Underwater Investigation
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3 possible mechanisms to drown
• Fresh water • Water enters lungs à absorbed into circulation (by osmosis) à blood dilution à red blood cells swell & rupture à potassium released à death by hyperkalaemia. • Salt water • Water enters lungs à water from blood moves into lungs (by osmosis) à blood thickens à failure of circulation. • Surfactant • Water disrupts surfactant à air units (alveoli) collapse à hypoxia.
Risk of deep diving
If you ascend/descend too quickly: • Pulmonary barotrauma – caused by rapid pressure changes • Can cause pneumothorax, pneumomediastinum, alveolar rupture, air embolism • Decompression sickness – caused by formation of nitrogen bubbles in blood • Can cause fatigue, pain, but more severely, stroke-like symptoms.
PMI findings: Internal Signs in drown victim
• Lung changes • No clear pattern in weights • Lung over inflation – emphysema aqueosum • Haemolytic staining of the aorta (fresh water) • Water in stomach (Wydler’s sign) • Haemorrhage of middle ear Not always resent not exclusive to drowing.
External signs in PMI finding for Underwater
• Signs of immersion • ‘washer woman’ hands, mud/debris in mouth, abrasions etc • Foam around nose • Disappears with time, disturbed by resuscitation
Diving Physiology Descend = ↑ pressure so your lungs will?
lungs will compress
Diving physiology. Ascend = ↓ pressure your lungs will
de-compress
Pulmonary barotrauma – caused by rapid pressure changes, can cause
pneumothorax, pneumomediastinum, alveolar rupture, air embolism
Decompression sickness – caused by formation of nitrogen bubbles in blood • Can cause
fatigue, pain, but more severely, stroke-like symptoms