Volatile anesthetics Flashcards
Vapor vs. gas
Vapor- at ambient temp is a liquid form
Gas- ambient temp is only gaseous form
What anesthetizes the patient?
Vaporizer delivers inhalant by volume %, BUT partial pressure of inhalant in alveoli anesthetizes the pt.
When do biological systems reach equilibrium?
when partial pressure of inhalant is the same in different compartments
You put sevo in iso vaporizer, what will happen to your patient?
Sevo: vapor pressure 160 mmHg
Iso: vapor pressure 240 mmHg
Animal will wake up!
What is Mac?
Minimum alveolar concentration, that defines the potency of a drug as gas % per 1 atm.
Does partial pressure of a gas depend on temperature & atmospheric pressure?
Just temperature, but atmospheric pressure can change the vapor concentration of the gas in the carrier gas.
What factors decrease MAC?
old age, hypothermic, hyponatremia, anemia, hypercapnia, hypoxia, pregnancy, drugs (benzo, GABA adrenergic, non-GABA, opioids), trauma
Whats the goal of inhaled anesthetics?
reach partial pressure (NOT concentration) consistent with anesthesia in the brain!
How many time constants is required for 95% concentration to be achieved?
3
Solubility
ratio of concentration within gas and blood, that also determines MAC higher partition coefficient the lower the MAC
high blood: gas partition coefficient means:
gas is more dissolved in blood so have a slower induction!
- iso
Low blood: gas partition coefficient means:
low blood solubility so does not take long to saturate blood & goes directly to brain & rapid induction/ quick recovery
- sevo
In the recovery phase- when does the animal normally wake up?
animal wakes up at 30-40% MAC
Anesthetic uptake & Elimination are affected by what factors?
Blood solubility of inhalant, CO & Alveolar ventilation
