GE CARESCAPE, User Manual

Page: 298 / 548

Airway gases
Volume
sampled during
expiration 10 ml 5 ml 3.33 ml 2.5 ml
Total volume
sampled 15 ml 7.5 ml 5 ml 3.75 ml
Sidestream gas sampling
The E-modules use a sidestream gas sampling method. It means that a sample of
patient’s respired gases from the sampling site is transported through a sampling
line to the module for analysis.
A sidestream gas analyzer takes a constant sample from the patient airway adapter
at the following sample rates:
●
CARESCAPE respiratory modules: 120 ml/min
●
Compact airway modules: 200 ml/min
●
E-miniC: 150 ml/min
Total sample size volume during one respiratory cycle depends on the respiration rate.
Minimum Alveolar Concentration (MAC)
NOTE
CARESCAPE respiratory modules and compact airway
modules only.
The use of either traditional MAC or MACage is selected during monitor configuration.
The MACage provides age and temperature compensated measurement. To enable
MACage calculations, enter patient’s age to the monitor and attach a temperature
sensor. If the patient’s age is not given, the monitor shows normal MAC even if
MACage has been selected.
NOTE
The MAC value displayed by the monitor is that of exhaled
air, and it does not always correspond to the amount of
anesthetic in the patient’s organs.
CAUTION
Patient-specific MAC is affected by several factors such as
patient age and body temperature.
MAC and MACage
The minimum alveolar concentration (MAC) concept is based on the assumption that
in a steady state, the alveolar partial pressure of a gas is equal to the partial pressure
in the effector organ of the central nervous system. MAC values are used to estimate
the level of anesthesia caused by volatile anesthetics.
The MAC value can be displayed in a numeric parameter window: 1 MAC is the alveolar
concentration (end-tidal) of the agent at which 50% of patients do not respond to
a noxious or surgical stimulus. The value is calculated from the actual measured
anesthetic agent and N
2
O values with empirical formulas based on statistical studies
with anesthetized patients.
The monitor can display two different MAC values, MAC or MACage, based on different
formulas. The use of MAC or MACage is selected during installation and configuration.
298 CARESCAPE Modular Monitors 2062971-001