Drowning is any degree of respiratory impairment because of immersion or submersion in a liquid.1 It is the third leading cause of unintentional injury death worldwide, and there are an estimated 4,000 fatal unintentional drownings and 8,000 nonfatal drownings annually in the U.S. alone.2 Drowning tends to occur in those aged 1 to 25, with trauma or a toxicologic event often accompanying many of those aged 17 to 25.3 Drowning also occurs at a greater frequency in those aged 55 or more.3 In this latter group a primary cardiac event should be considered as an inciting event.
Explore This IssueACEP Now: Vol 42 – No 07 – July 2023
Cardiac Arrest in Drowning
The progression to cardiac arrest in drowning starts with water entering the upper airway. This may cause laryngospasm and up to 4L of swallowed liquid.4 Once the upper airway is overwhelmed, the liquid then enters the lower airways which causes bronchospasm, direct alveolar injury, surfactant washout, foam formation, and hypoxemia.5 After approximately 1 minute of submersion, patients typically lose consciousness and become apneic. It is imperative to understand that hypoxemia is the key pathophysiologic mechanism that leads to cardiac arrest, typically pulseless-electrical-activity (PEA) arrest, which occurs typically after 10 minutes of submersion. Thus, management should be directed toward correcting hypoxemia.
The mainstays of correcting hypoxemia in the unstable drowning patient include high fraction of inspired oxygen, positive end-expiratory pressure, mechanical ventilation, and extracorporeal membrane oxygenation.6 Patients with severe respiratory distress are at risk of respiratory failure within hours of drowning as surfactant regeneration takes about two days to occur.7 Some indications for a definitive airway include impending respiratory failure or apnea, failed non-invasive ventilation, inability to protect the airway, and presence of upper airway foam.3 After the airway has been secured, if hypoxemia persists, the patient should be considered for extracorporeal membrane oxygenation, especially if concomitant severe hypothermia is at play.8
Drowning may be secondary to trauma or a toxicologic or cardiac event, and parallel management should also be directed at these whenever present. Hypothermia is not uncommon in drowning victims. It is imperative to identify hypothermia using a rectal temperature and manage it appropriately in tandem with drowning management.
Cervical spine (C-spine) immobilization in trauma patients has been associated with increasing time to definitive care, difficult airways, and increased mortality in patients with penetrating injuries, and also with pressure ulcers.9,10 Thus, C-spine immobilization of the drowning patient should be limited to those cases with a mechanism of injury concerning for significant C-spine injury. An analysis of 2,000 drowning victims found that only one in 200 suffered C-spine injuries, and all of these patients had both neurologic signs on physical exam and a concerning mechanism of injury.11