Drowning

Christopher M. Cielo, DO, FAAP

Introduction/Epidemiology

•Drowning is the process of experiencing respiratory impairment from submersion or immersion in liquid.

•Drowning outcomes can be classified as “death,” “no morbidity,” or “morbidity” (further categorized as “moderately disabled” or “severely disabled”). According to the World Health Organization, there were 360,000 drowning deaths worldwide in 2015. It is the leading cause of death for boys 5–14 years of age worldwide.

•Drowning is second only to motor vehicle injury as the leading cause of death from unintentional injury in the United States.

•Most drowning deaths in children <1 year old occur in the bathtub.

•The highest rate of drowning occurs in 1- to 4-year-olds left unattended at residential pools. Flooding and irrigation ditches are other sources of drowning.

•Older children are more likely to drown in open water. Risk factors include male sex, black race, and alcohol use.

•Medical conditions, including epilepsy and prolonged QT syndrome, increase the risk for drowning.

Pathophysiology

•Drowning may occur from the airway going below the surface of the water (submersion) or liquid being splashed over the face (immersion).

•Young children may struggle for 10–20 seconds, and adolescents may struggle for 30–60 seconds before submersion.

•Initially, water entering the mouth is spat out or swallowed and/or the victim holds his or her breath.

•When the inspiratory drive becomes too high to resist, water is aspirated into the airways.

Pulmonary

•Aspiration of water may lead to laryngospasm.

•Additional aspiration continues, and hypoxemia quickly leads to loss of consciousness.

•Water in the alveoli causes washout of surfactant and disrupts the osmotic gradient. This disrupts the integrity of the membrane, increasing permeability and causing electrolyte shifts.

•The end result is pulmonary edema, atelectasis, and bronchospasm.

•Initial tachycardia leads to bradycardia, then pulseless electrical activity and ultimately asystole.

•A progressive decrease in cardiac output contributes to hypoxia. By 3–4 minutes, myocardial hypoxia leads to circulatory failure.

•There is a progressive decrease in arterial blood oxygen saturation, and the victim loses consciousness from hypoxia.

Neurological

•Profound hypoxia and medullary depression eventually lead to death.

•Hypothermia can reduce the consumption of oxygen in the brain, delaying cellular anoxia and adenosine triphosphate depletion.

First Response

Rescue

•In areas where lifeguards are present, fewer than 0.5% of rescues require cardiopulmonary resuscitation (CPR), but almost 30% of rescues by bystanders require CPR.

•If possible, assist the victim from outside the water by using a pole or buoy.

•Emergency medical services should be notified as soon as safely possible.

Initial Resuscitation

•In-water resuscitation may increase the likelihood of a good outcome if performed by a trained rescuer.

•If only in respiratory arrest, the victim will usually respond to rescue breaths alone.

•If there is no response to rescue breaths, the victim should be removed from the water as quickly as possible. Immediate CPR efforts are critical.

•Five rescue breaths should be given because water in the airways makes ventilation more difficult.

•Because drowning causes a primary respiratory failure, CPR with chest compressions alone is not recommended.

•Vomiting is common in drowning resuscitation. Abdominal thrusts should not be used to remove fluid because they may cause aspiration.

Initial Management

•The goal is to reverse anoxia from submersion as quickly as possible and limit secondary hypoxic injury.

•When available, bag-mask ventilation with 100% oxygen should be used to correct hypoxia.

•The cervical spine should be protected if there is potential for traumatic neck injury.

•Wet clothing should be removed to prevent ongoing heat loss.

•Patents with increased work of breathing or hypercapnia should be treated with mechanical ventilation.

•In unconscious patients, after securing the airway and restoring circulation, serial blood gases should be monitored for resolution of respiratory or metabolic acidosis. Respiratory acidosis is caused by hypoventilation, and metabolic acidosis is caused by lactic acidosis induced by tissue hypoxia.

•Patients should be rewarmed if hypothermic during resuscitation.

•Management in the intensive care unit (ICU) is similar to treatment of acute respiratory distress syndrome.

•Because ongoing pulmonary edema may occur, ventilator settings should not be weaned in the first 24 hours.

•In some patients, pulmonary collapse will require extracorporeal membrane oxygenation.

•Most victims should be observed for at least 6–8 hours, with serial vital sign checks and examination for signs of respiratory distress or pulmonary edema, even if asymptomatic at arrival to the emergency department.

Treating Associated Conditions

•Pulmonary: Pneumonia is uncommon in the initial presentation but may occur from polluted water, aspiration, or nosocomial pathogens. If pneumonia is suspected, antibiotic coverage should include waterborne pathogens, such as Pseudomonas and Proteus.

•Cardiovascular: Management of shock with intravenous fluid resuscitation and inotropic agents may be necessary.

•Neurological: Because of the risk for irreversible central nervous system injury due to hypoxia, restoring oxygenation is critical. Seizures may be difficult to treat. If the patient has good oxygenation but is unresponsive, consider performing head computed tomography and a toxicology screen. Therapeutic hypothermia after initial resuscitation may reduce neurological damage. Consider measures to reduce increased intracranial pressure (elevating the head of the bed in the absence of cervical spine injuries).

Expected Outcomes/Prognosis

•Bimodal outcomes: Most victims have either very good outcome or severe neurological sequelae or death.

•Cardiopulmonary arrest usually leads to multiorgan failure and frequent poor neurological outcome when compared to those with just respiratory arrest.

•Outcome is dependent on the duration of submersion and the time until initiation of treatment. There is no clear difference in survival between cold-water and warm-water drowning.

•The need for >30 minutes of CPR after submersion can be used to predict poor outcomes.

•Almost one-half of deeply comatose drowning victims admitted to the pediatric ICU die of hypoxic brain injury or have severe neurological damage.

•Intracranial hypertension is a predictor of poor outcome.

Prevention

•Anticipatory guidance provided by the pediatrician can be effective in reducing the incidence of drowning.