Cardiac Arrest & Resuscitation in Adults
Summary
Cardiac arrest is the cessation of effective cardiac mechanical activity. Survival depends on early recognition, early CPR, early defibrillation (for shockable rhythms), and high-quality post-resuscitation care. The 2021 Resuscitation Council UK guidelines emphasise high-quality CPR (rate 100-120/min, depth 5-6cm), minimising interruptions, and treating reversible causes (4 Hs and 4 Ts).
Key Facts
- Incidence: ~30,000 OHCA and ~28,000 IHCA per year in UK
- Survival to discharge: OHCA 8-10%; IHCA 15-25%
- VF/pVT survival: 25-35% with early defibrillation
- Each minute without CPR: 7-10% decrease in survival
- Bystander CPR: Doubles survival rates
Clinical Pearls
Push hard, push fast: Rate 100-120/min, depth 5-6cm, full chest recoil
Defibrillation within 3-5 minutes of VF/pVT gives best outcomes
After each 2-minute cycle: rhythm check, pulse check if organised rhythm, and consider reversible causes
Why This Matters Clinically
Cardiac arrest is the ultimate medical emergency. The quality of resuscitation directly impacts survival and neurological outcome. All healthcare professionals must be competent in BLS and understand ALS principles.
Incidence & Prevalence
- OHCA incidence: ~55 per 100,000 population/year
- IHCA incidence: ~1.5 per 1,000 hospital admissions
- VF/pVT as initial rhythm: 25% OHCA, 20% IHCA
- PEA/Asystole: More common initial rhythms (60-70%)
Demographics
- Age: Incidence increases exponentially over 65 years
- Sex: Male:female 3:1 for OHCA
- Underlying conditions: CAD 70%, cardiomyopathy 10%, channelopathies 5%
Risk Factors
| Category | Examples |
|---|---|
| Cardiac | Previous MI, heart failure, arrhythmias |
| Drugs | QT-prolonging medications, cocaine, digoxin |
| Metabolic | Hypokalaemia, hyperkalaemia, hypomagnesaemia |
| Environmental | Drowning, electrocution, hypothermia |
Overview
Cardiac arrest results from cessation of coordinated electrical activity or mechanical failure despite electrical activity. The resulting global ischaemia causes cellular injury within minutes.
Arrest Rhythms
| Rhythm | Mechanism | Treatment |
|---|---|---|
| VF | Chaotic ventricular depolarisation | Defibrillation |
| Pulseless VT | Organised fast ventricular rhythm without output | Defibrillation |
| PEA | Electrical activity without mechanical output | CPR + treat cause |
| Asystole | No electrical or mechanical activity | CPR + treat cause |
The 4 Hs and 4 Ts
Reversible Causes:
| 4 Hs | 4 Ts |
|---|---|
| Hypoxia | Tension pneumothorax |
| Hypovolaemia | Tamponade (cardiac) |
| Hypo/Hyperkalaemia | Toxins |
| Hypothermia | Thrombosis (coronary/pulmonary) |
By Initial Rhythm
| Rhythm Type | Category | Approach |
|---|---|---|
| VF/pVT | Shockable | Immediate defibrillation |
| PEA | Non-shockable | CPR + reversible causes |
| Asystole | Non-shockable | CPR + reversible causes |
By Location
- OHCA: Out-of-hospital cardiac arrest
- IHCA: In-hospital cardiac arrest
By Cause
- Cardiac: Ischaemic, arrhythmic, structural
- Non-cardiac: Hypoxia, trauma, overdose, drowning
During Resuscitation
- Rhythm monitoring: Identify shockable vs non-shockable
- End-tidal CO2: Confirms ventilation, indicator of ROSC (rise suggests ROSC)
- ABG/VBG: pH, lactate, K+, glucose
- Bedside echo: Cardiac activity, tamponade, RV dilation (PE)
- Point-of-care glucose: Hypoglycaemia as cause
Post-ROSC
- 12-lead ECG: ST changes, arrhythmias
- CXR: ETT position, pulmonary oedema, pneumothorax
- Bloods: Troponin, U&Es, FBC, coagulation, lactate trend
- CT head: If no clear cardiac cause
- CT coronary angiography: If STEMI or suspected coronary cause
- Echocardiography: LV function, structural abnormalities
Immediate Management: ALS Algorithm
Shockable Rhythm (VF/pVT):
- Defibrillation 150-360J biphasic
- Resume CPR immediately for 2 minutes
- Check rhythm after 2-minute cycle
- Adrenaline 1mg IV after 3rd shock, then every 3-5 minutes
- Amiodarone 300mg IV after 3rd shock
- Consider further amiodarone 150mg after 5th shock
Non-Shockable Rhythm (PEA/Asystole):
- CPR for 2 minutes
- Adrenaline 1mg IV as soon as IV access, then every 3-5 minutes
- Check rhythm after 2-minute cycle
- Identify and treat reversible causes
CPR Quality
- Rate: 100-120 compressions/minute
- Depth: 5-6 cm in adults
- Recoil: Complete chest recoil between compressions
- Minimise interruptions: Fraction over 80%
Post-ROSC Care
- Airway: Secure if not already
- Oxygenation: Target SpO2 94-98%
- Ventilation: Target normocapnia (PaCO2 4.5-6.0 kPa)
- Blood pressure: MAP over 65 mmHg
- Temperature: Targeted temperature management 32-36°C
- Coronary angiography: If STEMI or likely cardiac cause
- ICU admission: Neuroprognostication after 72 hours
During Resuscitation
- Rib fractures (common, not a reason to stop)
- Pneumothorax
- Aspiration
- Failed intubation
Post-ROSC
| Complication | Incidence | Management |
|---|---|---|
| Hypoxic brain injury | 60-70% | TTM, neuroprognostication |
| Myocardial stunning | Common | Inotropes, IABP |
| Aspiration pneumonia | 30% | Antibiotics if confirmed |
| DIC | 10-15% | Supportive |
Survival Rates
- OHCA survival to discharge: 8-10%
- IHCA survival to discharge: 15-25%
- VF/pVT with early defibrillation: 30-40%
- Good neurological outcome (CPC 1-2): 70% of survivors
Prognostic Factors
| Favourable | Unfavourable |
|---|---|
| Witnessed arrest | Unwitnessed |
| Early bystander CPR | No bystander CPR |
| VF/pVT rhythm | Asystole |
| Short no-flow time | Prolonged arrest |
| ROSC under 20 minutes | ROSC over 30 minutes |
Neuroprognostication
- Performed ≥72 hours post-ROSC
- Multimodal approach: clinical exam, EEG, somatosensory evoked potentials, CT/MRI
Landmark Studies
TTM Trial (2013) PMID: 24237006
- No difference between 33°C vs 36°C target temperature
- Both groups had good outcomes compared to historical controls
TTM2 Trial (2021) PMID: 34133859
- 33°C vs normothermia (under 37.8°C)
- No benefit of hypothermia over targeted normothermia
PARAMEDIC2 Trial (2018) PMID: 30012709
- Adrenaline vs placebo in OHCA
- Improved overall survival but not neurologically favourable survival
Guidelines
- Resuscitation Council UK Guidelines 2021
- European Resuscitation Council Guidelines 2021
- AHA Guidelines 2020
What is Cardiac Arrest?
Cardiac arrest is when the heart suddenly stops pumping blood around the body. This is different from a heart attack (where blood supply to the heart is blocked). Without immediate treatment, it is fatal within minutes.
What to Expect
- Your loved one needed emergency resuscitation
- They will be in intensive care for monitoring
- Cooling treatment may be used to protect the brain
- Doctors will assess brain function after at least 72 hours
- The team will keep you updated regularly
Recovery
- Some people make a full recovery
- Others may have memory or cognitive difficulties
- Cardiac rehabilitation is available for survivors
- Support groups exist for survivors and families