Pediatrics

Submersion injuries: Drowning/Near Drowning

OVERVIEW: What every practitioner needs to know

Submersion injuries are the second leading cause of death in the pediatric population and a significant cause of disability in children. According to the recent World Health Organization (WHO) bulletin report, drowning is a major global public health concern.

In 2005, the WHO adopted the following definition of drowning: “Drowning is the process of experiencing respiratory impairment from submersion/immersion in liquid.” There was also consensus that the terms wet, dry, active, silent, and secondary drowning would no longer be used. The drowning outcomes should be either death, morbidity, or no morbidity, which leads to more reliable and comprehensive epidemiology data that in turn help develop preventative measures for this common public health problem.

Near drowning is defined as "survival, even if temporary, but beyond 24 hours after the submersion episode."

Submersion injuries are classified based on the temperature of the water or the type of water in which submersion occurs. Warm water drowning occurs when the water temperature is equal or greater than 20°C, and cold water drowning is temperatures less than 20°C.

Even though initial clinical management is the same, there is an academic classification difference between fresh and salt water submersion injuries.

Submersion can be primary or secondary to any other underlying pathology (syncope or altered mental status from intoxication, dysrhythmias, seizure, or hypoglycemia). Regardless, the initial management is the same.

History and physical exam gives key information for assessing the need of diagnostic tests in looking for secondary causes or risk factors for submersion. Specific diagnostic tests may be done based on the submersion victim’s signs and symptoms or to assess prognosis.

Early and effective resuscitation of the submersion victim is associated with good prognosis. Depending on the condition of the victim, if a rescuer is unsure about the need to resuscitate the victim, resuscitation measures should be started with rescue breaths even while the victim is in the water. Chest compressions, if needed, should be done with the patient placed on firm flat surface. The goal for treatment is to establish and maintain optimal oxygenation, ventilation, and circulation to prevent the long-term, irreversible effects of prolonged hypoxic-ischemic injuries.

The key to prevention of submersion injuries is through effective community awareness and education. Pediatricians need to play a leadership role in this effort due to high incidence rates in the pediatric population. Physicians can discuss water safety with patients and families at every opportunity during patient care and during routine well-child visits as well.

Are you sure your patient has a submersion injury? What are the typical findings for this disease?

The circumstances surrounding a submersion play a key role in diagnosis. The submersion victim may be asymptomatic or may present with signs and symptoms. Submersion for even a few seconds can lead to laryngospasm or wheezing. Victims may have coughing, choking, and gagging with even a very short episode of submersion, due to aspiration. Submersion victims experience some hypoxia, which can lead to respiratory distress, hypopnea, or apnea.

Hypothermia is also very commonly associated with submersion in both cold and warm water drowning. Hypothermia can lead to muscle weakness and dysrhythmias. One of the most concerning presentations is altered mentation or loss of consciousness. Some submersion victims present dead after a prolonged period of submersion.

Important relevant factors to be gleaned by the patient's history are the submersion victim’s age, submersion time, water temperature, water tonicity, degree of water contamination, symptoms, associated injuries (especially cervical spine and head), presence of co-ingestants, underlying medical conditions, type and timing of rescue and resuscitation efforts, and response to initial resuscitation.

Other important historical factors include shortness of breath, difficulty breathing, or apnea; persistent cough, wheezing, aspiration of foreign material, or exposure to contaminated water; level of lost consciousness at presentation and/or a history of lost consciousness; anxiety, fatigue, and changes in behavior patterns; vomiting diarrhea; and coincidental alcohol or drug use.

Pertinent past medical history, particularly history of seizure disorder, diabetes mellitus, severe arthritis, neuromuscular disorder, and a psychiatric history can be particularly important in diagnosing whether the event is primary or secondary. A study found the risk of drowning increases 15 to 19 fold for those with epilepsy. A number of studies worldwide document drowning to be a non-infrequent method for suicide, especially among older individuals. Although an uncommon cause, a cardiac history is important to obtain, including that of ion channelopathies and sudden arrhythmic death syndromes, including prolonged QT syndrome.

Based on the signs and symptoms, the submersion victim may be initially classified into 1 of the following 4 groups (Table I):

Table I.

Four types of submersion injuries according to presenting symptoms
Groups Presenting Symptoms
Asymptomatic None
Symptomatic Altered vital signs (hypothermia, tachycardia, bradycardia); Anxious appearance; Tachypnea, dyspnea, hypoxia; Altered level of consciousness or neurologic deficit.
Cardiopulmonary Arrested Apnea, Asystole (55%); Ventricular tachycardia/fibrillation (29%); Bradycardia (18%); Immersion syndrome
Dead Normothermic with asystole; Rigor mortis; No apparent central nervous system (CNS) function

What other disease/condition shares some of these symptoms?

Injuries with the same signs and symptoms can be unintentional or intentional submersion. Explore the possibility of a submersion injury associated with child abuse, neglect, or Munchausen syndrome by proxy. Past medical, family, and social history along with the details of the presentation of current events, helps distinguish between intentional vs. unintentional submersion injury.

Also consider whether the submersion injury is the primary or secondary cause of the presenting sign and symptoms. For example, patients with seizure disorders can have seizures while in water and have secondary submersion injury. Arrhythmias, head or spinal cord trauma, intoxication/ingestion, hypoglycemia, or suicide can be the primary problem that could lead to a submersion injury.

What caused this disease to develop at this time?

A submersion incident must be thought of as a primary or secondary event. Common causes of submersion can be grouped according to different age groups (Table II).

Table II.

Submersion injuries according to age group
Age Group Most Common Causes Consider Potential Underlying Disorders
Infant < 1 year Bathtub, bucket, or toilet bowl submersion. Child abuse, Munchausen syndrome by proxy Seizure disorder; hypoglycemia; syncopal episode (from dysrhythmia due to long QT syndrome; cardiomyopathy or coronary artery disease); poor neuromuscular control such as that seen with certain pediatric neurologic disorders; major depression or suicide; anxiety/painc disorder.
1-5 years Residential pool submersion Child abuse, Munchausen syndrome by proxy
6-18 years Lake, river, ocean, or other natural body submersion Neglect, boating, intoxication, recreational drug use

In a 2003 study, an analysis of intentional newborn deaths (72 cases < 1 year old) showed that the 2 major causes were asphyxiation: by strangulation (41%) and drowning (27%).

Australian, Scottish, and Canadian data showed that 30%-50% of older adolescents and adults who drowned in boating incidents presented with significant blood alcohol concentrations. Poor judgment and substance abuse (alcohol or other recreational drugs) in conjunction with boat operation may often lead to accidental submersion injury.

Submersion injury can be coupled with cervical spine injury and head trauma associated with surfing, water skiing, scuba diving in shallow waters, and jet skiing. A detailed history from the family or the bystander provides a key component in the diagnosis and differentiation of primary vs. secondary causes.

Submersion injuries usually occur silently and rapidly. Rarely do bystanders report the classic image of a victim helplessly gasping and thrashing in the water. The most common presentation is the ominous scenario of a motionless individual found floating in the water or one who has quietly disappeared beneath the surface.

Typical incidents involve a toddler left temporarily unattended by a distracted caretaker, a young child left under the supervision of an older sibling, an adolescent found floating in the water, or a victim diving and not resurfacing. Less typically, submersion injury may be a deliberate form of child abuse and infant homicide, including Munchausen syndrome by proxy.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

No laboratory studies can confirm the diagnosis of submersion.

Laboratory studies can be important in confirming a secondary causes for submersion injury. Rapid blood glucose level determination can confirm if hypoglycemia is a primary cause. A blood alcohol level and urine toxicology screen for use of drugs can screen for intoxication as a primary cause.

Additional laboratory tests are helpful to look for post-submersion complications with multi-organ system involvement. CBC count and coagulation profile are useful if there is concern of infection or coagulopathy. Submersion can lead to electrolyte disturbances, so checking electrolyte levels is appropriate. If initial test results show elevated serum creatinine level, marked metabolic acidosis, abnormal urinalysis, or significant lymphocytosis, serial estimations of serum creatinine should be performed. Acute renal impairment is known to occur frequently in near drowning, and, while usually mild (serum creatinine level < 0.3 mmol/L or 3.4 mg/dL), severe renal impairment requiring dialysis may occur.

Prolonged hypoxia may lead to metabolic acidosis and elevation of lactate level. A lactate level may be useful to gauge the significance and duration of hypoxia. Arterial blood gas (ABG) analysis is also a helpful clinical parameter, even in patients who are asymptomatic or mildly symptomatic. A surprising degree of hypoxia can exist without clinical signs.

Cardiac enzymes should be obtained if cardiac compromise or primary cardiac pathology is suspected as the primary cause leading to submersion.

Are there any other tests that may prove useful in diagnosing submersion injuries?

If the victim has respiratory distress or apnea, post-submersion history, along with the clinical assessment chest x-ray, is helpful in looking for evidence of aspiration pneumonia, pulmonary edema, or segmental atelectasis suggesting foreign body (e.g., silt or sand) and to assess the severity and follow-up of adult respiratory distress syndrome (ARDS).

Extremity, abdominal, or pelvic imaging or skeletal survey are indicated if there is suspicion of possible accidental trauma or child abuse associated with submersion.

Cervical spine radiograph or computed tomography (CT) scanning is indicated in individuals with an appropriate history of injury, neck pain, or if doubt exists about the circumstances surrounding the submersion injury. For an individual with altered mental status and a suggestive or unclear history, a noncontrast head CT scan can help rule out a central nervous system (CNS) bleed or anatomic abnormalities.

Magnetic resonance spectroscopy (MRS) provides quantitative data on the intracellular concentration of various hydrogen-based constituents that are altered by ischemia or hypoxia and therefore may be useful in submersion victims who have had a cardiopulmonary arrest.

A study evaluated MRI and MRS in 22 children admitted to the PICU after cardiopulmonary arrest following submersion injury. Abnormal signals were identified in areas of the cerebral cortex and basal ganglia. Abnormal cortical intensity on MRI T2-weighted images was seen in only 11 of 16 children who had a poor outcome (vegetative state or death), resulting in low sensitivity of 69% but specificity of 100% for predicting a poor outcome.

Echocardiography (in addition to electrocardiography) should be obtained if there is evidence of dysrhythmia or risk of underlying cardiac disease leading to submersion.

If you are able to confirm that the patient has a submersion injury, what treatment should be initiated?

The primary goal in the management of a submersion injury is to prevent long-term CNS sequelae by preservation of CNS perfusion and function. This can be achieved by appropriate and immediate resuscitation to establish adequate ventilation, oxygenation, and circulation.

Optimal pre-hospital care is the single most important factor in determining the outcome of immersion injury. Bystanders should call emergency medical services, if available. Rescuers should never assume the individual is unsalvageable unless the submersion victim has been obviously dead for a prolonged period of time.

Patients with cold water submersion can have severe hypothermia and may appear dead because of profound bradycardia and vasoconstriction. Rescue breathing should be performed immediately upon finding an apneic victim, even while still in water. The patient should be removed from the water as quickly as possible but with attention to cervical spine precautions. Management of the ABCs (Airway, Breathing, Circulation) is the priority, with particular attention to securing the earliest possible airway and providing adequate oxygenation and ventilation.

Immobilize the neck if the patient has facial or head injury, is unable to give an adequate history, or may have been involved in a diving or motor vehicle accident.

Frequent neurological assessments and Glasgow Coma Scale rating should be done.

Intrinsic compressions, or chest compressions that remove water from the lungs and do not provide CPR, are not recommended because there is no proof of effectiveness and they delay resuscitation, increasing the risk of patient vomiting and aspiration. Ventilation can be achieved even if there is fluid in the lung. Check and clear any foreign material and vomit obstructing the airway in the submersion victim with altered mental status.

For any submersion victim with respiratory signs or symptoms, immediately place 100% oxygen by mask and monitor the oxygen saturation. If the submersion victim has hypoxia or is dyspneic on 100% oxygen, the rescue team should consider the use of continuous positive airway pressure (CPAP) or early intubation with optimal positive end-expiratory pressure (PEEP).

Early literature suggested beginning rewarming early, but more recent studies propose that therapeutic cooling is beneficial in patients after out-of-hospital ventricular fibrillation cardiac arrest, as it reduces ischemic brain injury and death.

Further clinical research is needed to determine the most efficacious treatment strategy in drowning victims.

On arrival to the hospital, the immediate focus is on continuation of basic life support previously instituted by the rescue team or the initiation of appropriate care if acute clinical deterioration is present. A simultaneous, detailed evaluation and assessment for associated injuries must be considered.

If a history of diving is known, strongly consider potential spinal injuries.

Initiate appropriate treatment of hypoglycemia and other electrolyte imbalances; seizures; bronchospasm; and cold-induced bronchorrhea, dysrhythmias, and hypotension as necessary.

Look for evidence of ARDS; multiple organ system failure; nosocomial infection, especially aspiration pneumonia; hyperglycemia and/or gastric stress ulceration.

Cold-induced bronchorrhea or irritation of the tracheobronchial tree by inhaled water or particulate material can produce cough and bronchospasm, which can be treated with inhaled albuterol (beta-agonist bronchodilator). Manage these aggressively because they can worsen into hypoxia. In an alert and cooperative patient, use a trial of positive airway pressure (BiPAP)/CPAP, to provide adequate oxygenation before intubation is performed.

Intubation and mechanical ventilation is needed in any patient with:

1) Inadequate respiratory effort

2) Altered sensorium

3) Severe hypoxemia (unable to maintain pO2 of greater than 60-70 mm Hg in older children or >80 mm Hg in infant on 100% oxygen)

4) Severe acidosis

5) Severe and prolonged respiratory distress

6) High alveolar-arterial (A-a) gradient - PaO2 of 60-80 mm Hg or less on 15 L oxygen nonrebreathing mask

7) Respiratory failure - PaCO2 >45 mm Hg

8) Worsening ABG results

Intubated victims of submersion injury may require PEEP with mechanical ventilation to maintain adequate oxygenation. PEEP has been shown to improve ventilation patterns in the noncompliant lung in several ways, including shifting interstitial pulmonary water into the capillaries, increasing lung volume via prevention of expiratory airway collapse, providing better alveolar ventilation and decreasing capillary blood flow, and increasing the diameter of both small and large airways to improve distribution of ventilation. Management of submersion-related ARDS is similar to that of ARDS from other causes.

A bronchoscopy may be needed to remove foreign material, such as aspirated debris or vomitus plugs from the airway. Surfactant therapy has also been utilized in patients in the setting of respiratory failure associated with drowning, with improvements seen in ventilation, oxygenation, and fluid leak. Extracorporeal membrane oxygenation (ECMO) has been shown to be helpful in treating pulmonary insufficiency in individuals who remain hypoxic despite aggressive mechanical ventilation.

Signs of intravascular volume depletion are generally secondary to pulmonary edema and intracompartmental fluid shifts, regardless of the type of fluid aspirated. Rapid volume expansion may be indicated using isotonic crystalloid (20 mL/kg) or colloid. Inotropic support may be required using dopamine and/or dobutamine. Most acidosis is restored after correction of volume depletion and oxygenation.

The most critical part of management is prompt correction of hypoxemia and acidosis, which may cause ventricular dysrhythmias (typically ventricular tachycardia or ventricular fibrillation), bradycardia, and asystole.

Pulmonary hypertension may result from the release of inflammatory mediators, which may lead to increased right ventricular afterload, decreased left ventricular preload, and pulmonary perfusion. Myocardial dysfunction may result from pulseless electrical activity (PEA), dysrhythmias due to hypoxemia, acidosis, electrolyte disturbances, or hypothermia. These are usually transient in nature.

Hypothermia may also be present and exacerbate bradycardia or any other dysrhythmia, acidosis, and hypoxemia. Ascertaining whether the drowning occurred in warm or cold water is essential, as treatment is variant and dependent on the temperature of the water, rather than the patient. The benefits of resuscitative efforts should be continuously reassessed in such situations. The chart below outlines briefly the differences between treatments in these two scenarios (Table III).

Table III.

Differences in Treatment Between Cold-Water Drowning and Warm-Water Drowning
Cold-Water Drowning Warm-Water Drowning
Patients with severe hypothermia may appear dead because of profound bradycardia and vasoconstriction. Resuscitation should continue while aggressive attempts are made to restore normal body temperature. Patients arriving at the emergency department in cardiopulmonary arrest after a warm-water submersion have a dismal prognosis. The benefits of resuscitative efforts should be continuously reassessed in such situations. In cases of severe global brain injury, consideration should be given for maintaining mild systemic cooling (35-36°C) for 24-48 hours. Neuromuscular blocking agents are used for patient comfort and prevention of rigors during maintenance of hypothermia, which can compromise the neurological examination and assessment of the patient. There is a need for more studies to confirm the beneficial effect in pediatric post-drowning victims.

Hypermetabolic states such as fever or seizures, including subclinical seizures, should be treated aggressively. Blood glucose concentrations should be frequently monitored and normal glycemic values maintained. The Conn classification system can be used as a guideline to quantify the extent of cerebral hypoxia. The categories are as follows:

- Category A - Alert

- Category B - Blunted consciousness; admit and observe for pulmonary compromise, which may result in hypoxemia and worsen CNS injury

- Category C - Comatose (C1 - decorticate, C2 - decerebrate, and C3 - flaccid [worse prognosis than C1)

An EEG provides a good window of cortical and thalamic activity, but it should be interpreted cautiously because it can be affected by multiple confounding variables, such as sedatives, severe electrolyte abnormalities, and metabolic encephalopathies. Invasive monitoring of intracranial pressure has been suggested in both human and animal studies to be neither useful nor necessary. However, no large, well-controlled clinical trials specific to drowning have addressed intracranial pressure monitoring, electrophysiological monitoring, tissue oxygenation management, specific pharmacologic management, vigorous glucose control, and temperature management on neurologic outcome.

Manage patients who require care for significant cervical spine or head trauma in a facility capable of sophisticated neurologic monitoring and neurosurgical intervention. Begin early and aggressive rehabilitation to prevent disuse injury.

To manage infections, watch for evidence of pneumonia and CNS infection. Uncommon infections may present late and unusually. Prophylactic antimicrobial therapy has not proven beneficial.

Patient disposition depends on the history, the presence or absence of signs and symptoms or associated injuries, and the degree of immersion injury. If the patient or family is able to relay a good history of minor immersion injury, the patient is asymptomatic, and with completely normal examination, the patient may be discharged after a 6-hour observation period, with good anticipatory guidance.

All patients who are symptomatic or may be victims of child abuse require hospitalization.

Submersion victims of mild to moderate submersion, with mild symptoms that improve during observation, should be observed for a more prolonged period of time in the ED or observation unit. Individuals who display mild to moderately severe hypoxemia that is corrected easily with oxygen should be admitted to the hospital for observation. These patients can be discharged after resolution of hypoxemia if they have no further complications.

Patients require ICU stay if there is altered mental status or requirement for mechanical ventilation or inotropic support.

Long-term care is dictated by the nature and degree of residual functional impairment and the resources available in the community. Submersion victims with severe neurologic impairment may benefit from admission to a rehabilitation facility for aggressive physiotherapy, occupational, and speech therapies, as needed for each individual.

Some patients who have mild neurodeficits can get outpatient therapies and close physician follow-up.

What are the adverse effects associated with each treatment option?

N/A

What are the possible outcomes of submersion injuries?

Prognosis is related to the duration and magnitude of hypoxia. The most significant impact on the outcome occurs from the patient's response to the in-field resuscitation, before arriving at the hospital.

Submersion victims who are alert or mildly obtunded at presentation in the hospital, and who recover shortly from the pulmonary effects, have excellent prognosis and chance of full recovery.

Submersion victims requiring CPR at presentation to ED or are comatose, have fixed dilated pupils, or no spontaneous respiration have poor prognosis. In a number of studies, 35%-60% of individuals needing continued CPR on arrival to the ED die, and 60%-100% of survivors in this group experience long-term neurologic sequelae.

Pediatric studies indicate that children who require specialized treatment for drowning in the pediatric intensive care unit (PICU) experience at least a 30% mortality rate, and an additional 10%-30% experience severe brain damage. Varying degrees of neurologic as well as pulmonary insults typically complicate their courses.

Approximately 90%-100% of individuals who arrive in the ED with blunted mental status have been shown to survive without neurological deficit. Individuals who arrive in the ED comatose have significantly poorer outcomes. Approximately 34% died after presentation, and an additional 10%-23% survived with severe neurological outcome.

Despite aggressive cerebral resuscitation attempts, neurological outcome has been largely poor in severe pediatric and adult drowning incidents. In post submersion-associated hypoxic ischemic encephalopathy (HIE), the EEGs obtained within 72 hours and afterward show a characteristic pattern of changes associated with poor outcome: initially diffuse delta waves, poor sleep–wake differentiation, and abnormal reactivity are noted, which later change to attenuation of fast frequencies, enhancement of delta waves, and loss of sleep–wake pattern, and then finally development of a burst-suppression pattern.

What causes this disease and how frequent is it?

Lack of appropriate preventative and safety measures around water is the main cause of submersion injuries. The most common risk factors leading to submersion injuries are lack of supervision and safety barriers. Infants most often drown in bathtubs, buckets, or toilets, and children between 1 to 4 years of age in residential pools.

A lack of appropriate adult supervision and placement of protective fences or screens when children are in or around any body of water lead to submersion injuries. A lack of appropriate safety measures and not using life jackets lead to submersion injuries in natural water settings like lakes, ponds, rivers and ocean.

In 2008, the U.S. Coast Guard received reports of 4,789 boating incidents, which included 3,331 boaters injured and 709 deaths. Of boating fatalities, 72% were due to drowning and 90% of the victims were not wearing life jackets; the remainder of the fatalities were due to trauma, hypothermia, carbon monoxide poisoning, or other causes.

Alcohol use is involved in up to 50% of adolescent and adult water recreation-associated deaths and 20% of boating fatalities. Sun exposure and heat heightens the effect of alcohol on balance, coordination, and judgment.

Drowning is the most common cause of unintentional death in individuals with seizure disorders, and the bathtub is the site of the highest drowning risk.

Fatal drowning remains the second leading cause of unintentional death in the 1 to 14 year age group children. In children in the 1 to 4 year age group, drowning is the leading cause of unintentional death; most drowning occurs in residential swimming pools. The most recent data on the incidence of drowning is from the 2007 CDC Web-based Injury Statistics Query and Reporting System (WISQARS), which reported 3443 fatal unintentional drownings, with an average of 10 deaths per day, in the United States. Boating-related accidents caused an additional 496 deaths, which included drowning and other causes. In the United States, males have 4 times more risk than females for dying from drowning-related injuries.

Children 14 years of age or younger account for 20% of fatal drownings. For every single fatal drowning incident, there are 4 nonfatal submersion injuries requiring ED care. Most toddler group incidents occur in bathtubs and swimming pools. Drowning incidents in adolescent and young adult groups (aged 15-24 years) occur in natural bodies of water.

Submersion injuries tend to occur most frequently on weekends (40%) in the summer months (May through August). Sixty-two percent of drowning incidents are seen in rural areas and warm climate areas in the southern and western parts of the United States. The risk is not only due to rural residence and lower socioeconomic status, but also to the educational level of parents. This suggests that targeted public health intervention strategies might prove effective in decreasing the number of submersion incidents.

There is a difference in the incidence of drowning and fatal drowning in different race groups. Data from 2000 to 2007 showed that across all ages, the fatal unintentional drowning rate for African Americans was 1.2 times that of whites. For American Indians and Alaskan Natives, this rate was 1.7 times that of whites. The fatal drowning rate of African American children aged 5 to 14 years is 3.1 times that of white children of similar age. For American Indian and Alaskan Native children, the fatal drowning rate is 2.2 times higher than for white children. Minorities participate less in water-related activities than whites, so their drowning rates (per exposure) may be higher than currently reported.

How do these pathogens/genes/exposures cause the disease?

The pathophysiology of submersion is primarily related to the multiorgan effects of hypoxemia and acidosis. Hypoxemia and the resultant change in acid-base balance may lead to the development of myocardial dysfunction and electrical instability, cardiac arrest, and central nervous system (CNS) ischemia. Sudden immersion of young children in cold water (< 20°C) may stimulate the mammalian diving reflex and produce apnea, bradycardia, and vasoconstriction of nonessential vascular beds with shunting of blood to the coronary and cerebral circulation.

The most important contributory factors to morbidity and mortality from near drowning are hypoxemia, causing a decrease in oxygen delivery to vital tissues.

Submersion injury occurs when a person is submerged in any liquid. After initial breath holding, the individual attempts to breathe and thus either aspirates water (previously referred to as "wet drowning") or has laryngospasm without aspiration (previously referred to as "dry drowning"). Fluid-induced laryngospasm or bronchospasm may contribute to hypoxia.

Although most patients with submersion injury have aspirated a small amount of water or gastric contents into their lungs, approximately 10%-20% of patients have become asphyxiated without evidence of aspiration. This depends on the duration of submersion. When the victim is submerged for a longer time and unable to breathe air, it leads to oxygen depletion and carbon dioxide retention. As the oxygen tension in blood drops further, laryngospasm releases, and the victim gasps, hyperventilates, possibly aspirating variable amounts of liquid. This leads to further hypoxemia.

A study reviewing 578 drowning victims’ autopsies demonstrated that 98.6% had evidence of water in their lungs. Active ventilation during submersion is required to aspirate water, as there is no passive water flow into the lungs after the victim’s death. Significant gas exchange impairment occurs with 1-3 mL/kg fluid aspiration. Aspiration produces vagally mediated pulmonary vasoconstriction and hypertension. Many patients with a relatively short duration of hypoxia may develop increased pulmonary capillary permeability and leak, destroying the alveolar surfactant layer.

In salt water drowning, surfactant washout occurs, and protein-rich fluid exudates rapidly into the alveoli and pulmonary interstitium. This produces alveolar instability, atelectasis, decreased compliance, intrapulmonary shunting, and raised pulmonary vascular resistance, with marked ventilation/perfusion (V/Q) mismatching, resulting in rapid induction of serious hypoxia.

Pulmonary hypertension may initially occur secondary to inflammatory mediator release and later also due to CNS ischemia-related autonomic instability. Cardiac dysfunction and increased vascular resistance can lead to increased left atrial pressure and pulmonary capillary engorgement, causing further pulmonary capillaries to leak. In a small number of patients, aspiration of vomitus or other foreign material may result in occlusion of bronchi, bronchospasm, pneumonia, abscess formation, or inflammatory damage to alveolar capillary membranes causing air trapping and worsening hypoxemia.

All these pathophysiological changes create the clinical presentation of acute lung injury and later development of acute respiratory distress syndrome (ARDS). This commonly complicates drowning victims' survival, affecting their risk for morbidity and mortality.

Pulmonary infection and other less common sites of infection, such as the sinuses or central nervous system, may result from unusual water-borne and soil organisms in immunocompetent individuals. As such, these infections may present late (1-3 wk) and atypically.

Hypothermia and global hypoxic-ischemic injury to the brain can lead to autonomic instability, which causes hypertension, tachycardia, and increased vascular resistance. Hypoxemia causes a decrease in myocardial function. The myocardial dysfunction and increased vascular resistance leads to decreased cardiac output and thus, shock. The clinical presentation is of “cold shock,” with poor pulses and perfusion, causing dysfunction in multiple end organs (such as the kidneys, liver, heart and brain).

Rhabdomyolysis and acute tubular necrosis are well-recognized sequelae seen with submersion-related hypoxic-ischemic injuries. A short duration of submersion-related hypoxemia with early resuscitation and supportive medical care usually leads to full recovery of end organ function.

Clinically important abnormalities of intravascular volume and electrolytes are not commonly seen in surviving submersion victims. Hemodilutional hyponatremia with hypervolemia is seen on postmortem examination of fresh water drowning victims, and hypovolemic hypernatremia is seen in salt water drowning victims. Hypermagnesemia has also been described in association with salt water drowning. Ingestion of large volumes of fresh water, rather than aspiration, is the likely cause of clinically significant electrolyte disturbances, such as hyponatremia, in children after drowning. Hypoxia from aspiration and ischemia due to poor cardiac output/shock causes metabolic acidosis (low pH), which further affects the electrolyte disturbances and compromises normal cellular function.

CNS damage may occur because of prolonged hypoxia, and ischemia may lead to primary and secondary injury from sustained acidosis, edema, hyperglycemia, hypotension, reperfusion, release of excitatory neurotransmitters, impaired cerebral autoregulation, and seizures. This results in a certain pathological sequence, with failure of energy supply to neuronal cells, causing lipid peroxidation and production of free radicals. This in turn triggers the inflammatory responses, release of excitotoxic neurotransmitters, causing disruption of neuronal and glial cell structure and functions. Neuronal cell loss or death is followed by “delayed neuronal dropout” some days after the initial injury.

Additional CNS insult may result from concomitant head or spinal cord injury. Autonomic instability (so-called diencephalic / hypothalamic storm) is common after severe hypoxic and ischemic brain injury and traumatic brain injury. CNS injury has proven to be a major determinant of patient outcome.

A child will lose consciousness after 2 minutes of immersion. Irreversible brain damage occurs after 4-6 minutes. Most children who survive are discovered within 2 minutes of submersion. Most children who die are found after 10 minutes. If the period of ischemia is limited, with core hypothermia and early resuscitation, the injury may be limited and recovery with minor neurologic sequelae is possible.

Other clinical manifestations that might help with diagnosis and management

N/A

What complications might you expect from the disease or treatment of the disease?

Submersion can lead to several forms of complications including neurologic injury, pulmonary edema and ARDS, secondary pulmonary infection, multiple organ system failure, acute tubular necrosis (secondary to hypoxemia), myoglobinuria, and hemoglobinuria.

Are additional laboratory studies available; even some that are not widely available?

N/A

How can submersion injuries be prevented?

Prevention is the key, and community education is the key to prevention. Submersion injuries can be prevented by:

  1. Designating a responsible adult to watch young children while in the bathtub, in or around a pool, or around natural bodies of water. The supervising adult should not be distracted by any other activity (such as talking on the phone, reading or mowing the lawn) during the time of supervision. It is best practice to supervise via “touch supervision”, meaning the responsible party stays close enough to reach the child at all times. Touch supervision should be provided for preschool children at all times.

  2. Formal swimming lessons can protect young children from drowning. Supervision and barriers such as pool fencing are still necessary even when children have completed swimming lessons.

  3. Become certified or renew certification in CPR. CPR performed by bystanders has been shown to improve outcomes in drowning victims. Thus, having CPR skills can help save a life or improve the outcomes of submersion victims.

  4. Employ the buddy system so that children and even adults never swim alone. Always swim with a buddy or select swimming sites that have lifeguards.

  5. Avoid drinking alcohol before or during swimming, boating, or water skiing. Do not drink alcohol while supervising children.

  6. Ensure the proper use of life jackets when children are in or around natural bodies of water, even if they know how to swim. Air-filled or foam toys, such as “water wings”, “noodles”, or inner-tubes, are toys and not designed to keep swimmers safe.

Safety around swimming pools

Install a 4-sided pool fence, at least 4 feet high, that completely separates the pool area. Access to the pool should have self-closing and self-latching gates that open outward with latches that are out of reach to children. Additional barriers, such as automatic door locks or alarms, can be helpful to prevent access or notify you if someone enters the pool area.

Removal of toys immediately after use around the pool is important, because the presence of toys may encourage children to enter the pool area unsupervised or lean over the pool and potentially fall in.

Safety around natural bodies of water

Always use U.S. Coast Guard approved life jackets when boating, regardless of distance to be traveled, size of boat, or swimming ability of boaters.

Make sure the local weather conditions and forecast are safe for swimming or boating. Strong winds and thunderstorms with lightning strikes are dangerous.

Know the meaning of and obey warnings represented by colored beach flags. Review the color warnings for each beach visited because different beaches may use different colors. Watch for dangerous waves and signs of rip currents, and know how to keep yourself safe in these conditions.

What is the evidence?

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Ongoing controversies regarding etiology, diagnosis, treatment

Resuscitation First responders, including EMS and professional ocean lifeguards, should be well versed in providing the time critical institution of advanced interventions, such as airway management. As near drownings are not frequent, refresher training can play an excellent role in skill maintenance. With the current move toward compression-only CPR, further study needs to be performed in the specific hypoxic and potentially hypothermic milieu of drowning before this is routinely performed.

Temperature management Optimal temperature management in drowning patients is a current topic of significant research controversy and clinical interest. A panel of experts was convened at the 2002 World Congress on Drowning, who made the following consensus recommendations on drowning management. "The highest priority is restoration of spontaneous circulation, subsequent to the continuous monitoring of core/and or brain (tympanic) temperatures, which is mandatory in the ED and intensive care unit and, to the extent possible, in the prehospital setting. Drowning victims with restoration of adequate spontaneous circulation who remain comatose should not be actively warmed to temperature values above 32-34°C. If core temperature exceeds 34°C, hypothermia should be achieved as soon as possible and sustained for 12 to 24 hours..." Evidence to support the use of any neuroresuscitative pharmacologic therapy is insufficient.

Therapeutic hypothermia (TH) improves oxygen supply to ischemic brain areas, decreases cerebral metabolic demand, and decreases increased intracranial pressure. In 2002, the American Heart Association, followed in 2003 by the European Resuscitation Council, based on the results of blinded, randomized, multicenter clinical trials, recommended therapeutic hypothermia as a treatment modality for out-of-hospital comatose victims of cardiac arrest. At least 4 separate case reports of drowning victims in patients with full neurologic recovery after coma and cardiac arrest suggest that therapeutic hypothermia may confer neuroprotection. Newer literature, based on extensive preclinical modeling of cellular response to ischemia and reperfusion injury, and analyzing long-term outcome, suggests that therapeutic hypothermia is highly effective in reducing ischemic brain injury.

This area needs additional vigorous clinical research to determine the most efficacious treatment strategy. In the interim, it would appear appropriate for individual jurisdiction EMS directors to meet with their local referral hospital(s) to determine current temperature management strategy.

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