BIOM 3090 Lecture Notes - Lecture 24: Tracheal Tube, Inhalational Anaesthetic, Anaesthetic Machine
9 Jun 2018
School
Department
Course
Professor
Inhalant Anesthetics
Pharmacokinetics
- Volatile liquids used in vaporizer connected to oxygen flow system of
anesthetic machine
o Liquid isoflurane anesthetic
o Colour-coded anesthetic bottle adapter only fits proper vaporizer
o Isoflurane vaporizer
- Main components of a machine for administering inhalant anesthetics
o Pressure valve
o Precision vaporizer – accurate & precise control of % anesthetic
added to oxygen flow to patient, regardless of temp. fluctuations
▪ A bimetallic strip increases flow through the bypass chamber
when temperature increases
o Reservoir bag
o CO2 absorbent
o Inflatable cuff
o Endo-tracheal tube
- Anesthetic machine is connected to patient via an endotracheal tube
o Endotracheal tube with inflatable cuff prevents:
▪ Anesthetic vapour escaping into the operating room
▪ Inhalation of saliva or stomach content
o Anesthetic vapour delivered with oxygen → absorbed from lungs into
blood → distributed to tissues
- Constant delivery of fresh gas with controlled % of anesthetic maintains
anesthesia
- Eliminated mainly by exhalation; some metabolism (% metabolized depends
on drug)
- In an emergency, modern volatile hydrocarbon inhalants can be removed
from the body very rapidly
o E.g. patient too deep & stops breathing → reduce anesthetic
concentration (adjust vaporizer) and apply artificial respiration →
drug concentration in body falls within a minute or two → breathing
resumes
Balanced Anesthesia
- Four requirements for optimal anesthesia:
o Unconsciousness
o Analgesia
o Amnesia
o Muscle relaxation
- Historically achieved by administering a high concentration of a single drug
(e.g. ether or chloroform)
- Problem:
o Unconsciousness can be maintained with relatively low
concentrations of inhalant anesthetics, but analgesia and muscle
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Document Summary
Volatile liquids used in vaporizer connected to oxygen flow system of anesthetic machine: liquid isoflurane anesthetic, colour-coded anesthetic bottle adapter only fits proper vaporizer, isoflurane vaporizer, pressure valve. Anesthetic machine is connected to patient via an endotracheal tube: endotracheal tube with inflatable cuff prevents, anesthetic vapour escaping into the operating room. Inhalation of saliva or stomach content: anesthetic vapour delivered with oxygen absorbed from lungs into blood distributed to tissues. Constant delivery of fresh gas with controlled % of anesthetic maintains anesthesia. Eliminated mainly by exhalation; some metabolism (% metabolized depends on drug) Four requirements for optimal anesthesia: (cid:498)balanced(cid:499) anesthesia: unconsciousness, analgesia, amnesia, muscle relaxation. Historically achieved by administering a high concentration of a single drug (e. g. ether or chloroform) Problem: unconsciousness can be maintained with relatively low concentrations of inhalant anesthetics, but analgesia and muscle relaxation often require much higher concentrations of these drugs greater brainstem depression greater risk to patient.
