Anesthesia Adjuncts (Exam IV) Flashcards
β agonism results in activation of _____ which then produces _______.
Adenylyl Cyclase (AC)
cAMP
S2
Does Ca⁺⁺ influx or efflux during β agonism?
Influx
S2
What type of receptors are β receptors?
GPCR
S2
What types of β receptors are there and where are they primarily located?
- β1 - Heart
- β2 - Lungs
- β3 - Fat/Muscle
S3
What type of affinity are Beta-blockers and what happens at high doses?
Selective affinity
Selectivity is lost at high doses of Beta Blockers
S4
Chronic administration of β blockers results in what effect on receptors?
Receptor upregulation (aka ↑ # of receptors)
After β receptor desensitization from prolonged catecholamine exposure, what drug class can restore receptor responsiveness?
β-blockers
How do β blockers protect myocytes from perioperative ischemia?
By ↓O₂ demand on the heart
What do some Beta blockers do to arterial vascular tone and afterload?
reduce arterial vascular tone and decrease afterload
S5
T/F. β blockers will potentiate renin release.
false. β blockers will inhibit renin release
decreases C.O.
How will β blockers affect the cardiac foci action potential?
Prolong Phase 4
↓ dysrhythmias during ischemia and reperfusion.
How will β blockers affect diastolic perfusion time?
β blockers will increase diastolic perfusion time.
What type of HTN is a possible indication for β blocker therapy?
Essential Hypertension
Sy
What is SCIP?
Describe the protocol and its goals.
- 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.
S7
What were the three β1 selective agents discussed in lecture?
- Metoprolol
- Atenolol
- Esmolol
not cause vasodilation
S9
What percentage of β receptors in the myocardium are β1 ?
75%
S9
Do cardio-selective β-blockers cause vasodilation?
No
S9
What non-selective β-blocker has active metabolites and is generally shitty for anesthesia?
Propanolol
S10
Differentiate the clearance mechanisms of metoprolol and esmolol.
- Metoprolol = Hepatic
- Esmolol = Plasma cholinesterases
S10
Differentiate the E½ of metoprolol and esmolol.
Metoprolol E½ = 3-4 hours
Esmolol E½ = 9 minutes
S10
When propanolol is given, what effect lasts longer, negative inotropy or negative chronotropy?
Negative chronotropy (bradycardia) lasts longer
S11
What is a possible reason why the heart rate slowing effects of propanolol last longer than the negative inotropic effects?
Possible β1 sub-receptor types (ex. β1A, β1B, etc.)
S11
Propanolol will decrease the clearance of which two important anesthetic drug classes?
- Opioids
- Amide LA’s
d/t lower C.O. /HR
S11
What drug is the most selective β1 antagonist?
Atenolol
What are the three benefits of Atenolol?
- Good for non-cardiac sx CAD patients (↓ complications for 2 years)
- No insulin-induced hypoglycemia
- Does not cross the BBB (no fatigue)
What is the dose for Atenolol?
5mg q10min IV
What is the dose of metoprolol?
1mg q5min
(Given in 5mg “blocks”)
What two PO formulations of metoprolol are there?
- Metoprolol Tartate = multiple doses per day
- Metoprolol Succinate = One dose per day
S13
What β blocker would be used for treat intubation stimuli?
Esmolol
S14
What are the onset and offset of esmolol?
Onset: 5 min
Offset: 10-30min
S14
What is the initial dose for esmolol?
20-30mg IV
S14
Caution should be taken when giving esmolol with which two conditions?
Why?
- Cocaine and/or epinephrine
- Can cause pulmonary edema and cardiac collapse
S14
Are the effects of CCBs and β-blockers additive?
No, synergistic
S14