Anesthesia Adjuncts (Exam 4)

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 blocker 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 = 0.15 hours (9 minutes)

Question 19

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

Answer 19

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

Question 20

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

Answer 20

• Opioids
• Amide LA’s

Question 21

What drug is the most selective β1 antagonist?

Answer 21

Atenolol

Question 22

What are the three benefits of Atenolol?

Answer 22

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

Question 23

What is the dose for Atenolol?

Answer 23

5mg q10min IV

Question 24

What is the dose of metoprolol?

Answer 24

1mg q5min until 5mg is given

Question 25

What two formulation of metoprolol are there?

Answer 25

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

Question 26

What β blocker would be used for treat intubation stimuli?

Answer 26

Esmolol

Question 27

What are the onset and offset of esmolol?

Answer 27

Onset: 5 min Offset: 10-30min

Question 28

What is the dose for esmolol?

Answer 28

20-30mg IV

Question 29

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

Answer 29

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

Question 30

Are the effects of CCBs and β-blockers additive?

Answer 30

No, synergistic

Question 31

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

Answer 31

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

Question 32

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

Answer 32

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

Question 33

What 2ⁿᵈ messengers are potentiated by α1 agonism?

Answer 33

IP₃ → Ca⁺⁺ release from SR

Question 34

What occurs with α2 agonism?

Answer 34

↓ release of NE in the brainstem

Question 35

Is phenylephrine primarily a venoconstrictor or an arterioconstrictor?

Answer 35

Venous constriction > arterial constriction

Question 36

Phenylephrine clinically mimics norepinephrine but is....

Answer 36

less potent and longer lasting

Question 37

What is the normal dosing of phenylephrine?

Answer 37

100mcg/mL

Question 38

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

Answer 38

- Reflex bradycardia - Stopping the drug

Question 39

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

Answer 39

7:1

Question 40

Is Labetalol a selective β antagonist?

Answer 40

No: non-selective β and selective α1 antagonist

Question 41

What is the dose for labetalol?

Answer 41

2.5 - 5mg IV; 10mg max

Question 42

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

Answer 42

Esmolol *Labetolol could drop the dBP too much*.

Question 43

Which drug is an indirect acting sympathomimetic?

Answer 43

Ephedrine *Releases NE*

Question 44

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

Answer 44

- 2-8mcg IVpush - 1-5 min

Question 45

What is the infusion dose of epinephrine for β2 effects?

Answer 45

1-2 mcg/min

Question 46

What is the infusion dose of epinephrine for β1 effects?

Answer 46

4 mcg/min

Question 47

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

Answer 47

10-20 mcg/min

Question 48

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

Answer 48

Epinephrine

Question 49

What catecholamine will have the greatest effect on SVR?

Answer 49

Phenylephrine

Question 50

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

Answer 50

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

Question 51

Why does tachyphylaxis occur with ephedrine?

Answer 51

Ephedrine depletes NE stores

Question 52

What is the preferred sympathomimetic for parturient patients? Why?

Answer 52

Ephedrine (It doesn't effect uterine blood flow)

Question 53

How does phenylephrine compare to ephedrine in parturient patients?

Answer 53

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

Question 54

What is the mechanism of action of vasopressin?

Answer 54

Stimulation of vascular V1 receptors → arterial vasoconstriction

Question 55

What drug would be utilized for catecholamine-resistant hypotension?

Answer 55

Vasopressin

Question 56

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

Answer 56

Vasopressin *Can occur with both ACEi and ARBs*.

Question 57

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

Answer 57

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

Question 58

How can vasodilators alleviated pulmonary congestion?

Answer 58

By decreasing venous return via venodilation

Question 59

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

Answer 59

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

Question 60

What does nitroprusside vasodilate?

Answer 60

Arterial **and** venous vasculature

Question 61

What vasodilator absolutely requires arterial line monitoring?

Answer 61

Nitroprusside.

Question 62

What is the dose of Nitroprusside?

Answer 62

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

Question 63

When is nitroprusside used?

Answer 63

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

Question 64

What drug is used to treat cyanide toxicity?

Answer 64

Methylene blue

Question 65

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

Answer 65

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

Question 66

Where does nitroglycerin work?

Answer 66

- Coronary arteries - Venous capacitance vessels

Question 67

Would nitroglycerin increase or decrease preload?

Answer 67

↓ preload

Question 68

Does nitroprusside or nitroglycerin exhibit tachyphylaxis?

Answer 68

Nitroglycerin

Question 69

What is the nitroglycerin dose?

Answer 69

5 - 10 mcg/min

Question 70

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

Answer 70

- Glucagon - Nitroglycerin

Question 71

What are the indications for nitroglycerin?

Answer 71

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

Question 72

How does hydralazine work?

Answer 72

↓ Ca⁺⁺ release and systemic arterial vasodilation

Question 73

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

Answer 73

- Peak: 1 hour - ½-life: 3-7 hours

Question 74

What is the initial dose of hydralazine?

Answer 74

2.5mg

Question 75

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

Answer 75

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

Question 76

How do CCBs generally work?

Answer 76

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

Question 77

CCBs will ______ blood pressure and ________ coronary blood flow.

Answer 77

decrease; increase

Question 78

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

Answer 78

Nicardipine

Question 79

What is the dose of nicardipine?

Answer 79

5mg/hr (2.5mg titration per hour) up to 15mg/hr (MAX)