Uptake/Distribution of VA Flashcards
definition of MAC
Fe agent or alveolar concentration at which 50% of patients don’t move upon noxious stimuli
brain concentration of MAC
estimated by alveolar concentration or Et concentration
MAC awake
1/3 - 1/4 MAC
patient able to respond appropriately
MAC intubation
> > MAC
more stimulating than incision
MAC incision
= MAC
MAC BAR
30-40% > MAC
blunt/no autonomic responses
factors that decrease MAC (12)
- hypothermia
- severe hypotension
- age
- opioids/ketamine
- chronic amphetamine use
- reserpine/a-methyldopa
- cholinesterase inhibitors
- IV LA
- pregnancy
- hypoxemia- PaO2 < 40
- anemia
- a2-agonists
factors that increase MAC (5)
- hyperthermia
- hyperthyrodism
- alcoholism
- dextroamphetamine
- young age
factors that DO NOT effect MAC (6)
- duration of anesthesia
- sex
- metabolic acid-base status
- hypercapnia/hypocapnia
- isovolemic anemia
- hypertension
awareness
postop recall of events occurring during GA
amnesic wakefulness
responsiveness during GA without postop recall
dreaming
any experience that patients are able to recall postop that they think occurred during GA & that they believe is dreaming
explicit memory
conscious recollection of previous experiences (awareness)
implicit memory
changes in performance or behavior that are produced by previous experiences but without conscious recollection of experience
lambda/Ostwald coefficient
- mls of gas that will dissolve in 1ml of blood at 37C
- when Pp of agent in blood and gas are in equilibrium, coefficient tells you how much agent is dissolved for each ml causing anesthesia
Henry’s Law
amount of gas that dissolves in a liquid is directly proportional to the Pp of gas over the liquid
VRG
- brain, heart, kidney, liver
- 10% body mass ~ 75% CO
- 70ml blood/100ml tissue/min
- high uptake d/t perfusion
- N2O 50% equilibrated 2 min; 90% in 4-8 min
Muscle
- 50% body mass ~ 19% CO
- 3ml blood/100ml tissue/min
- N2O 50% equilibrated in 20-25 min
- Sevo 50% equilibrated in 80 min
- full equilibration in 2-4 hours
Fat
- 20% body mass ~ 6% CO
- 400ml/min
- N2O 50% equilibrated in 75 min
- Sevo 50% equilibrated in 30 hours