Acute Respiratory Distress Syndrome (ARDS) in Near-Drowning

Pathophysiology and Risk Factors

When a person is submerged in freshwater, several pathophysiological changes occur, including aspiration of freshwater causing surfactant washout and inactivation, hypoxemia due to ventilation-perfusion mismatch, pulmonary hypertension and shunting contributing to worsening oxygenation, and an inflammatory cascade triggered, leading to alveolar damage, in patients who experience submersion in freshwater with loss of consciousness 1
The drowning process begins with voluntary breath-holding, followed by laryngospasm, and eventually, when the victim's arterial oxygen tension drops significantly, the victim actively breathes liquid, with the amount of liquid inhaled varying between victims, but changes in the lungs occurring rapidly, in the context of near-drowning 1
Submersion duration is the most important predictor of outcome in drowning, as it represents the amount of anoxia, with a submersion duration of 3 minutes being a significant risk factor for ARDS, according to the American Heart Association 2

Patients with near-drowning who have been resuscitated require close monitoring of respiratory status with serial arterial blood gases, supplemental oxygen to maintain adequate saturation, early consideration of positive pressure ventilation (CPAP/PEEP) if respiratory distress develops, and lung-protective ventilation strategies if intubation becomes necessary, to manage the potentially life-threatening complication of ARDS 1
The severity of ARDS can vary widely, from mild hypoxemia to severe respiratory failure requiring mechanical ventilation, and even patients who initially appear to recover may deteriorate within hours due to progressive lung injury, emphasizing the need for close monitoring and early intervention, as recommended by the American Thoracic Society 2