Flashcards in Pharm Quiz #6 Deck (53)
What is the current definition of Anesthesia?
Immobility in the face of noxious stimuli and amnesia for intraoperative events
The ___ the MAC of an anesthetic, the ___ the oil-gas partition.
The ___ the oil-gas partition coefficient, the ___ potent the vapor.
How does the blood gas partition coefficient affect potency?
What is the relationship between MAC and the oil-gas partition?
it is inverse
What is the relationship between lipid solubility and anesthetic potency?
The greater the lipid solubility, the greater its potency.
What is the "take-home" message about OGPC?
The higher the OGPC, the greater the lipid solubility is and the greater the potency is because OGPC x MAC in atmospheres = 1.8 atms
What is the modern theory of anesthesia?
Potency determined by position and orientation of anesthetic in the bilayer.
What are two ways pain is meditated by immobility?
1. enhancing K+ ion channels
2. Glycine and GASBa receptors mediated reduction of spinal neuron action potentials
Where are Isoflurane sites of action in the brain(3)?
2. cerebral cortex
2 primary receptors of Isoflurane involved in the CNS.
2. Nicotinic acetylcholine receptors
What are the 3 goals of Isoflurane administration?
1. reversible effect on the CNS producing immobility in the face of noxious stimuli AND amnesia
2. immobility mediated via spinal cord anesthesia
3. amnesia mediated by the brain
What are the physical properties of Isoflurane?
racemic mixture of 50:50(R and S optical isomers)
ethereal and pungent odor
BGPC of 1.46
OGPC of 91
vapor pressure of 238
metabolism rate of 0.2%
Does Isoflurane produce compound A?
What is the MAC value for Isoflurane?
What factors reduce Isoflurane MAC?
age, opioids, benzos, clonidine, nitrous oxide, barbs, pregnancy, epidural anesthesia, local anesthesia, shock, trauma, major illnesses, hypothermia, hypothyroidism
Isoflurane prefers blood ___ times more than the gas phase, its blood gas partition coefficient would be ___?
1.4( or 1.4:1)
Isoflurane's BGPC is ___ than des/sevo, suggesting induction and emergence ___ than des/sevo.
Isoflurane's use on ___ cases will ___ recovery more than use on ___ cases.
longer, slow, shorter
How does Isoflurane compare to other volatile agents in speed emergence?
Isoflurane has greater solubility than sevo and des so more it enters the arterial side of circulation from the lungs, prolonging emergence. Likewise, obese patients may experience a slower emergence with Iso.
Does Isoflurane have any mutagenic affects?
No, although it may weakly decrease the body's ability to fight infection.
How does the addition of nitrous oxide for an equal MAC fraction with Isoflurane affect ventilatory status?
It lessens the ventilatory depressant effects
What is the state describing Isoflurane's affect on the lungs?
breathing like a lizard on a hot rock
The dose related to ventilatory depressant effects of Iso that leads to apnea is?
around 2 MAC
Isoflurane causes airway irritation beginning at about what MAC?
1, so not at sub-MAC doses. By the time the patient is ready to extubate your much lower than this.
In the VA from greatest to less airway irritation: Des--->Iso--->Sevo
Should Isoflurane be used for inhaled induction?
NO! it has a pungent odor
For a deep extubation, what MAC Iso is needed?
at least 0.85
How does Isoflurane affect ANS response to incubation as compared to Sevoflurane?
Iso blocks ANS response to intubation greater than Sevo
What affect does Iso have on hypoxic pulmonary vasoconstriction(HPV)?
Iso alters HPV minimally @ routine anesthetic concentrations with minimal clinical significant. HPV is a mechanism that diverts blood flow from hypoxic areas to optimize gas exchange.