Cardiopulmonary Resuscitation (CPR) - Adult

Overview

Cardiopulmonary resuscitation (CPR) is a lifesaving technique combining chest compressions and rescue ventilations to maintain circulatory flow and oxygenation during cardiac arrest.[1] High-quality CPR is the cornerstone of resuscitation, with survival heavily dependent on immediate recognition of cardiac arrest and initiation of effective compressions and ventilation.[2]

Clinical Pearl: For every minute delay in starting CPR, survival from cardiac arrest decreases by 7-10%. Bystander CPR doubles or triples survival rates for out-of-hospital cardiac arrest.[3]

CPR maintains approximately 25-30% of normal cardiac output and 30-40% of normal myocardial blood flow when performed optimally.[4] This critical perfusion sustains vital organ viability until advanced life support and definitive treatment can be provided.

Key quality parameters for effective CPR:[1]

• Compression rate: 100-120 per minute
• Compression depth: 5-6 cm (2-2.4 inches)
• Chest recoil: Complete recoil between compressions
• Compression:ventilation ratio: 30:2 (until advanced airway placed)
• Minimized interruptions: Chest compression fraction > 80%

Exam Detail: MRCP/FRACP and FRCEM commonly test CPR quality metrics, compression-to-ventilation ratios, and indications for hands-only versus conventional CPR. USMLE emphasizes bystander CPR and AED use.

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Epidemiology

Impact of Bystander CPR

Global CPR Training and Performance

Training coverage:

• Only 20-30% of adults in developed countries trained in CPR[7]
• Bystander CPR rates: 40-60% in developed nations, > 10% in developing countries[8]
• Compression-only CPR (hands-only) increases bystander willingness to perform CPR by 50-70%[9]

CPR quality in practice:

• Actual compression depth median: 37-42mm (below 50mm target)[10]
• Only 15-20% of compressions meet both rate and depth targets simultaneously[11]
• Compression fraction in real arrests: 60-70% (below 80% target)[12]
• Rescuer fatigue significant after 1-2 minutes, necessitating rotation[13]

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Aetiology and Pathophysiology

Mechanisms of Blood Flow During CPR

Two primary theories explain circulatory flow during chest compressions:[14]

1. Cardiac Pump Theory:

• Direct compression of the heart between sternum and spine
• Closure of atrioventricular valves during compression creates forward flow
• Dominant mechanism at higher compression rates (> 100/min)

2. Thoracic Pump Theory:

• Increased intrathoracic pressure during compression propels blood
• Venous valves prevent retrograde flow
• Dominant during slower compressions or with simultaneous ventilation

Clinical Pearl: In reality, both mechanisms contribute. Optimal CPR technique maximizes both cardiac compression and intrathoracic pressure changes to generate forward flow.[14]

Physiological Effects of High-Quality CPR

Cardiovascular:

• Systolic BP: 60-80 mmHg (with compressions)
• Diastolic BP: 20-40 mmHg
• Mean arterial pressure: 40-50 mmHg
• Coronary perfusion pressure: 15-25 mmHg (threshold for ROSC: > 15 mmHg)[15]
• Cardiac output: 25-33% of normal[4]

Cerebral perfusion:

• Cerebral blood flow: 30-40% of normal during optimal CPR[16]
• Critical threshold for neuronal viability: > 20-25% of baseline
• Inadequate CPR (> 20% baseline flow) → progressive neuronal injury

Metabolic:

• Oxygen delivery reduced to 25-30% of normal
• Metabolic acidosis develops (lactic acidosis from tissue hypoxia)
• CO₂ elimination impaired (venous CO₂ rises, arterial CO₂ variable)

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Clinical Presentation

Recognition of Cardiac Arrest

The diagnosis must be made rapidly (> 10 seconds):[1]

Primary assessment criteria:

1. Unresponsive - No response to verbal stimuli ("Are you okay?") or shoulder tap
2. Not breathing normally - Absent breathing or only agonal gasps
3. No pulse (healthcare providers only) - Absent carotid pulse on > 10 second check

Clinical Pearl: Agonal gasps occur in 40-60% of cardiac arrests initially and should be recognized as a sign of cardiac arrest, NOT normal breathing.[17] They are brief, irregular gasps that indicate need for immediate CPR.

Situations Requiring CPR

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Investigations

CPR is a clinical intervention requiring no investigations before initiation. Investigations should NOT delay CPR.

During CPR (if resources available)

ETCO₂ interpretation during CPR:[20]

• > 10 mmHg → Poor CPR quality or low cardiac output, improve compressions
• 10-20 mmHg → Adequate CPR
• Sudden rise to 35-45 mmHg → Likely return of spontaneous circulation (ROSC), check pulse

Exam Detail: ETCO₂ is both a quality indicator during CPR and an early sign of ROSC. A sudden rise to near-normal values (35-40 mmHg) should prompt immediate pulse check.[20]

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Management

Basic Life Support (BLS) Algorithm - Adult

The universal sequence for cardiac arrest recognition and initial management:[1,2]

1. Ensure Safety

• Check environment is safe for rescuer and victim
• Activate personal protective equipment if available (gloves, face shield)

2. Check Responsiveness

• Tap shoulders firmly
• Shout "Are you okay?"
• If unresponsive → Call for help immediately

3. Activate Emergency Services

• Lone rescuer with mobile phone: Call emergency services (999/911), activate speaker
• Lone rescuer without mobile phone: Perform 2 minutes CPR first (if unwitnessed), then call
• Multiple rescuers: One person calls while another starts CPR

4. Check Breathing and Pulse (simultaneously, > 10 seconds)

• Open airway: Head tilt-chin lift (or jaw thrust if trauma suspected)
• Look, listen, feel: Normal breathing? (ignore agonal gasps)
• Check carotid pulse (healthcare providers only, > 10 seconds)

5. Position Patient

• Supine on firm, flat surface
• Remove/open clothing over chest

6. Begin Chest Compressions

7. Deliver Rescue Breaths (if trained and willing)

8. Continue CPR 30:2 until:

• Advanced help arrives
• AED/defibrillator available
• Patient shows signs of life
• Rescuer becomes exhausted
• Environment becomes unsafe

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Chest Compressions - Technique

Clinical Pearl: Compressions are the most critical component of CPR. If unable or unwilling to give rescue breaths, compression-only CPR is acceptable and far better than no CPR.[9]

Hand Position and Technique[1]

Hand placement:

1. Locate lower half of sternum (center of chest between nipples)
2. Place heel of one hand on sternum
3. Place heel of other hand on top of first hand
4. Interlock fingers, keep fingers off ribs

Body position:

• Shoulders directly over hands
• Arms straight, elbows locked
• Use body weight to compress (not arm muscles)

Compression technique:

• Depth: 5-6 cm (2-2.4 inches) in average adult[1]
  • Minimum 5 cm (2 inches)
  • Maximum 6 cm (2.4 inches) - excessive depth may cause injury without benefit[21]
• Rate: 100-120 compressions per minute[1]
  • Too slow (> 100/min) → inadequate coronary perfusion
  • Too fast (> 120/min) → inadequate recoil time and filling
• Complete chest recoil: Allow chest to return to normal position between compressions
  • Leaning on chest between compressions reduces venous return by 20-30%[22]
• Minimize interruptions: Target compression fraction > 80%
  • Compression fraction = (time compressions performed) / (total arrest duration)

Exam Detail: Common exam error: Stating compression depth as "2 inches" without specifying the 5-6cm range. The 2020 guidelines specify both imperial and metric with clear upper limit to avoid excessive depth.[1]

Compression Quality Metrics[11]

Rescuer Rotation and Fatigue[13]

Evidence for rotation:

• Compression depth decreases by 10-20% after 1 minute
• Quality deteriorates significantly after 2 minutes
• Rescuers often unaware of their own fatigue

Rotation strategy:[1]

• Rotate every 2 minutes (at rhythm check intervals)
• Swap smoothly with > 5 second pause
• Incoming rescuer prepares in advance
• Use feedback devices if available to monitor quality

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Rescue Breathing - Technique

Airway Opening[1]

Head tilt-chin lift (standard):

1. Place one hand on forehead, tilt head back
2. Place fingertips of other hand under chin, lift upward
3. Avoid pressing on soft tissues under chin

Jaw thrust (if spinal injury suspected):[24]

1. Kneel at head of patient
2. Place fingers behind angles of jaw
3. Lift jaw forward without extending neck
4. Maintain in-line spinal stabilization

Ventilation Technique[1]

Mouth-to-mouth:

1. Maintain head tilt-chin lift
2. Pinch nose closed
3. Take normal breath (not deep breath)
4. Seal lips around patient's mouth
5. Blow steadily over 1 second
6. Watch for chest rise
7. Allow passive exhalation
8. Deliver second breath (total 2 breaths)

Bag-mask ventilation (healthcare providers):[25]

• Two-person technique preferred (one seals mask, one squeezes bag)
• One-person: E-C clamp technique
  • "E": 3rd, 4th, 5th fingers form "E" lifting jaw
  • "C": Thumb and index finger form "C" sealing mask
• Tidal volume: 500-600 mL (enough for visible chest rise)
• Deliver over 1 second
• Avoid excessive rate and volume (causes gastric insufflation)

Clinical Pearl: Each rescue breath should take 1 second and produce visible chest rise. Excessive ventilation (too fast or too much volume) increases intrathoracic pressure, reduces venous return, and decreases coronary perfusion pressure by 20-30%.[26]

Common ventilation errors:

• Excessive tidal volume → gastric distension, aspiration risk
• Too rapid delivery → increased intrathoracic pressure
• Hyperventilation → respiratory alkalosis, reduced cerebral blood flow
• Inadequate seal → air leak, no chest rise
• Prolonged inspiratory time → reduced time for compressions

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CPR Sequence and Ratios

Standard CPR (30:2 Ratio)[1]

Cycle structure:

1. 30 chest compressions at 100-120/minute (~18 seconds)
2. 2 rescue breaths over 1 second each (~4-5 seconds including airway repositioning)
3. Repeat cycle
4. Continue until:
   • AED/defibrillator arrives
   • Advanced life support team takes over
   • Patient shows signs of life
   • Rescuer exhausted

Time per cycle: ~22-24 seconds = 2.5-2.7 cycles/minute

Compression fraction with 30:2 CPR:

• 18 seconds compressions / 23 seconds total = 78% compression fraction
• Acceptable, though > 80% target
• Any additional pauses further reduce compression fraction

Compression-Only CPR (Hands-Only CPR)[9]

Indications:[1,27]

• Untrained lay rescuer
• Rescuer unwilling/unable to give breaths
• Telephone CPR instructions from dispatcher
• Suspected cardiac etiology (witnessed sudden collapse in adult)

Technique:

• Continuous chest compressions at 100-120/minute
• No pauses for ventilation
• Compression fraction approaches 100%

Evidence:[9,27]

• Non-inferior to conventional CPR for witnessed cardiac arrest in first 6-8 minutes
• Survival similar or improved vs 30:2 CPR when performed by lay rescuers
• Likely inferior for prolonged arrests > 10 minutes (progressive hypoxemia)
• Definitely inferior for respiratory arrest (drowning, choking, overdose)

Exam Detail: Key point for exams: Compression-only CPR is acceptable for untrained/unwilling lay rescuers and suspected cardiac arrests. Healthcare providers should perform conventional 30:2 CPR unless advanced airway in place.[1,9]

CPR with Advanced Airway in Place[1]

Once endotracheal tube or supraglottic airway inserted:

Compressions:

• Continuous at 100-120/minute (no pauses for ventilation)
• Compression fraction approaches 100%

Ventilations:

• 10 breaths per minute (1 breath every 6 seconds)
• Asynchronous with compressions
• Avoid hyperventilation (common error)

Advantages:

• Eliminates interruptions for ventilation
• Maximizes compression fraction
• Simplifies coordination

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Special Circumstances

Pregnancy (> 20 Weeks Gestation)[28]

Modifications:

• Manual uterine displacement: Displace uterus to left to relieve aorto-caval compression
  • Rescuer places hands on right side of uterus, pushes leftward
  • Maintains displacement throughout CPR
• Prepare for perimortem caesarean section: If no ROSC after 4 minutes, deliver within 5 minutes of arrest[28]
• Standard compression depth and rate otherwise

Trauma Cardiac Arrest[29]

Reversible causes prioritized:

• Tension pneumothorax → Bilateral needle decompression
• Hemorrhage → Control bleeding, massive transfusion protocol
• Cardiac tamponade → Resuscitative thoracotomy if penetrating chest trauma

CPR modifications:

• Open chest compressions if thoracotomy performed
• Consider resuscitative endovascular balloon occlusion of aorta (REBOA) if available

Drowning[18]

Initial management difference:

• 5 initial rescue breaths before starting compressions
  • "Rationale: Hypoxia is primary mechanism, not VF"
  • Oxygenation priority before circulation
• Then standard 30:2 CPR
• Remove from water only if safe to do so
• CPR can be started in shallow water if rescuer safety ensured

Opioid Overdose[30]

• Standard CPR as described
• Administer naloxone (intranasal 2mg or IM 0.4-2mg) if available
• Naloxone does NOT replace CPR - continue compressions and ventilation
• Respiratory arrest may precede cardiac arrest - rescue breathing alone may suffice if pulse present

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Automated External Defibrillator (AED) Use[1]

AED deployment:

1. Turn on AED - follow voice prompts
2. Attach pads to bare chest (anterolateral or anteroposterior position)
3. Stop CPR, ensure no one touching patient
4. AED analyzes rhythm automatically
5. If shock advised:
   • Ensure all clear ("I'm clear, you're clear, everyone clear")
   • Press shock button
   • Immediately resume CPR for 2 minutes (do NOT check pulse)
6. If no shock advised:
   • Immediately resume CPR for 2 minutes
7. AED will re-analyze after 2 minutes

Clinical Pearl: The most common error with AED use is prolonged pause after shock delivery to check pulse. Post-shock, immediately resume CPR for 2 minutes regardless of rhythm.[1]

Public access defibrillation (PAD):

• Widely deployed in airports, train stations, shopping centers, sports facilities
• Bystander AED use increases survival from 10% to 30-40% in shockable rhythms[31]
• Fully automated external defibrillators (AEDs) can deliver shock without button press

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Quality Improvement: Real-Time Feedback Devices[32]

Available technologies:

• Accelerometer-based devices - measure compression depth and rate (e.g., TrueCPR, CPRmeter)
• Force sensors - measure applied force and recoil
• Audiovisual feedback - metronomes, visual depth indicators
• Smartwatch/wearable devices - recent development showing promise[33]

Evidence for feedback devices:[32,34]

• Improve compression depth by 5-10mm
• Improve compression rate adherence by 20-25%
• Improve complete recoil by 15-20%
• Variable impact on survival outcomes (some studies positive, others neutral)
• Most beneficial for training and skill retention

Limitations:

• Device setup may delay CPR initiation
• Over-reliance on technology
• False feedback if device malfunction
• Cannot replace proper technique and training

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Complications

Complications of CPR

Clinical Pearl: Rib fractures occur in 30-50% of CPR recipients and are NOT a contraindication to continuing CPR. Fear of causing injury should never prevent or stop CPR in cardiac arrest.[35]

Post-ROSC assessment:

• Chest X-ray to identify fractures, pneumothorax
• Clinical examination for chest wall instability
• Analgesia for chest wall pain

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Prognosis

Survival Determinants

Utstein survival predictors:[36]

Chain of Survival[2]

The five links determining outcomes:

1. Recognition and activation - Call emergency services immediately
2. Early CPR - Bystander CPR doubles/triples survival
3. Rapid defibrillation - Each minute delay reduces survival 7-10%
4. Advanced life support - ACLS medications, advanced airway
5. Post-resuscitation care - Targeted temperature management, PCI, neuroprotection

Breaking any link substantially reduces survival.

Neurological Outcomes

Exceptions allowing longer arrests:[37]

• Hypothermia (> 30°C) - neuroprotection from cold
• Witnessed arrest with continuous CPR - no true "no-flow" period
• Young age (> 50 years) with shockable rhythm

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Prevention and Screening

Primary Prevention - CPR Training

Target populations for training:

• All healthcare professionals (mandatory)
• Teachers and school staff
• Caregivers of high-risk individuals
• Family members of cardiac patients
• General public (public health campaigns)

Training approaches:[38]

• Standard courses: 4-6 hours, instructor-led (BLS/HEARTSAVER)
• Brief compression-only training: 30-60 minutes for lay public
• Video self-instruction: Effective for skill acquisition
• Refresher training: Every 1-2 years (skills decay after 3-12 months)

Secondary Prevention - High-Risk Individuals

Patients requiring CPR skills training for family members:

• Recent myocardial infarction or cardiac arrest survivors
• Heart failure (EF > 35%)
• Implantable cardioverter-defibrillator (ICD) recipients
• Hypertrophic cardiomyopathy
• Long QT syndrome or other channelopathies
• Chronic kidney disease on hemodialysis
• Severe COPD

Public access defibrillation (PAD) programs:[31]

• AED deployment in public spaces increases bystander defibrillation rates from > 5% to 20-40%
• Most effective in high-traffic areas (airports, casinos, sports venues)
• Lay responder AED use within 3 minutes achieves 60-70% survival for VF arrests[31]

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Key Guidelines

1. AHA 2020 Guidelines: Adult Basic and Advanced Life Support[1]
2. ERC 2021 Guidelines: European Resuscitation Council Adult Basic Life Support[39]
3. ILCOR 2020 CoSTR: International Consensus on CPR and ECC Science[40]
4. Resuscitation Council UK 2021: Adult Basic Life Support Guidelines[41]

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Exam Scenarios

SBA Question 1

Scenario: A 55-year-old man collapses in the outpatient clinic. He is unresponsive with no palpable pulse. You begin CPR immediately. What is the correct chest compression depth for an adult?

A) 2-3 cm
B) 3-4 cm
C) 4-5 cm
D) 5-6 cm
E) 6-7 cm

Answer

Answer: D) 5-6 cm

The 2020 AHA and 2021 ERC guidelines specify chest compression depth of 5-6 cm (2-2.4 inches) for adult CPR.[1,39] Compressions should be:

• Minimum 5 cm (to generate adequate intrathoracic pressure and cardiac output)
• Maximum 6 cm (excessive depth may cause injury without additional benefit)

Shallower compressions (> 5 cm) are the most common quality error, occurring in > 50% of CPR attempts, and reduce ROSC rates by approximately 50%.[10]

SBA Question 2

Scenario: You are teaching a lay rescuer CPR. They ask about the compression-to-ventilation ratio. What is the correct ratio for single-rescuer adult CPR before an advanced airway is placed?

A) 15:2
B) 30:2
C) 100:2
D) Continuous compressions only (no ventilations)
E) 5:1

Answer

Answer: B) 30:2

For adult CPR (single or two-rescuer) before an advanced airway is in place, the compression:ventilation ratio is 30:2 - 30 chest compressions followed by 2 rescue breaths.[1]

This ratio applies to:

• Lay rescuer CPR
• Healthcare provider CPR
• Single-rescuer or two-rescuer scenarios

Once an advanced airway (endotracheal tube or supraglottic airway) is placed, compressions become continuous at 100-120/min with asynchronous ventilations at 10 breaths/min.[1]

Option D (continuous compressions only) is acceptable for untrained/unwilling lay rescuers performing "hands-only CPR," but the standard taught ratio is 30:2.[9]

SBA Question 3

Scenario: During CPR on a 68-year-old woman, the team has placed an endotracheal tube and confirmed placement with waveform capnography. What is the appropriate ventilation rate now?

A) 1 breath every 2 seconds (30 breaths/min)
B) 1 breath every 3 seconds (20 breaths/min)
C) 1 breath every 6 seconds (10 breaths/min)
D) 2 breaths after every 30 compressions
E) 1 breath every 12 seconds (5 breaths/min)

Answer

Answer: C) 1 breath every 6 seconds (10 breaths/min)

Once an advanced airway is in place during CPR, ventilations should be delivered at 10 breaths per minute (1 breath every 6 seconds), asynchronous with continuous chest compressions at 100-120/min.[1]

This strategy:

• Maximizes compression fraction (approaches 100%)
• Avoids hyperventilation (which increases intrathoracic pressure and reduces venous return)
• Simplifies coordination (no need to pause compressions for breaths)

Option D (2 breaths after 30 compressions) was correct BEFORE advanced airway placement but is now obsolete once the airway is secured.[1]

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Viva Scenario

Examiner: "You are shopping in a supermarket when a middle-aged man suddenly collapses in front of you. Walk me through your immediate actions."

Candidate approach:

Scene safety and initial assessment (10 seconds): "First, I would quickly assess scene safety - ensure there are no hazards to myself or the patient. I would approach the patient, tap his shoulders firmly and shout 'Are you okay?' to assess responsiveness. If he doesn't respond, I would immediately call for help - shout for someone to call 999 (or 911) and bring an AED if available."

Airway and breathing check: "I would open the airway with a head tilt-chin lift maneuver and simultaneously check for breathing and a pulse. I would look for chest rise, listen for breath sounds, and feel for a carotid pulse - this should take no more than 10 seconds. If there is no pulse and no normal breathing (ignoring agonal gasps if present), I would immediately start CPR."

Examiner: "There is no pulse and he is not breathing. Demonstrate your CPR technique."

Candidate: "I would position the patient flat on his back on the firm floor, expose his chest, and begin chest compressions:

Chest compressions:

• Hand position: Heel of one hand on the lower half of the sternum (center of chest), heel of other hand on top, fingers interlocked
• Body position: Shoulders directly over hands, arms straight, elbows locked
• Compression depth: 5-6 cm using my body weight
• Compression rate: 100-120 compressions per minute - I might count aloud or use a mental rhythm like 'Stayin' Alive' by the Bee Gees which has the right tempo
• I would ensure complete chest recoil between compressions - not leaning on the chest

After 30 compressions, I would give 2 rescue breaths:

Rescue breaths:

• Maintain head tilt-chin lift to keep airway open
• Pinch nose closed
• Take a normal breath myself
• Seal my lips around his mouth
• Blow steadily over 1 second watching for chest rise
• Allow passive exhalation, then deliver second breath

Then I would immediately resume compressions, continuing 30:2 cycles until help arrives or an AED is available."

Examiner: "Someone brings an AED. What do you do?"

Candidate: "I would:

1. Turn on the AED immediately - it will give voice prompts to guide me
2. Attach the pads to his bare chest in the anterolateral position (one pad right upper chest below clavicle, one pad left lower chest below armpit)
3. Ensure no one is touching him while the AED analyzes the rhythm
4. If the AED advises a shock, I would make sure everyone is clear - 'I'm clear, you're clear, everyone clear' - then press the shock button
5. Immediately resume CPR after shock delivery for 2 minutes without checking pulse
6. The AED will prompt me to stop for rhythm reanalysis every 2 minutes
7. Continue this cycle until advanced help arrives or the patient shows signs of life

If the AED advises 'no shock', I would immediately resume CPR for 2 minutes."

Examiner: "Good. What if you were unwilling or unable to give rescue breaths?"

Candidate: "That would be completely acceptable. I would perform continuous chest compressions at 100-120 per minute without pauses - this is called 'hands-only CPR' or compression-only CPR. Evidence shows this is nearly as effective as conventional CPR for witnessed adult cardiac arrests, especially in the first 6-8 minutes, and is strongly encouraged rather than doing nothing.[9] The priority is high-quality chest compressions."

Examiner: "The patient achieves ROSC after 8 minutes. What position would you place him in now?"

Candidate: "If he achieves return of spontaneous circulation but remains unconscious, I would place him in the recovery position (lateral recumbent position) to:

• Maintain an open airway
• Allow drainage of secretions/vomit
• Prevent aspiration
• Monitor his breathing and pulse

I would continue to monitor him closely until paramedics arrive, checking pulse and breathing frequently. If he stops breathing or loses his pulse again, I would immediately resume CPR."

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Patient Explanation (Layperson Level)

"CPR stands for cardiopulmonary resuscitation - it's an emergency technique used when someone's heart stops beating. When the heart stops, blood stops flowing to the brain and other vital organs. Brain cells start dying within 4-6 minutes without oxygen, so immediate action is critical.

CPR has two main parts: chest compressions and rescue breaths.

Chest compressions involve pushing hard and fast on the center of the chest. You compress the heart between the breastbone and spine, which squeezes blood out to the body and brain. You need to push about 2 inches deep (5-6 cm) at a rate of 100-120 pushes per minute - about the beat of the song 'Stayin' Alive.'

Rescue breaths involve blowing air into the person's lungs to provide oxygen. You give 2 breaths after every 30 compressions.

If you're not trained or uncomfortable giving breaths, it's completely fine to do compression-only CPR - just push continuously on the chest. This is much better than doing nothing and can double or triple the person's chance of survival.

The most important things to remember:

1. Call for help immediately - dial 999 or 911
2. Start compressions right away - every second counts
3. Push hard and fast - you can't push too hard when someone's heart has stopped
4. Don't stop until help arrives or the person wakes up

Don't worry about hurting someone or doing it perfectly. When someone's heart has stopped, they are already in the worst possible situation - you can only help, not make it worse. Even imperfect CPR is infinitely better than no CPR."

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References

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2. Merchant RM, Topjian AA, Panchal AR, et al. Part 1: Executive Summary: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2020;142(16_suppl_2):S337-S357. doi:10.1161/CIR.0000000000000918

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12. Christenson J, Andrusiek D, Everson-Stewart S, et al. Chest compression fraction determines survival in patients with out-of-hospital ventricular fibrillation. Circulation. 2009;120(13):1241-1247. doi:10.1161/CIRCULATIONAHA.109.852202

13. Hightower D, Thomas SH, Stone CK, et al. Decay in quality of closed-chest compressions over time. Ann Emerg Med. 1995;26(3):300-303. doi:10.1016/s0196-0644(95)70076-5

14. Paradis NA, Martin GB, Rivers EP, et al. Coronary perfusion pressure and the return of spontaneous circulation in human cardiopulmonary resuscitation. JAMA. 1990;263(8):1106-1113.

15. Reynolds JC, Salcido DD, Menegazzi JJ. Coronary perfusion pressure and return of spontaneous circulation after prolonged cardiac arrest. Prehosp Emerg Care. 2010;14(1):78-84. doi:10.3109/10903120903349796

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