11.1 Cardiopulmonary Resuscitation, Life Support Protocols & Arrhythmia Recognition

Cardiopulmonary Resuscitation, Life Support Protocols & Arrhythmia Recognition

Clinical Core: In cardiac arrest and acute hemodynamic collapse, survival depends upon immediate high-quality cardiopulmonary resuscitation (CPR), rapid defibrillation of shockable dysrhythmias, and algorithmic Advanced Cardiac Life Support (ACLS) interventions. The registered nurse must rapidly differentiate shockable rhythms (Ventricular Fibrillation and pulseless Ventricular Tachycardia) from non-shockable rhythms (Asystole and Pulseless Electrical Activity), direct emergency pharmacology, coordinate closed-loop team communication, and systematically investigate reversible physiological triggers.

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Basic Life Support (BLS): The CAB Sequence & High-Quality CPR Metrics

The fundamental operational sequence for adult resuscitation is CAB (Chest compressions, Airway, Breathing). Historical ABC approaches delayed life-saving myocardial perfusion while rescuers attempted airway maneuvers and rescue breaths. Because cardiac arrest victims retain residual oxygen in their pulmonary vasculature and arterial blood for several minutes, the immediate generation of coronary perfusion pressure through external cardiac compressions represents the paramount survival determinant.

Quantitative Criteria for High-Quality Chest Compressions

Substandard chest compressions fail to generate the minimum coronary perfusion pressure ($\ge 15\text{ mmHg}$) required for Return of Spontaneous Circulation (ROSC). Rescuers must strictly enforce the following evidence-based parameters:

Automated External Defibrillation (AED) Execution and Rescuer Safety

When an AED arrives at the bedside of an unresponsive, pulseless victim:

1. Power On the AED: Immediate device activation prompts audible and visual instructions.
2. Expose and Prep Chest: Quickly wipe away excess moisture or diaphoresis. Clip excessive chest hair if it prevents pad-to-skin adhesion. Remove transdermal medication patches (e.g., nitroglycerin, fentanyl) and wipe the skin clean to avoid electrical arcing or superficial cutaneous burns.
3. Pad Placement: Apply self-adhesive defibrillator pads in the standard anterolateral position (one pad below the right clavicle, lateral to the sternum; the second pad lateral to the left nipple, midaxillary line with its top margin below the axilla). Alternatively, use the anteroposterior position (one pad over the left precordium, the other on the back behind the heart). If an implanted pacemaker or defibrillator is present (palpable subcutaneous bulge), place the pad at least 1 inch (2.5 cm) away from the device.
4. Rhythm Analysis: Call out clearly, "Stand clear, do not touch the patient!" Ensure no rescuer is touching the patient, bed, or lines while the device analyzes.
5. Shock Delivery and Immediate CPR Resumption: If a shock is advised, confirm visual clearance from head to toe ("I'm clear, you're clear, all clear!"), depress the shock button, and immediately resume chest compressions starting with compressions. Never pause to recheck a pulse or rhythm immediately following defibrillation. Run 2 continuous minutes (5 cycles) of CPR before the AED re-analyzes.

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Advanced Cardiac Life Support (ACLS): Shockable Rhythms

Shockable cardiac arrest encompasses two specific electrocardiographic entities: Ventricular Fibrillation (VF) and pulseless Ventricular Tachycardia (pVT).

• Ventricular Fibrillation: Characterized by chaotic, disorganized, polymorphic waveforms with no discernible P waves, QRS complexes, or T waves. The myocardium trembles asynchronously, producing zero stroke volume.
• Pulseless Ventricular Tachycardia: A regular, monomorphic or polymorphic wide-complex tachycardia ($>100\text{ bpm}$) that fails to generate mechanical ventricular ejection or a detectable arterial pulse.

Algorithmic Resuscitation Sequence for VF / pVT

1. First Shock Delivery: Deliver an immediate unsynchronized shock (biphasic: manufacturer recommended 120–200 Joules, or maximum available dose; monophasic: 360 Joules).
2. CPR Cycle 1 (2 Minutes): Immediately resume CPR for 2 continuous minutes. Establish intravenous (IV) or intraosseous (IO) access. Prepare the first dose of epinephrine.
3. Rhythm Check & Second Shock: Pause briefly ($<10\text{ seconds}$) to verify rhythm. If VF/pVT persists, deliver a second defibrillation shock.
4. Epinephrine Administration (CPR Cycle 2): Immediately resume CPR for 2 minutes. Administer Epinephrine 1 mg IV/IO (1:10,000 concentration), flushed with a 20 mL bolus of 0.9% normal saline and brief extremity elevation. Repeat Epinephrine every 3 to 5 minutes throughout resuscitation. Epinephrine acts as a potent $\alpha_1$-adrenergic agonist, inducing peripheral vasoconstriction that elevates aortic diastolic pressure, thereby augmenting myocardial and cerebral perfusion.
5. Rhythm Check & Third Shock: If VF/pVT persists after 2 minutes of CPR, administer the third defibrillation shock.
6. Antiarrhythmic Administration (CPR Cycle 3): Immediately resume CPR for 2 minutes. Administer first-line antiarrhythmic pharmacotherapy:
   • Amiodarone: Administer 300 mg IV/IO rapid bolus diluted in 20 to 30 mL D5W or 0.9% normal saline. If VF/pVT recurs or persists after a subsequent 2-minute cycle, administer a second dose of 150 mg IV/IO.
   • Lidocaine Alternative: If amiodarone is unavailable, administer Lidocaine 1.0 to 1.5 mg/kg IV/IO initial bolus, followed by 0.5 to 0.75 mg/kg IV/IO every 5 to 10 minutes (maximum cumulative dose $3\text{ mg/kg}$).
7. Waveform Capnography Monitoring ($ETCO_2$): Connect an end-tidal $CO_2$ detector to the advanced airway.
   • $ETCO_2 < 10\text{ mmHg}$ reflects inadequate compression mechanics or low pulmonary blood flow.
   • An abrupt, sustained rise in $ETCO_2$ to $35\text{ to }40\text{ mmHg}$ indicates an immediate surge in pulmonary blood flow generated by endogenous cardiac output, serving as a reliable physiological indicator of Return of Spontaneous Circulation (ROSC) without stopping CPR.

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ACLS: Non-Shockable Rhythms & The Reversible H's and T's

Non-shockable arrest rhythms include Asystole and Pulseless Electrical Activity (PEA).

• Asystole: The complete absence of ventricular electrical and mechanical activity ("ventricular standstill"). Rescuers must verify true asystole by confirming flatline in two perpendicular ECG leads, checking cable connections, and increasing monitor gain.
• Pulseless Electrical Activity (PEA): The presence of an organized or semi-organized electrical rhythm on the cardiac monitor (sinus bradycardia, junctional rhythm, idioventricular rhythm) in the absence of a palpable pulse or measurable blood pressure.

Non-Shockable Management Principles

• Defibrillation is Strictly Contraindicated: Electrical shocks delivered to an asystolic or PEA heart cause massive parasympathetic stimulation and myocardial thermal injury, abolishing any residual pacemaker potential.
• Early Epinephrine: Deliver Epinephrine 1 mg IV/IO immediately upon recognizing a non-shockable rhythm, and repeat every 3 to 5 minutes.
• Continuous High-Quality CPR: Maintain 2-minute cycles of compressions with minimal interruptions.
• Systematic Investigation of Reversible Causes: Survival in PEA and asystole relies almost entirely upon rapid clinical identification and immediate correction of underlying physiological triggers.

The Reversible Causes: Comprehensive H's and T's Table

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Post-Cardiac Arrest Care & Targeted Temperature Management (TTM)

Following ROSC, the client enters the critical post-cardiac arrest syndrome phase, marked by brain injury, myocardial stunning, systemic ischemia/reperfusion injury, and ongoing pathological cascades.

Hemodynamic and Oxygenation Optimization

• Oxygenation Targets: Titrate $FiO_2$ to maintain arterial oxygen saturation ($SpO_2$) between 92% and 98% (avoiding hyperoxia, which generates destructive reactive oxygen species). Maintain $PaCO_2$ strictly between 35 and 45 mmHg; avoid hyperventilation because hypocapnia causes potent cerebral vasoconstriction, drastically reducing cerebral blood flow.
• Hemodynamic Parameters: Maintain Mean Arterial Pressure (MAP) $\ge 65\text{ mmHg}$ and systolic blood pressure $\ge 90\text{ mmHg}$. Administer warmed isotonic crystalloids and titrate continuous vasoactive infusions (Norepinephrine 0.1 to 0.5 mcg/kg/min, Epinephrine 2 to 10 mcg/min, or Dopamine 5 to 20 mcg/kg/min).

Targeted Temperature Management (TTM) Protocols

Temperature control aims to limit secondary brain injury after ROSC. Recent trials show that preventing fever matters more than deep cooling.

• Inclusion Criteria: Adult clients who achieve ROSC following cardiac arrest but remain comatose (unresponsive or exhibiting no purposeful response to verbal commands).
• Target Temperature Range: The 2025 AHA guidelines recommend deliberate temperature control between 32 °C and 37.5 °C, maintained for at least 36 hours, in adults who do not follow commands after ROSC. Preventing fever is the key aim.
• Core Temperature Monitoring: Utilize continuous core temperature monitoring via an esophageal temperature probe, advanced bladder catheter, or pulmonary artery catheter (avoid tympanic or axillary measurements).
• Shivering Suppression: Shivering triples metabolic rate and oxygen consumption, elevating intracranial pressure. Suppress shivering proactively using sedatives (propofol, dexmedetomidine), opioids (fentanyl), surface counter-warming, and intermittent or continuous neuromuscular blocking agents (e.g., cisatracurium).

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Life-Threatening Peri-Arrest Arrhythmias

Symptomatic Bradycardia (Heart Rate $<50\text{ bpm}$)

1. Clinical Assessment: Determine whether the bradycardia is causing signs of poor end-organ perfusion: acute hypotension, altered mental status, ischemic chest discomfort, acute pulmonary edema, or signs of shock.
2. First-Line Pharmacology: Administer Atropine sulfate 1 mg IV push rapidly. Repeat every 3 to 5 minutes to a maximum cumulative dose of 3 mg.
   • Mechanism: Antimuscarinic agent that blocks acetylcholine at the sinoatrial (SA) and atrioventricular (AV) nodes.
   • Clinical Caveat: Atropine is generally ineffective in wide-complex high-grade AV blocks (Mobitz Type II second-degree or third-degree complete AV block with wide QRS), where the conduction defect resides infra-nodally in the bundle of His or Purkinje fibers.
3. Second-Line Interventions (Transcutaneous Pacing): If atropine is ineffective or high-grade AV block is present, initiate Transcutaneous Pacing (TCP) without delay:
   • Set pacing rate between 60 and 80 beats per minute.
   • Increase electrical current (milliamperes, mA) until electrical capture is achieved (characterized by a pacemaker spike followed immediately by a wide QRS complex and tall T wave).
   • Confirm mechanical capture by palpating a right femoral or radial pulse matching the pacer spikes (do not palpate the carotid artery, as electrical pectoralis muscle twitches can mimic a pulse).
   • Provide IV analgesia and sedation (fentanyl, midazolam) for conscious clients receiving TCP.
   • Alternative infusions: Dopamine infusion (5 to 20 mcg/kg/min) or Epinephrine infusion (2 to 10 mcg/min).

Acute Tachyarrhythmias (Heart Rate $\ge 150\text{ bpm}$)

1. Stability Triage: Evaluate for signs of hemodynamic instability (hypotension, acute heart failure, ischemic chest pain, altered mental status).
2. Unstable Tachycardia (Narrow or Wide QRS):
   • Perform immediate Synchronized Cardioversion.
   • Critical Nursing Precaution: Rescuers must activate the "SYNC" mode on the defibrillator. The device flags the peak of each R wave with an on-screen marker, delivering electrical energy synchronously with the R wave. This prevents firing during the vulnerable ventricular repolarization period (the T wave), which would precipitate refractory Ventricular Fibrillation (the R-on-T phenomenon).
3. Stable Regular Narrow-Complex Tachycardia (Supraventricular Tachycardia - SVT):
   • Vagal Maneuvers: Execute the Modified Valsalva Maneuver (straining against 40 mmHg pressure for 15 seconds, followed immediately by passive leg elevation to 45 degrees).
   • Adenosine Pharmacotherapy: If vagal maneuvers fail, administer Adenosine 6 mg rapid IV push via a large-bore cannula in the antecubital fossa, followed instantly by a 20 mL normal saline flush and brief arm elevation. Adenosine has an ultra-short half-life ($<10\text{ seconds}$) and acts by transiently blocking AV nodal conduction. Warn the client of acute flushing, chest tightness, and a brief period of monitored asystole. If conversion does not occur within 1 to 2 minutes, administer a second rapid dose of 12 mg IV push.