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Near-Drowning/Drowning

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Near-Drowning/Drowning
Kevin N. Waninger
Basics
The terms “drowned” and “near-drowned” have been used to describe the outcomes dead or alive, respectively. The term “near-drowned” has also been used to describe patients who subsequently died from drowning. This usage has led to uncertainty about the meaning of the term. Therefore, the term “near-drowning” has lost favor. The term “drowned” will continue to refer to a person who died or suffered injury from drowning.
Description
  • Drowning is a process resulting in primary respiratory impairment from submersion or immersion in a liquid medium. The pathophysiology is primarily related to abnormal gas exchange, with resultant hypoxia.
  • Hypoxia may result from laryngospasm causing no pulmonary gas exchange, or aspiration of fluids causing pulmonary injury and subsequent disruption of productive gas exchange.
  • The drowning process is a continuum that begins when the victim's airway lies below the surface of a liquid, usually water, at which time the victim voluntarily holds their breath.
  • Breath-holding is usually followed by an involuntary period of laryngospasm secondary to the presence of liquid in the oropharynx or larynx, resulting in hypoxemia, hypercarbia, and acidosis.
  • During this laryngospasm, there is no exchange of air, and the victim may swallow large quantities of water. As arterial oxygen tension drops further, laryngospasm abates, and the victim actively breathes liquid. The amount of liquid inhaled varies considerably from victim to victim.
  • Changes occur in the lungs, body fluids, blood-gas tensions, acid-base balance, and electrolyte concentrations, which are dependent on the composition and volume of the liquid aspirated and the duration of submersion. Surfactant washout, pulmonary HTN, and shunting also contribute to the development of hypoxemia.
  • The clinical presentation and prognosis vary due to different water temperatures, different fluid properties (fresh water, seawater, Dead Seawater, water contaminated with chemicals and bacteria), and the variety of environments (from toilets to hurricane sea conditions) in which drowning occurs.
  • The heart and brain are the organs at greatest risk for permanent, detrimental changes from relatively brief periods of hypoxia. Posthypoxic encephalopathy, with or without cerebral edema, is the most common cause of death in hospitalized drowning victims.
  • Reinstitution of adequate ventilation and oxygenation before the occurrence of circulatory arrest and irreversible nervous system damage results in complete and dramatic restoration of function (if aspiration does not occur).
  • When aspiration occurs, due to ventilation/perfusion mismatch and shunting, prolonged hypoxemia and subsequent complications are more likely to occur.
Epidemiology
Drowning incidents occur in swimming pools, lakes, rivers, streams, storm drains, hot tubs, bathtubs, and even toilets and buckets in toddlers.
  • In 2005, there were 3,582 fatal unintentional drownings in the U.S., averaging 10 deaths per day.
  • >25% of fatal drowning victims were children <15 yrs old, and of all children 1–4 yrs old who died, almost 30% died from drowning. An additional 710 people died from drowning and other causes in boating-related incidents.
  • A swimming pool is 14 times more likely than a motor vehicle to be involved in the death of a child age 4 and under.
  • For every child who dies from drowning, another 4 receive emergency department care for nonfatal submersion injuries.
  • Male: Female ratio in drowning is 4:1.
  • Although drowning rates have slowly declined, fatal drowning remains the 2nd-leading cause of unintentional injury-related death for children ages 1–14 yrs.
  • 19% of drowning deaths involving children occur in public pools with certified lifeguards present. Of all preschoolers who drown, 70% are in the care of 1 or both parents at the time of the drowning, and 75% are missing from sight for <5 min.
  • The majority of children who survive without sequelae are discovered within 2 min following submersion, and most children who die are found after 10 min.
Incidence
  • In 2005 there were 3,582 fatal unintentional drownings in the U.S., averaging 10 deaths per day.
  • Children under 5 and adolescents (ages 15–24) have the highest drowning rates.
Prevalence
  • Rates of fatal drowning are notably higher among African Americans (1.3×) and American Indians and Alaskan Natives (1.8×) compared to Caucasians.
  • For children ages 5–14, the fatal drowning rate of African American children (3.2×) and American Indian and Alaskan Native children (2.4×), is higher than for white children.

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Risk Factors
  • Unattended children at water sites; inadequate adult supervision
  • Alcohol and/or drug abuse (50% cases involving adolescents and adults)
  • Limited swimming ability and exhaustion
  • Trauma
  • Risky behavior in the water; rough play
  • Deliberate prolonged submersion, intentional hyperventilation before breath-hold diving; young children more susceptible to the diving reflex, triggered by submersion of face in cold water, with bradycardia and redistribution of blood flow to heart and brain
  • Exacerbation of existing medical problems (seizure disorder, cardiac disease, diabetes, syncope, cerebrovascular accident)
  • Cold-water immersion or hypothermia; cold shock response; young children more susceptible, due to larger body surface-to-mass ratio; decreases the metabolic rate, survival to full recovery possible
  • Scuba: Contamination of air supply with toxic gases (ie, carbon monoxide), running out of air at depth
  • Oxygen-induced seizures in divers using oxygen-enriched air mixtures
  • Panic/anxiety
  • Improper fencing of pools (at least 5 feet high with self-closing latches)
General Prevention
Drowning is preventable! Prevention is the key:
  • Parental supervision of children around water; watch empty pails, buckets, toddlers around toilets.
  • Carefully watching children while they bathe
  • Swimming lessons: Children 1–4 yrs old who drowned were significantly less likely to have attended swimming classes than matched controls (1)[B].
  • The American Academy of Pediatrics recommends that all children be taught to swim after age 5, but makes no recommendation for younger children.
  • Adequate pool fencing; wearing properly sized life jackets
  • Improved pool design preventing children from being trapped when submerged
  • Poor pool maintenance resulting in murky or cloudy water
  • Instruction/supervision of lifeguards in methods of waterfront surveillance and resuscitation techniques
  • Education of public in prudent consumption of alcoholic beverages
  • Impose severe sanctions against boaters who are intoxicated.
  • Encourage people to learn to swim, understand the limits of their swimming ability, and never swim alone.
  • Restricted swimming areas; post proper signage in areas of dangerous underwater tow; pay attention to the weather, tides and water conditions, and especially currents. Currents are usually perceived from the outside as weaker than they actually are.
  • Understand the water environment where you are swimming, diving, or boating.
  • Instruct greater numbers of the public in Basic Life Support (BLS) or Cardiopulmonary Resuscitation (CPR).
  • Bring a cordless telephone to the pool so children are not left unsupervised while answering a phone call.
Etiology
  • Unexpected submersion. Struggle does not always occur.
  • Aspiration of variable amounts of water. Grossly contaminated water poses a risk of pulmonary infection.
  • Laryngospasm
  • Hypoxia
  • Metabolic acidosis
  • Myocardial dysfunction
  • Coagulation abnormalities
  • Multisystem organ dysfunction with renal failure
  • CNS dysfunction
Diagnosis
Pediatric considerations:
  • Hypothermia may be protective.
  • Family history of sudden death by drowning may suggest a genetic cause for syncope, such as long QT.
History
  • See “Risk Factors.”
  • Information from witnesses or emergency medical services personnel at the scene
Physical Exam
  • Cardiac presentation depends on severity of exposure; ranging from sinus tachycardia to cardiac arrest and apnea. It is not uncommon for these patients to require but respond to prolonged CPR. Children who still require CPR at the time they arrive at the emergency department have a poor prognosis, with at least half of survivors suffering significant neurologic impairment.

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  • The process of drowning is characterized by a gradual decrease in arterial oxygen saturation with a simultaneous decrease in cardiac output. Cardiac arrest is, therefore, not sudden but is preceded by a brief period of tachycardia and HTN, followed by bradycardia with hypotension and electromechanical dissociation (pulseless electrical activity).
  • Ventricular fibrillation is rare after submersion, unless resulting from acute hypothermia or triggered by mechanical irritation, and will frequently not respond to defibrillation. The automated external defibrillator will not play a major role in improving the success of resuscitation after drowning (2,3)[A].
  • Whether the drowning event occurs in fresh water or seawater, the end result is pulmonary edema, a decrease in pulmonary compliance, and an increase in the ventilation/perfusion mismatch.
  • Patients with water aspiration may present with minimal symptoms, severe pulmonary edema, or frank cardiopulmonary arrest. Cyanosis, dyspnea, and/or copious pulmonary secretions may be present.
  • Cerebral edema/injury
  • Evidence of trauma/cervical spine injury
  • Hypothermia; full vital signs with rectal temperature required
Diagnostic Tests & Interpretation
Lab
  • Most drowning victims do not aspirate enough fluid to cause life-threatening changes in blood volume.
  • Life-threatening electrolyte abnormalities occur when the amount of aspirated fluid is >22 mL/kg of body weight.
  • Aspiration of this volume of water is unlikely in humans who survive the drowning process (<15%).
  • Rarely is there a need for emergent treatment of electrolyte abnormalities unless very large volumes of water are aspirated or the drowning event occurs in a highly concentrated liquid medium such as the Dead Sea.
  • Arterial blood gases
  • CBC; significant changes of hemoglobin and hematocrit are seldom seen in human drowning victims.
  • Chemistry panels usually normal, but rule out hyperkalemia, hypernatremia, hyponatremia, or signs of renal failure
  • Urinalysis
  • Prothrombin time/international normalized ratio (coagulation panel)
  • Alcohol and toxicology screen
Imaging
  • Chest x-rays may be normal initially, or show infiltrates ranging from a patchy distribution to global pulmonary edema.
  • CT scan of head may be needed to rule out acute or chronic intracranial process in unconscious patients.
  • Obtain cervical spine films if you suspect head/neck trauma.
Differential Diagnosis
  • Consider a potential underlying cause of submersion injury, such as alcohol or drug intoxication, myocardial infarction, syncope (long QT syndrome), seizure (including O2-induced), stroke, hypoglycemia, or trauma.
  • Head or spinal cord injury/trauma
  • Venomous stings by aquatic animals
  • Decompression sickness or arterial gas embolism, nitrogen narcosis from scuba diving
  • Consider child abuse/neglect
Treatment
Pre-Hospital
  • ABCs, remove wet clothing, initiate rewarming as soon as possible, IV with 0.9% normal saline (watch fluids in patients with pulmonary edema)
  • Initiate cardiopulmonary resuscitation as soon as possible if indicated; begin in the water if can be done without putting rescuer at risk; although unusual, recovery with normal neurologic function has been reported even after prolonged cardiac arrest.
  • Basic life support, and sometimes rescue breathing alone, performed by laypersons, play a key role in the survival of the drowning victim (3)[A].
  • Avoid further aspiration; apply cricoid pressure during bag-valve-mask ventilation.
  • Secure airway and protect against aspiration of stomach contents; intubation with 100% oxygen
  • Strict cervical spine precautions (2,3)[A]
  • The subdiaphragmatic thrust (Heimlich) maneuver to remove water from the abdomen is not recommended unless a foreign body is suspected of obstructing the airway (2,3)[A].
ED Treatment
  • Correct hypoxia, titrate to oxygen saturation, intubation with positive end-expiratory pressure can be effective in reversing the abnormal V/Q relationships. In patients who are alert, nasal continuous positive airway pressure may be needed for ventilation support.

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  • The risk for aspiration from water and stomach contents is still present, so strict aspiration precautions with elevation of head of bed if possible are recommended.
  • If bronchospasm is present or suspected, give nebulized beta-2-agonist treatments.
  • Evaluate and treat traumatic injuries.
  • If in cardiopulmonary arrest, initiate Advanced Cardiac Life Support measures; continue resuscitation until core temperature >32°C, or until spontaneous pulse and respirations return.
  • Follow temperature and continue rewarming efforts if indicated.
  • Insert a nasogastric tube to decompress the stomach.
  • Insert Foley catheter, if needed.
  • Check and correct severe electrolyte abnormalities and monitor acid-base balance. Correct acidosis with sodium bicarbonate administration for pH <7.1.
  • Antibiotics needed only in those patients who become febrile, develop new pulmonary infiltrates, or have purulent secretions. Prophylactic antibiotics do not improve morbidity or mortality (3)[A].
  • Steroids have been shown to be ineffective in treating the pulmonary issues of drowning, and may worsen outcome by interfering with the normal healing process (3)[A].
  • Management of patients with suspected hypoxic brain injury includes hyperventilation (maintain PaCO2 at 25–30 mm Hg), head elevation (if no C-spine injury is present), diuretics, and muscle relaxants.
  • It appears that in the absence of hypothermia that may have occurred during the drowning process, aggressive brain resuscitation in the neurologically impaired drowning patient, using current techniques, is of limited benefit in returning patients to normal neurologic function.
In-Patient Considerations
Admission Criteria
  • ICU:
    • Patients who required CPR or artificial resuscitation
    • Abnormal chest x-ray
    • Arterial blood gas abnormalities
    • Glasgow Coma Scale (GCS) <13
  • Admit observation:
    • Submersion unknown or >1 min
    • History of cyanosis or apnea
    • Required brief assisted ventilation
    • GCS >13
    • Delayed pulmonary edema (up to 12 hr)
    • Delayed neurologic abnormalities
Discharge Criteria
  • Questionable history of submersion, after observation in emergency department for 6–8 hr
  • Normal chest x-ray
  • No respiratory distress
  • No neurologic deterioration
  • Discharge to reliable home, with instructions to return for shortness of breath or mental status changes
Ongoing Care
Prognosis
  • Prognosis of resuscitated drowning victim is related to degree of damage secondary to the anoxic episode and the duration of immersion and pulmonary insult.
  • Residual complications of near-drowning may include intellectual impairment, convulsive disorders, and pulmonary or cardiac complications.
References
1. Brenner RA, Taneja GS, Haynie DL, et al. Association between swimming lessons and drowning in childhood: a case-control study. Arch Pediatr Adolesc Med. 2009;163:203–210.
2. Bierens JJ, Knape JT, Gelissen HP. Drowning. Curr Opin Crit Care. 2002;8:578–586.
3. Layon AJ, Modell JH. Drowning: Update 2009. Anesthesiology. 2009;110:1390–1401.
Additional Reading
Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. Web-based Injury Statistics Query and Reporting System (WISQARS) [online]. (2008) [cited 2008 March 23]. Available from: URL: www.cdc.gov/ncipc/wisqars. Accessed on September 12, 2009.
Idris AH, Berg RA, Bierens J, et al. Recommended guidelines for uniform reporting of data from drowning: the “Utstein style.” Circulation. 2003;108:2565–2574.
Papa L, Hoelle R, Idris A. Systematic review of definitions for drowning incidents. Resuscitation. 2005;65:255–264.
Codes
ICD9
994.1 Drowning and nonfatal submersion
Clinical Pearls
  • Medical authorities traditionally made a great distinction between salt water and fresh water drowning. The theory was that because of its high salt content, seawater in the lungs would affect the body very differently from fresh water in a variety of ways. Although this is true in theory, very few survivors of near-drowning ingest enough water to make a difference, and this rarely becomes an issue in treating patients who arrive at the hospital. In practice, water temperature and the presence of any contaminants are much more important considerations.
  • Hypoxia is the main threat in drowning victims, and resuscitation efforts should be directed toward restoration of optimal oxygenation.


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