Exam 3 Part I Flashcards by Brandon Edmondson

increased Temperature = _______ MAC = ____________ potency = ___________ Oil : gas solubility coefficient

increase; decrease; decrease

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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

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Inhalation agents are highly _________ soluble and _____________

lipid; diffusible

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level of anesthesia is related to the ________________________ of the anesthetic agents which is continuously measured via _________________

alveolar concentration; End tidal (of the agent)

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____________/_____________ of inhalational agent in in the lungs is ASSUMED (only assumption) to be the same as in the _____________

concentration/partial pressure; brain

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T/F: inhalational agents quickly reach equilibirium in the highly perfused body compartments (central compartment/vessel rich group)

TRUE

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end tidal of inhalational agent takes about ______________ minutes before it is truly representative of brain concentration

15 min

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how do you control the inspired partial pressure of inhlational agent

adjusting the dial

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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

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solubility effects of inhalational agents in the anesthesia machine potentially ______________ administration, but effects cease after ____________ minutes of administration

slows; 15

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small quantities of inhalational agent being retained in the machine is a huge issue for ___________________

malignant hyperthermia susceptible patients

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all anesthetic gases are triggers of MH except ________________

N2O

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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)

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____________ fresh gas flow increases the speed of uptake of INH agent

increasing

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what is THE most important way to increase the partial pressure of volatile agent in the lungs

fresh gas flow

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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

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the saturation of agent in the lungs is based on _____________________

first order kinetics (fraction of drug picked up/unit of time)

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what is time constraints

calculates the time to get to 95% (of INH) max concentration of the circuit

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how many time constraints = 95% max [ ] of the circuit

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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

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Vapor pressure is _______________ dependent

temperature

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Inhalational agents are ______________ at room temperature

liquids

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what is room temperature

20 C (68 F)

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temperature vapor pressure relationship is based off ________________ prinicple

LeChateliers

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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?

1. 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

1. 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

1. 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

1. 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

1. 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

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

1. 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

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

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)

1. 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)

1. 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

1. increase FGF (**best one for you pt) 2. increase Mv 3. turn dial up (increase concentration)

circulatory factors to INH agents

1. 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)