Epidemiology

Submersion simply means going under water. To avoid confusion, especially in reporting, the International Liaison Committee on Resuscitation recommends that the following previously used terms no longer be used: dry and wet drowning, active and passive drowning, silent drowning, secondary drowning, and drowned versus near-drowned.¹ In 2002, the World Congress on Drowning adopted a uniform definition of drowning: “the process resulting in primary respiratory impairment from submersion/immersion in a liquid medium.”²

Drowning is an important cause of childhood morbidity and is among the top 10 causes of mortality (Fig. 134.1). Drowning is estimated to kill 500,000 people every year worldwide. Eighty percent of these episodes take place in low-income countries and low-income groups. About 80% of drowning episodes are deemed preventable.^3,4

Fig. 134.1 Ten leading causes of injury deaths by age group highlighting unintentional injury deaths, United States—2007.

MV, Motor vehicle.

(Adapted from National Center for Injury Prevention and Control, Centers for Disease Control and Prevention. Web-based Injury Statistics Query and Reporting System [database]. Available at http://www.cdc.gov/ncipc/wisgars/.)

Overall rates of drowning have dropped in all age groups, probably as a result of improved awareness, use of preventive measures, and other factors (Box 134.1). Inadequate supervision is the main risk factor for drowning in children. Most toddlers who drown do so in their own home pools, most infants drown in bathtubs, and adults and older children drown in fresh water. Fencing of private pools reduces the risk for drowning.⁵

Pathophysiology

Injuries from drowning result mainly from asphyxia and subsequent hypoxic-ischemic damage to vital organs. The event starts with panic because of air hunger and, eventually, aspiration of fluid into the hypopharynx. Reflex laryngospasm occurs but is usually brief before the victim aspirates large amounts of fluid into the lungs. Further aspiration can occur if the victim vomits and aspirates gastric contents. Aspiration is the end result of all drowning, and the old terminology of dry and wet drowning should not be used.^6,7 Changes in intravascular volume, hematocrit, and electrolyte concentration as a result of aspiration are usually mild and not clinically significant. Both salt water and fresh water cause lung injury. The effect of tonicity on the intravascular compartment is minimal.^8,9

The diving reflex is one of the unique phenomena described in children. Caused by vagal stimulation when the face is exposed to cold water (<10° C), this reflex is characterized by apnea, bradycardia, and intense vasoconstriction. It is presumed that this reflex can play a neuroprotective role in cold water submersion. Hypothermia slows cerebral metabolism when the body has had time to cool before aspiration or with submersion in extremely cold water and may also contribute to neuroprotection.

Presenting Signs and Symptoms

Manifestations vary from no symptoms to death and depend on the severity of hypoxemia. Cervical spine injuries are uncommon with drowning unless trauma is suspected (e.g., diving and boating accidents, falls, crashes).

Respiratory signs and symptoms can vary in severity and may be delayed. They result from aspiration of fluid and loss of surfactant and include shortness of breath, wheezing (rhonchi, crepitations), pulmonary edema, and acute respiratory distress syndrome. Symptoms of aspiration pneumonia may develop later from aspiration of infected material.

Neurologic symptoms also vary. Patients may be asymptomatic, irritable, or confused; have seizures; or be comatose at initial evaluation. Deterioration can occur in asymptomatic patients and those with mild symptoms. Symptoms and signs of increased intracranial pressure appear late and are due to hypoxic brain injury.

Arrhythmias can also develop early or late and further compromise cardiorespiratory status. Hypoxia, acidosis, and hypothermia can lead to bradycardia, tachycardia, hypotension, hypertension, arrhythmias, and asystole.

Differential Diagnosis

Although the diagnosis of drowning is obvious, it is important to rule out medical conditions that may predispose a person to submersion, as well as the possibility of child abuse.

Prognostic Factors

Treatment

Prehospital Management

CPR at the scene is the most important initial step. It can be started even if the victim is still in the water. After the airway is secured and oxygenation and ventilation are ensured, the patient should be transferred to the nearest hospital. Further management at the scene depends on the availability of personnel experienced in advanced life support (Fig. 134.2). Most drowning victims should be transferred to an emergency department (ED) regardless of the initial appearance at the scene. Exceptions are those with obvious rigor mortis, lividity, and decay.

Fig. 134.2 Algorithm for prehospital treatment of drowning victims.

ABC, Airway, breathing, and circulation (ABCs of resuscitation); CPR, cardiopulmonary resuscitation.

Emergency personnel dealing with a drowning victim should avoid the following:

• Maneuvers to expel water out of the lungs (i.e., abdominal thrusts)

• Cervical spine immobilization if no trauma is suspected

• Rough handling of a hypothermic patient (may induce arrhythmias)

• Delay in transport to the hospital after optimizing respirations

Management of Hypothermia

For a detailed discussion of hypothermia, refer to Chapter 131. Hypothermia is defined as a core body temperature lower than 35° C. Depending on the temperature, hypothermia may be mild, moderate, or severe. This condition should be anticipated and treated in drowning victims. Notably, standard thermometers may not accurately measure low temperatures. Rewarming techniques are discussed in Chapter 131.

Next Steps in Care and Patient Education

Because of lung injury, loss of surfactant, and pulmonary edema, some patients will need higher end-expiratory pressure for optimal oxygenation. As PEEP is increased, blood pressure and cardiac output should be monitored because they can be compromised by high end-expiratory pressure. Intensive monitoring of cardiac, respiratory, and neurologic status and for complications such as aspiration pneumonia is indicated.

Some reports suggest that therapeutic hypothermia can improve neurologic outcome after out-of-hospital cardiac arrest and therefore recommend induction of hypothermia in drowning victims after restoration of spontaneous circulation as a neuroprotective therapy. Further studies of this approach are needed, especially regarding its use in children.^11,12

No evidence supports the use of prophylactic antibiotics, corticosteroids, barbiturate therapy, or intracranial pressure monitoring in patients who have drowned.

Patients who are completely asymptomatic in the ED and whose arterial blood gas levels in room air, electrolytes, and chest radiographic findings are normal can be discharged after being observed for 6 hours. All others should be admitted to the hospital.