Eventually no voluntary effort will prevent respiration, and the victim will attempt to breathe. The point at which this occurs is determined by carbon dioxide and oxygen levels. In approximately 15% of drowning victims, laryngospasm occurs and prevents aspiration of liquid (dry drowning); however in most cases, the victims aspirate the liquid, thus leading to what is termed “wet drowning.”⁴

The common denominator in all submersions, whether wet or dry, is hypoxia. Once the victim is unconscious, all airway reflexes are lost, and fluid passively flows into the airways. This is then followed by cardiac arrest. The acidosis and hypoxia that occur can lead to serious derangements in many organ systems in victims who survive the initial incident.

Submersion in Cold Water

Submersion in cold water has long been thought to be associated with a better prognosis and increased survival rate, especially in pediatric patients. Children have a large surface-area-to-body-weight ratio, which leads to hypothermia more quickly than in an adult. Aspiration of cold water can also hasten the onset of hypothermia. This quick cooling of the brain is thought to result in a reduced metabolic demand thus protecting the brain.^5,6

Another theory suggests that the mammalian “diving reflex” reduces metabolic demand through a combination of slowing of heart rate, shunting of blood to the brain, and airway closure. It is important to remember that although submersion in cold water in a cold environment has been associated with a better prognosis, in warmer settings hypothermia is actually associated with a poorer prognosis and is often representative of prolonged submersion times and poor or absent perfusion.

It is critical to obtain a core temperature in all victims of submersion incidents who present to an emergency department; resuscitation efforts must persist until normal core temperature is reached.³

CRITICAL DECISION

Should all victims of submersion incidents be evaluated in an emergency department?

It is commonly accepted that any patients with residual symptoms such as coughing, wheezing, tachypnea, or low oxygen saturation after a submersion incident, even if they are awake and cognizant, should be transported to an emergency department to be observed for progressive respiratory insufficiency for a period of 4 to 6 hours.

In the emergency department, the patient’s ABCs should be carefully assessed, and any abnormalities should be addressed with respiratory support, circulatory support, and appropriate neurologic resuscitation.

Once the ABCs have been addressed, it is important to obtain a detailed history of the event, including submersion time, type of water, field interventions, and signs of life in the field. It is also important to note carefully the circumstances of the submersion incident to assess for the possibility of associated issues such as hypoglycemia, seizure, myocardial infarction, head or neck injury, or other underlying pathology or even non-accidental injury.