Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
123 Cards in this Set
- Front
- Back
|
nitrous oxide MAC
|
MAC in 100% O2 105
MAC in 70% N2O-N/A Blood:Gas partition coefficient 0.47 |
|
|
Halothane(Flouthane)
|
MAC in 100% O2 0.75
MAC in 70% N2O 0.29 BG Partition coefficient 2.4 |
|
|
Methoxyflurane(penthrane)
|
MAC in 100% 02 0.16
MAC in 70% N2O 0.07 BG partition coefficient NA |
|
|
Enflurane(Ethrane)
|
MAC in 100% O2 1.7
MAC in 70% N2O 0.57 BG partition coefficient NA |
|
|
Isoflurane(forane)
|
MAC in 100% O2 1.2
MAC in 70% N2O 0.50 BG partition coefficient 1.4 |
|
|
Desflurane(Suprane)
|
MAC in 100% O2 6.0
MAC in 70% N2O 2.8 BG partition coefficient 0.42 |
|
|
Sevoflurane(Ultane)
|
MAC in 100% O2 2.0
MAC in 70% N2O .66 BG partition coefficient 0.65 |
|
|
What is MAC?
|
alveolar concentration of an inhaled agent at which 50% of patients do not respond to skin incision or noxious stimuli
|
|
|
Potency is directly related to lipid solubility, True or False
|
TRUE
|
|
|
What is general anesthesia(GA)?
|
An ultered physiological state characterized by REVERSIBLE loss of consciousness, analgesia of the entire body, amnesia, and some degree of muscle relaxation
(one authors definition) |
|
|
How is GA achieved?
|
IV agents:
propofol barbiturates Inhaled Gases |
|
|
List the phases of GA
|
Induction
Maintenance Emergence |
|
|
All drugs we give for GA are potents hemodynamic depressants, True or False?
|
TRUE
|
|
|
List methods of GA administration
|
Mask
LMA ETT |
|
|
If nitrous oxide is administered over days what may it lead to?
|
aplastic anemia and DEATH
|
|
|
When was Nitrous Oxide (NO)introduced?
|
By Horace Wells in 1844
|
|
|
Does NO have ANALGESIC effects?
|
YES, fairly potent analgesic, utilized in dental offices
|
|
|
What is a down fall of NO?
|
Post-op nausea and vomiting
Diffuses into air containing spaces and expands them |
|
|
When not to use NO
|
bowel cases
penumothroax(known or suspect) inner ear surgeries pneumocephalus |
|
|
Nitrous Oxide is how many times more soluble then nitrogen?
|
37
|
|
|
Is NO flammable?
|
No but will support combustion
|
|
|
What was the first COMPLETE anesthetic?
|
Diethyl Ether
|
|
|
When was Diethy Ether introduced?
|
By William Morton in 1846
|
|
|
What has been argued as the greatest discovery in medicine?
|
Diethyl Ether
|
|
|
What supplied most of the anesthetics for nearly a century?
|
Diethyl Ether along with NO and chloroform
|
|
|
Where was the first anesthetic administered?
|
Ether Dome in Boston
|
|
|
What revolutionized anesthesia?
|
Halothane(fluothane)
|
|
|
When was Halothane(fluothane) introduced?
|
1956
|
|
|
What is Halothane(fluothane)
|
halogenated alkane derivative
|
|
|
Why is Halothane(fluthane) good for induction?
|
it's non-pungency
|
|
|
What are two down falls of Halothane(fluthane)?
|
1)sensitizes myocardium to catecholamines
2)halothane hepatitis |
|
|
what do ALL alkanes do?
|
cause sensativity of myocardium to circulating catecholemines
|
|
|
What inhaled agents are pungent therefore NOT good for induction?
|
Desflurane(Suprane) and
Isoflurane(forane) |
|
|
Methoxyflurane(penthrane)
|
Introduced 1960
Halogenated Methylethyl ether MOST potent inhaled anesthetic |
|
|
Why was methoxyflurane(penthrane) discontinued from clinical practice?
|
nephrotoxicity
|
|
|
Enflurane(ethrane)
|
Introduced 1973
Halogenated methylethyl ether |
|
|
What has Enflurane(ethrane) been implicated in?
|
Flouride induced nephrotoxicity
|
|
|
Isoflurane(forane)
|
introduced in 1981
halogenated methylethyl ether Isomer of enflurane Cost effective Popular |
|
|
what do isomers of different drugs do?
|
change the side effects
|
|
|
Is Isoflurane(forane) a soluble agent?
|
yes, it will take longer to wake your patient
(MAC is 1.2) |
|
|
Although all agents can act on hemodynamics Isoflurane(forane) is relatively benign, true or false
|
True, dose dependent
|
|
|
What is the most insoluable agent?
|
Desflurane(suprane)
MAC=6 |
|
|
Desflurane(suprane)
|
Introduced in 1992
Fluorinated methylethyl ether requires heated vaporizer LEAST soluble inhaled agent MOST pungent agent |
|
|
What happend if Desflurane(suprane) reacts with dessicated CO2 absorbents?
|
Forms carbon monoxide-potentially lethal
(would take days at high FGF for this to happen, Tim's example it FGF was left on over the weekend) |
|
|
What about Des makes it necessary for it to have it's own vaporizer?
|
Highest vapor pressure
|
|
|
Sevoflurane(ultane)
|
Introduced in 1993
fluorinated methyl isopropyl ether non-pungency and low solubility make it an ideal agent for inhalation induction |
|
|
What does Sevoflurane(ultane) form when it reacts with dessicated CO2 absorbents?
|
Compound A
|
|
|
Describe Compound A
|
-injury to corticomedullary junction of the kidney
-proteninuria, enzymuria, renal necrosis demonstrated in RODENTS(not documented in HUMANS) -concentrations correlate inversely with fresh gas flow rates |
|
|
Thinking of compound A
|
FGF of 1LPM for 2 MAC hours, then increase FGF to 2 LPM
|
|
|
State the Meyer-Overton theory
|
Anesthetic dissolves in the lipid bilayer of the neuronal membranes thereby disrupting neuronal transmission
|
|
|
Meyer-Overton Rule:
|
anesthetic potency correlates directly with lipid solubility
|
|
|
Meyer-Overton rule disproved how?
|
disproved because not all gases that are lipid soluble are anesthetics
|
|
|
Modulation of neurotransmitter/receptor activity
Excitatory: |
serotonin
acetylcholine glutamate |
|
|
Modulation of neurotransmitter/receptor activity
Inhibitory: |
GABA
Glycine |
|
|
What is the primary neurotransmitter in the CNS that our agents work on?
|
GABA
(inhibitory NT, helps keep things under control) |
|
|
MAC measures what?
|
anesthetic potency
|
|
|
MAC values are additive:
|
0.5 MAC of Sevo + 0.5 MAC of Iso = 1 MAC of des
|
|
|
What will increase your MAC value?
|
young
Alcohoo-chronic abuse hypernatremia amphetamines: acute Cocaine ephedrine |
|
|
By what % does MAC decrease with age?
|
6% per each decade of life after the age of 30
|
|
|
Up to 1 year of age need higher MAC value, true or false?
|
TRUE
|
|
|
Describe partial pressure
|
The pressure contribution that a gas makes to the total pressure exerted by a mixture of gases
|
|
|
what is atmospheric pressure at sea level?
|
760mmHg
|
|
|
Oxygen is 21% of room air, what is its partial pressure?
|
21% x 760=160
|
|
|
What is our goal with anesthesia?
|
to achieve a constant partial pressure of anesthetic in the brain
|
|
|
What moves gases?
|
partial pressure gradients
|
|
|
How does anesthetic get to the brain?
|
arterial circulation
|
|
|
Partial pressure is the driving force
|
moving from areas of higher partial pressure to lower
|
|
|
The brain(Pbr) equilibrates with the paritial pressure of anesthetic in arterial blood(Pa) which equlibrates with the partial pressure of anesthetic inthe alveoli(PA) which the anesthetist controls via the inspired concentration of anesthetic (PI)
|
.
|
|
|
What does hypoventilation do to PaCO2?
|
PaCO2 rising but sats will still look good
|
|
|
Desflurane (suprane) is delivered to the patient at an inspired concentration of 6%, what is the INSPIRED partial pressure?
|
0.06 x 760mmHg=45.6 (46)
|
|
|
What is assumed to mirror the partial pressure of the anesthetic in the brain?
|
Alveolar partial pressure (PA)
|
|
|
What are the "windows to the brain"?
|
The alveoli
|
|
|
How long does equilibration take?
|
6-8 minutes
|
|
|
What determines alveolar partial pressure?
|
Input(delivery) of anesthetic agent into the alveoli minus uptake of the agent by the arterial blood
|
|
|
Name the resevoir groupt
|
Vessel Rich Group (VRG)
Muscle Group (MG) Fat Group (FG) Vessel Poor Group (VPG) |
|
|
The VRG consist of what?
|
Brain, heart, liver, kidneys, and lungs
|
|
|
What % of blood flow does this group receive?
|
75%
|
|
|
What does the MG consist of?
|
Muscle and skin
|
|
|
What % of blood flow(cardiac output) does the MG group receive?
|
20%
|
|
|
What does the FG consist of?
|
Adipose tissue
|
|
|
What % of blood flow does the FG receive?
|
5%
|
|
|
Inhaled anesthetics are very soluble in fat, what does this do?
|
Functions as large reservoirs for anesthetic-during long anesthetic cases
|
|
|
Why will alveolar concentration never reach 100%?
|
because of uptake to the other organs
|
|
|
solubility
|
solubility governs the rate of increase and decrease in alveolar concentration during the induction and recovery from anesthesia
|
|
|
Lower solubility =
|
faster induction
|
|
|
higher solubility=
|
slow induction
|
|
|
Solubility
|
how much inhaled anesthetic is "dissolved" in the blood
|
|
|
Solubility of inhaled anesthetics is denoted by what?
|
blood:gas partition coefficients
|
|
|
Again....
|
gases will move from higher partial pressure to lower partial pressure until they reach equilibrium
|
|
|
What is a partition coefficient
|
is a distribution ratio describing how the anesthetic gas distributes itself between two phases at equilibrium
|
|
|
What does a blood:gas partition coefficient of 0.5 mean?
|
means that the concentration of anesthetic in the blood is half that present in the alveoli when the partial pressures are identical
|
|
|
what does the solubility determine when doing anesthesia?
|
the solubility of an anesthetic gas determines the speed of induction and the speed of emergence
|
|
|
insoluble agents undergo significantly less uptake than soluble agents, what is the consequence?
|
the alveolar concentration (partial pressure) rises much faster with an insoluble agent and induction is FASTER
|
|
|
again.....
|
we can see how important solubility is!!
|
|
|
Give the blood gas partition coefficients...
|
Halothane 2.4
Isoflurane 1.4 Desflurane 0.42 Sevoflurane 0.65 |
|
|
Know Fi/Fa chart
|
see chart
|
|
|
Pharmacodynamics of inhaled agents on the CNS
|
Amnesia:
inhaled anesthetics provide excellent amnesia |
|
|
At what MAC do inhaled anesthetics provide amnesia?
|
0.5 MAC
|
|
|
Analgesia of inhaled anesthetics is minimal at best....
|
.2-.3 MAC does not alter pain perception in healthy volunteers
NEED to supplement with opioids |
|
|
Cerebral Vascular Response
|
POTENT cerebral vasodilitation
INCREASED cerebral blood flow and INCREASED ICP |
|
|
What will inhaled anesthetics DECREASE in the CNS?
|
DECREASED cerebral metabolic oxygen consumption (CMRO2)
|
|
|
A decreased CMRO2 is a good thing why?
|
it is neuroprotective
|
|
|
Inhaled anesthetics are peripheral dilators, true or false?
|
TRUE
|
|
|
All agents produce dependent reductions in MAP secondary to what?
|
peripheral vasodilitation
|
|
|
What agent produces minimal to no change in MAP?
|
Nitrous Oxide
|
|
|
Care should be taken when giving agents to patiens who cannot tolerate a low MAP
|
CAD-they could infarct on the table for you!!
Chronic HTN-dont allow to drop pressure too much |
|
|
What agents cause the GREATEST myocardial depression?
|
Halothane and Enflurane
|
|
|
Avoid doses of epinephrine greater than what?
|
1.5mcg/kg
|
|
|
What do agents do to the respiratory system?
|
DECREASED minute ventilation
INCREASED resp rate |
|
|
What do anesthetics blunt response to?
|
Hypoxia and hypercarbia
|
|
|
Agents are excellent at what?
|
bronchodilition
|
|
|
What is the first action during an intraoperative bronchospasm?
|
increase inspired concentration of inhaled anesthetic
|
|
|
All inhaled agents provide a minor degree of what?
|
muscle relaxation
|
|
|
Inhaled agents significantly potentiate the effects of the IV neuromuscular blockers, true or false?
|
TRUE
|
|
|
malignant hyperthermia is what type of disorder?
|
hypermetabolic disorder or skeletal muscle
|
|
|
Malignant hyperthermia...
|
uncontrolled release of calcium from the sarcoplasmic reticulum resulting in intracellular hypercalcemia
|
|
|
What will be the first sign of MH?
|
increased ETCO2.....rising quickly...35-50-70-100!!!!!
|
|
|
Sympathetic Nervous system s/s in MH....
|
tachycardia
tachypnea ventricular dysthythmias hyperthermia-late sign masseter muscle regidity"lock jaw" precipitates MH 60% of the time |
|
|
Is nitrous oxide safe for malignant hyperthermia?
|
YES
|
|
|
treatment
|
GET HELP FAST
d/c volatile agents and succinylcholine hyperventilate with 100% O2 halt procedure change circuit and CO2 absorbant |
|
|
Med to tx MH
|
Dantrolene 2.5mg/kg rapidly IV
|
|
|
MH tx cont....
|
bicarb for acidosis 1-2mEq/kg until blood gas available
Cool pt with core temp >39 dysrhythmias usu respond to tx of acidosis and hyperkalemia |
|
|
What can calcium channel blockers do in the presence of dantrolene?
|
May cause hyperkalemia or cardiac arrest
|
