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
_______________ is considered the ED50 of INH agents
MAC
increased MAC = ___________ potency
decreased
_________________ allows for comparison of INH agents (assuming that alveolar [ ] = brain [ ] )
MAC
approximately __________ MAC prevents skeletal muscle movement in > 95% of patients
1.3
T/F: MAC values for INH agents are synergistic
false they are additive
generally it takes ____________ minutes for the alveoli and the brain to equilibrate at normal flow rates of INH agent
10-15 min
what is MAC - awake
the concentration at which 50% of pts will respond to the command “open your eyes”
MAC awake is approximately ___________ - _________ MAC
1/3-1/2
_____________ concentration is usually associated with amnesia or loss of recall
MAC-awake
with which type of MAC (MAC-bar vs MAC-awake) would the pt be able to maintain their own airway
MAC awake
what is MAC-BAR
the concentration necessary to block the adrenergic response to skin incision (i.e. block HR and BP increase)
_____________ exceeds normal MAC levels
MAC-BAR
MAC-BAR is approximately ______ - _______ MAC
1.5-2.5
what are some factors that decrease MAC
- hypothermia 2. neonates and elderly 3. acute ETOH 4. hyponatremia (common with turp procedure) 5. alpha 2 agonists 6. lithium 7. benzos 8. barbituates 9. narcotics 10. lidocaine 11. PaO2 < 38 mmHg 12. BP < 40 13. sepsis 14. pregnancy
what are factors that will increase your MAC
- hyperthermia 2. infants (1mo - 1 yr) 3. drug induced increase in catecholamines (cocaine, MAOIs) 4. chronic ETOH (d/t CYP +) 5. red headed females
why do red headed females have increase MAC
d/t melanocyte stimulating hormone receptor mutation which affects the kappa opioid receptors ability to occupy the receptor affects females > males
what has NO effect on MAC
- gender 2. duration of anesthetic 3. muscle relaxants 4. hyperkalemia/hypokalemia 5. hyper/hypocapnia 6. metabolic alkalosis 7. HCT > 10 8. HTN
> than age 40, MAC decreases by _______% per decade
6
patient is conscious and rational but perception of pain is diminished, this is which stage of anesthesia
stage I: analgesia
what are the stages of anesthesia
- analgesia 2. delrium 3. surgical 4. medullary depression
__________________ is the stage of anesthesia where the patient is unconscious but body responds reflexively and irrationally to stimuli.
stage II: delirium
which stage of anesthesia will there be breath holding, but the airway protection is intact and pupils dilate
stage II: delirium
laryngospasm is most likely to occur during which anesthetic stage
stage II: delirum
what are the characteristics of stage III: surgical anesthesia
increasing degree of muscle relaxation & loss of pharyngeal reflexes (pt unable to protect airway)
________________ stage anesthesia is where you will have CV and respiratory collapse
stage IV: medullary depression
patients will go through stage II of anesthesia very quickly with ___________, but spend more time in this stage during _____________
induction; emergence
which stage should your patient NOT be extubated in??
stage II
vapor pressure of halothane @ 1 atm
243-244
vapor pressure of isoflurane @ 1 atm
238-240
vapor pressure of sevoflurane @ 1 atm
157-160
vapor pressure of desflurane @ 1 atm
664-672
blood : gas solubility (onset) of halothane
2.4 - 2.54
blood : gas solubility (onset) of isoflurane
1.40 - 1.46
blood : gas solubility (onset) of sevoflurane
0.65-0.68
blood : gas solubility (onset) of desflurane
0.42-0.45
blood : gas solubility (onset) of N2O
0.46
what is the oil:gas solubility (potency) of halothane
224
what is the oil : gas solubility (potency) of isoflurane
99
what is the oil : gas solubility (potency) of sevoflurane
50.0 -53.4
what is the oil : gas solubility (potency) of desflurane
18.7
what is the oil : gas solubility (potency) of N2O
1.4
what is the MAC of halothane @ 1 atm
0.75-0.76
what is the MAC of isoflurane @ 1 atm
1.15
what is the MAC of sevoflurane @ 1 atm
1.85 - 2.0
what is the MAC of desflurane @ 1 atm
6
what is the MAC of N2O @ 1 atm
104
what is the ventilation effect of INH agents
the faster/deeper a pt breathes the faster the onset/offset of the anesthetic agent (speeds induction/emergence)
why does uptake of INH agent slow down over time
tissue compartments become more saturated (based on diffusion gradient)
poor lung function or VQ mismatch would _______________ onset and emergence, thus the __________________ effect would not work for these pts
prolong; ventilation
what is the concentration effect
increasing the concentration of INH agent above MAC will speed onset of action
concentration effect is similar to _____________________
loading dose
concentration effect is aka _______________
overpressuring (the vaporizer)
what is the 2nd gas effect
administering a slow agent and a fast agent simultaneously, the fast agent will increase the rate of uptake of the 2nd (slower) gas
T/F: the second gas effect applies to fast gases like desflurane
false; slower gases
what is the theory behind the MOA of the 2nd gas effect (using N20 and isoflurane as ex)
N2O moves faster in and out of alveoli than O2 or isoflurane –> N2O moves into alveoli, occupying space, then leaves, this leaves alveoli space void, thus making more room for inhalational agent –> filling quicker –> faster concentration –> faster diffusion
overpressuring and 2nd gas effect works well with ____________ INH agents, but have less effect on __________ INH agents
slow; fast
factors that increase the rate of rise of alveolar concentration/inspired concentration (FA/FI)
- low blood gas solubility (gammaB) 2. low CO (Q) 3. high minute ventilation (VA) 4. high Pa - Pv (pulmonary arterial and venous blood partial pressure) 5. high anesthetic concentration (FI)
factors that decrease the rate of rise of alveolar concentration/inspired concentration (FA/FI)
- high blood gas solubility (gammaB) 2. High CO (Q) 3. low minute ventilation (VA) 4. low Pa-Pv (pulmonary arterial; venous blood partial pressure) 5. low anesthetic concentration (FI)
what are the 3 ways you increase the onset/depth of the inhalational agent
- increase FGF (**best one for you pt) 2. increase Mv 3. turn dial up (increase concentration)
circulatory factors to INH agents
- longer the agent is delivered –> greater perfusion to all body parts 2. higher the CO the faster the INH is carried away from the lungs (slows the rise of brain and lung concentration)
