Bradycardia

 Atropine  Dopamine infusion  Epinephrine infusion

Atropine



Mechanism of Action

Inhibits the actions of acetycholine on structures innervated by postganglionic sites (smooth/cardiac muscle, SA/AV nodes)

Atropine

 

Indications

    First drug for symptomatic sinus bradycardia May be beneficial in AV block or asystole Second drug in asystole or slow PEA Organophosphate poisoning; large dose may be needed

Precautions

    MI and hypoxia – atropine increases oxygen demand Avoid in hypothermia Not effective for 2 nd the rhythm) type II or new 3 rd degree block (may slow Doses < 0.5 mg may cause a paradoxical slowing

Atropine

Don’t delay pacing for severely symptomatic (unstable) patients.

   

Asystole or slow (<60)PEA

  1 mg IV/IO push Repeat every 3 to 5 minutes (if rhythm persists) to max. of 3 mg.

Bradycardia

  0.5 mg IV every 3-5 minutes as needed; max. of 3 mg.

Use shorter dosing interval and higher doses in severe clinical situations

Endotracheal Administration

 2-3 mg diluted in 10 mL water or NS

Organophosphate Poisoning

 Large doses (2-4 mg or higher) may be necessary

Dopamine



Mechanism of Action

Stimulates adrenergic receptors; dose dependent.

Dopamine

  

Indications

  Second-line drug for symptomatic bradycardia Hypotension with signs and symptoms of shock

Precautions

    Correct hypovolemia with volume before initializing Use caution with cardiogenic shock and associated CHF May cause tachydysrhythmias; excessive vasoconstriction Don’t mix with sodium bicarbonate

IV Administration

  Infusion at 5-20 mcg/kg/min.

Titrate to patient response; taper slowly

Epinephrine

 Mechanism of Action Stimulates adrenergic receptors and is not dose dependent like dopamine.

Epinephrine



Indications

    Cardiac arrest  VF; VT; asystole; PEA Symptomatic bradycardia  After atropine; alternative to dopamine Severe hypotension  When atropine and pacing fail; hypotension accompanying bradycardia; phosphodiesterase enzyme inhibitors Anaphylaxis; severe allergic reactions  Combine with large fluid volume; corticosteroids; antihistamines

Epinephrine

 

Precautions

   May increase myocardial ischemia, angina, and oxygen demand High doses do not improve survival; may be detrimental Higher doses may be needed for poison/drug induced shock

Dosing

     Cardiac arrest 1 mg (1:10,000) IV/IO every 3-5 min.

High dose up to 0.2 mg/kg for specific drug OD’s Infusion of 2-10 mcg/min.

Endotracheal of 2-2.5 times normal dose SQ/IM 0.3-0.5 mg

Tachycardia

 Adenosine  Diltiazem  Metoprolol  Amiodarone  Lidocaine  Magnesium Sulfate

Adenosine



Mechanism of Action

Slows impulse formation in the SA node; slows conduction time through AV node; depresses left ventricular function and restores NSR.

Adenosine

 Indications  1 st drug for stable, narrow complex, regular SVT  May consider for unstable SVT while preparing for cardioversion  Wide-complex tachycardia thought to be, or determined to be reentry SVT  Does not convert atrial fibrillation, atrial flutter, or VT  Diagnostic maneuver; stable narrow-complex SVT

Adenosine

 Contraindications/Precautions  Poison/drug induced tachycardia is contraindicated  2 nd and 3 rd degree block is contraindicated  Transient side effects; flushing, CP, asystole, brady, ectopy  Less effective with theophylline or caffeine  If used for VT may cause worsening of clinical condition  Transient periods of sinus brady or ventricular ectopy common after termination of SVT  Safe in pregnancy

Adenosine

 Place supine or mild reverse Trendelenburg  6 mg rapidly followed by 20 mL flush  May repeat at 12 mg every 1-2 minutes if unsuccessful

Diltiazem



Mechanism of Action

Inhibits calcium movement across cell membranes of cardiac and smooth muscle. Causes vasodilation, decreses heart rate and contractility, slows SA and AV conduction.

Diltiazem



Indications

 Controlling ventricular rate in a-fib or flutter  After adenosine to treat refractory reentry SVT if adequate blood pressure 

Contraindications/Precautions

  Do not use with wide-complex rhythms Do not use with poison/drug induced tachycardia   Avoid in WPW Avoid in AV nodal blocks  Blood pressure may drop from peripheral vasodilation

Diltiazem



Rate control

 15-20 mg (0.25 mg/kg) IV over 2 minutes  After 15 min. another 20-25 mg (0.35 mg/kg) IV over 2 minutes, if needed 

Maintenance Infusion

 5-15 mg/hour; titrated to physiologically appropriate heart rate

Metoprolol



Mechanism of Action

Selectively blocks beta-1 receptors, slowing sinus heart rate, decreasing cardiac output, and decreasing BP.

Metoprolol



Indications

 Administer to all patients with suspected MI or unstable angina, absent contraindications  Second-line agent for SVT refractory to adenosine  To reduce myocardial ischemia in MI patients with elevated heart rate and/or blood pressure  Emergency antihypertensive therapy for acute hemorrhagic or ischemic stroke

Metoprolol

 Contraindications/Precautions   Hemodynamically unstable patients should not receive   Signs of heart failure Low cardiac output  Increased risk for cardiogenic shock Relative contraindications: 1 st , 2 nd , 3 rd degree blocks; active asthma; reactive airway disease; severe bradycardia; hypotension < 100 mmHg   Concurrent administration of calcium channel blockers can cause serious hypotension Monitor cardiac and pulmonary status throughout

Amiodarone



Mechanism of Action

Prolongs myocardial cell action potential duration and refractory period by direct action on all cardiac tissue; decreases AV and SA conduction rates.

Amiodarone

 Indications  Life threatening dysrhythmias    VF/pulseless VT unresponsive to shock, CPR, and vasopressor Recurrent hemodynamically unstable VT Seek expert opinion for other uses  Contraindications/Precautions  Bradycardia  2 nd and 3 rd degree block  Do not administer with meds that prolong QT interval (procainamide)

Amiodarone

 VF/VT – 300 mg IV/IO in 20-30 mL NS. Can follow with ONE dose of 150 mg in 3-5 minutes, if needed.

 Life threatening dysrhythmias  150 mg over 10 minutes. May repeat every 10 minutes as needed.

Lidocaine



Mechanism of Action

Decreases depolarization, automaticity, and excitability of ventricle during diastole by direct action, reversing ventricular dysrhythmias.

Lidocaine



Indications

 Alternative to amiodarone in VF/VT arrest  Stable monomorphic VT  Malignant PVC’s  Can be used if Torsades is suspected 

Contraindications/Precautions

 Prophylactic use in AMI is contraindicated  Reduce maintenance dose in liver impaired patients  Discontinue infusion if toxicity develops

Lidocaine



Cardiac Arrest

 Initial dose is 1-1.5 mg/kg  Refractory VF 0.5-0.75 mg/kg in 5-10 min. Max 3 mg/kg  Endotracheal dose 2-4 mg/kg 

Perfusing Dysrhythmia

 0.5-0.75 mg/kg up 1-1.5 mg/kg dosing range. Repeat if necessary at lower range to total dose of 3 mg/kg 

Maintenance Infusion

 1-4 mg/min

Magnesium Sulfate



Mechanism of Action

Increases magnesium levels in cases where prolonged QT interval is thought to be secondary to hypomagnesemia.

Magnesium Sulfate

 Indications  Torsades is suspected in cardiac arrest  Lfe-threatening ventricular dysrhythmias in digitalis OD  Precautions  Fall in BP with rapid administration  Use caution in renal failure  Dosing  Arrest 1-2 g over 5-20 min.

 Torsades w/ pulse 1-2 g over 5-60 min.

Vasopressin



Mechanism of Action

Causes vasoconstriction with reduced blood flow, increasing core perfusion during cardiac arrest.

Vasopressin

 Indications  Alternative to epinephrine in adult refractory VF/VT  Alternative to epinephrine in asystole or PEA  Contraindications/Precautions  Potent peripheral vasoconstrictor (increased demand upon resuscitation)  Dosing  Single dose of 40 u that replaces either the 1 st or 2 nd of epinephrine. Epinephrine can be resumed 3-5 minutes after dose  Can be used endotracheally; no suggested dose