User's Manual Part 3

6-21
6.3.8. Multi-Gas (Anesthetic Agents) Option Overview, P/N 3886
(Not intended for neonatal use)
The Anesthetic Agent option determines the concentration of certain gases using the infrared
(IR) light absorption measurement. The gases that can be measured by the module absorb IR
light and the system can detect up to two agent concentrations greater than 0.1%. Each gas
has its own absorption characteristic. The gas is transported into a sample cell, and an optical
IR filter selects a specific band of IR light to pass through the gas. For multiple gas
measurements, there are multiple IR filters. The higher the concentration of gas in a given
volume the more IR light is absorbed. This means that higher concentration of IR absorbing gas
cause a lower transmission of IR light. The amount of IR light transmitted after it has been
passed through an IR absorbing gas is measured. From the amount of IR light measured, the
concentration of gas present can be calculated.
Oxygen is measured via paramagnetic phenomenon. See appendix E for full technical details.
The measurement provides:
1. An CO
2
waveform.
2. End tidal CO
2
value (EtCO
2
): the EtCO
2
value measured at the end of the expiration phase.
3. Fraction of inspired CO
2
(FiCO
2
): the smallest CO
2
value measured during inspiration.
4. Airway respiration rate: the number of breaths per minute, calculated from the CO
2
waveform.
5. Anesthetic Gases (Sevoflurane, Isoflurane, Dexflurane, Enflurane and Halothane).
6. Nitrous Oxide: N
2
O.
7. Inspired Oxygen: O
2.
8. MAC - Minimum Alveolar Concentration.
! WARNING
• Whenever a patient is under anesthesia or connected to a ventilator, constant attention
by qualified medical personnel is needed.
• Continuous exposure to waste anesthetic gases (including halogenated agents and
nitrous oxide) is not recommended. Always attach the waste gas connection
scavenging/evacuation tubing. Avoid venting any waste anesthetic gas directly into the
room air as exposure to these gases above the recommended OHSA limits could result.
• Minimum alveolar concentration (MAC) values are empirical and are not absolute
values. The MAC values correspond to those of healthy adults and cannot be applied to
children. Age and other individual factors influencing the behavior of volatile agents are
not taken into account.
• Organic vapors (e.g. from cleaning agents) in the sampling line or room air may alter
anesthetic agent readings.
• Certain substances (e.g. acetone, methane, or similar hydrocarbons) can result in
inaccurate readings and a false mixed agent alarm.
• The use of inhalers or nebulizers can result in inaccurate readings and a false mixed
agent alarm.
• Alcohol in the patient’s breath may modify the anesthetic agent readings.
NOTE
• If questionable anesthetic agent gas measurements are observed, examine all gas
sampling line connections, and the anesthesia gas machine and/or vaporizer settings,
before adjusting anesthesia delivery.