BeneVision N22/N19 Patient Monitor Operator’s Manual 23 - 5
• Position the airway adapter so that the part connecting to the gas sample line is pointing upwards.
This prevents condensed water from passing into the gas sample line and causing an occlusion.
• The watertrap collects water drops condensed in the sample line and therefore prevents them from
entering the module. To avoid blocking the airway, empty the watertrap container whenever half
full.
• The watertrap has a filter preventing bacterium, water and secretions from entering the module.
After long-term use, dust or other substances may compromise the performance of the filter or even
block the airway. In this case, replace the watertrap. Replacing the watertrap once a month is
recommended.
• Do not apply adult watertrap to the neonatal patient. Otherwise, patient injury could result.
• To extend the lifetime of the watertrap and module, disconnect the watertrap from the module and
set the operating mode to Standbywhen AG monitoring is not required.
23.6 MAC Values
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 80601-2-55 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.
MAC values are listed below:
* indicates 1 MAC nitrous oxide can only be reached in hyperbaric chamber.
• 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.
• 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:
Where N is the number of all agents (including N
2
O) that the AG module can measure, EtAgent
i
is the
concentration of each agent, and AgentVol
age
i is the concentration of each agent at 1 MAC with age correction.
The formula for calculating age correction of 1 MAC is:
For example, the Des concentration at 1 MAC of a 60-year old patient is
.
Agent Des Iso Enf Sev Hal
N
2
O
1 MAC 6% 1.15% 1.7% 2.1% 0.77% 105%*
MAC
EtAgent
AgentVol
age
i
-------------------------------------
i0
=
N1
–

=
MAC
age
MAC
40
10
0.00269 age 40
–()×–()
×=
6% 10
0.00269 age 40
–()×–()
×
6% 0.88
×=
To Next Page
Loading...
Need help?
General
