5.3 CPR Protocols & Automated External Defibrillator (AED)

5.3 CPR Protocols & Automated External Defibrillator (AED)

Core Principle: Cardiopulmonary resuscitation (CPR) manually preserves artificial forward blood flow to the brain and myocardium until an Automated External Defibrillator (AED) or advanced medical care can terminate lethal dysrhythmias. Every second of delay or interruption in chest compressions precipitously drops coronary perfusion pressure and survival probability.

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1. Cardiac Arrest Recognition & Physiology

Cardiac arrest is the abrupt cessation of mechanical cardiac pump function, causing immediate loss of arterial blood pressure and systemic tissue perfusion. Without oxygenated blood flow, cerebral electrical activity ceases within 10 seconds, and irreversible neuronal death begins within 4 to 6 minutes.

                   CARDIAC ARREST RECOGNITION TRIAD

     1. UNRESPONSIVENESS     ──► No response to voice or painful stimulation
     2. ABSENT / AGONAL      ──► No chest rise, or isolated, gasping, snorting
        BREATHING                efforts (agonal respirations)
     3. ABSENT CAROTID PULSE ──► No definite carotid pulse felt within 10 SECONDS
                                 (Simultaneous pulse and breathing check)

Agonal Gasps vs. Normal Respiration

Agonal gasps are reflexive, irregular, labored snorting or gasping sounds originating from the dying brainstem. They occur in up to 40% of cardiac arrests in the first several minutes.

Exam Warning: Agonal gasps are NOT normal breathing. Responders must recognize agonal gasps as a sign of cardiac arrest and initiate immediate high-quality CPR without delay.

Carotid Pulse Palpation Guidelines

• Locate the casualty's thyroid cartilage (Adam's apple) using the index and middle fingers.
• Slide fingers laterally into the groove between the trachea and sternocleidomastoid muscle.
• Palpate for at least 5 but no more than 10 seconds.
• If you do not feel a definite pulse within 10 seconds, presume cardiac arrest and immediately begin chest compressions.

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2. High-Quality Adult CPR Parameters

High-quality CPR is the single greatest determinant of survival from sudden cardiac arrest. International resuscitation bodies (ILCOR, AHA, ERC) establish precise metrics that every certified mariner must execute.

                       HIGH-QUALITY ADULT CPR METRICS

  COMPRESSION RATIO      COMPRESSION RATE       COMPRESSION DEPTH     CHEST RECOIL
     30 : 2                 100 – 120              5 – 6 cm            100% COMPLETE
  [30 Compressions to     [Compressions           [2.0 – 2.4 Inches]   [No Leaning on
   2 Rescue Breaths]        Per Minute]                                 Chest Wall]

Detailed CPR Parameters Breakdown

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3. Rescue Breaths & Ventilation Mechanics

Rescue ventilations deliver oxygen to the lungs to maintain alveolar gas exchange during CPR. Rescuers should utilize barrier devices to prevent pathogen transmission.

                        VENTILATION TECHNIQUES

       POCKET MASK WITH ONE-WAY VALVE             BAG-VALVE-MASK (BVM)
            [Single Rescuer]                         [Two Rescuers]
                   ▲                                        ▲
                   │                                        │
     • Position at casualty's head            • Rescuer 1: Holds E-C clamp with
     • Form "C-E" clamp with thumb/index        both hands, lifts jaw
     • Tilt head back, lift chin              • Rescuer 2: Squeezes bag over 1 sec
     • Deliver 1-second breath                • Delivers ~500–600 mL tidal volume

Guidelines for Effective Ventilation

1. Duration: Deliver each rescue breath over exactly 1 second.
2. Volume: Deliver sufficient volume to produce a visible gentle chest rise (approximately 500 to 600 mL tidal volume in adults).
3. Compression-to-Ventilation Ratio: Deliver 2 rescue breaths after every 30 compressions (30:2). The pause between the 30th compression and resumption of compressions must not exceed 10 seconds.

The Dangers of Hyperventilation (Over-Ventilation)

• Increased Intrathoracic Pressure: Excessive ventilation volume or rate elevates pressure within the pleural space, compressing the superior and inferior vena cava. This dramatically restricts venous return to the heart, causing a catastrophic drop in cardiac output generated by compressions.
• Gastric Insufflation: Forcing excessive air into the pharynx forces the lower esophageal sphincter open, distending the stomach. This triggers regurgitation of gastric contents into the pharynx, leading to massive pulmonary aspiration and chemical pneumonitis.

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4. Automated External Defibrillator (AED) Integration

An Automated External Defibrillator (AED) is a sophisticated computerized medical device that analyzes the casualty's cardiac rhythm and, if indicated, delivers a controlled electrical shock to terminate fatal dysrhythmias.

                       CARDIAC ARREST RHYTHM TYPES

     SHOCKABLE RHYTHMS (AED Advises Shock)     NON-SHOCKABLE RHYTHMS (No Shock)
     • Ventricular Fibrillation (VF)           • Asystole ("Flatline")
       (Disorganized, chaotic twitching)         (Total absence of electrical activity)
     • Pulseless Ventricular Tachycardia (pVT) • Pulseless Electrical Activity (PEA)
       (Rapid, non-perfusing wide complexes)     (Organized electrical rhythm, no pulse)

Mechanism of Defibrillation

Defibrillation does not "jumpstart" a dead heart. Instead, the high-voltage electrical shock simultaneously depolarizes the entire myocardium, terminating the chaotic electrical storm of VF/pVT. This momentary cellular silence allows the heart's natural pacemaker—the Sinoatrial (SA) Node—to resume an organized, perfusing sinus rhythm.

The Universal 4-Step AED Operating Protocol

                        UNIVERSAL AED SEQUENCE

    [STEP 1: POWER ON]       ──► Open lid or press Power button immediately
            │
    [STEP 2: ATTACH PADS]    ──► Bare & dry chest; apply self-adhesive pads
            │
    [STEP 3: ANALYZE RHYTHM] ──► Clear casualty ("STAND CLEAR!"); do not touch
            │
    [STEP 4: SHOCK / RESUME] ──► If shock advised: Clear & press Shock button
                                 ──► IMMEDIATELY RESUME CPR (30:2) starting
                                     with chest compressions

Detailed AED Application Steps

1. Power On Immediately: Turn on the AED as soon as it arrives at the scene. Listen to and follow all automated voice prompts.
2. Expose and Prepare Chest:
   • Strip all clothing from the casualty's upper torso.
   • Dry the skin: If the casualty is wet, sweaty, or pulled from the sea, wipe the chest dry with a towel.
   • Excessive chest hair: Press pads firmly; if the AED prompts "Check Pads," rip off pads to remove hair, or quickly shave pad application sites with the razor in the AED kit.
   • Implanted Pacemakers / ICDs: If a hard, disc-like lump with surgical scar is visible under the skin (usually upper left chest), place the AED pad at least 2.5 cm (1 inch) away from the device.
   • Transdermal Medication Patches: Remove any nitro or nicotine patches with gloved hands and wipe residue before placing pads.
3. Pad Placement (Antero-Lateral Configuration):
   • Pad 1 (Upper Right): Right anterior chest, directly below the clavicle (collarbone), to the right of the sternum.
   • Pad 2 (Lower Left): Left lower chest, mid-axillary line, 5th–6th intercostal space, several centimeters below the left axilla (armpit).
4. Rhythm Analysis & Shock Delivery:
   • When the AED states "Analyzing heart rhythm, do not touch the patient," the rescuer must command loudly: "STAND CLEAR!" Ensure no one is touching the casualty, stretcher, or connected lines.
   • If a shock is advised: Visual scan from head to toe ("I'm clear, you're clear, everyone's clear!"), then press the flashing Shock button (or stand back if fully automated).
5. Immediate Post-Shock Protocol:
   • IMMEDIATELY resume CPR (30:2) starting with chest compressions right after the shock is delivered.
   • DO NOT stop to check for a carotid pulse or breathing.
   • Continue CPR for 2 minutes (approximately 5 cycles of 30:2) until the AED prompts for the next rhythm analysis.

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5. Two-Rescuer Team Dynamics & Compressor Rotation

Rescuer fatigue develops rapidly during CPR. Research proves that compression depth declines significantly after just 1 to 2 minutes of continuous compressions, even when the rescuer denies feeling tired.

                     TWO-RESCUER CPR SYNCHRONIZATION

    RESCUER 1 (Compressor)               RESCUER 2 (Airway & AED)
    • Performs 30 chest compressions     • Manages airway & pocket mask / BVM
    • Counts compressions aloud          • Delivers 2 rescue breaths
    • Maintains high rate (100-120/min)  • Operates AED
                                         • Monitors compression quality & depth

         🔄 ROTATE ROLES EVERY 2 MINUTES (5 CYCLES OF 30:2)
            Transition during AED analysis in LESS THAN 5 SECONDS

Seamless Role Switching Protocol

• Timing: Switch compressor roles every 2 minutes (approx. 5 cycles of 30:2), ideally timed with the AED rhythm analysis.
• Execution: Rescuer 2 moves into position at the chest while Rescuer 1 takes over the airway/BVM. The entire transition must take less than 5 seconds to prevent drop in coronary perfusion.

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6. Special Shipboard Resuscitation Environments

• Wet Decks & Metal Surfaces: AEDs are completely safe to use on steel ship decks. If the casualty is lying in standing water (bilges, flooded deck), drag them to a dry area and towel-dry the chest before attaching pads. Rescuers should avoid standing directly in puddles connecting them to the casualty.
• Vessel Motion in Heavy Seas: In rolling seas, rescuers should adopt a wide kneeling stance with knees spread wide, stabilizing themselves against bulkheads or using deck tie-downs while maintaining continuous compressions.
• Hypothermic Cardiac Arrest: In cold-water immersion cases ("not dead until warm and dead"), the cold myocardium resists both defibrillation and drugs. Current European Resuscitation Council guidance is specific: if VF/pVT is present, deliver up to 3 shocks; if VF persists, withhold further defibrillation attempts until the core temperature is above 30°C (86°F). Adrenaline is withheld entirely below 30°C and given at 6–10 minute intervals above it. Compression and ventilation rates are unchanged from normothermic CPR. Continue uninterrupted high-quality CPR with active rewarming and, where reachable, transfer toward extracorporeal rewarming.