BLS Algorithm | Basic Life Support (CPR) Protocol

Chain of Survival (AHA 2020)

Each link must be activated rapidly — time to first compression & defibrillation = primary determinant of survival.

📞

Early Recognition & Activation

Call 911/Code Blue

🫁

Early CPR

Push Hard & Fast

⚡

Early Defibrillation

AED within 3-5 min

🏥

Advanced Life Support

ACLS/Drugs/Airway

🧊

Post-Cardiac Arrest Care

TTM/PCI/Neuro

BLS Algorithm — Stepwise

1

Scene Safety & Responsiveness

Ensure scene is safe. Tap shoulders firmly & shout "Are you okay?" Check for no breathing or only gasping (agonal respirations = cardiac arrest). Simultaneously check carotid pulse (healthcare provider) — ≤10 seconds.

2

Activate Emergency Response & Get AED

If unresponsive with no normal breathing & no pulse: Activate code/call 911. Send someone for AED/defibrillator. If alone with phone — call first, put on speaker, begin CPR. Lone rescuer with unwitnessed collapse in child → 2 min CPR first, then call.

3

Begin High-Quality CPR — C-A-B Sequence

Compressions FIRST (C), then Airway (A), then Breathing (B). Start chest compressions immediately. 30:2 ratio (single/two rescuer adult), 15:2 (two-rescuer child/infant).

100-120/min

Rate

≥2 inches

Depth (5-6cm)

Full Recoil

Allow chest wall

4

AED Arrives — Analyze & Shock

Power on AED → attach pads → allow analysis → if shockable rhythm (VF/pVT): deliver shock → immediately resume CPR for 2 min. If non-shockable (Asystole/PEA): resume CPR immediately. Minimize interruptions to <10 seconds.

5

Continue Until ROSC or ACLS Team

Continue CPR cycles. Rotate compressors every 2 minutes (or every 5 cycles) to prevent fatigue. Check rhythm every 2 min. Continue until: ROSC (spontaneous breathing, pulse, movement), ACLS team takes over, or termination criteria met.

Critical Decision: Pulse Present but No Breathing

If pulse is present but patient is not breathing normally → Rescue breathing only: 1 breath every 5-6 seconds (adults) = 10-12 breaths/min. Recheck pulse every 2 minutes. If pulse becomes absent → start full CPR.

High-Quality CPR Parameters

Parameter	Adult (Puberty+)	Child (1yr–Puberty)	Infant (<1yr)
Compression Depth	≥2 in (5-6 cm)	≈2 in (5 cm) — ⅓ AP	1.5 in (4 cm) — ⅓ AP
Rate	100-120/min	100-120/min	100-120/min
Hand Position	Heel of 2 hands, lower ½ sternum	1 or 2 hands, lower ½ sternum	2 fingers (single) or 2 thumb-encircling (2-rescuer)
C:V Ratio (1 rescuer)	30:2	30:2	30:2
C:V Ratio (2 rescuer HCP)	30:2	15:2	15:2
With Advanced Airway	Continuous compressions at 100-120/min + 1 breath every 6 sec (10/min) — no pausing
Chest Recoil	Allow FULL chest recoil between compressions — do NOT lean on chest
Interruptions	Minimize to <10 seconds. Chest compression fraction (CCF) goal >60%, ideally >80%

⚠️ Common CPR Errors

• Inadequate depth (<5 cm) — most common error
• Excessive rate (>120/min) — reduces filling time
• Incomplete recoil (leaning) — ↓ venous return, ↓ coronary perfusion
• Excessive ventilation — ↑ intrathoracic pressure, ↓ venous return
• Prolonged interruptions — every pause ↓ coronary perfusion pressure
• Compressor fatigue — quality declines after ~2 min even if unperceived

✓ Quality Metrics & Feedback

• ETCO₂: If intubated, target >10 mmHg (indicates adequate perfusion); if <10 after 20 min → poor prognosis
• Arterial line: Diastolic BP >25 mmHg = adequate CPP goal
• Coronary Perfusion Pressure (CPP): Target >15 mmHg for ROSC
• ScvO₂: Target >30% during CPR
• Use real-time CPR feedback devices when available

Hands-Only CPR (Lay Rescuer)

For untrained bystanders or those unwilling to give breaths: continuous chest compressions at 100-120/min without ventilation. Effective for first several minutes in adult witnessed VF/VT arrest (oxygen reserve in blood). Dispatcher-assisted CPR should guide this approach.

AED & Defibrillation

⚡ AED Steps

1. Power ON the AED
2. Attach pads — right infraclavicular + left lateral (V5-V6 position). Ensure dry skin, remove patches, shave if needed
3. Clear patient — "ANALYZING… EVERYONE CLEAR"
4. If shock advised → "CLEAR!" → deliver shock
5. Immediately resume CPR for 2 minutes
6. Repeat analysis after 2 min cycle

Pad Placement Options

Anterolateral (default): Right infraclavicular + left mid-axillary at V5-V6
Anteroposterior: Anterior left precordium + posterior left infrascapular — may be superior in refractory VF
Pregnancy: Standard position; pads do NOT harm fetus. Defibrillation IS indicated.
Implanted devices: Place pad ≥1 inch (2.5 cm) away from pacemaker/ICD generator
Transdermal patches: Remove, wipe skin, then apply pads

Defibrillation Energy Levels

Device	1st Shock	Subsequent	Notes
Biphasic (adult)	120-200 J	Equal or escalating	Follow manufacturer; if unknown → max dose
Monophasic (adult)	360 J	360 J	All shocks at 360 J
Pediatric (manual)	2 J/kg	4 J/kg (max 10 J/kg)	Use pediatric pads/attenuator <8 yr
AED (child <8yr)	Use pediatric dose attenuator if available		If unavailable → use standard adult AED

⏱ Time is Critical

Survival from VF/pVT decreases 7-10% per minute without CPR. With bystander CPR the decline is reduced to 3-4%/min. Defibrillation within 3-5 min of collapse can achieve 50-70% survival.

Airway Management in BLS

Basic Airway Maneuvers

Head Tilt-Chin Lift: Default maneuver. Tilt head back with one hand on forehead, lift chin with fingertips of other hand. Opens oropharynx.
Jaw Thrust: For suspected C-spine injury. Place fingers behind mandibular angles, displace jaw anteriorly. NO head extension.
If jaw thrust inadequate: AHA 2020 — use head tilt-chin lift even with suspected spine injury (airway takes priority over immobilization).

Ventilation Methods

Mouth-to-mouth: Pinch nose, create seal, give 1 sec breath watching for chest rise
Mouth-to-nose: When mouth cannot be opened/sealed
Pocket mask: Preferred — barrier protection + supplemental O₂ port
Bag-Valve-Mask (BVM): 2-person technique preferred. EC-clamp grip. Deliver 600 mL tidal volume (enough for visible chest rise)
Mouth-to-stoma: For laryngectomy/tracheostomy patients

⚠️ Ventilation Pitfalls

• Avoid excessive ventilation — causes gastric distension, ↑ intrathoracic pressure, ↓ venous return & cardiac output
• Each breath: 1 second duration, just enough for visible chest rise
• Do NOT hyperventilate — even with advanced airway, limit to 10 breaths/min
• If chest doesn't rise: reposition airway, ensure adequate seal, consider obstruction

Foreign Body Airway Obstruction (FBAO)

Conscious Adult/Child — Severe Obstruction:

1. Ask "Are you choking?" — if cannot speak/cough/breathe
2. Abdominal thrusts (Heimlich maneuver)
3. Repeat until effective or patient becomes unconscious
4. Pregnant/obese → chest thrusts instead

Unconscious — After FBAO:

1. Lower to ground, activate emergency response
2. Begin CPR (30:2) — compressions may dislodge object
3. Each time airway opened: look for visible object → remove if seen
4. Do NOT perform blind finger sweeps

Infant FBAO: 5 back blows (slaps) + 5 chest thrusts (two-finger). NO abdominal thrusts in infants. Repeat cycles until object expelled or infant becomes unresponsive → begin infant CPR.

Special Resuscitation Situations

🤰 Cardiac Arrest in Pregnancy

• Left lateral uterine displacement (LUD): Manual displacement of gravid uterus to the left to relieve IVC compression
• Standard BLS with NO modification to compression depth or rate
• Defibrillation at standard energy — safe for fetus
• Remove fetal monitors during defibrillation
• Perimortem C-section (PMCS): If ≥20 weeks & no ROSC within 4-5 min → emergent delivery to improve maternal resuscitation
• IV access above the diaphragm preferred

🌊 Drowning

• Exception to C-A-B: Use A-B-C sequence — hypoxia is primary insult
• Begin rescue breaths as soon as possible, even in water if trained
• 5 initial rescue breaths recommended
• C-spine precautions only if mechanism suggests (diving, high-speed water sports)
• Do NOT attempt to drain water from lungs — delays CPR
• Hypothermia common — prolonged resuscitation justified ("not dead until warm and dead")

🥶 Hypothermia

• Pulse check extended to 30-45 seconds (bradycardia expected)
• If no definite pulse → start CPR
• Defibrillation: If core temp <30°C, may attempt 1 shock; if unsuccessful, defer further shocks until rewarmed to >30°C
• Medications: Withhold or space ACLS drugs if core temp <30°C (impaired metabolism)
• Continue CPR during rewarming — do not terminate until normothermic
• Target rewarming: ECMO/cardiopulmonary bypass is gold standard for severe hypothermic arrest

⚡ Electrocution / Lightning Strike

• Ensure source is disconnected before touching patient
• Lightning: Safe to touch immediately (no retained charge)
• Lightning may cause VF/asystole — standard BLS/ACLS
• Reverse triage in mass lightning events: treat apparently dead first (they may respond to early CPR); walking wounded can wait
• Watch for associated trauma (falls, blasts)

💊 Opioid Overdose

• Suspected opioid OD with definite pulse but no/abnormal breathing → Naloxone + rescue breathing
• Naloxone (Narcan): 2 mg IN (intranasal) or 0.4 mg IM — may repeat every 4 min
• If no pulse → full CPR + naloxone (naloxone alone won't help in cardiac arrest)
• AHA 2020: Lay rescuers should administer naloxone when available for suspected OD
• Recovery position after ROSC if breathing adequately

🫀 Anaphylaxis Leading to Arrest

• Epinephrine IM (0.3-0.5 mg of 1:1000) is first-line — give immediately if anaphylaxis suspected
• If cardiac arrest: standard BLS + early epinephrine IV (1 mg of 1:10,000 per ACLS)
• Aggressive fluid resuscitation (distributive shock)
• Prolonged CPR may be required (young, healthy patients with reversible cause)

Pediatric & Neonatal Resuscitation

Age Definitions (AHA)

Neonate

Birth – 28 days

Infant

<1 year

Child

1yr – Puberty

Infant BLS Key Differences

• Check brachial pulse (not carotid) — ≤10 seconds
• Compression technique: 2-finger (single rescuer) or 2-thumb encircling hands (2-rescuer — preferred, generates higher pressures)
• Depth: 1.5 inches (4 cm) or ⅓ AP diameter
• Landmark: Just below nipple line on sternum
• Cover mouth AND nose for rescue breaths (mouth-to-mouth-and-nose)
• Compression rate: 100-120/min (same as adult)
• Most pediatric arrests are RESPIRATORY in etiology → ventilation is critical

👶 Neonatal Resuscitation (NRP) — Delivery Room

Follows Neonatal Resuscitation Program (NRP) algorithm — distinct from pediatric BLS.

Initial Steps (within 30 seconds):

• Warm (radiant warmer, plastic wrap for <32 wk)
• Dry (unless premature — leave in wrap)
• Stimulate (flick soles, rub back)
• Position airway (sniffing position, suction only if obstruction)
• Delayed cord clamping ≥30-60 sec if vigorous

If HR <100 or gasping/apneic:

• PPV (Positive Pressure Ventilation) — most important intervention in neonatal resuscitation
• Rate: 40-60 breaths/min ("breathe-two-three, breathe-two-three")
• Start with 21% FiO₂ (room air) for ≥35 weeks; 21-30% for <35 weeks
• Titrate O₂ by SpO₂ targets (preductal, right hand)
• Reassess at 15-30 seconds of effective PPV

If HR <60 despite effective PPV × 30 sec:

• Start chest compressions: 2 thumb-encircling technique
• Ratio: 3:1 (compressions:ventilations) = 90 compressions + 30 breaths/min = 120 events/min
• Depth: ⅓ AP diameter of chest
• Increase FiO₂ to 100% when compressions initiated
• Consider intubation (ETT) and UVC for epinephrine access

If HR remains <60 despite compressions + PPV:

• Epinephrine: 0.01-0.03 mg/kg IV/UVC (1:10,000) — preferred route
• ET route: 0.05-0.1 mg/kg (higher dose needed)
• Volume expansion: 10 mL/kg NS if suspected hypovolemia/blood loss
• Reassess — consider pneumothorax, congenital anomaly

Neonatal Target SpO₂ (Preductal — Right Hand)

Time After Birth	Target SpO₂
1 min	60-65%
2 min	65-70%
3 min	70-75%
4 min	75-80%
5 min	80-85%
10 min	85-95%

ACLS Cardiac Arrest Medications

These are ACLS-level drugs given during cardiac arrest resuscitation — included for completeness as the natural next step after BLS.

Epinephrine (Adrenaline)

Dose: 1 mg IV/IO every 3-5 minutes

Concentration: 1:10,000 (0.1 mg/mL) for IV

Timing: VF/pVT → after 2nd shock; PEA/Asystole → as soon as possible

MOA: α₁ vasoconstriction → ↑ aortic diastolic pressure → ↑ coronary & cerebral perfusion pressure

Pediatric: 0.01 mg/kg (0.1 mL/kg of 1:10,000) IV/IO q3-5min

Amiodarone

Indication: VF/pVT unresponsive to defibrillation + CPR + epinephrine

Dose: 300 mg IV/IO bolus (1st dose) → 150 mg (2nd dose if needed)

Pediatric: 5 mg/kg IV/IO bolus (max 300 mg); may repeat to 15 mg/kg/day

Lidocaine (Alternative to Amiodarone)

Dose: 1-1.5 mg/kg IV/IO (1st dose) → 0.5-0.75 mg/kg q5-10min (max 3 mg/kg)

Pediatric: 1 mg/kg IV/IO loading dose

Sodium Bicarbonate

Dose: 1 mEq/kg IV

Indications: Hyperkalemia, TCA overdose, pre-existing metabolic acidosis, prolonged arrest. NOT routine.

Calcium Chloride / Gluconate

Dose: CaCl₂: 20 mg/kg (10% solution) slow IV push; Ca Gluconate: 60 mg/kg

Indications: Hyperkalemia, hypocalcemia, calcium channel blocker OD, hypermagnesemia. NOT routine in arrest.

Magnesium Sulfate

Dose: 1-2 g IV/IO diluted in 10 mL D5W over 5-20 min (or push in arrest)

Indication: Torsades de Pointes (polymorphic VT with long QT)

Reversible Causes — H's & T's

H's:

• Hypovolemia
• Hypoxia
• Hydrogen ion (acidosis)
• Hypo/Hyperkalemia
• Hypothermia

T's:

• Tension pneumothorax
• Tamponade (cardiac)
• Toxins
• Thrombosis — pulmonary
• Thrombosis — coronary