Anesthetics

Question 1

How do anesthetics affect the respiratory and cardiovascular systems?

Answer 1

Causes bronchodilation and depresses respiratory system. (Asthma complicates anesthetic situation)

Most have hypotensive effect. (Usually take anticholinergics to prevent bradycardia)

Question 2

4 stages of anesthesia

Answer 2

Analgesia- loss of pain

Excitement- possibly violent. Inc heart rate. Want to avoid.

Surgical anesthesia- regular respiration and relaxation of skeletal muscle. Eye reflexes stop.

Medullary paralysis- severe depression of respiratory. Avoid.

Question 3

MOA inhaled anesthetics

Answer 3

No specific receptors. Interaction with ion channels causes hyper polarization. Some facilitate GABA mediated inhibition

Eliminated by exhale.

Question 4

MOA IV anesthetics

Answer 4

MOA is unknown. 
Rate of transfer to brain increases if: 
1. Not bound to proteins 
2. Lipophillic
3. Small 
4. Non ionized. 

Often used for rapid induction of anesthesia. Then maintained with inhaled.

Question 5

MOA local anesthetics

Answer 5

Blocks painful stimuli from point of stimulus to the spinal cord.

Target NA channels in the axon, blocking them. Preventing depolarization. Blocks information transfer about painful stimuli from the point of stimulus to the spinal column.

Admin is as close as possible to axons of pain sensors.

Question 6

3 groups of anesthetics

Answer 6

Inhaled, IV, local. Local can either be injected or topical.

Question 7

Indications for topical (local) anesthetics
Max concentration?
Dosages?

Answer 7

K debridement, dx(pt comes in with painful eye and they can’t open it), technique.
**has max effective concentration.
Dose- small applications at 30 sec intervals. Admin only to seated patients and never used as a prolonged therapeutic regimen!!

Question 8

Topical side effects

Answer 8

Loose K epithel
Stinging
Rare allergic rxn
Anesthetic induced K syndrome- 6 days/6 weeks of self admin. Loss of epithelium, stromal edema.

Question 9

Topical (local) drugs.

Which has the longest onset, which has the longest duration?

Answer 9

Cocaine: Onset 5-10 minutes, lasts 20 minutes (complete) and 2 hours (incomplete) **Only topical anesthetic that has vasoconstriction. Prolonged anesthesia but not more intense. decreases systemic absorption

Tetracaine, Proparacaine, Benoxinate: All three have 10-20 second onset, 10-20 minute duration.

Lidocaine: Onset 20-60 seconds, lasts 5-30 minutes.

Longest onset: cocaine (1)
Longest duration: Lidocaine (last)

Question 10

Injected (local) drugs

Which has the longest onset, which has the longest duration?

Answer 10

Mepivicaine hydrochloride: shortest onset. 3-5 min onset, 3 hour duration.

Bupivicaine hydrochloride: Longest onset and duration. 4-12 mins, 4-12 hours.

Procaine hydrochloride: Shortest duration. 30-45 min duration.

Lidocaine hydrochloride: Short duration. 60 min duration.

Question 11

Injection of local drugs. Indications?

Answer 11

For tissue infiltration- lid lesion or chalzaion. Facial nerve block or retrobulbar nerve block.

If there is infection or inflammation, increase dose due to acidosis preventing the drug from entering the cell.

Epi often used in combo since it is a vasoconstrictor.

*Excessive drug can affect motor control or cause arrhythmias.

**Epi often added income, especially for lid lesion/chalazion. Vasoconstrictor, monitor systemic sympathetic side effects.

Question 12

Tetracaine is an ester of ____. May inhibit actions of topical ____

Answer 12

PABA. Sulfonamides. (interferes with sulfa drugs)

Same with benoxinate and proparacaine.