From the EM Model
6.0 Environmental Disorders
6.5 Submersion Incidents

It is estimated that there are between 8,000 and 9,000 deaths per year from drowning in the United States, and the incidence worldwide is believed to be in the range of 140,000 deaths per year.¹

More than one in four fatal submersion incident victims are children 14 years old or younger.²

Male victims predominate in all age groups and are four times as likely to die from submersion incidents as are females.2 The use of intoxicants, particularly alcohol, is frequently associated with submersion incidents. The ability to swim, interestingly, does not appear to be consistently related to drowning rates.³

On emergency department presentation, victims of submersion incidents may be anywhere in the spectrum of illness from asymptomatic to comatose or in cardiac arrest.

Emergency physicians must be able to recognize the sometimes subtle signs of a significant submersion injury and understand the treatment principles for submersion incidents.

Case Presentation

A 9-year-old boy presents with his mother complaining of a bump and abrasion on his head. The family was at a family picnic, and the children were swimming in a quarry. The child was playing with some older cousins jumping from the dock onto inner tubes. The mother reports that the boys were “roughhousing” on the inner tube, and her son got pushed off the tube. When he tried to surface he was under the dock and hit the top of his head. One of the older boys pulled him out from under the dock and brought him to his mother. The patient was upset and crying, stating that the bump on his head hurt. While she was trying to calm him down, he coughed several times and then vomited a small amount of clear liquid, but she says he has been fine ever since. She was concerned that the abrasion on his head might need stitches. She brought him straight from the quarry, which was about 30 minutes away.

Vital signs are blood pressure 105/58, pulse rate 92, respiratory rate 18, temperature 36.8°C (98.2°F), and oxygen saturation 97% on room air.

On examination, the child is well appearing and in no acute distress. Head examination reveals a small 2-cm by 2-cm cephalohematoma on his scalp with a small abrasion. Pupils are equal, round, and reactive, and the oropharynx is without abnormality. Lung examination reveals a faint expiratory wheeze, and the child is noted to have an occasional dry cough, but his mother says he has had a “spring cold.” Heart examination reveals a normal rate and regular rhythm, with no appreciable murmurs. The abdomen is nontender, and the neurologic examination is nonfocal.

Pathophysiology of Submersion

The typical timeline of events in drowning begins with panic and struggling, accompanied by uncontrolled hyperventilation that can lead to aspiration of large amounts of water. As the victim becomes submerged, breath-holding occurs and panic continues, resulting in the rapid development of hypoxia, hypercapnia, and acidosis.

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.

Baseline chest radiographs, pulse oximetry, and arterial blood gases are typically recommended, although recent evidence suggests they may not be necessary in some asymptomatic cases.⁷

Cranial imaging with computed tomography (CT) can be useful if there is concern for traumatic head injury. The decision to use CT to evaluate for hypoxic injury is less clear-cut. A retrospective study of children who were victims of submersion incidents showed that CT often does not immediately show evidence of brain injury. The most common pattern of injury seen on delayed imaging (at 24 hours) was loss of grey-white matter differentiation consistent with hypoxic ischemic encephalopathy. Bilateral edema and bilateral basal ganglia infarcts were also appreciated. Intra- or extra-axial blood and unilateral abnormalities were not seen.⁸

Patients who have a normal room air oxygen saturation, normal pulmonary examination, and Glasgow Coma Scale score above 13 may be discharged home. All others should be admitted.^7,9

Contaminants

Freshwater lakes contain bacteria and protozoa. Seawater contains bacteria, algae, sand, and other particulates that can have a deleterious effect on the lung tissue, necessitating bronchoscopic lavage. Pool water is relatively devoid of bacteria, but chlorine can be irritating to the tracheobronchial tree, and it is very hypotonic. The major direct pulmonary insult is related to a reduction of surfactant and subsequent high surface tension and reduced compliance and atelectasis.

CRITICAL DECISION

Should prophylactic antibiotics be started in victims of submersion incidents?

Antibiotics should not be started prophylactically in all victims of submersion incidents. In patients who develop secondary lung infections, culture and sensitivity testing is essential to identify the causative agents and guide antimicrobial treatment, because microbes such as Aeromonas hydrophilia, which are not sensitive to common antibiotic regimens, can be present.3,4 If an Aeromonas infection is proved, aminoglycosides and second- or third-generation cephalosporins such as ceftazidime are preferred.

CRITICAL DECISION

What else should be considered when treating victims of submersion incidents?

Keep in mind the possibility that a medical emergency preceded and caused the submersion incident, especially in unusual instances such as an adult submerged in a bathtub.

Depending on the specific case and clinical suspicion, an ECG and cardiac testing, toxicology screening, anticonvulsant medication serum levels, etc., might be warranted.

In children, report any suspicious submersion incident to social services and the necessary authorities.

Case Resolution

Because the 9-year-old who had bumped his head while swimming had faint wheezing and coughing, the emergency physician decided to keep the child for observation for four hours. A chest radiograph was obtained and appeared normal. A few hours into his observation, the patient’s oxygen saturation was noted to be 92% on room air. Arterial blood gasses were obtained and revealed respiratory acidosis and mild hypoxemia, which was corrected with oxygen delivered by nasal cannula.

Repeat chest film 12 hours later showed mild bilateral interstitial infiltrates. At this time, the patient was admitted to the pediatric floor for further observation. Sputum cultures grew only normal flora; he remained afebrile, and antibiotics were not needed.

After three days in the hospital, the patient no longer had an oxygen requirement, his oxygen saturations were improved, he was completely asymptomatic, and he was discharged home.

Summary

Victims of submersion incidents can present anywhere on the spectrum of illness from completely asymptomatic to cardiorespiratory arrest. Frequently, asymptomatic patients can be safely discharged home if vital signs remain stable and the patient remains asymptomatic after a four- to six-hour period of observation. Patients who develop any symptoms during observation or who have abnormal vital signs should be admitted for further observation and treatment.

References

1. Centers for Disease Control and Prevention. Swimming and recreational water safety. In: Health Information for International Travel 2005-2006. Atlanta, GA: US Department of Health and Human Services, Public Health Service; 2005.
2. Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. Web-based Injury Statistics Query and Reporting System (WISQARS). 2008. Available at: www.cdc.gov/ncipc/wisqars. Accessed March 23, 2008.
3. Newman AB, Stewart RD. Submersion incidents. In: Auerbach PD, ed. Wilderness Medicine: Management of Wilderness and Environmental Emergencies. Chicago, IL: Mosby; 1995:1209-1233.
4. Falk JL, Escowitz HE. Submersion injuries in children and adults. Semin Respir Crit Care Med. 2002;23(1):47-55.
5. Robinson MD, Seward PN. Submersion injury in children. Pediatr Emerg Care. 1987;3:44-49.
6. Falk JL, Escowitz HE. Submersion injuries in children and adults. Semin Respir Crit Care Med. 2002;23:47–55.
7. Swanson ME, Tilelli JA, Causey AL. Predicting discharge in uncomplicated near-drowning. Am J Emerg Med. 2000;18(1):9-11.
8. Rafaat KT, Spear RM, Kuelbs C, et al. Cranial computed tomographic findings in a large group of children with drowning: diagnostic, prognostic, and forensic implications. Pediatr Crit Care Med. 2008;9:567-572.
9. Pratt FD, Haynes BE. Incidence of “secondary drowning” after saltwater submersion. Ann Emerg Med. 1986;15:1084-1087.