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Flashcards in Anesthesia Deck (17):
1

Halothane

-Halogenated hydrocarbon inhalation
-CNS effect: increase intracranial pressure
-CV effects: Decreased myocardial contractility and stroke volume leading to lower arterial blood pressure; Sensitizes myocardium to catecholamines ↑ automaticity. Epi may trigger arrhythmia.
-Malignant hyperthermia may occur with ALL inhalation anesthetics except nitrous oxide, most commonly seen with halothane.
-Advantage: potent and cheap, no laryngospasm

2

Isoflurane

-Halogenated hydrocarbon inhalation
-Advantage: potent, <10 min induction, less hepatotoxic and renal toxic than halothane
-Disadvantage: smells bad, arrhythmias

3

Desflurane

-Halogenated hydrocarbon inhalation

4

Sevoflurane (7 fluorines)

-Halogenated hydrocarbon inhalation (newer one)
-High potency
-Fast onset of action (low blood solubility) and rapid recovery
-No metabolism
*Almost perfect inhalation anesthetic

5

Nitrous oxide

-Low blood solubility (rapid onset)..2nd gas effect
-Disadvantage: MAC 104%, no muscle relaxing effect, diffusion hypoxia if rapidly discontinued

6

Pentobarbital

-Injectable anesthetic

7

Thiopental (Pentothal)

-Injectable anesthetic
-Rapid onset and short action
-Facilitates GABA induced Cl- entry into neurons, leading to CNS depression
*Use caution: anesthetic dose is b/t 50-75% of LD50

8

Propofol

-Injectable anesthetic
-Rapid induction (50 s) and recover (4-8 minutes)
-May be given alone to maintain anesthesia or used for induction as part of balanced anesthesia technique
-Most significant respiratory effect is apnea!! Don't walk out of room i.e Michael Jackson
-May result in injection site pain
**DON'T USE FOR SLEEP, highest % of abuse is by anesthesiologists going to for a 'cat nap' 40% don't wake up

9

Midazolam (Versed)

-Benzodiazepine
-Facilitates GABA induced Cl- entry into neurons by increasing the frequency of opening of Cl- channels, leading to CNS depression
-Most important for amnesia (anterograde)
-Insufficient for anesthesia!!!

10

Ketamine

-Injectable anesthetic
-Related to phencyclidine PCP
-Causes dissociative anesthetic (patient appears to be awake, but they are totally unaware)- good for surgery on the back so you don't need to get them hooked up to breathing apparatus i.e. they breathe on their own.
-Principal drawback is the occurrence of emergence reactions (delirium and hallucinations)
**Abuse potential due to PCP like effect. Known as Special K on the street.
**Rapid action anti-depressant? Future..

11

Fentanyl (Sublimaze) & Sulfentanyl (Sufenta)

-Injectable anesthetic Opioid
-High dose: hemodynamic stability, respiration must be maintained artificially and may be depressed into the postoperative period
*Usually supplemented with inhalation anesthetic, benzodiazepine or propofal

12

What are the 4 stages of anesthesia? (In general)

1. Analgesia and amnesia (ends w/loss of consciousness); Good
2. Delirium (begins with loss of consciousness, patients may become combative; get out of this as quickly as possible); Bad
3. Surgical anesthesia (Plane I-IV: I light surgical IV excessive surgical); good
4. Medullary depression (stage of reactive OD, patient can die); Bad OOPS

13

How do you accomplish balanced anesthesia?

-General anesthetic - Loss of awareness or consciousness
-Benzodiazepine - Amnesia
-Opioid – Analgesia, blunting autonomic NS
-Neuromuscular blocker - Skeletal muscle relaxation

14

What is the Partial pressure of oxygen needed?

21% (79% max can be anesthetic)

15

What is the minimum alveolar concentration? (MAC)

Dose of anesthetic (vol%) producing surgical anesthesia in 50% of patient population (ED50).

*Lowest MAC drugs are the most potent example: sevoflurane (1.71% of the mixture). Nitrous oxide requires 104%..NOT EFFECTIVE for anesthetic. Only for analgesia.

*Need 1.3-1.5 MAC for light anesthesia, 2 MACs for deep anesthesia

16

What is the difference between lipid solubility and blood solubility?

Lipid solubility: responsible for potency. Increased lipid solubility, increase potency. Also leaves slower.
Blood solubility: the more water soluble, the slower time of onset

17

What is the second gas effect?

Rapid uptake of first anesthetic from alveoli into blood creates a negative pressure in alveoli
-Draws in more of a second inhaled anesthetic agent whose alveolar uptake might otherwise be slow
*Nitrous goes first, gets in fast, creates vacuum, sucks in halothane. Get out of 2nd stage quickly
*Diffusion hypoxia is a risk with nitrous during recovery