Exam 3 Part I Flashcards
increased Temperature = _______ MAC = ____________ potency = ___________ Oil : gas solubility coefficient
increase; decrease; decrease
methods of pain relief prior to 1840
- drugs: hashish, alcohol, opium derivatives 2. physical methods: packing limb in ice, ischemia with a tourniquet, blow to the head, strangulation 3. restraints
Inhalation agents are highly _________ soluble and _____________
lipid; diffusible
level of anesthesia is related to the ________________________ of the anesthetic agents which is continuously measured via _________________
alveolar concentration; End tidal (of the agent)
____________/_____________ of inhalational agent in in the lungs is ASSUMED (only assumption) to be the same as in the _____________
concentration/partial pressure; brain
T/F: inhalational agents quickly reach equilibirium in the highly perfused body compartments (central compartment/vessel rich group)
TRUE
end tidal of inhalational agent takes about ______________ minutes before it is truly representative of brain concentration
15 min
how do you control the inspired partial pressure of inhlational agent
adjusting the dial
factors that affect the inhalational agent uptake d/t solubility in the anesthesia machine
- solubility of agent in the ventilator 2. solubility of agent in absorbent 3. small quantities of agent are retained in the machine
solubility effects of inhalational agents in the anesthesia machine potentially ______________ administration, but effects cease after ____________ minutes of administration
slows; 15
small quantities of inhalational agent being retained in the machine is a huge issue for ___________________
malignant hyperthermia susceptible patients
all anesthetic gases are triggers of MH except ________________
N2O
how can you decrease the risk of MH in suceptible patients 2/2 anesthesia machine retaining small quantities of inhalational agents
flush machine prior to use: 1. 100% O2 at 10L/min 2. run for 20 minutes 3. change absorbant 4. remove vaporizers 5. may vary by machine ideal: INH free machine (i.e. machine that has never had gas run through it)
____________ fresh gas flow increases the speed of uptake of INH agent
increasing
what is THE most important way to increase the partial pressure of volatile agent in the lungs
fresh gas flow
when you want to quickly increase the speed of uptake (P.P of agent) of INH agent you should increase the FGF to _____________
6-8 L/min
the saturation of agent in the lungs is based on _____________________
first order kinetics (fraction of drug picked up/unit of time)
what is time constraints
calculates the time to get to 95% (of INH) max concentration of the circuit
how many time constraints = 95% max [ ] of the circuit
3
what is the calculation for time constraint based on flow?
TC = volume of circuit (constant #)/FGF = time (min) –> time (min) x 3 time constraints = 95% max [ ] of the circuit
Vapor pressure is _______________ dependent
temperature
Inhalational agents are ______________ at room temperature
liquids
what is room temperature
20 C (68 F)
temperature vapor pressure relationship is based off ________________ prinicple
LeChateliers
LeChatliers principle (temperature) =
increase temperature increase vapor pressure
what is vapor pressure
the pressure exerted by a vapor over a liquid (at equilibrium)
what is the indicator of speed of uptake and elimination of a INH agent?
blood: gas solubility coefficient
what is the blood: gas solubility coefficient a ratio/proportion of?
amount of agent that blood soluble vs the amount of agent that is lipid soluble
a HIGH blood : gas solubility coefficient would indicate what?
- slow moving gas –> slower induction and slower emergence 2. less drug released for uptake 3. decreased brain and spinal cord uptake
isoflurane has a blood : gas solubility coefficient of 1.4, what does this indicate
1.4 x as much iso stays in the blood (non-usable) for every 1 molecule that enters the tissues (brain)
as temperature of liquid DECREASES (through pt body temp) the blood : gas solubility __________________
INCREASES
a patient is hypothermic near the end of the case, you know the patient is going to take longer to emerge from general anesthetic due to the _____________________
increased blood : gas solubility coefficient
partition coefficient
- reflects solubility of anesthetic 2. distribution ratio of how INH agent distributes itself btwn two phases at equilibrium (pp equal in both phases) 3. description of the ability/capacity of the blood phase or tissue phase to accept the anesthetic
what is the oil : gas solubility coefficient
the indicator of an anesthetic’s potency–the higher the coefficient, the more potent the agent
a HIGH oil : gas solubility coefficient represents what
high lipid solubility , meaning agent will cross BBB easier
which agent would you expect to have the highest oil : gas solubility coefficient (of the gases we still use today in the USA)
isoflurane (it is the most potent so has the highest oil : gas solublity coefficient = 99)
_____________________ describes how the agent moves through the tissue to get to the receptor
oil: gas solubility coefficient
which agent would you expect to have the LOWEST oil: gas solubility coefficient
Nitrous oxide (is the least potent so should have the smallest O:G = 1.4)
temperature is ________________ proportional to oil: gas solubility coefficient
inversely
what is the definition of MAC
concentration of INH agent at 1 atm that prevents skeletal muscle movement in response to surgical stimulation in 50% of patients