Types of Drowning

Note: The WHO also states that older descriptive terms such as wet, dry, active, passive, silent, and secondary drowning should no longer be used in formal documentation - instead outcomes should be classified as death, morbidity, or no morbidity. However, these terms remain widely used in forensic and clinical teaching, so both frameworks are presented below.

• Rosen's Emergency Medicine, p. Background and Importance
• Parikh's Textbook of Medical Jurisprudence, p. Classification

Classification Overview

1. Typical (Wet) Drowning

A. Fresh Water Drowning

• Large quantities of hypotonic water cross the alveolar membrane into the circulation
• Causes hypervolaemia - blood volume may increase by up to 50% within 2-3 minutes
• Red blood cells swell and burst (haemolysis), releasing potassium
• Results in: hyponatraemia, hyperkalemia, haemoglobinaemia, haemoglobinuria
• Fresh water denatures/alters pulmonary surfactant (rather than washing it away)
• The heart suffers combined insults: anoxia + hypervolaemia + potassium excess + sodium deficit
• Death typically from ventricular fibrillation within 4-5 minutes

B. Salt Water Drowning

• Hypertonic seawater draws fluid from the circulation into the lungs (opposite direction to fresh water)
• Causes fulminating pulmonary oedema with progressive hypovolaemia
• Results in circulatory shock and eventual cardiac asystole
• Death typically takes 8-12 minutes (slower than fresh water drowning)

In practice, distinguishing fresh vs. salt water drowning at autopsy is often not possible.

• Parikh's Textbook of Medical Jurisprudence, p. 222-223

2. Atypical Drowning

A. Dry Drowning

• Accounts for approximately 10-20% of all submersion casualties
• Water contacts the nasopharynx or larynx, triggering sustained laryngospasm
• Little or no water enters the air passages or lungs
• Death results from asphyxia due to the laryngospasm itself
• Classical autopsy signs of drowning (waterlogged lungs, froth, etc.) are absent
• This is generally the best type for successful resuscitation
• Parikh's Textbook of Medical Jurisprudence, p. 223
• P C Dikshit Textbook of Forensic Medicine, p. Types of Drowning

B. Immersion Syndrome (Hydrocution / Vagal Inhibition / Submersion Inhibition)

• Accounts for approximately 1-2% of drowning cases
• Death results from cardiac arrest due to vagal inhibition, not from water inhalation
• Triggered by:
  • Sudden contact with cold water (at least 5°C below body temperature) stimulating skin nerve endings
  • Cold water entering the ears, nasal passages, pharynx, or larynx
  • Impact of water on the epigastrium (belly flop, horizontal entry)
  • Feet-first or "duck diving" by the inexperienced
• Mechanisms: vagal stimulation leading to asystole, or ventricular fibrillation from QT prolongation after massive catecholamine release
• Alcohol greatly increases the risk (vasodilation + central vasomotor effects)
• Also seen in emotionally tense individuals (e.g. intending suicides) where reflex arcs are more active
• Rosen's Emergency Medicine, p. 1108; The Essentials of Forensic Medicine and Toxicology, p. 360

C. Submersion of the Unconscious

• Victim enters water already unconscious or becomes unconscious immediately
• Predisposing conditions:
  • Epilepsy
  • Cardiac disease (especially myocardial ischaemia)
  • Hypertension with dizziness
  • Intoxication (alcohol)
  • Head injury/concussion during the fall
  • Rupture of a cerebral aneurysm or cerebral haemorrhage
• Autopsy findings: incomplete picture of drowning - lung ballooning may be absent, froth formation negligible
• Parikh's Textbook of Medical Jurisprudence, p. 223

D. Near-Drowning / Secondary Drowning Syndrome

• Refers to survival following a submersion event (at least initially)
• Survivors may develop delayed complications:
  • Hypoxic encephalopathy
  • Fibrosing alveolitis (from infection by contaminants in inhaled water)
  • Pulmonary oedema, ARDS (stiff, heavy lungs without oedematous appearance)
  • Electrolyte disturbances, haemoglobinuria, sepsis, metabolic acidosis
  • Chemical pneumonitis, cerebral oedema, cardiac arrhythmias, myocardial anoxia
• Death may occur 30 minutes to several hours after apparent resuscitation in about 20% of cases
• 5-10% of survivors develop serious neurological damage
• Microscopically: ischaemic red neurons in brain; ARDS pattern in lungs

Note: The WHO now discourages the term "near-drowning" - the preferred terminology is simply "drowning with no morbidity" or "drowning with morbidity" depending on outcome.

• Parikh's Textbook of Medical Jurisprudence, p. 223-224; The Essentials of Forensic Medicine and Toxicology, p. 360

Summary Table