[Systemic pathologic physiology parameters changes in sheep drowning: a control study in freshwater and seawater]

Area of Science:

• Physiology
• Pathology
• Toxicology

Background:

• Drowning is a leading cause of accidental death.
• Understanding the physiological and pathological differences between freshwater and seawater drowning is crucial for effective treatment.
• Sheep are a suitable animal model for studying drowning due to physiological similarities to humans.

Purpose of the Study:

• To compare the systemic pathologic physiology parameter changes in sheep drowning in freshwater and seawater.
• To investigate the hemodynamic, urinary, and organ-specific pathological changes following freshwater versus seawater drowning.

Main Methods:

• 24 healthy crossbred sheep were randomly divided into freshwater and seawater drowning groups (12 each).
• Drowning models were created by endotracheal injection of 10-25 mL/kg freshwater or seawater.
• Hemodynamic parameters, urine changes, and organ pathology (heart, kidney, liver, spleen, intestine) were assessed at various time points up to 120 minutes post-drowning.

Main Results:

• Freshwater drowning resulted in decreased left ventricular maximum systolic force index (dPmax), increased cardiac output (CO) and blood volume, systemic tissue edema, and hemoglobinuria.
• Seawater drowning led to significantly decreased mean arterial pressure (MAP), CO, and pulmonary artery wedge pressure (PAWP) compared to freshwater drowning, with some tissue atrophy.
• Hemoglobinuria was observed in the freshwater group but not in the seawater group.

Conclusions:

• Freshwater drowning causes significant systemic tissue edema and hemolysis, alongside altered cardiac dynamics.
• Seawater drowning results in a more severe depression of cardiac output and blood volume, with evidence of tissue atrophy.
• The distinct physiological responses highlight the importance of differentiating between freshwater and seawater immersion in drowning incidents.