CHPPC Module 12, Section 2: Mastering ACLS/PALS Pharmacology
MODULE 12: CODE CARTS & EMERGENCY PREPAREDNESS

Section 2: Mastering ACLS/PALS Pharmacology

You have mastered the anatomy of the crash cart and your role on the code team. Now, we dive into the science that drives the action. This section is a deep exploration of the core pharmacology of resuscitation. We will move beyond simply handing off a syringe and delve into the mechanisms, doses, and critical timing of the key medications used in the Advanced Cardiovascular Life Support (ACLS) and Pediatric Advanced Life Support (PALS) algorithms. Your expertise in these areas is what transforms you from a medication preparer into a true medication expert, capable of anticipating needs and ensuring the safe, effective use of these powerful drugs under the most intense pressure.

2.1 Foundations of Resuscitation Pharmacology

The principles that guide medication use in a crisis.

Resuscitation pharmacology is unlike any other area of medicine. The therapeutic window is narrow, the stakes are absolute, and the time for decision-making is compressed into seconds. The entire system is built on a foundation of evidence-based algorithms, standardized doses, and rapid vascular access. Understanding these foundational principles is essential before we can discuss the individual drugs.

Retail Pharmacist Analogy: The No-Nonsense “Morning After Pill” Protocol

When a patient requests emergency contraception, you don’t engage in a long, meandering conversation. You follow a clear, evidence-based, and highly efficient protocol. You ask a series of specific questions about timing and contraindications. You know the standard dose of levonorgestrel is 1.5mg. You counsel on the key points of efficacy and side effects. The entire interaction is guided by an established algorithm to ensure safe and effective provision of a time-sensitive medication.

The ACLS and PALS guidelines are the ultimate expression of this concept. They are meticulously researched, internationally recognized algorithms that provide a step-by-step “if this, then that” roadmap for managing a cardiopulmonary arrest. When you give 1mg of epinephrine, you aren’t just following an order; you are executing a critical step in a global standard of care, just as you do when you dispense emergency contraception according to protocol. Your role is to know that protocol as well as anyone in the room.

2.1.1 The Primacy of IV/IO Access

In a cardiac arrest, the peripheral circulation is virtually nonexistent. For medications to work, they must get to the central circulation and the heart as quickly as possible. This is achieved through two primary routes:

  • Intravenous (IV): A large-bore IV catheter (18 or 20 gauge) placed in a large vein, ideally in the antecubital fossa (the crook of the elbow) or higher, is the preferred route. After a drug is pushed, it MUST be followed immediately by a 20 mL saline flush to propel the medication from the peripheral vein into the central circulation.
  • Intraosseous (IO): If IV access cannot be established quickly (within ~60-90 seconds), the next step is IO access. A specialized power driver is used to insert a needle directly into the bone marrow of the proximal humerus (shoulder) or proximal tibia (shin). The bone marrow is a non-collapsible vascular space that provides immediate access to the central circulation. For a pharmacist, there is no difference: drugs and fluids can be given via IO just as they are via IV.

The endotracheal (ET) route for administering drugs is no longer recommended due to erratic and unpredictable absorption.

2.2 The Adult Cardiac Arrest Algorithm (ACLS): A Pharmacist’s Deep Dive

Navigating the two sides of the algorithm: shockable vs. non-shockable rhythms.

The ACLS cardiac arrest algorithm is a forked road, with the path determined by the patient’s cardiac rhythm. Your pharmacological interventions depend entirely on which path the team is on. The two paths are:

  • Shockable Rhythms: Ventricular Fibrillation (VF) and pulseless Ventricular Tachycardia (pVT). These are chaotic electrical rhythms that can potentially be reset by an electrical shock (defibrillation).
  • Non-Shockable Rhythms: Asystole (flatline) and Pulseless Electrical Activity (PEA), where there is an organized electrical rhythm but no corresponding pulse. Electricity is not helpful here; the focus is on high-quality CPR and medications.

2.2.1 Epinephrine: The Universal Constant of Cardiac Arrest

Regardless of the rhythm, epinephrine is the cornerstone of pharmacological management in cardiac arrest. It is the first and most frequently administered drug in both sides of the algorithm.

Epinephrine Masterclass

  • Mechanism of Action: While we learn in school that epinephrine is a potent beta-1 agonist (increasing heart rate and contractility), this is NOT its primary benefit in cardiac arrest. Its life-saving effect comes from its potent alpha-1 adrenergic agonism. This causes profound systemic vasoconstriction, which increases aortic diastolic pressure. This, in turn, increases coronary perfusion pressure (CPP), the force driving blood flow to the heart muscle itself during the relaxation phase of CPR compressions. A higher CPP is strongly associated with a higher chance of achieving ROSC.
  • Dose & Timing: 1 mg (10 mL of 1:10,000 solution) IV/IO push, repeated every 3-5 minutes for the entire duration of the code. There is no maximum dose. The timing is critical; the recorder nurse will call out the time of each epi administration, and the team leader will use this to time the next dose.
  • Pharmacist’s Role: Your job is to make the provision of epinephrine flawless. When the first dose is called, you hand it off and immediately start thinking about the second. Note the time. At the 3-minute mark, you should be proactively stating to the team leader, “It has been 3 minutes since the last dose of epinephrine.” This cognitive offloading is immensely valuable to a code leader managing multiple tasks.

2.2.2 Pharmacology of Shockable Rhythms (VF/pVT)

In VF/pVT, the treatment sequence is Shock -> CPR -> Drug. After the second shock, if the patient is still in VF/pVT, the first dose of epinephrine is given. If the patient is still in VF/pVT after the third shock, the focus turns to antiarrhythmics.

Drug Mechanism of Action ACLS Dose in Cardiac Arrest Pharmacist’s Focus
Amiodarone Complex drug with effects on sodium, potassium, and calcium channels (Class III dominant). It prolongs the action potential duration and refractory period, helping to terminate re-entrant ventricular arrhythmias. First Dose: 300 mg IV/IO bolus.
Second Dose: 150 mg IV/IO bolus (if VF/pVT persists after more shocks).		 This is the first-line antiarrhythmic. You must be prepared to provide the 300mg dose after the third shock. If it is not in a pre-filled syringe, you must draw it up quickly. Be ready with the smaller 150mg dose for a potential second request later in the code.
Lidocaine Class IB antiarrhythmic that blocks sodium channels, primarily in ischemic tissue. It shortens the action potential duration and is effective for terminating ventricular arrhythmias. First Dose: 1-1.5 mg/kg IV/IO bolus.
Second Dose: 0.5-0.75 mg/kg every 5-10 minutes (Max 3 mg/kg).		 Considered a second-line alternative if amiodarone is unavailable or ineffective. This requires a weight-based calculation. You must get an estimated weight from the team, perform the calculation, and announce the prepared dose in milligrams.

2.3 Managing Symptomatic Bradycardia & Tachycardia

Pharmacology for patients with a pulse, but who are unstable.

Not every rapid response or “code” call is for a full cardiac arrest. Often, you will be called for a patient who has a pulse but is hemodynamically unstable due to a rhythm that is too slow (bradycardia) or too fast (tachycardia). In these cases, the pharmacology is completely different.

2.3.1 The Symptomatic Bradycardia Algorithm

The key word is “symptomatic.” A heart rate of 45 in a marathon runner is normal. A heart rate of 45 in an elderly patient with a blood pressure of 70/40, altered mental status, and signs of shock is a medical emergency. The first-line drug is always atropine.

  • Atropine: An anticholinergic drug that blocks the effect of the vagus nerve on the SA and AV nodes, thereby increasing the heart rate.
    Dose: 1 mg IV push, repeated every 3-5 minutes up to a maximum total dose of 3 mg.
    Pharmacist’s Role: Provide the 1mg pre-filled syringes as requested and keep track of the cumulative dose given. You must know that atropine is unlikely to work in high-degree AV blocks (Mobitz II or Third-Degree) where the block is below the level of the AV node. In these cases, you should anticipate the failure of atropine and be ready to prepare a second-line infusion.
  • Dopamine & Epinephrine Infusions: If atropine is ineffective, the next step is a continuous infusion of a chronotropic agent to chemically “pace” the heart.

    Deep Dive: Preparing Chronotropic Infusions

    This is a core pharmacist competency during a bradycardia emergency. You must be able to prepare either drip from memory.

    • Dopamine Drip: Standard concentration is often 400mg in 250mL of D5W. The usual starting dose for bradycardia is 5-20 mcg/kg/min. You will calculate the initial rate in mL/hr for the nurse.
    • Epinephrine Drip: Standard concentration is often 1mg in 250mL of NS or D5W. The usual starting dose is 2-10 mcg/min. This is NOT a weight-based drip.

    Your role is to clarify which agent the physician wants, state the standard concentration, prepare the drip, and provide the starting rate to the nurse programming the infusion pump.

2.3.2 The Tachycardia Algorithm: Adenosine

For a patient who is unstable due to a tachycardia, the treatment is immediate synchronized cardioversion (an electrical shock). But if the patient is stable with a regular, narrow-complex tachycardia (SVT), the go-to drug is adenosine.

Adenosine: The Pharmacological Reboot

Adenosine is a unique, ultra-short-acting drug that essentially causes a transient chemical heart block in the AV node, lasting for just a few seconds. The goal is that this brief “reboot” will break the re-entrant circuit causing the SVT and allow the heart’s normal sinus rhythm to resume.

  • Dose: First Dose: 6 mg rapid IV push. Second Dose: 12 mg rapid IV push if the first dose is ineffective.
  • Administration Technique: This is the most important part. Adenosine has a half-life of <10 seconds. It must be given into a large vein (like the AC) and pushed as fast as possible, followed immediately by a 20 mL saline flush to get it to the heart.
  • Pharmacist’s Role: When you are asked for adenosine, you should grab both the drug syringe AND a 20mL saline flush syringe. Hand them both to the nurse and verbally coach them on the technique: “Give the adenosine as fast as you can, and immediately slam the flush in right behind it.” You should also warn the patient and team that there will be a brief period of asystole on the monitor, which is the expected effect.

2.4 The Pediatric Emergency (PALS): A Masterclass in Weight-Based Dosing

Children are not “little adults”: The critical differences in PALS pharmacology.

Responding to a pediatric code is one of the highest-stress events in a hospital. The emotional intensity is high, and the margin for error is nonexistent. From a pharmacy perspective, every action is dictated by the child’s weight. Your ability to perform rapid, accurate, weight-based calculations is the single most important skill you bring to the room. In a pediatric code, you are not just the medication expert; you are the team’s primary safety officer for dosing.

2.4.1 The Broselow Tape: Your Most Important Cognitive Aid

In the chaos of a pediatric emergency, you cannot be expected to memorize dozens of weight-based doses. The universal standard of care is to use a length-based resuscitation tape, most commonly the Broselow Pediatric Emergency Tape. The child is measured with the tape, and their length corresponds to a color zone. This color zone provides pre-calculated doses and equipment sizes, dramatically reducing the risk of calculation errors.

Your Role: As soon as a pediatric code is announced, your first question upon arrival should be, “What is the weight or Broselow color?” All of your subsequent actions will be based on that single piece of information. You should have a PALS reference guide or app that is organized by the Broselow colors.

2.4.2 PALS vs. ACLS: Critical Drug Dosing Differences

While the algorithms are conceptually similar, the doses are profoundly different. Internalizing these differences is critical for patient safety.

THE MOST IMPORTANT CONCEPT: PEDIATRIC EPINEPHRINE

This is the single most dangerous point of confusion between ACLS and PALS and has led to fatal ten-fold overdoses. You must commit this to memory.

  • Adult Dose: 1 mg of the 1:10,000 concentration (0.1 mg/mL). This is the concentration in the adult pre-filled syringes.
  • Pediatric Dose: 0.01 mg/kg of the 1:10,000 concentration.

NEVER use an adult epinephrine PFS for a pediatric patient without first drawing up the correct weight-based dose into a smaller, labeled syringe. For a 10kg child, the dose is 0.1mg (or 1mL from the PFS). Giving the entire 10mL adult syringe would be a catastrophic ten-fold overdose. Your primary safety role is to prevent this from ever happening.

Drug/Intervention ACLS (Adult) Dose PALS (Pediatric) Dose Key Pharmacist Consideration
Epinephrine (Cardiac Arrest) 1 mg IV/IO 0.01 mg/kg IV/IO Confirm concentration (1:10,000). Calculate mL dose. Announce dose in both mg AND mL.
Amiodarone (VF/pVT) 300 mg, then 150 mg 5 mg/kg (max 300mg) Calculate total mg dose. Prepare the correct volume from a standard vial.
Lidocaine (VF/pVT) 1-1.5 mg/kg 1 mg/kg Simple weight-based calculation. The dose is similar, but must be calculated.
Adenosine (SVT) 6 mg, then 12 mg 0.1 mg/kg (max 6mg), then 0.2 mg/kg (max 12mg) Calculate the small mg and volume required. Prepare in a small, labeled syringe.
Synchronized Cardioversion Varies by device (e.g., 120-200J) 0.5-1 J/kg, then 2 J/kg While not a drug, you should be aware of the energy difference. It highlights the weight-based paradigm.
Dextrose (Hypoglycemia) 25g (50mL of D50W) 0.5-1 g/kg (e.g., 2-4 mL/kg of D25W or 5-10 mL/kg of D10W) NEVER give D50W to a small child. It is dangerously hyperosmolar. You must have D10W or D25W bags or syringes available and calculate the mL dose.