Exam 2: Lecture 10: Maintenance of Anesthesia Flashcards
What are some commonly used Inhalants
- Isoflurane
- Sevoflurane
- Desoflurane
- N20 (nitric oxide)
- Halothane (not available in the USA)
T/F: The desire for inhalents is to be
- Less reactive
- Less potent
- Nonflammable
- Halogentation (adding Fl, Cl, or Br)
False! everything is true expect you wanr them to be more potent
What properties determine the method of administration for Inhalants
- Boiling point
- Liquid density (specific gravity)
- vapor pressure
What properties help determine the kinetics in the patient for inhalants
Solubility of gas
- Blood/gas partial coefficient
- Oil/gas partition coefficient
Define Gas related to inhalants
Agents that exist in gaseous form at room temperature and sea level pressure
EX: N2O
Define Vapor related to inhalants
gaseous state of a substance that at ambient temperature and pressure is liquid
EX: Isoflurance, sevoflurance, halothane and desoflurance
What are the 4 gas laws the describe predictable behavior of gases
- Boyle’s law
- Charles’s law
- Gay Lussac’s law
- Daltons law of partial pressure
What is defined as the change in state from a liquid to a gas
vaporization
As equilibrium is reached during vaporization and no further loss of molecules to the gas phase occurs, the gas phase would be called?
Saturated at this point
What is said the be the measure of the ability to evaporate (enter the gas phase)
- saturated vapor pressure = max concentration of molecules in vapor state
- Temperature dependent, unique for each anesthetic agent
Vapor pressure of an anesthestic
Does temperature of liquid need to increase or decrease for more molecules escapes liquid phase and enters the gas phase
increases
- This leads to higher vapor pressure
If the temperature of liquid decreases what happens?
Lower vapor pressure / concentration
Does SVP (Saturated vapor pressure) of most anesthetics mean it is safest for clinical use?
NO!! you have to control the amount delivered to the patient
How do you control the amount of SVP that goes into a patient
Vaporizer
gas diverted into 2 streams
- By pass
- Vaporizing chamber
How are modern vaporizers classified
- Variable bypass
- Concentration calibrated
- Agent specific
- Temperature compenstated
Define blood / gas coefficient
In blood and tissue effects rate of uptake and distribution in body = speed of induction and recovery
Define Oil / gas partition coefficient
Solubility in lipid (oil) correlates with anesthetic potency
- ISO more than SEVO
Does more or less gas dissolve in solvent as temperature increases
less
Which agent will have a longer induction and recovery period based on blood/gas partiion coefficent (PC)?
A: Agent A: blood/gas PC 1.46
B: Agent B: Blood/gas PC 0.68
A
What are the two main ways to increase alveolar delivery
- Increased inspired anesthesic concentration
- Increased alveolar ventilation
What category do the following fit under with Factors that rapidly change alveolar PA?
- Increased vaporization of agent
- Increased vaporizer dial setting
- Increased fresh gas flow (Double the O2 rate)
- Decreased gas vlume of patient breathing circuit
Increased inspired anesthetic concentration for increased alveolar delivery
What category do the following fit under with Factors that rapidly change alveolar PA?
- Increased minute ventilation
- Decreased dead space ventilation
Increased alveolar ventilation in increased alveolar delivery
What are the 3 steps to decrease removal from alevoli
- Decreased blood solubility of anesthesic
- Decreased cardiac output
- Decreased alveolar venous anesthesic gradient
Which anestheic gas has the desired % metabolized
Isoflurance and 0.2%
