22.2 Cardiac Emergency Drugs

Cardiac Emergency Drugs

Cardiac emergency drugs are fast-acting medications used to treat life-threatening heart events like cardiac arrest, severe arrhythmias, and cardiogenic shock. Because these situations can deteriorate in seconds, understanding each drug's mechanism, indication, and nursing priorities is essential for safe practice in critical care.

Key Characteristics

• These drugs are administered through intravenous (IV), intramuscular (IM), or endotracheal (ET) routes to ensure rapid absorption and onset of action.
• They require continuous monitoring of vital signs (blood pressure, heart rate, cardiac rhythm, oxygen saturation) to evaluate effectiveness and catch complications early.
• Side effects can be significant, including hypotension, new dysrhythmias, and in rare cases anaphylaxis. The potency that makes these drugs effective also makes them dangerous.
• They're almost always used alongside other interventions like CPR and defibrillation as part of Advanced Cardiac Life Support (ACLS) protocols, not as standalone treatments.

Actions and Indications

Epinephrine

• An alpha- and beta-adrenergic agonist that stimulates the sympathetic nervous system. Alpha effects cause peripheral vasoconstriction (raising blood pressure), while beta effects increase cardiac output and cause bronchodilation.
• Indicated for cardiac arrest, severe anaphylaxis, and bradycardia unresponsive to atropine. It's the cornerstone drug in ACLS cardiac arrest algorithms.

Atropine

• An anticholinergic agent that blocks vagal (parasympathetic) stimulation of the sinoatrial (SA) node, which allows the heart rate to increase.
• Indicated for symptomatic bradycardia to improve cardiac output and tissue perfusion. Note that current ACLS guidelines no longer recommend atropine for asystole or pulseless electrical activity (PEA).

Amiodarone

• A Class III antiarrhythmic that prolongs the action potential duration and refractory period in cardiac muscle cells, suppressing abnormal electrical activity.
• Indicated for ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT) that don't respond to defibrillation. It's the first-line antiarrhythmic in cardiac arrest.

Lidocaine

• A Class IB antiarrhythmic that suppresses ventricular ectopy by decreasing automaticity and conductivity in the myocardium.
• Indicated for VF and pulseless VT when amiodarone is unavailable or contraindicated. Think of it as the backup antiarrhythmic.

Dopamine

• A catecholamine with dose-dependent effects, which is what makes it unique:
  • Low dose (1–5 mcg/kg/min): increases renal and mesenteric blood flow
  • Moderate dose (5–10 mcg/kg/min): increases cardiac contractility and heart rate (beta-1 effects)
  • High dose (10–20 mcg/kg/min): causes vasoconstriction (alpha effects)
• Indicated for cardiogenic shock and symptomatic bradycardia unresponsive to atropine.

Vasopressin

• An antidiuretic hormone (ADH) analog that stimulates V1 receptors on blood vessels, causing vasoconstriction and increasing systemic vascular resistance.
• Can be used in cardiac arrest as an alternative or adjunct to epinephrine. Its role in current ACLS algorithms has been somewhat reduced, but it remains an option when initial resuscitation efforts are unsuccessful.

Critical Nursing Considerations

Ensure proper dosing and administration route

• Double-check the drug, dose, and route against the order and facility protocol before every administration. In the chaos of a code, medication errors happen easily.
• Use appropriate techniques for each route: IV push through a large-bore line with a rapid flush, IM into the deltoid or vastus lateralis, and ET administration diluted and instilled through the endotracheal tube.

Monitor patient response and vital signs

• Assess blood pressure, heart rate, cardiac rhythm, and $SpO_2$ before and after each dose.
• Look for signs of improvement: return of spontaneous circulation (ROSC), improved capillary refill, better skin color, and increasing level of consciousness.
• Watch for adverse reactions, including new dysrhythmias (ventricular ectopy, tachycardia, or worsening bradycardia), hypotension, and signs of anaphylaxis (rash, bronchospasm, angioedema). Intervene immediately if these occur.

Maintain airway and ventilation

• Ensure a patent airway and provide supplemental oxygen. These drugs can't do their job if the patient isn't being oxygenated.
• Assist with intubation and mechanical ventilation when indicated to protect the airway and optimize gas exchange.

Perform ongoing assessments

• Continue CPR and defibrillation per ACLS guidelines. Drugs support resuscitation, but high-quality chest compressions and timely defibrillation remain the priorities.
• Obtain and interpret a 12-lead ECG to identify the underlying rhythm and guide further treatment.
• Administer additional medications (antiarrhythmics, vasopressors) and IV fluids (crystalloids, blood products) as ordered.

Document thoroughly

• Record the time, dose, route, and site of every administration. During a code, a dedicated recorder is invaluable.
• Note changes in vital signs, cardiac rhythm, and clinical status after each intervention.
• Communicate findings clearly to the healthcare team and update family members to ensure continuity of care.

Essential Patient Education

For patients who survive a cardiac emergency and are prescribed ongoing cardiac medications, education focuses on several areas:

Medication adherence

• Stress the importance of taking medications exactly as prescribed to maintain therapeutic levels. Abruptly stopping certain cardiac drugs can cause rebound hypertension or recurrent arrhythmias.

Recognizing side effects

• Common side effects include dizziness, fatigue, and GI upset (nausea, vomiting). Patients should know which side effects are expected and manageable versus which require medical attention.
• Instruct patients to seek immediate help for signs of allergic reaction (hives, facial swelling), difficulty breathing, or chest pain.

Lifestyle modifications

• Encourage regular physical activity (at least 30 minutes most days), a heart-healthy diet low in saturated fat and sodium, and stress management techniques.
• Discuss smoking cessation and limiting alcohol intake as key steps in reducing cardiovascular risk.
• Emphasize the importance of regular follow-up appointments for monitoring blood pressure, cholesterol, and cardiac function.

Emergency preparedness

• Teach patients and caregivers to recognize signs of a cardiac emergency: chest pain, sudden shortness of breath, and syncope (fainting).
• Make sure they know how to activate emergency medical services (call 911) and what information to provide: location, symptoms, and relevant medical history.
• Encourage patients to carry a current medication list, allergy information, and medical history at all times so emergency responders can provide accurate, timely treatment.

Medication storage and disposal

• Store medications in a cool, dry place away from sunlight and moisture. Keep them out of reach of children and pets.
• Dispose of expired or unused medications safely through pharmacy take-back programs rather than flushing or discarding in household trash.