Flashcards in Quiz 10 - Inhalation Agents and MAC Deck (41):
What is MAC amnesia?
25% MAC (blocks anterograde memory in 50% of awake patients)
What is MAC awake?
50% MAC - prevents eye opening on verbal command
What is MAC intubation?
130% MAC - concentration required to prevent movement and coughing during ETT intubation
What is MAC BAR?
150% MAC - concentration that blocks adrenergic response to skin incision
What factors increase MAC?
Age - term infant to 6mos has highest MAC
Chronic ETOH abuse
What are some factors that decrease MAC?
- Hypothermia (every 1 degree C drop in temp, MAC decreases 2-5%)
- Acute ETOH ingestion
- Premature infants
- preop meds
Factors that have no effect on MAC
- Thyroid gland dysfunction
MAC for ISO?
1.15 (according to notes)
MAC for Sevo?
2.05 (according to notes)
MAC for Des?
6 (according to notes)
MAC for N2O?
105 (according to notes)
MAC for Halothane?
What alveolar factors influence uptake?
Inspired concentration, Alveolar ventilation, Anesthetic system, uptake from alveolar space
What is the single most important factor determining the speed of induction and rate of emergence?
How is solubility of gasses expressed?
Blood:Gas partition coefficient
Blood gas coefficient for Des?
Blood gas coefficient for N2O?
Blood gas coefficient for Sevo?
0.68 (according to notes)
Blood gas coefficient for Iso?
1.4 (according to notes)
Which gas will have the quickest onset a poorly soluble agent or a highly soluble agent?
the poorly soluble agent
How does Cardiac Output affect induction of anesthesia?
CO is inversely proportional to the speed of induction - low CO will have quicker induction
What is Second Gas effect?
The ability of a gas (N2O) with rapid induction to speed up the rise in alveolar pressure of a second gas (agent)
What is diffusion hypoxia?
dilution of alveolar oxygen by a large amount of N2O "outgassing" - rapid desaturation can be seen - stop N2O before extubating and turn 100% oxygen on.
Is N2O a good analgesic?
Does N2O increase or decrease PONV?
When should you avoid N2O use?
when you have enclosed gas spaces: Pneumothorax, bowel obstruction, inner ear...
Will N2O increase or decrease PVR?
increase PVR - especially in pt with pre-existiing pulmonary HTN
Is N2O flammable?
No, but it is an O2 source and supports combustion
How does N2O affect methionine synthesis?
It inhbits (important for B12 and DNA sythesis)
What can long term use of N2O lead to?
peripheral neuropathy and megaloblastic anemia
How does Halothane affect contractility?
Halothane has a dose dependent decrease in contractility. Will also decrease BP, CO. SVR and PVR stay normal
What gives Halothane its sweet odor?
What effect can Halothane have on children? What do they require preanesthesia?
causes Vagal stimulation in children (bradycardia especially > 1 MAC) pretreat with atropine
What side effect does Halothane have on the heart?
sensitzes the heart to catecholemines, dysrhythmogenic - use epi with caution!
Iso and Des are good for inhalation induction (t/f)
False, the pungent odor can iritate sensitive airways
Will Iso and Des increase HR?
yes when rapidly increasing doses (norepi)
What is coronary steal syndrome and which agent causes it?
normal coronaries dilate and stenotic ones don't so blood is shunted away from diseased vessels - caused by Iso
Does Sevo have a pungent smell?
No, makes it a good choice for inhalation induction and children tolerate high levels within significant hemodynamic changes
what is a side effect of Sevo you need to look for in children?
How does Sevo form Compound A?
Formed with low fresh gas flow, high temps, high agent, dry baralyme, and long cases.
- is nephrotoxic, hepatotoxic, and brain toxic