The editors and current author would like to thank and acknowledge the significant contribution of the previous author of this chapter from the 2004 first edition, Dr. Francisco J. Garcia. This current third edition chapter is a revision and update of the original author’s work.

A 14-month-old male infant presents to the emergency department (ED) via ambulance in cardiopulmonary arrest. His mother left him playing in the living room. After 30 minutes, she was unable to find him inside the house. He was found at the bottom of the swimming pool. The screen door which leads to the pool was found to be open. Initially, he was cold, blue, and limp. She started cardiopulmonary resuscitation (CPR) after calling 911. The Emergency Medical System (EMS) team performs CPR and resuscitation en route to the hospital. The infant is intubated, and epinephrine is administered via the tracheal tube. An intraosseous (IO) line is established, and epinephrine is given via IO route as well. After 35 minutes of CPR in the ED, the infant is pronounced dead.

There has been much discussion on drowning nomenclature. The World Conference on Drowning definition is widely accepted, defining drowning as “the process of experiencing respiratory impairment from submersion/immersion in liquid.” The term itself does not imply the final outcome, which is instead classified as fatal/nonfatal, or death/morbidity/no morbidity. Terms such as wet, dry, secondary, or near drowning are considered ambiguous, inaccurate, and should not be used (1,2).

In the United States, drowning is the leading cause of unintentional injury-related death in children ages 1 to 4. For children ages 5 to 14, drowning is the second leading cause of unintentional injury-related death after motor vehicle accidents (3). Submersion injuries have a bimodal age distribution. The first peak is seen in infants and toddlers less than 4 years of age, who are susceptible to submersion in swimming pools, baths, or household buckets. The highest drowning rates are among children ages 1 to 4. Lack of caregiver supervision and suboptimal barriers to water access are contributing factors. The second peak occurs in adolescents (aged 15 to 19 years) and is associated with risk-taking behaviors as well as alcohol and illicit drug use before swimming, usually in natural water settings. Coexisting trauma and suicide intent should always be considered in this older age group. Adolescent males have twice the mortality rate compared to adolescent females. This may likely be due to increased exposure to water, overestimation of skills, underestimation of dangerous situations, and engagement in riskier behaviors.

The risk of drowning varies by host and environmental factors. The following factors increase the risk of drowning (1,4):

1) Inadequate or lapse in adult supervision.

2) Inability to swim or overestimation of swimming capability.

3) Alcohol or illicit drug use. Alcohol is a leading factor in drowning deaths in adolescents.

4) Epilepsy. Drowning is the most common cause of unintentional injury-related death in individuals with epilepsy.

5) Autism spectrum disorder. Wandering has been reported to be the most likely behavior associated with increased drowning risk.

6) Cardiac arrhythmias. Exertion and cold-water immersion can cause a fatal arrhythmia in individuals with long QT syndrome.

7) Trauma, myocardial infarction, or stroke.

The pathophysiologic event following drowning is hypoxia (2). In fatal and nonfatal drownings, most victims will go through a period of struggle, panic, and breath-holding. Inspiratory reflex eventually occurs, causing hypoxemia either by water aspiration or laryngospasm. This will lead to hypoxia (especially cerebral and cardiac), possibly followed by loss of consciousness and death. The extent of hypoxic-ischemic injury determines the final outcome.

Clinical risk factors previously differentiated salt water versus freshwater submersions with the concern that tonicity of aspirated water can affect blood volume or electrolyte levels. Research data has shown that the difference does not appear to be clinically significant in most instances given most victims of any age do not aspirate enough fluid (2,4).

Any organ system can get affected after a submersion injury as a result of asphyxia, hypoxia, and acidosis. Respiratory failure, aspiration pneumonia, barotrauma, and acute respiratory distress syndrome (ARDS) are frequent complications. Arrhythmias as well as cardiogenic shock may also be seen. Renal dysfunction is a common finding secondary to acute tubular necrosis. Liver and gastrointestinal dysfunction may also occur. However, it is the irreversible hypoxic-ischemic damage to the brain that accounts for most of the long-term complications.

Risk factors that have been identified as indicators of irreversible neurologic injury and mortality include (2,4):

1) Submersion longer than 5 minutes.

2) Resuscitation not attempted for 10 minutes or longer after rescue.

3) Resuscitation duration longer than 25 minutes.

4) Asystole on arrival to the emergency department.

5) Arterial blood pH <7.1.

6) Glasgow Coma Scale <5.

7) Apnea after cardiopulmonary resuscitation.

The management of the drowning victim starts in the field with bystander CPR and activation of EMS. Immediate resuscitation using both compression and ventilation CPR is the most effective means to improve outcome (1,5). The goal is to improve oxygenation and ventilation as rapidly as possible to minimize cerebral hypoxic-ischemic damage. The neck should be immobilized if there is concern for a spinal cord injury, otherwise routine cervical spine immobilization is not recommended as it may interfere with airway management. The Heimlich maneuver is not recommended in the case of drowned patients. Patients should be kept warm and dry. Hypotension should be treated aggressively. All patients should be transported quickly to the ED for further evaluation and treatment. Initially, vital signs and core temperature are obtained, followed by respiratory, cardiovascular, and neurologic evaluation. The patient should be assessed for concurrent traumatic injuries. Initial laboratory tests include: arterial blood gas (ABG), chest radiograph, electrolytes and serum glucose. Optional tests to be considered include: CBC, renal function tests, liver function tests, and urinalysis. Even the ABG is optional in many instances since oxygenation can be measured via pulse oximetry, the pCO₂ can be assessed by end tidal pCO₂ and clinical assessment of air exchange, and the metabolic acid-base status can be determined from the serum bicarbonate. The serum bicarbonate or base excess is an indicator of the duration of hypoxia (hence, tissue asphyxia risk). Low serum bicarbonate values suggest prolonged hypoxia and greater asphyxia risk. The degree of sodium abnormality (hyponatremia in a fresh water submersion and hypernatremia in a salt water submersion) is an indicator of the volume of ingested water during the submersion event.

Most pediatric drowning victims should be observed for at least 6 to 8 hours, even if they are asymptomatic upon presentation to the ED. There is some risk for minimally symptomatic children to experience some level of respiratory distress with progression to pulmonary edema during the first 4 to 8 hours post submersion (2). The risk for late onset pulmonary edema and/or late onset cerebral edema risk is likely greater for victims with greater degrees of hypoxia and tissue asphyxia. The phenomenon is sometimes known as dry drowning in which the amount of water that enters the lungs is minimal, yet the lung tissue hypoxia sustained results in late onset pulmonary edema. Patients who are awake, alert, and in no distress can be discharged from the ED after a period of observation, especially in those who have a clear chest radiograph and minimal changes in their bicarbonate and sodium levels.

Although the survival rate has improved with advances in emergency care, prevention is the best strategy. Parental supervision of infants and children while in and around water is essential. Both the Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) have online guides available for parents detailing drowning prevention. The technical report released in 2021 by the American Academy of Pediatrics (AAP) supports swimming lessons for children older than 1 year (1). This recommendation changed from 2000, which previously endorsed swimming lessons only after age 4.

Moreover, children and adolescents prone to conditions such as syncope and seizures should always have a partner. The Haddon injury prevention matrix for drowning prevention recommends mandating pool fencing or the installation of four-sided fencing that isolates the pool from the house (i.e., the house itself should not open directly into the pool area). Currently, pool covers and alarms are not recommended as a substitute for fencing. Finally, all parents and caregivers should be trained in CPR, since rapid institution of effective oxygenation and ventilation after a submersion injury has been associated with improved outcomes.

Questions
1. All of the following are considered risk factors for drowning except:
   a. Head trauma
   b. Alcohol use
   c. Upper respiratory infection with wheezing
   d. Seizure disorder
   e. Illegal drug use

2. True/False: The AAP supports swimming classes for children over 1 year of age.

3. Which of the following factors is associated with a poor outcome in a drowning case?
   a. Low blood sugar level
   b. Submersion longer than 5 minutes
   c. Drug or alcohol use
   d. Return of spontaneous cardiac rhythm following CPR
   e. CPR for less than 3 minutes

4. Which of the following interventions will improve the outcome in a drowning victim?
   a. Early intubation
   b. Transfer to a trauma center
   c. Intravenous access
   d. Early bystander CPR
   e. Cervical spine precautions

5. All of the following are complications after a submersion injury except?
   a. Acute respiratory distress syndrome (ARDS)
   b. Arrhythmias
   c. Renal dysfunction
   d. Hypernatremia
   e. Aspiration pneumonia

References
1. Denny S A, Quan L, Gilchrist J, et al; AAP Council on Injury, Violence, and Poison Prevention. Prevention of Drowning. Pediatrics. 2021;148(2):e2021052227.
2. Thomas AA, Caglar D. Chapter 91. Drowning and Submersion Injury In: Kliegman RM, St. Geme JW, Blum NJ, et al (eds). Nelson Textbook of Pediatrics, 21st edition. 2020, Elsevier, Philadelphia, PA. pp:607-614.
3. Centers for Disease Control and Prevention. Injury prevention and control: WISQARS injury statistics. https://wisqars.cdc.gov/data/lcd/home. Accessed August 2, 2022.
4. Chandy D, Weinhouse G. Drowning (Submersion Injuries). UpToDate. 2021. https://www.uptodate.com/contents/drowning-submersion-injuries. Wolters Kluwer Health, Inc. Accessed August 2, 2022.
5. Best RR, Harris B, Walsh JL, & Manfield T. Pediatric Drowning: A Standard Operating Procedure to Aid the Prehospital Management of Pediatric Cardiac Arrest Resulting from Submersion. Pediatr Emerg Care. 2020;36(3):143–146

Answers to questions
1. c
2. True
3. b
4. d
5. Hypernatremia may occur in a saltwater submersion victim, but it is not considered clinically important in most instances, and it is not considered to be a complication.