m and m 9 - IV anes

Question 1

Barbiturates mechanism of action is ________, and their main location of action is _______

Answer 1

Increase duration of opening of GABA receptors

Reticular activating system

Question 2

Thiopental and Thiamylal both have higher lipid solubility, greater potency and more rapid onset of action than other barbiturates. Whym structurally?

Answer 2

Substitution of oxygen with sulfur on C-2 increases lipid solubility, both thiopental and thiamylal have sulfurs at this position

Question 3

While thiopental and thiamylal have higher lipid solubility, greater potency and more rapid onset, what is a disadvantage of these drugs? (3)

Answer 3

• Very alkaline (pH over 10)
• Unstable (2 week shelf life)
• Painful on injection, assoc with venous thrombosis

Question 4

What is the major reason for termination of effect of barbiturates, redistribution, metabolism or elimination?

Answer 4

Redistribution - mainly to muscle will decrease concentration of central barbiturates to about 10% of peak doses by 20-30 mins

Question 5

What are some factors that can alter pharmacokinetics of barbiturates?

Answer 5

• Low albumin (highly protein bound)
• Hypovolemia (decrease Vd)
• Acidosis

Question 6

Under what situations is the duration of action / half life of barbiturates become context sensitive?

Answer 6

With prolonged administration (i.e. drips or redosing) the peripheral compartments become saturated, making duration of action dependent on elimination

Question 7

Where is the principal site of metabolism of barbiturates? are the metabolites active or inactive?

Answer 7

Liver, water soluble inactive metabolites

Question 8

Why is recovery from methohexital faster than from other barbiturates?

Answer 8

Methohexital has greater hepatic extraction and is therefore cleared more rapidly by the liver

Question 9

What are the effects of barbiturates on cardiovascular system?

Answer 9

Can be unpredictable based on underlying volume status, autonomic tone. Generally, Will cause decreased BP (primary) and reflex tachycardia. Will maintain CO due to tachycardia and reflex increase in contractility

Question 10

What are conditions that make patients prone to wide swings in CV function after barbiturates?

Answer 10

• Hypovolemia
• Poorly controlled hypertension
  Under these conditions, may be unable to maintain CO and would have wide swings in BP/HR. Can prevent with adequate preop hydration

Question 11

Effect of barbiturates on respiratory function?

Answer 11

Will depress medullary ventilatory center, decreasing response to hypoxia and hypercapnia

Question 12

True or false, barbiturates will blunt response to airway Instrumentation, decreasing propensity for bronchospams/laryngospasm.

Answer 12

False, in suceptible patients (asthmatics), barbiturates alone won’t block airway reflexes, therefore can have bronchospasm. Can also have laryngospasm in lightly anesthetized patients

Question 13

What is the effect of barbiturates on cerebral blood flow, cerebral perfusion pressure, intracranial pressure, etc?

Answer 13

Will constrict cerebral vasculature, causing decrease in cerebral blood flow, cerebral blood volume and intracranial pressure. However, cerebral perfusion pressure increases because arterial blood pressure drops LESS than intracranial pressure

Question 14

Although barbiturates decrease cerebral blood flow, why is this usually inconsequential?

Answer 14

It induces an even greater drop in cerebral O2 consumption

Question 15

What are EEG changes seen with barbiturates?

Answer 15

Baseline low voltage fast activity (small doses) to high voltage slow activity with burst suppresion to electrical silence with maximal doses

Question 16

True or false, barbiturates are also analgesic.

Answer 16

False, in some causes may lower pain threshold

Question 17

True or false, barbiturates can cause muscle relaxation

Answer 17

False, can actually cause Involuntary skeletal muscle contraction e.g. methohexital

Question 18

What is a disease state where barbiturates should absolutely be avoided?

Answer 18

Acute intermittent porphyria (can promote aminolevulinic acid synthetase, which increases formation of porphyrin)

Question 19

What class of barbiturates are more likely to cause histamine release? Significance?

Answer 19

Thiobarbiturates (sulfure containing) can cause histamine release, significant for asthmatic or atopic patients

Question 20

True or false, CNS depressants potentiate the effects of barbiturates.

Answer 20

True - alcohol, opioids and antihistamines are examples

Question 21

Benzos vs barbiturates, how does function at GABA receptor differ?

Answer 21

Barbs increase duration of opening, benzos increase frequency of opening

Question 22

What property (structural) of midazolam improves its water solubility (vs other benzos)?

Answer 22

Imidazole ring

Question 23

Benzos, (midaz, loraz and diazepam) are available PO, IM and IV. What is the exception that isn’t FDA approved for PO use?

Answer 23

Midaz is not approved for PO use, despite the use in this route in pediatrics

Question 24

Which of the commom benzos isn’t as well tolerated IM (Pain) with unpredictable absorption?

Answer 24

Diazepam

Question 25

Which of the common Benzos has the slowest onset? Why?

Answer 25

Lorazepam, because it is the least lipid soluble

Question 26

What pharmacokinetic property accounts for awakening after benzo administration?

Answer 26

Redistribution

Question 27

True or false, benzos are highly protein bound?

Answer 27

True, up to 90-98%

Question 28

What is the major organ associated with benzo biotransformation? Excretion?

Answer 28

Metabolism is liver, excretion is urine

Question 29

Which benzo has an active phase 1 metabolite? Which can a second peak in plasma concentrations 6-12 hours post administration and why?

Answer 29

Diazepam and diazepam. Second peak is from enterohepatic circulation

Question 30

Renal failure will cause prolonged sedation in patient who receive which benzo?

Answer 30

Midazolam, due to accumulation of alpha-hydroxymidazolam

Question 31

Benzos do not depress cardiac function except when _____

Answer 31

Coadministered with opioids

Question 32

What is the effect of benzos on respiration?

Answer 32

Will cause respiratory depression, ESPECIALLY if administered IV

Question 33

What is the effect of benzos on cerebral oxygen consumption, cerebral blood flow and intracranial pressures?

Answer 33

Decreases all these parameters, but not to the extent of barbiturates

Question 34

True or false, benzos cause muscle relaxation mediated at the neuromuscular junction?

Answer 34

False, the muscle relaxation is mediated at the spinal cord level

Question 35

True or false, induction with benzos is as fast as seen with thiopental and propofol

Answer 35

False, it is significantly slower, with a slower recovery

Question 36

What are three drugs that are known to interact with benzos?

Answer 36

Cimetidine - decreases metabolism of diazepam (decreases activity of CYP-450) Erythromycin - blocks metabolism of midazolam, increasing it duration of action Heparin - increases free drug concentrations by displacing diazepam from free drug binding sites

Question 37

What is the mechanism by which ketamine works, beyond NMDA antagonism?

Answer 37

Dissociative anesthetic, dissociates thalamus from limbic system

Question 38

What drug of abuse is ketamine structurally similar to? How do potencies compare?

Answer 38

Phencyclidine, Ketamine is 10% as potent

Question 39

What are specific clinical situations where ketamine is useful?

Answer 39

Trauma, hypovolemia - produces sympathetic stimulation

Question 40

What is the induction agent that can be used IM for children and uncooperative adults?

Answer 40

Ketamine

Question 41

What is a way to decrease the hallucinogenic effects of ketamine?

Answer 41

Co-admin with a benzo (e.g. Midazolam) or propofol

Question 42

Awakening from ketamine is from [redistribution / metabolism]?

Answer 42

Redistribution

Question 43

Ketamine has multiple metabolites that are chemically active. Which is chemically active? Where is it mainly metabolized?

Answer 43

Active metabolite is norketamine, metabolized in the liver

Question 44

Major route of ketamine metabolite excretion is the ____

Answer 44

Kidney

Question 45

Ketamine [increases/decreases] HR, CO and BP. These effects are mediated by [central/peripheral] effects, main mechanism?

Answer 45

Increases, unique among IV anesthetics Central effects Inhibit re-uptake of NE after release from nerve terminals

Question 46

A group of patients to avoid ketamine bolus (i.e. induction dose) in? A group that it might benefit?

Answer 46

Avoid in patients with CAD - Increase myocardial work | Beneficial in patients with shock

Question 47

Under what conditions does ketamine cause apnea?

Answer 47

If given as a bolus, especially with opioids on board

Question 48

Generally, what is the effect of ketamine on the respiratory system?

Answer 48

It is a bronchodilator

Question 49

What is the effect of ketamine on salivation? How is this mitigated?

Answer 49

Increases salivation, may need to pretreat with glycopyrrolate

Question 50

What is the effect of ketamine on cerebral O2 consumption, blood flow and intracranial pressure?

Answer 50

It increases all these parameters

Question 51

What is the effect of ketamine on the MSK system?

Answer 51

Can cause myoclonic activity, which may not be detected on EEG

Question 52

What drugs can be used to attenuate the cardiostimulatory effects of ketamine?

Answer 52

Diazepam, midazolam

Question 53

What happens if ketamine is co-administered with adrenergic antagonists?

Answer 53

This will unmask the cardio-depressive effects of ketamine, which are usually overwhelmed by its sympathetic stimulation

Question 54

What is the major MSK effect associated with etomidate? What is the mechanism? How can this be attenuated?

Answer 54

30-60 % incidence of myoclonus Mechanism is disinhibition of CNS areas that control extrapyramidal motor activity Attenuate with opioids

Question 55

What is the mechanism for awakening from etomidate (metabolism, redistribution, etc)?

Answer 55

Redistribution

Question 56

Where is etomidate metabolized

Answer 56

Metabolized in the liver by hepatic microsomal enzymes and plasma esterases

Question 57

Effects of etomidate on CV system?

Answer 57

Minimal

Question 58

True Or false, etomidate by itself is enough anesthetic for direct laryngoscopy?

Answer 58

False, will end up with increased HR and BP from this stimulation

Question 59

Effect of etomidate on Respiratory system?

Answer 59

Minimal, even induction doses of etomidate don't result in apnea

Question 60

What is the effect of etomidate on SSEP?

Answer 60

It increases the amplitude of somatosensory evoked potentials

Question 61

Etomidate is associated with [increased/decreased] PONV?

Answer 61

Assoc with increased PONV

Question 62

What is the effect of etomidate on the endocrine system?

Answer 62

Inhibits enzymes assoc with cortisol and aldosterone synthesis. Long term use assoc with increased mortality in septic patients

Question 63

True or false, egg allergy is a contraindication for propofol use?

Answer 63

False. Although propofol has egg lecithin, it is from the egg yolk, while most egg allergies are to egg white (albumin).

Question 64

What way is propofol associated with sepsis?

Answer 64

The formulation can cause growth of microorganisms. Needs to be used within 6 hours of opening the container

Question 65

How should propofol dosing be altered in the elderly? Why?

Answer 65

Decrease dose in the elderly, because of decreased Vd (less muscle mass)

Question 66

What is propofol infusion syndrome?

Answer 66

Long Term use in critically Ill children or young NSG patients causes lipemia, metabolic acidosis and death

Question 67

Effect of propofol on CV system?

Answer 67

Decrease BP, SVR, preload and cardiac contractility

Question 68

Effects of propofol on the baroreflex?

Answer 68

Blunts this reflex, leading to more hypotension

Question 69

In what group of patients is the CV depressant effects of propofol most marked? (3)

Answer 69

- Extremes of age - Beta blockers use - Impaired ventricular function

Question 70

Effects of propofol on respiratory system?

Answer 70

blocks response to hypoxia and hypercarbia

Question 71

True or false - propofol can cause release of histamine, causing wheezing in asthmatic patients

Answer 71

True, however, incidence of wheezing is less with propofol compared to etomidate and barbiturates

Question 72

Effect of propofol in cerebral blood flow and intracranial pressure?

Answer 72

Decreases both

Question 73

Significance of propofol use on cerebral perfusion pressure?

Answer 73

Can cause significant decrease in CPP, because it also decreases arterial pressure, therefore may need to support arterial pressure to maintain adequate CPP

Question 74

Effect of propofol on PONV?

Answer 74

Decreases PONV

Question 75

True or false, propofol is contraindicated in epileptic patients?

Answer 75

False, propofol has actually been used to treat seizures

Question 76

Midazolam [increases/decreases] amount of propofol needed for anesthetic purposes

Answer 76

Decreases