Drowning

1. Definition and Causes

- Definition: Drowning is a form of asphyxia due to fluid aspiration into air-passages, typically
caused by submersion in water or other liquids.
- Submersion Not Fully Required: Complete submersion isn't necessary; submersion of the
nose and mouth alone for a sufficient period can be fatal.

2. Statistics

- Global Mortality: Approximately 150,000 people die from drowning each year worldwide.

3. Duration of Submersion in Fatal Cases

- Initial Immersion: The body initially sinks due to the fall's force and body's specific gravity
(1.08) but rises back to the surface due to natural buoyancy.
- Reflexive Inhalation: Sudden immersion in cold water can lead to reflexive water inhalation due
to skin stimulation.

4. Sequence of Events Leading to Death

- Breath Holding: The victim may hold their breath until CO2 levels in blood and tissues trigger
the respiratory center, causing inevitable water inhalation.
-Struggle for Air: Crying for help and struggling can lead to water inhalation, coughing, and
disruption of breathing rhythm.
- Vomiting and Aspiration: Struggling can cause vomiting and subsequent aspiration of gastric
contents, further worsening the condition.
- Cerebral Hypoxia: Continued oxygen deprivation leads to irreversible cerebral hypoxia and
eventually death.

1. Wet Drowning (Primary Drowning)

• Description: Water is inhaled into the lungs, leading to severe chest pain.
• Outcome: Death typically occurs within minutes of submersion due to cardiac arrest or
ventricular fibrillation.
• Prevalence: Common in drowning cases.

2. Dry Drowning
 • Description: Water does not enter the lungs, but death results from sustained laryngeal
spasm caused by water entering the nasopharynx or larynx.
• Symptoms: Thick mucus, foam, and froth may develop, creating a plug.
• Prevalence: Seen in 10 to 20% of immersion cases, often observed in individuals under
the influence of alcohol or sedative hypnotics.
• Unique Feature: Resuscitated victims may experience panoramic views of past life and
pleasant dreams without distress.

3. Secondary Drowning (Post-Immersion Syndrome)

• Definition: Occurs in victims who are initially resuscitated and survive for 24 hours
after submersion.
• Complications: May develop hypoxemia leading to various complications including
brain damage, pulmonary edema, cardiac arrhythmias, pneumonitis, fever, sepsis, metabolic
acidosis, chemical pneumonitis, and cerebral edema.
• Mortality: Death may occur within hours after resuscitation in approximately 20% of
cases.
• Long-Term Effects: Survivors may experience serious neurologic damage in 5 to 10%
of cases.

4. Immersion Syndrome (Hydrocution or Submersion Inhibition)

• Cause of Death: Cardiac arrest due to vagal inhibition triggered by specific stimuli
associated with cold water immersion.
• Stimuli for Vagal Inhibition:
• Cold water stimulating nerve endings on body surfaces.
• Water striking the epigastrium.
• Cold water entering ear drums, nasal passages, pharynx, and larynx.
• Occurrence: Seen in 1 to 2% of drowning cases.
• Factors Influencing Severity: Alcohol consumption increases effects due to
vasodilation of skin vessels and potential central effects on the vasomotor center.

Pathophysiology of Drowning

- General Factor: Deprivation of oxygen is a critical factor across all types of drowning.
- Pulmonary Alveolar Exchange: Water entering the alveoli triggers an exchange process
influenced by osmotic pressure differences between blood and water.
Causes of Death

1. Asphyxia
- Mechanism: Inhalation of fluid obstructs air passages, causing circulatory and respiratory
failure due to myocardial and respiratory center anoxia.

2. Ventricular Fibrillation
- In Fresh Water Drowning: Death occurs in 3 to 5 minutes due to anoxia and disturbed sodium-
potassium ratio, leading to arrhythmias like ventricular tachycardia and fibrillation.

3. Laryngeal Spasm
- Cause: Inrush of water into nasopharynx or larynx triggers spasm, further complicating
respiration.

4. Vagal Inhibition
- Triggers: Cold water immersion, high emotion/excitement, unexpected submersion.

5. Exhaustion
- Contribution: Physical exhaustion can lead to drowning in certain scenarios.

6. Injuries
- Types: Skull fractures, cervical vertebrae dislocations, concussion due to impact against solid
objects or water during fall.

Fatal Period
- Duration: Death typically occurs within 4 to 8 minutes of complete submersion.
- Duration: Death typically occurs within 4 to 8 minutes of complete submersion.

Post-mortem Appearances

External Signs
- Clothing and Skin: Wet, cold, moist, pale skin due to vascular contraction; clothing remains
wet.
- Post-mortem Lividity: Light-pink or dusky/cyanotic skin coloration; often seen on face, chest,
hands, feet, and calves.
- Petechial Hemorrhages: Occasionally seen beneath conjunctivae and lower eyelids.
- Tongue: Swollen and protruded; may exhibit petechial hemorrhages rarely.

Internal Signs
- Lungs:
- Ballooning Effect: Lungs may cover pericardial sac, bulge out of chest post-removal
(ballooning), due to fluid and air in bronchi.
- Condition: Over distended with torn alveolar walls; presence of oedema fluid (emphysema
aquosum).

Microscopic Examination
- Alveolar Distension: Distention of alveoli, alveolar ducts, and bronchioles; thinning of septa;
capillary congestion and hemorrhages.
- Froth Formation: Occurs within minutes of drowning due to water irritation of airway mucosa.

Specific Findings
- Stomach Contents: Water presence in approximately 70% of cases; chemical and microscopic
nature of water aids in confirmation of drowning.
- Brain and Organ Appearance: Swollen brain with flattened gyri; congestion in other organs;
potential bruising/rupture of muscles due to violent struggle.
- Middle Ear Hemorrhages: Common in drowning cases due to forced water entry via Eustachian
tubes during respiratory efforts.
Diatoms

Definition: Microscopic unicellular or colonial algae with silica-impregnated cell walls.

Structure: Diatoms have a complex, silica-based cell wall called a frustule.
Characteristics:
• Contains chlorophyll and diatomin (brown pigment).
• Belongs to the class Bacillariophyceae.
• Approximately 15,000 species worldwide.
• Vary greatly in size (2 microns to 1 mm in length/diameter).
• Most species range from 10 to 80 microns in length.
• Shape varies (circular, triangular, oval, etc.).

Methods of Diatom Detection

1. Digestion with Acids

Material (e.g., tissue) is digested with nitric acid and sulfuric acid.
2. Incineration and Dissolution
Material is incinerated in an electric oven, and ashes are dissolved with nitric acid.
3. Microscopic Examination
Water is squeezed from lungs, centrifuged, and sediment examined under a microscope.
Tissue sections are directly examined under a microscope to detect diatoms.

Circulation and Distribution in the Body

• Diatoms in drowning fluid (ruptured alveolar wall contents) enter lymph channels and
pulmonary veins, reaching the left heart.
• Diatoms are transported to various body tissues (brain, bone marrow, liver, skeletal
muscle) via circulation in a live body.
• Presence in bile and urine suggests systemic distribution post-drowning.
 • Presence in bile and urine suggests systemic distribution post-drowning.

Forensic Examination Techniques

• Bone Marrow Examination

• Preferred site: Long bones (femur, tibia, humerus, sternum).
• Marrow is curretted out for diatom analysis.
• Tissue Sampling
• Kidney, lung, liver, or brain tissue is washed and sampled for diatom detection.