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Near-Drowning: Life-Saving Steps

William J. Reed, MD

Emergencies Series Editor: Warren B. Howe, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 26 - NO. 7 - JULY 98


In Brief: Cervical-spine injury, trauma, and hypothermia should be considered in all sports-related near-drownings. The focus of resuscitation should be on prompt restoration of respiration, CPR, and advanced cardiac life support with cervical-spine precautions. A subset of near-drowning victims can be discharged after only 4 to 6 hours of observation. Although total drowning deaths have decreased 45% in the past 15 years, a greater emphasis on public education to prevent drowning remains in order.

Drowning is defined as death by suffocation in a liquid, and near-drowning is defined as recovery, at least temporarily, following suffocation in a liquid (1). Both are submersion accidents. There is some controversy over how to describe those who die within 24 hours of a submersion accident. Some authors refer to this as "secondary drowning" and even extend the time period to 72 hours. Others consider anyone who dies within 24 hours of a submersion accident a drowning victim, and still others attribute late deaths to their associated complications like acute respiratory distress syndrome, neurologic death, or pneumonia.

The vast majority of drownings (85% to 90%) are "wet" drownings wherein the victim aspirates water (see "The Pathophysiology of Drowning and Near-Drowning," page 34) (2,3). (Some "wet" drownings are thought to be due to pulmonary edema from marked negative intrathoracic pressures incurred during desperate attempts at inhalation over a closed glottis.) The remaining 10% to 15% are "dry" drownings secondary to laryngospasm. A drowning sequence has been described that begins with panic or struggle and is followed by breath-holding, apnea, fluid swallowing, and either aspiration or laryngospasm ending in unconsciousness and death (4). The "breath-hold breakpoint," the point at which it becomes impossible to voluntarily continue to hold one's breath, occurs at a partial pressure of carbon dioxide (PaCO2) of roughly 55 mm Hg but varies widely among individuals and can be maximized by training (5).

An All-Too-Common Occurrence

Although most literature still quotes an annual US drowning death rate of 8,000, this was actually the rate in 1980. In 1994, according to the most recent data available, drownings accounted for 4,589 deaths, 689 of which were sports related (6). Although this represents a 45% drop in total drowning deaths and a 60% drop in sports-related drownings over the past 15 years (figure 1: not shown), drowning is still the fourth most common cause of accidental death in adults and the third most common cause of accidental death in children 0 to 4 years of age. In some states, drowning is the leading cause of accidental death among children under 5 years old (7).

Sports-related near-drownings make up 15% of the total, with the highest incidence among young adults (figure 2: not shown). Males predominate in all age-groups, and black children are at a higher risk than whites (2).

The exact incidence of near-drowning is unknown, but it is estimated to be from 2 to 20 times as common as drowning (3). Alcohol use is a commonly reported associated risk factor, noted in 40% to 50% of drownings. Other factors that are associated with an increased risk of a submersion accident include seizures, hypothermia, an inability to swim, fatigue or exhaustion, hyperventilation, illicit drug use, cerebrovascular accidents, myocardial infarctions, suicide, and child abuse or neglect (2,3,8).

One interesting risk factor for drowning and near-drowning is hyperventilation prior to breath-holding. Hyperventilation lowers the PaCO2, thus effectively removing rising PaCO2 as a respiratory stimulus and leaving only the falling partial pressure of oxygen (PaO2) to stimulate respiration. The problem is that falling PaO2 is only a weak respiratory stimulus, and in accordance with Dalton's law, PaO2 falls more quickly as the individual nears the surface. There is a sudden loss of consciousness just below the surface at a PaO2 of 25 to 30 mm Hg. This has been termed "shallow water blackout (5)."

Over 90% of drownings and near-drownings occur in freshwater, even in states with large coastal populations (2). Swimming pools represent the greatest risk to young children, and rivers, lakes, and ponds the greatest risk to adolescents. Other reported drowning locations include oceans, bathtubs, spas, buckets, and toilets. Child abuse should always be considered in drowning deaths of young children or infants.

Prompt, Effective Treatment

The primary focus of the resuscitation of the near-drowning victim is prompt initiation of respiratory support. The standard of care involves rapid and safe extrication, cervical-spine immobilization, and early initiation of cardiopulmonary resuscitation (CPR). Sports-related near-drownings require a high index of suspicion of cervical injury, especially with a diving or boating accident. Although in-water chest compressions are difficult (unless a surfboard is present), artificial respiration is recommended—with the jaw-thrust maneuver if cervical-spine injury is suspected. The importance of early CPR cannot be overemphasized: More than 90% of victims who arrive at the emergency department with a pulse survive neurologically intact (9).

Once thought to be beneficial, the Heimlich maneuver (and other postural drainage techniques) is of unproven benefit and should not be used unless obstruction of the airway is strongly suspected (10). When feasible, advanced cardiac life support should be instituted promptly. All victims should receive supplemental oxygen, and those with symptoms should be on 100% oxygen by non-rebreather mask. If the patient is in respiratory distress (apnea, loss of airway protection, neurologic deterioration, CO2 retention, or PaO2 less than 60 to 90 mm Hg on high-flow oxygen), he or she should be endotracheally intubated.

Emergency department management should include intravenous access, pulse oximetry, and electrocardiographic monitoring. Fluid resuscitation is often required. Cervical-spine injury must be presumed to exist until full radiographic and reliable clinical examinations can be accomplished. Hypothermia should be addressed if present. The adage that "no patient should be pronounced dead until warm and dead" applies.

All patients should have a chest radiograph and arterial blood gas analysis. Chest radiograph findings may be normal or reveal infiltrates, atelectasis, or pulmonary edema. Additional laboratory analysis of electrolytes, glucose, blood urea nitrogen, creatinine, liver function tests, urinalysis, and complete blood count are required for patients in whom admission is anticipated.

As in the prehospital setting, appropriate attention must be focused on the airway. If the patient is intubated, the addition of continuous positive airway pressure (CPAP) or positive end expiratory pressure (PEEP) is advised to maximize PaO2 when oxygen alone does not. CPAP by face mask and nasal CPAP are also effective in conscious patients who have spontaneous respirations and no risk of vomiting (11). Submersion injuries in divers require a heightened awareness and search for dysbaric injuries.

Prophylactic antibiotic therapy is of unproven benefit unless the aspirated water is known to be contaminated or if the clinician suspects the patient aspirated vomitus. In such cases broad-spectrum antibiotic therapy should be started promptly because the rapid development of lethal pneumonias and sepsis is possible (12). The routine use of steroids is unwarranted. Clinical evidence of bronchospasm is an indication for beta-agonists. If gastric distension is present, it should be treated with nasogastric tube decompression.

In the past, barbiturate coma and induced hypothermia were thought to improve the neurologic outcome in severe cases, but this has since been refuted (2,7). Likewise, artificial surfactant administration has not been shown to be effective in animal models (13), although one toddler was successfully treated with exogenous bovine surfactant (14). Warm butyl alcohol vapor may play a role in the future management of submersion victims (15).

Admission or Discharge

Not all survivors of near-drowning require admission. It is now recommended that patients who are asymptomatic and have normal vital signs, physical exam, chest radiograph, and pulse oximetry or arterial blood gas analysis can be discharged to home after 4 to 6 hours of observation in the emergency department. Noonan et al (16) recommend a 6- to 8-hour observation period for children. Patients who do not meet these criteria require admission.

Patients who are discharged from the emergency department should be accompanied by a friend or relative and be given follow-up instructions that include the symptoms of delayed pulmonary complications. Follow-up should occur within 1 to 3 days. Pulmonary edema has been reported up to 12 hours after a near-drowning (8).

In the most thorough review of outcomes in submersion-accident patients brought to the emergency department, Weinstein and Krieger (3) found that roughly 69% of victims survive intact, 6% survive with permanent neurological sequelae, and 25% die. For those presenting awake and alert, intact survival nears 100%, especially in the pediatric population.

It should also be noted that patients have been successfully resuscitated without neurologic sequelae from nonhypothermic near-drownings when they arrived in the emergency department without vital signs and required cardiotonic medications and CPR (17). Since no adequate predictors of intact survival exist, all submersion accident victims require aggressive resuscitation in the emergency department. If cardiovascular stability cannot be achieved after correcting hypothermia, the patient should be considered unresuscitable (2).

Water Sports Safety

Although drowning deaths have declined steadily over the last 15 years, sports-related drownings continue to make up 15% of the total. Sports-related drownings and near-drownings continue to be a significant cause of morbidity and mortality, especially among adolescents and young adults. Physicians and other professionals need to continue to emphasize water sports safety and the dangerous role of alcohol in submersion accidents.

References

  1. Modell JH: Drown versus near-drown: a discussion of definitions, editorial. Crit Care Med 1981;9(4):351-352
  2. DeNicola LK, Falk JL, Swanson ME, et al: Submersion injuries in children and adults. Crit Care Clin 1997;13(3):477-502
  3. Weinstein MD, Krieger BP: Near-drowning: epidemiology, pathophysiology, and initial treatment. J Emerg Med 1996;14(4):461-467
  4. Noble CS, Sharpe N: Drowning: its mechanism and treatment. Can Med Assoc J 1963;89:402-405
  5. Reed WJ: Current physiologic concepts of breath hold diving and drowning: implications in big wave surfing. Surfing Med 1997;16:3-4,18
  6. The mortality database in CDC Wonder on the World Wide Web (https://wonder.cdc.gov/, accessed May 26, 1998)
  7. Fields AI: Near-drowning in the pediatric population. Crit Care Clin 1992;8(1):113-129
  8. Orlowski JP: Drowning, near-drowning, and ice-water submersions. Pediatr Clin North Am 1987;34(1):75-92
  9. Modell JH, Graves SA, Kuck EJ: Near-drowning: correlation of level of consciousness and survival. Can Anaesth Soc J 1980;27(3):211-215
  10. Rosen P, Soto M, Harley J: The use of the Heimlich maneuver in near drowning: Institute of Medicine report. J Emerg Med 1995;13(3):397-405
  11. Dottorini M, Eslami A, Baglioni S, et al: Nasal-continuous positive airway pressure in the treatment of near-drowning in freshwater. Chest 1996;110(4):1122-1124
  12. Ender PT, Dolan MJ, Dolan D, et al: Near-drowning associated Aeromonas pneumonia. J Emerg Med 1996;14(6):737-741
  13. Anker AL, Santora T, Spivey W: Artificial surfactant administration in an animal model of near drowning. Acad Emerg Med 1995;2(3):204-210
  14. Suzuki H, Ohta T, Iwata K, et al: Surfactant therapy for respiratory failure due to near-drowning. Eur J Pediatr 1996;155(5):383-384
  15. Waugh WH: Potential use of warm butyl alcohol vapor as adjunct agent in the emergency treatment of sea water wet near-drowning. Am J Emerg Med 1993;11(1):20-27
  16. Noonan L, Howrey R, Ginsburg CM: Freshwater submersion injuries in children: a retrospective review of seventy-five hospitalized patients. Pediatrics 1996;98(3 pt 1):368-371
  17. Lavelle JM, Shaw KN: Near-drowning: is emergency department cardiopulmonary resuscitation or intensive care unit cerebral resuscitation indicated? Crit Care Med 1993;21(3):368-373

The Pathophysiology of Drowning and Near-Drowning

The pathophysiology varies somewhat between freshwater and saltwater submersion accidents and between drowning and near-drowning, but the essential pathophysiologic element in all these events is hypoxemia. Both respiratory and metabolic acidosis are common. The combination of hypoxemia and acidosis ultimately results in the devastating neurologic insults and cardiovascular changes in drowning and near-drowning victims.

In saltwater drownings and saltwater "wet" near-drownings (those that involve aspiration), the hypertonicity of the aspirated fluid draws intravascular fluid into the already fluid-filled alveoli, resulting in ventilation-perfusion abnormalities and intrapulmonary shunting. Intravascular hypovolemia, hemoconcentration, and electrolyte abnormalities can result, although this is not usually seen clinically in near-drowning survivors because they rarely aspirate enough water to produce these effects. Significant electrolyte abnormalities, however, have been described in near-drownings in the Dead Sea and in polluted waters (1,2).

In drownings and "wet" near-drownings, lung surfactant is inactivated, resulting in atelectasis and shunting. The hypotonic fluid of freshwater drownings and freshwater "wet" near-drownings can be absorbed into the intravascular space, resulting in hypervolemia, electrolyte abnormalities, and hemodilution, but, again, this is rarely seen clinically. A transudate can accumulate in the alveoli of both freshwater and saltwater "wet" submersion victims, leading to noncardiogenic pulmonary edema and acute respiratory distress syndrome and thereby worsening the ventilation-perfusion mismatch.

Significant hypothermia after submersion in cold water may play a protective role in submersion victims, especially in children. The protective effect on the brain is thought to be a combination of decreased metabolism and the diving response (3). Hypothermia in warm water submersion accidents, however, is a poor prognostic sign (4).

Neurologic injury and cardiac dysrhythmias due to hypoxemia and acidosis are serious complications of submersion accidents. Indeed, the critical clinical consequence of hypoxemia is cerebral injury and the resultant neurologic sequelae. Rarer complications include renal failure, hemolysis, and disseminated intravascular coagulation. The aspiration of sand, mud, algae, and other foreign debris poses unique management challenges.

References

  1. Yagil Y, Stalnikowicz R, Michaeli J, et al: Near-drowning in the Dead Sea: electrolyte imbalances and therapeutic implications. Arch Intern Med 1985;145(1):50-53
  2. Fromm RE Jr: Hypercalcemia complicating an industrial near-drowning. Ann Emerg Med 1991;20(6):669-671
  3. Gooden BA: Why some people do not drown: hypothermia versus the diving response. Med J Aust 1992;157(9):629-632
  4. DeNicola LK, Falk JL, Swanson ME, et al: Submersion injuries in children and adults. Crit Care Clin 1997;13(3):477-502


The views expressed in this article are those of the author and do not reflect the official policy or position of the Department of the Navy, the Department of Defense, or the United States government.

Dr Reed is a US naval flight surgeon, hyperbaric medical officer, and emergency medicine resident at the Naval Medical Center in San Diego. Dr Howe is the team physician at Western Washington University in Bellingham, Washington, and an editorial board member of The Physician and Sportsmedicine. Address correspondence to William J. Reed, MD, Dept of Emergency Medicine, Naval Medical Center, 34800 Bob Wilson Dr, San Diego, CA 92134-5000; e-mail to [email protected].


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