Cardiac - Antiarrhythmics

Question 1

MOA of Adenosine

Answer 1

Slows conduction time through the AV node, interrupting the re-entry pathways through the AV node, restoring normal sinus rhythm.

Question 2

Adenosine adult dosage

Answer 2

Peripheral IV: 6 mg, 12 mg, 12 mg
Central line: 3 mg, 6 mg, 6 mg

Question 3

Adenosine indications

Answer 3

Conversion and termination of supraventricular tachycardias

Question 4

Adenosine pharmacokinetics

Answer 4

Onset: Rapid
Duration: Brief
Half life: <10 seconds

Question 5

Adenosine contraindications

Answer 5

Hypersensitivity
2nd or 3rd degree AV node block
Sick sinus syndrome without artificial pacemaker

Question 6

Adenosine - how supplied

Answer 6

6 mg/2 ml ampoule

Question 7

Atropine MOA

Answer 7

competitively antagonizes acetylcholine at muscarinic receptors, producing parasympatholytic and vagolytic effects

Question 8

Atropine dosage

Answer 8

Bradycardia: 0.6 mg, repeat up to ~3 mg (Handbook)
1 mg, repeat up to 3 mg (UpToDate)
Organophosphate toxicity: 1-2 mg IM/IV, repeat till symptoms resolve

Question 9

Atropine pharmacokinetics

Answer 9

Onset: <2 mins
Peak: 3 mins
Duration: 2-6 hours

Question 10

Atropine contraindications

Answer 10

Tachycardia, narrow angle glaucoma, thyrotoxicosis, prostatic hypertrophy, myasthenia gravis

Question 11

Atropine - how supplied

Answer 11

Preload 1 mg/10 mL

Question 12

Labetalol MOA

Answer 12

competitively blocks adrenergic stimulation of beta1 receptors within the myocardium and beta2 receptors within bronchial and vascular smooth muscle and alpha1 receptors within vascular smooth muscle.

Question 13

Labetalol adult bolus dosage

Answer 13

Start at 20 - 80 mg slow IV push
Additional doses can be given (20-80 mg) at 10 min intervals until desired supine B/P is achieved or total cumulative dose of 300 mg.
Goal is to reduce mean arterial B/P by no more than 25% in first hour, then aim for 160/100-110 mmHg.

Question 14

Labetalol infusion dosing

Answer 14

0.5-2 mg/min. Adjust based on B/P response.
Max cumulative dose of 300 mg.

Question 15

Labetalol pharmacokinetics

Answer 15

Onset (IV): within 5 mins
Peak (IV): 5-15 mins
Duration (IV): 16-18 hours

Question 16

Labetalol infusion prep

Answer 16

Pump preset: 200 mg in 250 mL fluid = 0.8 mg/ml
VCH/Providence/BCCH: 200 mg in 100 mL = 2 mg/mL

Question 17

Labetalol contraindications

Answer 17

Bronchospastic airway disease
Obvious CHF
2nd or 3rd degree AV block
Cardiogenic shock
Severe bradycardia

Question 18

Lidocaine MOA

Answer 18

Sodium channel blocker. Class 1b. Decreases the membrane’s permeability to sodium, hyperpolarizing the membrane, inhibiting depolarization resulting in blockade of conduction of impulse.

Question 19

Lidocaine adult dosage

Answer 19

1-1.5 mg/kg IV bolus
Repeat at 0.5 -1 mg/kg.
Max dose of 3 mg/kg.

Question 20

Lidocaine pharmacokinetics

Answer 20

Onset: 45-90 seconds
Peak: 5-10 mins
Duration: 10-20 mins

Question 21

Lidocaine infusion prep

Answer 21

Pump preset: Dilute 1g in 250 mL fluid = 4 mg/mL
Premixed solutions available are 1 g in 250 mL D5W or 2g in 500mL D5W = 4 mg/ml

Question 22

Lidocaine contraindications

Answer 22

Wolff-Parkinson-White
3rd degree AV block
Ventricular escape rhythm

Question 23

Labetalol - how supplied

Answer 23

100 mg/5 ml vial

Question 24

Lidocaine - how supplied

Answer 24

Preload: 100 mg/5 mL