Anesthesia Adjuncts (Exam IV)

Question 1

β agonism results in activation of _____ which then produces _______.

Answer 1

Adenylyl Cyclase (AC)

cAMP

Question 2

Does Ca⁺⁺ influx or efflux during β agonism?

Answer 2

Influx

Question 3

What type of receptors are β receptors?

Answer 3

GPCR

Question 4

What types of β receptors are there and where are they primarily located?

Answer 4

• β1 - Heart
• β2 - Lungs
• β3 - Fat/Muscle

Question 5

Chronic administration of β blockers results in what effect on receptors?

Answer 5

Receptor upregulation (aka ↑ # of receptors)

Question 6

After β receptor desensitization from prolonged catecholamine exposure, what drug class can restore receptor responsiveness?

Answer 6

β-blockers

Question 7

How do β blockers protect myocytes from perioperative ischemia?

Answer 7

By ↓O₂ demand on the heart

Question 8

T/F. β blockers will potentiate renin release.

Answer 8

false. β blockers will inhibit renin release

Question 9

How will β blockers affect the cardiac foci action potential?

Answer 9

Prolong Phase 4

↓ dysrhythmias during ischemia and reperfusion.

Question 10

How will β blockers affect diastolic perfusion time?

Answer 10

β blockers will increase diastolic perfusion time.

Question 11

What type of HTN is a possible indication for β blocker therapy?

Answer 11

Essential Hypertension

Question 12

What is SCIP?
Describe the protocol and its goals.

Answer 12

• Surgical Care Improvement Protocol
• β-blockers must be given within 24 hrs of surgery for patients at risk for cardiac ischemia and ones already on β-blocker therapy.

Question 13

What were the three β1 selective agents discussed in lecture?

Answer 13

• Atenolol
• Metoprolol
• Esmolol

Question 14

What percentage of β receptors in the myocardium are β1 ?

Answer 14

75%

Question 15

Do cardio-selective β-blockers cause vasodilation?

Answer 15

No

Question 16

What non-selective β-blocker has active metabolites and is generally shitty for anesthesia?

Answer 16

Propanolol

Question 17

Differentiate the clearance mechanisms of metoprolol and esmolol.

Answer 17

• Metoprolol = Hepatic
• Esmolol = Plasma cholinesterases

Question 18

Differentiate the E½ of metoprolol and esmolol.

Answer 18

Metoprolol E½ = 3-4 hours
Esmolol E½ = 9 minutes

Question 19

When propanolol is given, what effect lasts longer, negative inotropy or negative chronotropy?

Answer 19

Negative chronotropy (bradycardia) lasts longer

Question 20

What is a possible reason why the heart rate slowing effects of propanolol last longer than the negative inotropic effects?

Answer 20

Possible β1 sub-receptor types (ex. β1_A, β1_B, etc.)

Question 21

Propanolol will decrease the clearance of which two important anesthetic drug classes?

Answer 21

• Opioids
• Amide LA’s

Question 22

What drug is the most selective β1 antagonist?

Answer 22

Atenolol

Question 23

What are the three benefits of Atenolol?

Answer 23

• Good for non-cardiac sx CAD patients (↓ complications for 2 years)
• No insulin-induced hypoglycemia
• Does not cross the BBB (no fatigue)

Question 24

What is the dose for Atenolol?

Answer 24

5mg q10min IV

Question 25

What is the dose of metoprolol?

Answer 25

1mg q5min (Given in 5mg "blocks")

Question 26

What two formulations of metoprolol are there?

Answer 26

- Metoprolol Tartate = multiple doses per day - Metoprolol Succinate = One dose per day

Question 27

What β blocker would be used for treat intubation stimuli?

Answer 27

Esmolol

Question 28

What are the onset and offset of esmolol?

Answer 28

Onset: 5 min Offset: 10-30min

Question 29

What is the initial dose for esmolol?

Answer 29

20-30mg IV

Question 30

Caution should be taken when giving esmolol with which two conditions? Why?

Answer 30

- Cocaine and/or epinephrine - Can cause pulmonary edema and cardiac collapse

Question 31

Are the effects of CCBs and β-blockers additive?

Answer 31

No, synergistic

Question 32

What two scenarios were given in class for a β1 indication over a non-selective β blocker?

Answer 32

- DM: β2 can cause hypoglycemia by insulin potentiation - Airway: blocking β2 potentiates bronchospasm

Question 33

What volatile anesthetic will cause the greatest additive depression when combined with a β blocker? The least? Why does this not matter?

Answer 33

- Enflurane = greatest additive depression - Isoflurane = least additive depression - Not significant between 1-2 MAC

Question 34

What 2ⁿᵈ messengers are potentiated by α1 agonism?

Answer 34

IP₃ → Ca⁺⁺ release from SR

Question 35

What occurs with α2 agonism?

Answer 35

↓ release of NE in the brainstem

Question 36

Is phenylephrine primarily a venoconstrictor or an arterioconstrictor?

Answer 36

Venous constriction > arterial constriction

Question 37

Phenylephrine clinically mimics norepinephrine but is....

Answer 37

less potent and longer lasting

Question 38

What is the normal dosing of phenylephrine?

Answer 38

100mcg/mL IV push

Question 39

What adverse effect results from phenylephrine? How is it resolved?

Answer 39

- Reflex bradycardia - Stopping the drug

Question 40

What is the ratio of β to α blockade for Labetalol?

Answer 40

7:1

Question 41

Is Labetalol a selective β antagonist?

Answer 41

No: non-selective β and selective α1 antagonist

Question 42

Which of the following receptors does Labetalol antagonize? A. α1 B. α2 C. β1 D. β2

Answer 42

A, C, and D

Question 43

What is the dose for labetalol?

Answer 43

2.5 - 5mg IV; 10mg max

Question 44

Which of the following drugs would you utilize for a post-carotid endarterectomy with a BP of 214/62 ? Labetalol Esmolol

Answer 44

Esmolol *Labetolol could drop the dBP too much*.

Question 45

Which drug is an indirect acting sympathomimetic?

Answer 45

Ephedrine *Releases NE*

Question 46

What is the IV push dose of epinephrine? How long does it last?

Answer 46

- 2-8mcg IVpush - 1-5 min

Question 47

What is the infusion dose of epinephrine for β2 effects?

Answer 47

1-2 mcg/min

Question 48

What is the infusion dose of epinephrine for β1 effects?

Answer 48

4 mcg/min

Question 49

What is the infusion dose of epinephrine for predominantly α effects?

Answer 49

10-20 mcg/min

Question 50

What catecholamine will have the greatest effect on heart rate and cardiac output?

Answer 50

Epinephrine

Question 51

What catecholamine will have the greatest effect on SVR?

Answer 51

Phenylephrine

Question 52

Which SNS agonist can be given IM? Why would this be done?

Answer 52

- Ephedrine IM 50mg - Long lasting increase in BP for OB patients.

Question 53

Why does tachyphylaxis occur with ephedrine?

Answer 53

Ephedrine depletes NE stores

Question 54

What is the preferred sympathomimetic for parturient patients? Why?

Answer 54

Ephedrine (It doesn't effect uterine blood flow)

Question 55

How does phenylephrine compare to ephedrine in parturient patients?

Answer 55

Phenylephrine has similar effects but has the additional benefit of a higher umbilical pH in neonates.

Question 56

What is the mechanism of action of vasopressin?

Answer 56

Stimulation of vascular V1 receptors → arterial vasoconstriction

Question 57

What drug would be utilized for catecholamine-resistant hypotension?

Answer 57

Vasopressin

Question 58

What drug would be used for ACE-Inhibitor induced resistant hypotension?

Answer 58

Vasopressin *Resistant hypotension can occur with both ACEi and ARBs*.

Question 59

How does Nitric Oxide cause vasodilation? *In broad terms*.

Answer 59

NO → GC → cGMP → Ca⁺⁺ inhibition and increased uptake.

Question 60

How can vasodilators alleviate pulmonary congestion?

Answer 60

By decreasing venous return via venodilation

Question 61

What does Nitroprusside dissociate on contact with? What is the result?

Answer 61

Dissociates on contact with oxyhemoglobin → methemoglobin, NO, and cyanide released.

Question 62

What does nitroprusside vasodilate?

Answer 62

Arterial **and** venous vasculature

Question 63

What vasodilator absolutely requires arterial line monitoring?

Answer 63

Nitroprusside.

Question 64

What is the dose of Nitroprusside?

Answer 64

**0.3** - 2 mcg/kg/min

Question 65

When is nitroprusside used?

Answer 65

- Hypotensive necessary surgeries (aortic, spine, etc.) - Hypertensive emergencies (post CEA's)

Question 66

What drug is used to treat cyanide toxicity?

Answer 66

Methylene blue

Question 67

What signs would tip you off to possible cyanide toxicity secondary to nitroprusside administration?

Answer 67

- ↑ need for nitroprusside - ↑ SvO₂ - Metabolic acidosis - LOC changes

Question 68

Where does nitroglycerin work?

Answer 68

- Coronary arteries - Venous capacitance vessels

Question 69

Would nitroglycerin increase or decrease preload?

Answer 69

↓ preload

Question 70

Does nitroprusside or nitroglycerin exhibit tachyphylaxis?

Answer 70

Nitroglycerin

Question 71

What is the nitroglycerin dose?

Answer 71

5 - 10 mcg/min

Question 72

What is the firstline treatment for sphincter of Oddi spasm? What is second?

Answer 72

- Glucagon - Nitroglycerin

Question 73

What are the indications for nitroglycerin?

Answer 73

- Acute MI - Controlled Hypotension - Sphincter of Oddi spasm - Retained placenta

Question 74

How does hydralazine work?

Answer 74

↓ Ca⁺⁺ release and systemic arterial vasodilation

Question 75

When does hydralazine peak? What is it's half-life?

Answer 75

- Peak: 1 hour - ½-life: 3-7 hours

Question 76

What is the initial dose of hydralazine?

Answer 76

2.5mg

Question 77

What are the three categories of CCBs? Where do each interact?

Answer 77

- AV Node (**Phenylalkylamines & Benzothiazepines**) - Vasculature (**Dihydropyridines**)

Question 78

How do CCBs generally work?

Answer 78

Bind and block VG-Ca⁺⁺ channels thus ↓ Ca⁺⁺ influx.

Question 79

CCBs will ______ blood pressure and ________ coronary blood flow.

Answer 79

decrease; increase

Question 80

Which CCB has the greatest coronary artery dilation and least myocardial depression?

Answer 80

Nicardipine

Question 81

What is the dose of nicardipine?

Answer 81

5mg/hr (2.5mg titration)