Anesthesia - Lichtblau Flashcards
Difference between anesthesia and analgesic
Complete loss of sensations/unconscious
Just loss of pain sensation
What are the main stages of anesthesia?
1) Analgesia and Amnesia (good)
- goes unconscious
2 )Delirium (bad. get thru here fast)
- unconscious
- can be agitated or combative
- blood pressure and respiration can happen
3) Surgical Anesthesia (good)
4) Medullary Depression (bad, overmedicate)
- could lead to cardio/resp. collapse
What 4 drug types are combined in order to achieve the aims of a balanced anesthesia?
General anesthetic - Loss of awareness or consciousness
Benzodiazepine - Amnesia
Opioid – Analgesia, BANS
Neuromuscular blocker - Skeletal muscle relaxation
With gas anesthetic, why can’t you go higher than about 79% gas concentration?
You need 20.9% oxygen at least to survive
If you want your anesthetic to be fast-acting, do you want the anesthetic to be highly soluble or less soluble in blood?
Less soluble
What is the difference between how anesthesia perfuses and leaves alveolar, vessel-rich, muscular, and fatty areas??
Alveolar and vessel rich areas enter and exit tissue quickly
Muscle group is much more gradual incline and decline of perfusion
Fat is extremely in allowing drug to enter and exit
What is the MAC?
No, not the computer smart alek… (alek? what is that)
MInimum Alveolar Concentration
- It is the does of anesthetic producing surgical anesthesia in 50% of patients
- To be sure this means you want to do about 1.3-1.5 MACs for surgical anesthesia
Greater lipid solubility in an anesthetic =
Greater lipid solubility in an anesthetic = greater potency
Increasing the partial pressure of a drug in the blood is much easier when:
The drug is less blood soluble
hard to increase partial pressure of drug in the blood when it is dissolves easily in blood
What’s the second gas effect?
Lichtblau thinks its garbage…
Often N2O is used, it rapidly enters blood and it creates a “negative pressure” in the alveoli that allows the second gas to enter more quickly
What is toxologically important about the way that anesthetic is eliminated from the body?
If you are working in the OR you need to be careful because reactive chemical metabolites can be eliminated through the skin and cause exposure
CNS and Cardio effects of haogentaed hydrocarbon anesthetics?
CNS
- Decrease brain metabolic rate
- Increase Cerebral blood flow
- Increase intracranial pressure
Cardio
- Decrease myocardial contractility
- Decrease stroke volume
What are the advantages and disadvantages of halothane?
Advantages:
- Potent
- Rapid induction/recovery
- inexpensive
- no larynx irritation
Disadvantages:
- Inadequtes analgesis and muscle relaxation
- depress cardiac output, blood pressure, and respiration
- sensitize myocardium to catecholamines
- hepatic toxicity risk (a lot of metabolism)
- Malignant hyperthermia
How do you treat maligant hyperthermia caused by halothane?
Cool patient, treat with dantrolene
So how is isoflurance in comparison to halothane?
Pretty similar.
Advantage - doesn’t sensitize myocardium to catecholamines
Disadvantage - Pungent odor!
What anesthetic was recently voted “nearly perfect?”
Sevoflurane
- low blood solubility
- high potency
Why is it impossible to use nitrous oxide by itself as an anesthetic?
MAC = 104%
So its impossible because you need 20.9% oxygen just to stay alive…
What happens if you discontinue nitrous oxide very rapidly during recovery?
hypoxia can occur
Advantage of nitrous oxide as anesthesia?
Very rapid onset due to low blood solubility
Why are intravenous drug anesthetics not useful by themselves for surgery?
Can do short procedures, but they don’t maintain anesthesia for long AND muscle relaxation is poor with them
Usually used to induce anesthesia
What is the mechanism of action for barbituates like thiopental, etomidate, and methohexital?
Why is toxicity an issue?
Mech: Facilitate GABA-induced Cl entry into neurons
Toxicity: Watch out because the anesthetic dose is between 50 and 75% of the LD50 (thats the dose that will kill 50% of people)
What do you use benzodiazepines like midazolam for?
What is their mechanism of action?
Use: Most important for amnestic action
Mech: Facilitates GABA-induced Cl entry into neurons
Name 1 advantage and 1 disadvantage of propofol for injection anesthesia:
Advantage: patients awake more clear-headed and not nauseous
Disadvantage: Pain at injection site
Principal drawback of using ketamine?
What kind of anesthesia does it produce?
Occurrence of emergence reactions (delirium and hallucinations)
Abuse
Produces dissociative anesthesia
