It’s 3 a.m. on Medical South. The night is progressing quietly when suddenly you hear the nurse’s aide frantically yelling, “Call a code blue!” Immediately, your stomach begins to turn inside out and your heart begins to race. Sound familiar?
Quite often, the main fear experienced by nurses is related to administration of emergency drugs. Familiarity with Advanced Cardiac Life Support (ACLS) emergency drug therapy guidelines for treatment of cardiac arrhythmias can diminish your apprehension. The American Heart Association (AHA) has formulated algorithms — protocols that prioritize treatment modalities for life-threatening cardiac arrhythmias.
During a code, drug therapy is not your first priority. Your first priority is Circulation, Airway, Breathing, Defibrillation (CABD), and determining a Differential Diagnosis. The AHA Emergency Cardiac Care approach uses the mnemonic, CABD, to remind us what to do in an emergency situation. It’s essential that first responders to a code perform high-quality CPR. Good quality CPR skills are essential to all ACLS interventions. Drugs, when required, play an important role in management of an arrest situation. Drug administration should not interrupt CPR. Instead, drugs should be delivered during CPR if at all possible. Drug therapy should be implemented after the ABCD survey, and after accurately assessing the cardiac rhythm. In the event emergency cardiac drug therapy is necessary, nurses will probably encounter one or more of the drugs discussed below during a code. Selection and timing of drugs for an arrest situation has been organized and simplified by standards provided in the ACLS algorithms. For more information on evidence-based treatment recommendations, go to http://circ.ahajournals.org/content/122/16_suppl_2.toc
.1 (Level A)
Most Frequently Encountered Drugs
A vasoconstricting drug is the first drug given in a pulseless rhythm. There are two vasopressors that are recommended by the AHA, epinephrine and vasopressin. Either may be the first drug given in a pulseless arrest. Pulseless arrests include ventricular Fibrillation, ventricular tachycardia, pulseless electrical activity (PEA), and asystole.
Epinephrine is a catecholamine that increases blood flow to the heart and brain, increases heart rate and blood pressure, and makes the heart more responsive to defibrillation. The usual dose of epinephrine is 1 mg IV push (IVP) with repeated doses every three to five minutes according to patient response. Each IV dose is followed by 20 mL normal saline (NS) flush. Epinephrine is supplied on crash carts in prefilled 10 mL syringes (10 mL = 1 mg, if a 1:10,000 dilution is used). AHA guidelines recommend a continuous infusion of epinephrine (2 mcg/min to 10 mcg/min) in symptomatic bradycardia or hypotension after atropine has been given, and while awaiting transcutaneous pacing, or if the use of a transcutaneous pacemaker has failed.
Vasopressin is an alternate vasopressor and has a longer half-life than epinephrine. It’s a powerful vasoconstrictor, producing the same effect as epinephrine, and can be used as an alternative to epinephrine for any pulseless cardiac arrest, (ventricular Fibrillation, ventricular tachycardia, asystole, or PEA). Vasopressin is a hormone that promotes reabsorption of water in the kidneys and causes peripheral vasoconstriction. If a pulseless rhythm persists after delivery of one or two shocks plus high-quality CPR, one dose of vasopressin may be given before or after epinephrine. When a shock is not advised, vasopressin may also be given to replace the first or second dose of epinephrine. The dose of vasopressin is 40 units and is administered IVP. Vasopressin is usually supplied in crash carts as a 20-unit vial. You will need two vials to equal 40 units. Because vasopressin is a potent peripheral vasoconstrictor and may provoke or worsen cardiac ischemia, it’s not recommended for use in responsive patients who have coronary artery disease.
Atropine is a drug that has a direct vagolytic effect, which increases the heart rate due to a parasympathetic action accelerating the rate of the sinus node discharge and improving AV conduction. Atropine is used to treat patients with symptomatic sinus bradycardia and symptomatic AV heart blocks. Atropine is not recommended for second-degree AV heart block Mobitz Type II or third-degree AV block with wide QRS complexes. Immediate pacing is recommended for these patients. According to the 2010 guidelines, atropine is no longer recommended for routine use in the management of PEA or asystole.1 (Level A)
Amiodarone is the preferred drug used in the treatment of life-threatening arrhythmias. The AHA recommends amiodarone as a first-line antiarrythmic for patients who experience cardiac arrest. Amiodarone is a potent vasodilator, and it also prolongs the action potential duration and the refractory period in the cardiac cycle, thereby decreasing the AV node conduction and heart rate, and slowing SA nodal conduction. Amiodarone is indicated for shock-refractory ventricular Fibrillation and pulseless ventricular tachycardia. It’s also used to treat wide-complex tachycardias and is used as an adjunct in electrical cardioversion of paroxysmal supraventricular tachycardia (PSVT). Amiodarone is also successfully used for rate control in Atrial Fibrillation or Atrial flutter and can be used in the management of stable tachycardia.
The recommended dose of amiodarone for ventricular Fibrillation and pulseless ventricular tachycardia is 300 mg IVP. Amiodarone is supplied in glass vials, therefore a filter needle is used to draw it up. If there’s no response to amiodarone in three to five minutes, consider a second dose of 150 mg IVP. Maximum cumulative dose of amiodarone is 2.2 g IV in 24 hours. The usual dose of amiodarone for stable wide-complex tachycardia is 150 mg IV over ten minutes. Additional infusions of 150 mg may be given every ten minutes as needed up to the maximum of 2.2 g in 24 hours. Follow a successful bolus of amiodarone with a maintenance infusion of 540 mg at a rate of 1 mg/min for 6 hours and then 0.5 mg/min for 18 hours. An in-line filter should be used during administration of amiodarone. Be aware that amiodarone may produce vasodilatation and hypotension, and may prolong the QT interval. Do not routinely administer amiodarone with procainamide or other drugs that prolong the QT interval, as doing so may lead to lethal arrhythmias. Use Amiodarone with caution in patients with renal failure. Amiodarone’s half-life is up to 40 days.
Lidocaine is no longer given for ventricular Fibrillation or pulseless ventricular tachycardia until after deFibrillation, epinephrine, or vasopressin, and if amiodarone is not available. Lidocaine suppresses automaticity and excitability of the HIS-Purkinje system during diastole. Through critical appraisal and expert discussion, lidocaine has now been classified as an “indeterminate” ACLS recommendation. It does no harm and has no benefit.
The dose of lidocaine for ventricular Fibrillation is 1 mg/kg to 1.5 mg/kg IVP, and may be repeated every three to five minutes to a maximum of 3 mg/kg. The dose for ventricular tachycardia is 1 mg/kg to 1.5 mg/kg IVP with doses of 0.5 mg/kg to 0.75 mg/kg repeated every five to ten minutes up to a maximum dose of 3 mg/kg. Following a successful lidocaine bolus, run a continuous IV infusion (2 Gm in 500 mL D5W) at 2 mg/min to 4 mg/min. Prophylactic lidocaine is not recommended.
Administer lidocaine with caution in patients with conduction disturbances, avoiding it completely for patients in third-degree heart block who have ventricular escape beats. Large doses of lidocaine may depress the sinus node and produce heart block. Lidocaine may be used for bradycardia in patients with ventricular escape beats if an external pacemaker in standby mode is on the patient, in case they become asystolic or develop symptomatic bradycardia. Also, you might want to reduce the dosage for those who have impaired hepatic function, pulmonary edema, or shock, and for patients over the age of 70. Be alert for signs and symptoms of toxicity, which may include drowsiness, disorientation, tinnitus, paresthesias, and seizures. If toxicity is suspected, stop the drip, hang a NS IV, and promptly notify the healthcare provider.
Adenosine is an antiarrythmic drug that works by slow initiation of SA node impulses and blocking AV conduction reentry. This drug is especially effective on re-entry tachycardia such as PSVT. Adenosine is the drug of choice for most narrow-complex tachycardias. It will not convert Atrial Fibrillation or Atrial flutter, but may be used as a diagnostic aid in determining the underlying rhythm because it produces a transient AV block that assists in clarifying the underlying rhythm. Adenosine is preferred over verapamil because of its transient effects, and because it does not produce hypotension. Adenosine is not used for wide-complex tachycardias of uncertain origin. ACLS guidelines recommend cardioversion for unstable wide-complex tachycardia of unknown type. Patients receiving adenosine should always be on a cardiac monitor.
The usual dose of adenosine is 6 mg given rapidly, (over 1 to 3 seconds) IVP in a large vein such as the antecubital, to enhance delivery to the heart. This is followed by 20 mL NS IV flush with elevation of the arm with the IV access. The second dose is 12 mg given one to two minutes later if there is no response to the first dose. The 12 mg dose may be repeated one more time after one to two minutes, if needed. The maximum dose is 30 mg. An important fact to keep in mind regarding adenosine is that it has an extremely short half-life (<10 seconds) and must be administered rapidly (one to three seconds) through the IV port that is closest to the systemic circulation. The onset of action of adenosine is usually 10 to 15 seconds. A stopcock setup with a NS filled syringe attached to one port and adenosine attached to another port assists in rapid administration necessary to get into the blood system quickly.
Because adenosine slows AV conduction, it is contraindicated in patients with second- or third-degree AV blocks who do not have artificial pacemakers. In addition, adenosine is contraindicated in patients taking theophylline derivatives, carbamazepine (Tegretol), or dipyridamole (Persantine), and pentoxphylline (Trentol), because they may interfere with the drugs action.
When administering adenosine, you must observe the cardiac monitor closely for brief periods of asystole, sinus bradycardia, or ventricular ectopy. Your patient may also experience flushing, bronchospasms, and dyspnea. These symptoms are usually short-lived and generally disappear within a minute. Emergency equipment should be immediately available in case resuscitation becomes necessary.