7H 6T

Hypoxia

Hypoxia Cyanosis, Low SpO₂, poor or absent, poor air entry, choking, drowning, overdose

Good ventilations, compressions, Give fluid bolus if indicated, control bleeding, keep warm.

Hypovolemia

Hypovolemia bleeding, trauma, vomiting/diarrhoea, dehydration, shock, flat neck veins

Hydrogen ion (Acidosis)

Hydrogen ion (Acidosis) prolonged downtime or poor perfusion (latic acid), DKA, Sepsis, Pt may have been hyperventilating (kussmaul breathing prior to arrest) QRS wide and arrythmias (potentially) arrest will likely be PEA > Asystole ETCO2 will likely be low <10mmHg

high-quality CPR and good volume ventilations to reduce acidosis, Sodium bicarbonate (only if ventilations are good), fluids.

Hyperkalemia

Hyperkalemia
Hx renal disease, missed dialysis, weakness prior to arrest, Crush Syndrome, rabdo (red urine/ strenuous exercise/ long lies), overdose of ACE inhibitors or ARBs, (red urine), TCA overdose (ends in mine, line or pin)

Calcium chloride, calcium gluconate, salbutamol 20mg neb adult, 5mg child, sodium bicarbonate. Flattened P waves > Peaked T waves > wide QRS > sinusoidal waves.

Potassium Level (mmol/L)	ECG Changes
5.5 – 6.5 (Mild)	- Tall, peaked T waves (especially in anterior leads V2–V4) - Shortened QT interval
6.5 – 7.5 (Moderate)	- Flatter or absent P waves - Prolonged PR interval - T wave peaks more prominent
7.5 – 8.5 (Severe)	- Widened QRS complex - Slurred or bizarre QRS morphology - T wave merges with QRS ("sine wave" begins)
> 8.5 (Critical)	- Sine wave pattern (fusion of QRS–T) - Ventricular fibrillation, asystole, or bradycardic PEA - Cardiac arrest imminent or ongoing

Hypokalemia

Hypokalemia
Hx of diuretic use, vomiting, diarrhoea, muscle cramps, weakness, insulin overdose, sizure of palpatations prior to arrest
Potassium chloride IV

magnesium sulfide if TDP or prolonged QT

Flatted T waves, ST depression, prominent U waves, prolonged QT.

Potassium Level (mmol/L)	ECG Findings
3.0 – 3.5 (mild)	- Flattened or inverted T waves - Prominent U waves (best in V2–V3)
2.5 – 3.0 (moderate)	- ST depression - Prolonged PR and QT intervals
< 2.5 (severe)	- U waves more prominent - Prolonged QT → Torsades de Pointes or VF - Ectopy, PVCs, VT, VF

Hypoglycemia

Hypoglycemia

Known diabetic, low GCS before arrest, BGL check

150 mL (15 g of glucose), followed by 100 mL (10 g) boluses every 5 minutes until the blood glucose level (BGL) exceeds 4.0 mmol/L.

paediatric patients, the dosage is 0.25 g/kg (2.5 mL/kg) of Glucose 10%, with additional 0.1 g/kg (1 mL/kg) boluses every 5 minutes as needed

Hypothermia

Hypothermia

Cold to touch, found outdoors, wet clothes, elderly or very young

Action: Begin active rewarming, continue CPR – “you’re not dead until you’re warm and dead”

Tension Pneumothorax

Tension Pneumothorax

Trauma, absent breath sounds on one side, distended neck veins, difficult ventilation, tracheal deviation, subcutaneous emphysema, chest pain sudden and pleuritic, increased work of breathing

Decompress chest (needle thoracostomy or finger thoracostomy if in scope)

Tamponade (Cardiac)

Tamponade (Cardiac)

Penetrating chest trauma, JVD, hypotension unresponsive to fluids, low voltage alternating QRS, arrect likely PEA

Rapid transport, continue CPR

Toxins (Overdose/Poisoning)

Toxins (Overdose/Poisoning)

Drug paraphernalia, medication packets, pinpoint or dilated pupils, known history

Action: Airway support, consider naloxone for opioid overdose, early hospital notification

Opioids

Heroin, oxycodone, fentanyl, methadone

Naloxone IM/IV/IN, oxygen, airway support

Benzodiazepines

Diazepam, temazepam, alprazolam (Xanax)

Supportive care, airway and ventilation

TCAs

Amitriptyline, nortriptyline, clomipramine

Sodium bicarbonate IV, manage arrhythmias, airway support

Paracetamol

Panadol, Panamax

N-acetylcysteine (NAC) IV (hospital), supportive

Beta Blockers

Metoprolol, atenolol, propranolol

Glucagon IV (if available), high-dose insulin/glucose (hospital), pacing

Calcium Channel Blockers

Verapamil, diltiazem, amlodipine

Calcium gluconate, high-dose insulin/glucose, vasopressors

Thrombosis – Cardiac (MI)

Thrombosis – Cardiac (MI)

History of chest pain, known cardiac disease, ECG pre-arrest (if available)

pre-alert hospital, PCI referral, thrombolysis

Thrombosis – Pulmonary (PE)

Thrombosis – Pulmonary (PE)

Sudden collapse, shortness of breath beforehand, swollen leg, long immobilisation (e.g., post-op, long haul flight)

Supportive care only prehospital – good CPR, consider PE in handover

Risk factors

Deep vein thrombosis (DVT) (most common source)

Recent surgery (especially pelvic, abdominal, or orthopaedic)

Cancer (especially metastatic or on chemotherapy)

Trauma or fractures (especially to lower limbs or pelvis)

Prolonged immobility (e.g. bed rest, long travel, hospitalisation)

Heart failure or chronic respiratory disease

Trauma

Trauma

Blunt or penetrating injury, visible wounds, obvious signs of major trauma

Control bleeding, decompress chest if indicated, rapid extrication and transport, keep warm, consider pelvic binder if significant mechanism.

Sudden collapse, no prodrome, previously talking normally

History

• Immediate collapse

• No dizziness

• No respiratory distress

• No gradual deterioration

More likely

• Thrombosis (coronary) → malignant arrhythmia

• Thrombosis (PE)

• Electrolyte (esp K+/Mg++) → arrhythmia

• Toxins → arrhythmia

• Pregnancy catastrophe

• Primary electrical problem

Less likely

• Hypoxia

• Hypovolaemia

• Acidosis

• Sepsis

Respiratory distress with deep respirations before arrest

(“breathing hard”, air hunger)

More likely

• Hypoxia

• Hydrogen ion (acidosis)

• Massive PE

• Severe asthma

• DKA

• Sepsis

Less likely

• Tamponade

• Primary arrhythmia

• Coronary thrombosis

Progressive collapse after days of vomiting

More likely

• Hypovolaemia

• Hypokalaemia

• Hydrogen ion

• Toxin (if ingestion)

Less likely

• Tamponade

• Tension pneumothorax

Pregnant + hyperemesis + ondansetron + sudden collapse

More likely

• Hypokalaemia

• Hypomagnesaemia

• QT prolongation → torsades

• PE

Less likely

• Hypothermia

• Tamponade

Chest pain then collapse

More likely

• Thrombosis (coronary)

• Arrhythmia

• Aortic catastrophe

Less likely

• Hypovolaemia

• Tension pneumothorax

SOB + pleuritic pain + collapse

More likely

• Thrombosis (PE)

• Hypoxia

Less likely

• Hyperkalaemia

• Hypothermia

Severe diarrhoea or gastro for days

More likely

• Hypovolaemia

• Electrolytes

• Acidosis

Less likely

• Coronary thrombosis

Dialysis patient missed treatment

More likely

• Hyperkalaemia

• Acidosis

Less likely

• Hypovolaemia

Collapse during exertion

More likely

• Coronary thrombosis

• Arrhythmia

• PE

• Structural cardiac disease

Less likely

• Hypothermia

Found collapsed / pill packets

More likely

• Toxins

• Acidosis

• Hypoxia

Less likely

• PE

Sudden deterioration after intubation / PPV

More likely

• Tension pneumothorax

Less likely

• Hypovolaemia

• Electrolytes

Trauma + increasing SOB + distended neck veins

More likely

• Tamponade

• Tension pneumothorax

• Hypovolaemia

Collapse after standing up with weeks of melaena (black, tarry, and foul-smelling stools)

More likely

• Hypovolaemia

Less likely

• Coronary thrombosis

Progressive confusion → reduced LOC → arrest

More likely

• Hypoxia

• Acidosis

• Hyperkalaemia

• Sepsis

Less likely

• Sudden PE

Fever, rigors, then arrest

More likely

• Hypoxia

• Acidosis

• Sepsis

Less likely

• Tamponade

Hx questions to ask during arrest (and what they narrow)

Ask	Looking for	Hs & Ts affected
What happened immediately before collapse?	Sudden vs progressive	All
Any chest pain?	ACS / PE	Thrombosis
Any SOB?	Respiratory	Hypoxia, PE
Vomiting/diarrhoea?	Fluid/electrolytes	Hypovolaemia, H+, K+
Any dialysis/kidney disease?	Electrolytes	Hyperkalaemia
Any medications?	QT, overdose	Toxins
Pregnancy?	PE, haemorrhage	Thrombosis, hypovolaemia
Any recent surgery/travel?	Clots	PE
Any infection?	Sepsis	H+, hypoxia
Trauma?	Bleeding/PTX	Hypovolaemia, Tension, Tamponade
Any syncope before?	Arrhythmia	Toxins, K+, coronary
Drug/alcohol use?	Toxic	Toxins
Any bleeding?	Volume loss	Hypovolaemia
Was collapse witnessed?	Timeline	Hypoxia vs sudden

Post ROSC cares

o   New patient’

o   ABCs              ( get suction ready)

o   12 lead ECG early and often

o   Resp                   Nuro             Cardiovascular       HTT

o   Maintain SPO2 >92%

o   Consider advanced airway

o   Maintain EtCO₂ of 30–40 mmHg – don’t hyperventilate!

o   Aim for SBP >100 mmHg or MAP >65 mmHg   250 bolus> repeat

o   BSL: target normal ranges → 4–8 mmol/L

o   Normothermia, (Keep Temp below 37.5)

o   Posture, consider raising head, Obese, PO, cerebral perfusion.

o   Adrenaline (bradycardia with poor perfusion) (SBP < 90 despite fluids)

o   CCP back-up             ↑20-50mcg, repeat @ 1 min ↑   ( infusion↑)

o   Transport to appropriate facility & notify