Anesthesia

Question 1

Barbiturates, MOA, Uses, SE, OD treatment, CI

Answer 1

Pheno-, pento-, secobarbital; thiopental
Increase DURATION of Cl- channel opening -> Increased GABA action
Sedatives for anxiety, seizures, insomnia, anesthesia induction (thiopental)
SE: Resp + CV depression, CNS depression exacerbated by EtOH, Dependence, P450 inducer
Supportive treatment for OD
CI: Porphyria

Question 2

Benzodiazepines, MOA, Uses, SE, OD treatment, CI

Answer 2

Diazepam (Valium), midazolam (Versed), -zepams, -zolams
Increase FREQUENCY of Cl- channel opening -> Increased GABA action
Anxiety, spasticity, status epilepticus (lorazepam, diazepam), DT detox, night terrors, sleepwalking, general anesthesia (amnesia, muscle relaxation), insomnia
SE: Dependence (short-actings: midazolam, oxazepam, triazolam), CNS depression exacerbated by EtOH. Less risk of OD than barbiturates.
Treat OD w/ flumazenil (competitive GABA antagonist at BZD receptor)

Question 3

Non-BZD hypnotics, MOA, use, SE

Answer 3

Zolpidem, Zaleplon, Eszopiclone (ZZZs)
Same mechanism as BZDs, effects reversed by flumazenil
Insomnia
SE: Ataxia, headaches, confusion
Short duration from rapid liver metabolism. Lower dependence risk than BZDs

Question 4

To act in the CNS, drugs must be…

Answer 4

Lipophilic or transported across BBB

Question 5

Low drug solubility in blood causes?

Answer 5

Rapid induction and recovery

Question 6

High drug solubility in lipid causes?

Answer 6

Increased potency (1/MAC)

Question 7

MAC

Answer 7

Minimal Alveolar Concentration of inhaled anesthetic to prevent half of subjects from moving in response to noxious stimuli.

Question 8

Inhaled anesthetics, MOA, effects, severe SE

Answer 8

Halothane, -fluranes (Desflurane, Sevoflurane), NO2
Unknown mechanism
Cause CV + Resp depression, nausea/emesis, increased cerebral blood flow/decreased cerebral metabolic demand
SE: Halothane = hepatotoxicity, Methoxyflurane = nephrotoxicity, Enflurane = convulsions, NO2 = gas expansion in body cavity. All + SCh except NO2 = Malignant hyperthermia (high fever, MSK contractions, treat w/ dantrolene)

Question 9

IV anesthesics

Answer 9

Barbiturate (thiopental), BZDs (midazolam), Ketamine, Opioids, Propofol

Question 10

What induces anesthesia?

Answer 10

Sedative (Propofol) + Narcotic

Question 11

Thiopental for anesthesia, use, distribution, effects

Answer 11

High lipid solubility = high potency
For induction, short surgical procedures
Rapidly redistributes into muscle & fat to terminate effects (not metabolized to stop effects)
Decreases cerebral blood flow

Question 12

BZDs (midazolam) for anesthesia, use, SE

Answer 12

Used adjunctively w/ gaseous anesthetics and narcotics

SE: Severe post-op CV/Resp depression (treat OD w/ flumenazil), anterograde amnesia

Question 13

Ketamine for anesthesia, mechanism, SE

Answer 13

PCP analog = dissociative anesthetic
Blocks NMDARs
CV stimulant, Increase cerebral blood flow
SE: Disorientation, hallucination, bad dreams

Question 14

Opioids for anesthesia

Answer 14

Morphine, fentanyl used w/ other CNS depressants during general anesthesia

Question 15

Propofol use, mechanism, SE

Answer 15

For sedation, rapid anesthesia induction, short procedures
Potentiates GABAa
Less post-op nausea than thiopental

Question 16

Local anesthetics, MOA, admin, considerations, uses, SE

Answer 16

Procaine, cocaine, tetracaine (esters); Lidocaine, mepivacaine, bupicvacaine (amides, 2 I’s in names)
Block Na+ channels from cytoplasmic side (penetrate membrane uncharged, form ion in cytosol to stay in neuron and bind channel)
Preferentially bind activated Na+ channels = best in rapidly firing neurons
Give w/ vasoconstrictors (epi) to enhance local action - less bleeding, systemic escape, and SE + more anesthesia. Don’t give epi for ears, fingers, nose, penis, toes
In infected tissue (more H+), alkaline anesthetics are charged before penetrating membrane = need more
For minor procedures, spinal anesthesia
Give amides if allergic to esters
SE: CNS excitation, CV toxicity (bupivacaine), hypertension, hypotension, arrhythmias (cocaine)

Question 17

Order of nerve blockade

Answer 17

Small diameter -> Large; Myelinated -> Unmyelinated
Overall size predominates over myelination:
Small myelinated -> Small unmyelinated -> Large myelinated -> Large unmyelinated
Order of loss: Pain -> Temp -> Touch -> Pressure

Question 18

Depolarizing neuromuscular blockers, target, MOA, phases, antidotes, SE

Answer 18

Both non-/depolarizers are for paralysis in surgery/mechanical ventilation, selective for motor nicotinic receptor (not autonomic)
Succinylcholine: Strong AChR agonist -> Sustained depolarization -> Prevent muscle contraction
Phase I (prolonged depolarization) - no antidote, potentiated by AChE inhibitors
Phase II (repolarized but blocked) - AChRs available, but desensitized; Antidote is AChE inhibitors
SE: High Ca++, K+, Malignant hyperthermia
CI: Peds due to risk of undiagnosed DMD

Question 19

Nondepolarizing neuromuscular blockers, mechanism, antidotes

Answer 19

Curare derivatives (e.g. -curium, -curonium [steroids])
Competitive AChR antagonists
Reversal of blockade w/ AChE inhibitors (Neostigmine - Must give w/ atropine to prevent muscarinic effects such as bradycardia; edrophonium; etc.)

Question 20

Dantrolene use, MOA

Answer 20

Prevents Ca++ release from SR of skeletal muscle

For malignant hyperthermia and neuroleptic malignant syndrome (tox of antipsychotics)

Question 21

Components of anesthesia

Answer 21

Analgesia (pain relief), amnesia (memory loss), immobilization
Accomplished by narcotic + propofol + muscle relaxant

Question 22

Induction agents + CV effects, CIs

Answer 22

Propofol - decrease SVR, BP, HR. CI in hypotension (sepsis, shock, bleeding, severe CHF)
Etomidate - slight BP decrease, no HR change. Good in adrenal suppression, hypotension, severe CHF. CI in CAD
Ketamine - increases BP, HR; sympathomimetic. Good in hypotension.

Question 23

Indications for a-line

Answer 23

Continuous direct beat-to-beat BP measurement
Severe CV disease
Potential need for vasoactive infusions
Frequent blood sampling
Potential hemodynamic instability
Inability to use noninvasive BP (obese, burns)

Question 24

Indications for central line

Answer 24

Surgeon request for post-op
Potential need for vasoactive infusions
Need for multiple ports
Secure IV access unavailable elsewhere
Measure pulmonary artery pressures

Question 25

Pediatric NPO recommendations for anesthesia

Answer 25

Solids - 8h
Milk - 6h
Breast milk - 4h
Clear liquids - 2h

Question 26

Formula for peds ETT size

Answer 26

Age/4 + 4

Question 27

Formula for peds ETT placement

Answer 27

Age/2 + 12 or ETT size * 3

Question 28

Laryngoscope for peds

Answer 28

Miller to lift larger, floppy epiglottis

Size 1 or 1.5

Question 29

Standard MAC values for des-, sevo-, iso-, and NO2

Changes in pregnancy?

Answer 29

Des = 6%
Sevo = 2%
Iso = 1.2%
NO2 = 105%
Decreases in pregnancy due to sedative effects of progesterone and more endogenous opioids

Question 30

Medications that do not cross placenta

Answer 30

Heparin, Insulin, Glycopyrrolate, NDNMBs (curares), SCh

Most everything else will cross

Question 31

O2 content equation

Answer 31

1.39HbO2sat + PaO2*0.003

Question 32

How to manage diabetic anesthesia patients?

Answer 32

Give 1/4-1/2 of usual AM insulin, monitor blood glucose, add dextrose if necessary. Usually glucose increases due to stress response from surgery.
Hold metformin, sulfonylureas due to long half-life and risk of hypoglycemia

Question 33

NDNMB undergoing Hoffman degen?

Answer 33

Cisatracurium

Question 34

Drugs raising intracranial pressure

Answer 34

Ketamine, nitrates, hydralazine, CCBs