveolar anesthetic concentration, and minimum
alveolar anesthetic concentration-awake. Anesth. Analg. 2001; 93:947-953
￭
Rampil I.J.; Zwass M.; Lockhart S.; Eger E.I. II; Johnson B.H.; Yasuda N.; Weiskopf
R.B.: MAC of I653 in surgical patients, Anesthesiology. 71 (3A):A269, September
1989
MAC values of different anesthetics in oxygen
Normal values (40-year-old patient) and compensated values (65-year-old and
3-year-old patients):
1 MAC 1 MAC (65 yrs) 1 MAC (3 yrs)
Halothane
0.75% 0.63% 0.97%
Enflurane
1.70% 1.43% 2.2%
Isoflurane
1.15% 0.97% 1.5%
Sevoflurane
2.05% 1.73% 2.65%
Desflurane
6.00% 5.05% 7.80%
N
2
O 100% 82%
N/A
The following illustration shows the Agent% corresponding to 1 MAC as function of age:
2062971-001 CARESCAPE Modular Monitors 299