Define 'drowning'. Enumerate the different modes of death in a case of drowning. List the postmortem findings in a case of wet drowning.

Definition of Drowning

As per the World Health Organization (WHO) and the World Congress on Drowning (2002), drowning is defined as "the process of experiencing respiratory impairment from submersion/immersion in liquid." This comprehensive definition focuses on the physiological event of respiratory difficulty due to being in a liquid medium, without necessarily implying a fatal outcome, although it often leads to death or significant health complications. From a forensic perspective, it is an asphyxial death where the entry of air into the lungs is prevented by water or other fluid obstructing the airways due to submersion of the mouth and nostrils.

Different Modes of Death in a Case of Drowning

Death in drowning cases can occur through several distinct physiological mechanisms, primarily stemming from the deprivation of oxygen (hypoxia). These modes are often interconnected and can manifest rapidly:

• Asphyxia due to Laryngeal Spasm (Dry Drowning): In approximately 10-15% of cases, initial submersion triggers a reflex spasm of the larynx (laryngospasm). This closes the airway, preventing water from entering the lungs but also blocking air intake. Death occurs rapidly due to acute oxygen deprivation, without significant aspiration of water into the lungs.
• Asphyxia due to Aspiration of Fluid (Wet Drowning): This is the most common mode. After an initial period of breath-holding, the body's increasing demand for oxygen leads to involuntary gasping and aspiration of water into the respiratory tract. This water displaces air in the alveoli, impairs gas exchange, and causes pulmonary edema, leading to severe hypoxia and eventually cardiac arrest.
• Vagal Inhibition (Reflex Cardiac Arrest): Sudden immersion, especially in cold water, can trigger a strong vagal reflex, leading to immediate cardiac arrest or severe bradycardia. This occurs due to the stimulation of nerve endings in the larynx and pharynx by cold water, causing a sudden cessation of heart function before significant water aspiration.
• Ventricular Fibrillation (Freshwater Drowning): In freshwater drowning, water aspirated into the lungs is hypotonic compared to blood. It rapidly passes through the alveolar-capillary membrane into the bloodstream, causing hemodilution and electrolyte imbalances, particularly hyponatremia and hyperkalemia. This can lead to ventricular fibrillation and cardiac arrest.
• Pulmonary Edema (Saltwater Drowning): In saltwater drowning, the aspirated water is hypertonic. It draws fluid from the blood into the alveolar spaces, resulting in severe pulmonary edema and hemoconcentration. This impairs oxygenation and leads to circulatory collapse.
• Cerebral Anoxia/Hypoxia: Regardless of the initial mode, the ultimate cause of death in drowning is irreversible brain damage due to prolonged lack of oxygen to the brain cells (cerebral anoxia and hypoxia). The brain is highly sensitive to oxygen deprivation, with irreversible damage often occurring within 4-6 minutes of submersion.
• Exhaustion and Hypothermia: While not direct modes of death, exhaustion from struggling and hypothermia (a drop in core body temperature, especially in cold water) can significantly contribute to and accelerate the drowning process by impairing physical capacity and vital organ function.

Postmortem Findings in a Case of Wet Drowning

The diagnosis of drowning, particularly wet drowning, in forensic pathology is complex as findings can be influenced by various factors such as the type of water, duration of submersion, and postmortem changes. However, several characteristic postmortem findings are often observed:

External Findings:

• Foam (Fungus of Foam): A persistent, fine, white, frothy foam (often mixed with blood in advanced cases) may be seen exuding from the nostrils and mouth. This is formed by the churning of air, water, and mucus in the respiratory passages due to vigorous respiratory efforts before death. A complete, fungiform formation of external foam is considered a highly suggestive sign of drowning.
• Cadaveric Spasm of Hands (Clutched Objects): The victim may be found clutching weeds, sand, or other foreign material from the bottom of the water body in their hands. This indicates a vital reaction, suggesting the person was alive and struggling at the time of submersion.
• "Washerwoman's Hands and Feet" (Maceration): Prolonged immersion in water leads to wrinkling, pallor, and thickening of the skin of the palms and soles, resembling a washerwoman's hands. This is a postmortem change, indicating the duration of immersion rather than a vital reaction.
• Goose Pimples (Cutis Anserina): The contraction of erector pili muscles due to cold water or fear, leading to a "goosebumps" appearance. This is a vital reaction, though not specific to drowning.
• Petechial Hemorrhages: While common in other forms of asphyxia, petechial hemorrhages (small pinpoint hemorrhages) are generally less prominent in drowning cases due to the relatively gradual nature of asphyxia.
• Mud, Sand, Weeds in Hair or Clothed: Presence of foreign material from the water source adhering to the body or clothes suggests submersion.

Internal Findings:

The internal findings are crucial for confirming wet drowning and often involve the respiratory and gastrointestinal systems:

1. Respiratory System:
   • Emphysema Aquosum: Lungs are typically voluminous, heavy, pale, and doughy to the touch. They often retain indentations of the ribs on their surfaces and may overlap the heart. This is due to overdistension of alveoli with water and air.
   • Water in Airway: Fluid (water or other liquid) may be found in the trachea and main bronchi, sometimes mixed with frothy foam. The presence of water is a key indicator of aspiration.
   • Foreign Material in Airway: Mud, sand, algae, or other debris from the water body may be found deep within the bronchi and even alveoli, indicating aspiration while alive.
   • Paltauf Spots (Hydrostatic Hemorrhages): These are subpleural hemorrhages, particularly visible on the surface of the lungs, caused by the rupture of distended capillaries and alveoli from increased intrathoracic pressure during violent respiratory efforts.
   • Diaphragm Position: The diaphragm is often depressed due to the hyperinflated lungs.
2. Gastrointestinal System:
   • Water in Stomach and Small Intestine (Wydler's Sign): A significant amount of water (often of the same type as the drowning medium) may be found in the stomach and small intestine, indicating gulping or swallowing of water during the struggle.
   • Debris in Stomach: Similar to airways, foreign material from the water body can be found in the stomach.
3. Circulatory System:
   • Blood Changes:
     • Freshwater Drowning: Blood is often diluted, appearing lighter and more fluid (hemodilution). There may be a decrease in red blood cell count and hemoglobin.
     • Saltwater Drowning: Blood may be hemoconcentrated, appearing darker and thicker. There may be an increase in red blood cell count and hemoglobin.
   • Cardiac Findings: Right-sided heart chambers may be dilated and full of blood, especially in freshwater drowning, due to increased blood volume returning to the heart.
4. Other Findings:
   • Paranasal Sinuses and Mastoid Cells: Fluid in these cavities can be observed, differentiating between freshwater and saltwater based on density measurements in imaging.
   • Diatom Test: The presence of diatoms (microscopic algae) from the drowning medium in distant organs (like bone marrow, liver, kidneys, brain) is a highly significant forensic test. It indicates antemortem aspiration and systemic circulation of water, confirming vital drowning.