Drowning

Background

Drowning remains a significant worldwide public health concern, ranking as the third leading cause of unintentional injury death and accounting for 7% of all injury-related deaths. It is a major cause of disability and death, particularly in children. At least one third of survivors sustain moderate-to-severe neurologic sequelae.^{[1, 2, 3]}

Exact definitions of drowning have varied widely.^[4] Drowning was previously defined as death secondary to asphyxia while immersed in a liquid, usually water, or within 24 hours of submersion.

At the 2002 World Congress on Drowning held in Amsterdam, a group of experts suggested a new consensus definition for drowning in order to decrease the confusion over the number of terms and definitions (>20) that have appeared in the literature.^[5]  This group developed a uniform definition that allowed more accurate analysis and comparison of studies, enabled researchers to draw more meaningful conclusions from pooled data, and improved the ease of surveillance and prevention activities.

The consensus definition states that drowning is a process resulting in primary respiratory impairment from submersion in a liquid medium. Implicit in this definition is that a liquid-air interface is present at the entrance to the victim's airway, which prevents the individual from breathing oxygen. The terms "wet drowning", "dry drowning", "active or passive drowning", "near-drowning", "secondary drowning", and "silent drowning" may be noted in historical references, yet they have been abandoned in favor of the general term "drowning." Terms describing outcomes were simplified to death, morbidity, or no morbidity.^[5]

Drowning usually occurs silently and rapidly. The classic image of a victim helplessly gasping and thrashing in the water is infrequently reported. The more ominous scenario of a motionless individual floating in the water or quietly disappearing beneath the surface is more typical.

Drowning may be further classified as cold-water or warm-water injury. Warm-water drowning occurs at water temperatures of 20°C or higher, and cold-water drowning occurs at water temperatures of less than 20°C. Although ice-cold water has been reported to be protective, especially in young children,^[6] prolonged immersions can nullify the effect of temperature on survivability.^[7] Hypothermia occurs commonly in drowning and is usually secondary to conductive heat loss during submersion, not synonymous with cold-water drowning.

Additional classification may include the type of water in which the submersion occurred, such as freshwater and saltwater, or natural bodies of water versus man made. Although initial treatment of submersion victims is not affected by the type of water, serum electrolyte derangements may be related to the salinity of the water (particularly if large amounts of water are ingested), while long-term infectious complications are primarily related to whether the victim was submersed in a natural or a man-made body of water.^[8]

Immediate threats include effects on the central nervous and cardiovascular systems (see Workup). Thus, the most critical actions in the immediate management of drowning victims include prompt correction of hypoxemia and acidosis (see Treatment).

The degree of CNS injury depends on the severity and duration of hypoxia. Posthypoxic cerebral hypoperfusion may occur. Long-term effects of cerebral hypoxia, including vegetative survival, are the most devastating (see Treatment).

Prevention is key for reducing morbidity and mortality from drowning. Community education is the key to prevention.

• References

Etiology

Drowning may be a primary event or may be secondary to events such as the following:

• Seizures
• Head or spine trauma
• Cardiac arrhythmias
• Hypothermia
• Alcohol and drug ingestion
• Syncope
• Apnea
• Hyperventilation
• Suicide
• Hypoglycemia

Causes tend to vary with the person’s age.

Infants

Infants most often drown in bathtubs or buckets of water. Most of these victims drown during a brief (< 5 min) lapse in adult supervision.

Bathtub and pail drownings may represent child abuse; carefully examine the child for other evidence of injury, review the child's history for previous events, and review the details of the incident very carefully with the child's parent or guardian.^{[9, 10]}

Children aged 1-5 years

Residential swimming pools are the most common venue.^{[10, 11, 12]} The US Consumer Product Safety Commission reports that a swimming pool is 14 times more likely than a motor vehicle to be involved in the death of a child younger than 5 years.

Many residential pools have no physical barrier between the pool and the home. Open gates are involved in up to 70% of drownings in cases involving fenced-in pools. Pools may also be accessed through unlocked windows when the pool area abuts the house.^[13]

A study from Australia on drowning in water tanks^[14] and one from Bangladesh on drowning in ditches, canals, and ponds^[15] illustrate that water exposure is both culturally and geographically related. Limiting access to such areas is an important target for prevention strategies.

Young adults aged 15-19 years

Young adults typically drown in ponds, lakes, rivers, and oceans. Approximately 90% of drownings occur within 10 yards of safety. Cervical spine injuries and head trauma, which result from diving into water that may be shallow or contain rocks and other hazards, have been implicated.^[16]

Alcohol and, to a lesser extent, other recreational drugs are implicated in many cases. Australian, Scottish, and Canadian data showed that 30-50% of older adolescents and adults who drowned in boating incidents were inebriated, as determined by blood alcohol concentrations.

All age groups

Any of the following may lead to drowning episodes in people of any age:

• Seizure disorder
• Myocardial infarction (MI) or syncopal episode
• Poor neuromuscular control, such as that seen with significant arthritis, Parkinson disease, or other neurologic disorders
• Major depression/suicide
• Anxiety/panic disorder
• Diabetes, hypoglycemia
• Water sports hazards, especially with personal watercraft
• Poor judgment and substance abuse (alcohol or other recreational drugs) in conjunction with boat operation
• Cervical spine injury and head trauma associated with surfing, water skiing, and jet skiing
• Scuba diving accidents and other injuries (eg, bites, stings, lacerations)

A study by the European Alliance Against Depression reviewed gender-specific suicide methods in 16 European countries.^[17] They found that women were more likely to choose drowning as a suicide method. They suggested that gender-specific prevention strategies should be developed.

Natural disasters

Drowning is a well-recognized complication of natural disasters, such as hurricanes and earthquakes, which produce tidal waves (tsunamis) and flooding. A study of loss of life from Hurricane Katrina analyzed 771 fatalities. Most involved elderly individuals and were caused by drowning due to the direct physical impact of flooding. Mortality was highest near severe levee breaches where water was moving at rapid velocity and in areas with increased water depth.^[18]

• References

Epidemiology

United States statistics

While drowning deaths have shown a gradual decline, from 2005-2014, there were an average of 3,536 fatal unintentional drownings (non–boating related) annually in the United States, which is about 10 deaths per day.^[19] An additional 332 drowning deaths occurred each year in boating-related incidents.^[20]  The US Centers for Disease Control and Prevention (CDC) reported 3,709 unintentional drowning deaths in 2017.^[21]

Drowning is the sixth leading cause of accidental death for people of all ages and the second leading cause of death for children aged 1-14 years, after motor vehicle collisions.^{[1, 22, 23]} This averages out to about 10 deaths per day in the United States.

Approximately one quarter of these deaths occur in children 14 years of age or younger. Four times as many children receive emergency department care for nonfatal injuries for every child that dies. A bimodal distribution of deaths is observed, with an initial peak in the toddler age group and a second peak in adolescent to young adult males. Fifteen percent of children admitted for drowning die in the hospital.

Drownings tend to occur most frequently on weekends (40%) in the summertime months (May through August). Drownings are seen more commonly in rural areas and in the southern and western United States (62%).^[24] In California, Arizona, and Florida, drowning is the number one cause of injury-related death.

Morbidity from submersion occurs in 12-27% of survivors aged 1-14 years. Preschool-aged boys are at greatest risk of submersion injury. A survey of 9,420 primary school children in South Carolina estimated that approximately 10% of children younger than 5 years had an experience judged a "serious threat" of drowning.

In 2008, the US Lifesaving Association reported more than 70,000 rescues from drowning at beach venues.^[25] California alone reports approximately 25,000 ocean rescues on its beaches each year. More than 4.5 million preventive actions, including moving swimmers from areas of rip currents and other hazards, were reported during this same period of time. Approximately 1 in 8 males and 1 in 23 females experience some form of water-associated event but never seek medical attention.

International statistics

Annually, an estimated 372,000 people die from drowning, which accounts for drowning to be a major public health problem worldwide. Global estimates of drowning are likely a significant underestimation of the actual public health impact. No annual international incidence of associated neurological injury has been reported.^[1]

Several of the most densely populated nations in the world fail to report nonfatal drowning incidents. This, along with the fact that in many instances no attempt is made to resuscitate at the scene^[26] and that many cases are never brought to medical attention, renders accurate worldwide incidence approximation and classification virtually impossible.^[27] The overall incidence of drowning has an estimated range of 20-500 times the rate of fatal drowning.

British data suggest that approximately 10% of drownings in the United Kingdome occur in the domestic setting, most frequently during baths, in water-filled containers both indoors and outdoors, and in garden ponds.^[28] Structures overhanging water posed a particular risk. Young children (< 5 years) and older adults were shown to be at highest risk.^{[28, 29, 30]}

The drowning site appears to be a function of availability. In areas of the world where bathing occurs in nearby streams, rivers, and lakes, data collected suggest that the incidence is^{[26, 31]} more similar to that found in industrialized nations in the adolescent and young adult groups (aged 15-24 y), where most incidents occur in natural bodies of water.

Hong et al suggest that this risk is due not only to rural residence and lower socioeconomic status but also to the education level of parents, which would suggest that targeted public health intervention strategies might prove to be effective in decreasing this incidence.^{[31, 32]}

Boating and related water sports, combined with alcohol consumption, increase both the likelihood and severity of submersion injuries. Risk-taking behaviors, especially in males, are similarly associated with increased morbidity and mortality.

An Australian study that focused on drowning risks at surf beaches found that in the 204 individuals studied, adolescent and adult males spent longer amounts of time in the water, were more likely to use surfing equipment, were more likely to consume more alcoholic beverages, and spent more time in deeper water. The authors hypothesized that over-representation of males in drowning statistics is in part a function of this greater exposure to deeper waters further from shore.^[33]

Males also generally feel more confident about their swimming abilities and their ability to return to shore if caught in a rip current.^[34]

The authors found no gender difference in the likelihood of holding a first aid qualification, cardiopulmonary resuscitation (CPR) certification, or prior swimming lesson participation. They suggested that larger, controlled studies should address the role of overconfidence, self-rated versus measured swimming competency, surf experience, ability to judge swimming conditions, and the use of flotation devices in relation to drowning risk.^[34]

This later study provided somewhat different data from that in a previous, smaller 2008 study by Morgan et al that indicated no difference in gender or age on likely surf-drowning risk, including preexisting medical conditions, presence of drugs or alcohol, or the likelihood of swimming without a buddy or in rip current conditions.^[35]

The Divers Alert Network (DAN) Annual Diving Report 2016 Edition reported 188 diving fatalities worldwide in 2014.^[36] However, an older report estimated scuba diving accounts for an estimated 700-800 deaths per year; etiologies include inadequate experience/training, exhaustion, panic, carelessness, and barotrauma.^[37] Denoble et al studied 947 recreational diving accidents from 1992-2003, during which 70% of the victims drowned. Drowning was usually secondary to a disabling injury, equipment problems, problems with air supply, and cardiac events in these individuals.^[38]

A 2009 Western Australian study reviewed 24 diving fatalities and found that the lack of formal certification (30%) was associated with the breach of safety practices.^[39] The authors noted that shore dives or dives from private crafts were fatal 3 times as often as dives from commercial boats. These researchers also found that dive depth, ignoring a preexisting medical condition, nonadherence to the buddy system, poorly planned dives, and the lack of establishment of positive buoyancy when in distress contributed to diving fatalities. Only twice was faulty equipment the cause, once during scuba and once during a "hookah" dive (ie, with surface-supplied air). Seventy percent occurred during the day. Twenty-five percent involved tourists.^[39]

A study of 19 reported fatalities in Australia in 2008 concluded that the causes of death included apnoeic hypoxia, trauma, and cardiac related issues. The study concluded that trauma from a marine creature, snorkeling or diving alone, apnoeic hypoxia, and preexisting medical conditions were factors in several deaths.^[40]

A Danish occupational medical study of 114 drowning fatalities in the period 1989-2005 among fishing industry seamen found that approximately one half of the deaths occurred during vessel disasters in rough weather, with capsizing and foundering, or collisions. One third occurred during other occupational accidents that caused the victim to go overboard. One third occurred when the victim underwent difficult disembarkation during nighttime hours in foreign ports or was intoxicated.^[41]

A Swedish study emphasized the contribution of alcohol and drugs to drowning deaths and the importance of considering such information in developing prevention programs. Although the number of drowning deaths has significantly decreased, men and middle aged and older people had a higher incidence. Among women, suicidal drowning was common.^[42]

A Canadian study of drowning during work-related and recreational helicopter crashes over water found that educational strategies to increase survival likelihood included wearing survival gear during the trip, prior escape training, ensuring that crew and passengers possessed appropriate knowledge of escape routes, and assuming appropriate crash positioning. They suggested that companies using helicopter transport over water should focus on regular and repeated safety training and improvement in safety measures on helicopters.^[43]

Accidental death, such as drowning, complicate tourism in many countries.^{[44, 45]} An Australian study found accidental drowning to be the cause of approximately 5% of all deaths in the 1068 visitor deaths reviewed.^[46]

Race-related demographics

Between 2000 and 2007, the rate of fatal accidental drowning for African Americans across all ages was 1.3 times that of whites; for Native Americans and Alaskan Natives, this rate was 1.7 times that of whites.^[22] However, the relative rates vary with age. African-American children aged 0-4 years exhibit a lower rate of drowning (2.32 per 100,000), probably secondary to less pool access. In older pediatric age groups, the incidence is 2-5 times higher.

In indigenous children and teenagers in the United States and Canada, injuries account for 71% of childhood deaths. In Alaska, drowning is the leading cause of death among indigenous children.

Focused interventions have targeted indigenous groups in Alaska. Over a 20-year period (1982-84 vs 2002 vs 2004), the age-adjusted mortality rate declined 28%, compared with a 5% decline for the United States as a whole. This author suggests that developmentally and culturally appropriate interventions and community-based educational interventions, such as a requirement for wearing personal flotation devices, 4-sided fencing of pools, and the prohibition of alcohol sale to minors, can be highly effective.^[47]

Between 1994 and 2005, drowning rates demonstrated an increase among white males 65 years and older and middle-aged white females (45-64 y) but showed a decrease in black boys, adolescents, and young adult males (5-24 y), black girls and adolescents (5-14 y), and white adolescents and young women (15-24 y).^[48]

Sex- and age-related demographics

Males are approximately 4 times more likely than females to have submersion injuries. This rate is consistent with increased risk-taking behavior in boys, especially in adolescence. Males are also 12 times more likely than females to be involved in a boat-related drowning; alcohol use is frequently a contributing factor. Only in bathtub incidents do girls predominate in incidence.

A bimodal age distribution is noted in persons with a submersion injury. Children younger than 4 years and adolescents aged 15-19 years are at highest risk. This bimodal distribution is predominantly observed in males, who have a much higher incidence of submersion injuries during adolescence than females do. Most toddlers drown in swimming pools and bathtubs, whereas most adolescents drown in natural bodies of water.

• References

Pathophysiology

The most important contributory factors to morbidity and mortality from drowning are hypoxemia and acidosis and the multiorgan effects of these processes. Central nervous system (CNS) damage may occur because of hypoxemia sustained during the drowning episode (primary injury) or may result from arrhythmias, ongoing pulmonary injury, reperfusion injury, or multiorgan dysfunction (secondary injury), particularly with prolonged tissue hypoxia.

After initial breath holding, when the victim's airway lies below the liquid's surface, an involuntary period of laryngospasm is triggered by the presence of liquid in the oropharynx or larynx. At this time, the victim is unable to breathe in air, causing 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.

Lunetta et al reviewed the autopsies of 578 individuals who had apparently drowned and found evidence of water in the lungs of 98.6% of those studied. As they noted, active ventilation while submerged is required to aspirate water, as water does not passively flow into the lungs once the victim is dead.^[49]

Depending upon the degree of hypoxemia and resultant acidotic change in acid-base balance, the person may develop myocardial dysfunction and electrical instability, cardiac arrest, and CNS ischemia.^[50] Asphyxia leads to relaxation of the airway, which permits the lungs to take in water in many individuals, although most patients aspirate less than 4 mL/kg of fluid.

Fluid aspiration of at least 11 mL/kg is required for alterations in blood volume to occur, and aspiration of more than 22 mL/kg is required before significant electrolyte changes develop. Ingestion of large volumes of freshwater, rather than aspiration, is the likely cause of clinically significant electrolyte disturbances, such as hyponatremia, in children after drowning.

Approximately 10-15% of individuals maintain tight laryngospasm until cardiac arrest occurs and inspiratory efforts have ceased. These victims do not aspirate any appreciable fluid (previously referred to as "dry drowning") (see the chart below).

View Image

Mechanism of hypoxia in submersion injury.

In young children suddenly immersed in cold water (< 20°C), the mammalian diving reflex may occur and produce apnea, bradycardia, and vasoconstriction of nonessential vascular beds with shunting of blood to the coronary and cerebral circulation.

Pulmonary effects

The target organ of submersion injury is the lung. Aspiration of as little as 1-3 mL/kg of fluid leads to significantly impaired gas exchange. Injury to other systems is largely secondary to hypoxia and ischemic acidosis. Additional CNS insult may result from concomitant head or spinal cord injury. The period of hypoxia/hypoxemia is initially limited to the duration of hypopnea or apnea and may resolve with initial rescue efforts. 

Patients with prolonged hypoxic episodes are prone to alveolar fluid aspiration resulting in vagally mediated pulmonary vasoconstriction, hypertension, and fluid-induced bronchospasm. Freshwater moves rapidly across the alveolar-capillary membrane into the microcirculation. Freshwater is considerably hypotonic relative to plasma and causes disruption of alveolar surfactant. Destruction of surfactant produces alveolar instability, atelectasis, and decreased compliance, with marked ventilation/perfusion (V/Q) mismatching. As much as 75% of blood flow may circulate through hypoventilated lungs.

Saltwater, which is hyperosmolar, increases the osmotic gradient and therefore draws fluid into the alveoli, diluting surfactant (surfactant washout). Protein-rich fluid then exudes rapidly into the alveoli and pulmonary interstitium. Compliance is reduced, the alveolar-capillary basement membrane is damaged directly, and shunting occurs. This results in rapid development of serious hypoxia.

The distinction between submersion fluid type is primarily academic and mostly connotes epidemiologic significance. Hypoxia serves as the primary insult and, with alveolar aspiration, culminates in surfactant disruption, alveolar collapse and derecruitment, intrapulmonary shunting, increased pulmonary vascular resistance, and ventilation-mismatch. These processes result in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).

Pulmonary hypertension may be exacerbated by inflammatory mediator release. In a minor percentage of patients, aspiration of vomitus, sand, silt, stagnant water, and sewage may result in occlusion of bronchi, bronchospasm, pneumonia, abscess formation, and inflammatory damage to alveolar capillary membranes.

Postobstructive pulmonary edema following laryngospasm and hypoxic neuronal injury with resultant neurogenic pulmonary edema may also occur. ARDS from altered surfactant effect and neurogenic pulmonary edema often complicate management.

Commonly, these edematous, noncompliant lungs may be further compromised by ventilator-associated lung injury (VALI). Newer modes of ventilation, including high-frequency oscillatory ventilation and airway pressure release ventilation, or an open-lung approach that limits tidal volumes to 6-8 mL/kg while using positive end-expiratory pressure (PEEP) to support optimal respiratory compliance, can help support oxygenation and ventilation with less risk of VALI than is associated with older methods of ventilation.

Pneumonia is a rare consequence of submersion injury and is more common with submersion in stagnant warm and fresh water. Uncommon pathogens, including Aeromonas, Burkholderia, and Pseudallescheria, cause a disproportionate percentage of cases of pneumonia. Because pneumonia is uncommon early in the course of treatment of submersion injuries, the use of prophylactic antimicrobial therapy has not proven to be of any benefit.

Chemical pneumonitis is a more common sequela than pneumonia, especially if the submersion occurs in a chlorinated pool or in a bucket containing a cleaning product.

Central nervous system effects

Hypoxic-ischemic brain injury is a foreboding sequelae of asphyxial cardiac arrest associated with drowning. The degree of CNS injury remains the major determinant of subsequent survival and long-term morbidity in cases of drowning. Two minutes after immersion, a child will lose consciousness. Irreversible brain damage usually 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.

The areas of high risk in the brain are the metabolically active subcortical tissues and those with watershed perfusion. Global brain injury occurs in cases of hypoxemia and low-flow states resulting in energy failure, lipid peroxidation, free radical production, inflammatory processes, and release of excitotoxic neurotransmitters. Neuronal and glial functions are disrupted. Asphyxial cardiac arrest results in the development of microinfarctions as well as selective neuronal injury.^{[51, 52]}

Primary CNS injury is initially associated with tissue hypoxia and ischemia. If the period of hypoxia and ischemia is brief or if the person is a very young child who rapidly develops core hypothermia, primary injury may be limited, and the patient may recover with minimal neurologic sequelae, even after more prolonged immersion.

In contrast, drowning that is associated with prolonged hypoxia or ischemia is likely to lead to both significant primary injury and secondary injury, especially in older patients who cannot rapidly achieve core hypothermia. Sources of secondary injury include the following:

• Reperfusion
• Sustained acidosis
• Cerebral edema
• Hyperglycemia
• Release of excitatory neurotransmitters
• Seizures
• Hypotension
• Impaired cerebral autoregulation

Although cerebral edema is a common consequence of prolonged submersion (or submersion followed by prolonged circulatory insufficiency), retrospective reviews and animal studies have not demonstrated any benefit from the use of intracranial pressure monitoring with diffuse axonal injury. However, as submersion injuries may be associated with trauma (especially to the head, neck, and trunk), focal or persistent neurologic deficit may indicate mass lesions or other injury amenable to surgical intervention.

Autonomic instability (diencephalic/hypothalamic storm) is common following severe traumatic, hypoxic, or ischemic brain injury. These patients often present with signs and symptoms of hyperstimulation of the sympathetic nervous system, including the following:

• Tachycardia
• Hypertension
• Tachypnea
• Diaphoresis
• Agitation
• Muscle rigidity

Autonomic instability has also been found to present as takotsubo stress-induced cardiomyopathy, with associated electrocardiographic changes, apical ballooning on echocardiogram, and elevated serum troponin levels.^[53]

Seizures may be the result of acute cerebral hypoxia, but they may also be inciting events that lead to loss of consciousness and inability to protect the airway.

Cardiovascular effects

Drowning may result in an acute asphyxial cardiac arrest, which emanates from hypoxemia that precedes the development of ischemia. This scenario results from initial cessation of gas exchange followed by worsening hypoxia and eventual cardiac arrest. Hypoxemia is the overriding insult.

Hypovolemia may be due to fluid losses from increased capillary permeability. Profound hypotension may take place during and after the initial resuscitation period, especially when rewarming is accompanied by vasodilatation. It is important to remain cognizant that many patients present with hypothermia due to prolonged submersion times rather than true cold-water submersion.

Myocardial dysfunction may result from ventricular dysrhythmias, pulseless electrical activity (PEA), and asystole due to hypoxemia, hypothermia, acidosis, or electrolyte abnormalities (less common). In addition, hypoxemia may directly damage the myocardium, decreasing cardiac output.

Pulmonary hypertension may result from the release of pulmonary inflammatory mediators, increasing right ventricular afterload and thus decreasing both pulmonary perfusion and left ventricular preload. However, although cardiovascular effects may be severe, they are usually transient, unlike severe CNS injury.

Primary arrhythmias, including long-QT syndromes (particularly type I) and catecholaminergic polymorphic ventricular tachycardia (CPVT), may predispose patients to fatal arrhythmias during swimming. Sudden, severe cardiovascular collapse in otherwise healthy patients with brief, witnessed immersion may be the result of existing cardiac conduction defects and may not represent secondary effects of immersion injury.^[54] Swimming may serve as an arrhythmogenic trigger and result in the diving reflex, which can lead to autonomic instability. The diving reflex is elicited by contact of the face with cold water and consists of breath-holding, bradycardia, and intense peripheral vasoconstriction. The exertion associated with swimming may additionally result in predisposition to syncopal events.

Infection

Infection in the sinuses, lungs, and CNS, as well as other less common sites, may result from unusual soil and waterborne bacteria, amebas, and fungi, including Pseudallescheria boydii and Scedosporium apiospermum,Naegleria, Balamuthia, as well as Burkholderia and Aeromonas organisms, and newly discovered human pathogens (Francisella philomiragia).^{[8, 55, 56, 57, 58, 59, 60, 61]} These infections are usually insidious in onset, typically occurring more than 30 days after the initial submersion injury. P boydii‒complex infections are difficult to treat and are often fatal.^{[57, 62, 63]}

Several investigators have suggested that the finding of evidence of seawater organisms, such as bioluminescent bacteria and plankton DNA, or normal inhabitants of the trachea in the bloodstream may be utilized as an additional indicator to support the conclusion of death by drowning in bodies discovered in aquatic environments.^{[64, 65]}

Other effects

The clinical course may be complicated by multiorgan system failure resulting from prolonged hypoxia, acidosis, rhabdomyolysis, acute tubular necrosis, or the treatment modalities. Disseminated intravascular coagulation (DIC), hepatic and renal insufficiency, metabolic acidosis, and GI injuries must be considered and appropriately managed.

• References

Prognosis

Patients who are alert or mildly obtunded at presentation have an excellent chance for full recovery. Patients who are comatose, those receiving CPR at presentation to the emergency department (ED), or those who have fixed and dilated pupils and no spontaneous respirations have a 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 mortality is at least 30% in children who require specialized treatment for drowning in the pediatric intensive care unit (PICU). Severe brain damage occurs in an additional 10-30%.

The neuroprotective effects of cold-water drowning are poorly understood. Intact survival of comatose patients after cold-water submersion is still quite uncommon. A 2014 study challenged the idea of improved survival in cold water drowning.^[66] Hypothermia in nonwinter probably means they were immersed longer and thus have a worse outcome.^[67]

Hypothermia profoundly decreases the cerebral metabolic rate, but neuroprotective effects seem to occur only if the hypothermia occurs at the time of submersion and only if very rapid cooling occurs in water with a temperature of less than 5°C (eg, if the individual broke through ice into the water).

Morbidity and death from drowning are caused primarily by laryngospasm and pulmonary injury, resulting hypoxemia and acidosis, and their effects on the brain and other organ systems. A high risk of death exists secondary to the subsequent development of acute respiratory distress syndrome (ARDS).

The adult mortality rate is difficult to quantify because of poor reporting and inconsistent record keeping. Thirty-five percent of immersion episodes in children are fatal; 33% of episodes result in some degree of neurologic impairment, with 11% resulting in severe neurologic sequelae.

Anecdotal reports of survival are noted in children with moderate hypothermic submersion (core temperature < 32°C), but most persons experiencing cold-water submersion do not develop hypothermia rapidly enough to decrease cerebral metabolism before severe, irreversible hypoxia and ischemia occur.

• References

Patient Education

Prevention strategies are of paramount importance. Community education is vital in promoting water safety, injury prevention, and CPR initiatives. Unfortunately, community activism often occurs only following a tragic death or injury.

Toddlers must not be allowed near bathrooms or buckets of water without immediate adult supervision. Children must never swim alone or unsupervised, and children younger than 4 years and any children who are unable to swim must be closely monitored by a responsible adult. Adults must be well aware of their own and their children's swimming limits.

Appropriate barriers must be used around pools, wading pools, and other water-containing devices at home. The US Consumer Product Safety Commission has published model regulations regarding pool fencing. Homeowners can stress that all caregivers know CPR, have immediate access to a poolside phone, and ensure their children know how to call 911. Most pool-related drownings occur within the first 6 months of pool exposure. Additionally, the absence of proper pool fencing is reported to increase the odds of pool-related drowning by three to fivefold.^[13]

Children must be taught safe conduct around water and during boating and jet- or water-skiing. Use of alcohol or other recreational drugs is not appropriate when swimming or engaging in other water sports, as well as when operating or riding in motorized watercraft. Appropriate boating equipment should be used, including personal flotation devices, and all boaters must understand weather and water conditions.

Parents are strongly urged to learn CPR and water safety training in case rescue and resuscitation are needed. A 1990 study found that 86% of pool owners supported voluntary CPR training, while 40% of those surveyed supported mandatory training.^[68] The American Academy of Pediatrics updated the policy statement in 2010, focusing on water safety as well as drain-entrapment hazards, dangers of inflatable pools, and benefits of swimming lessons.^[69]

For patient education information, see the Public Health Center and Environmental Exposures and Injuries Center, as well as Cardiopulmonary Resuscitation (CPR) and Drowning.

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History

All aspects of the drowning episode should be determined, including the circumstances around the actual submersion. Rarely does a patient present with the classic "Hollywood scenario" of a novice swimmer stranded in water, frantically struggling and flapping his or her arms in desperation. Experienced swimmers may experience syncope secondary to hypoxia after hyperventilating to drive off carbon dioxide, while deep-water divers may succumb to "shallow-water blackout" as they ascend.

Most persons are found after having been submerged in water for an unobserved period.

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

Intentional newborn deaths

In an analysis of intentional newborn deaths (72 coroner cases < 1 year), two of the major causes were asphyxiation by strangulation (41%) and drowning (27%).^[70] Studies have identified the following as risk factors for such newborn deaths:

• Young and unmarried mothers
• Parental depression
• Family financial problems
• Residence of the mother and child in households with unrelated male adults

The infant often was found to be at home alone with the caretaker-perpetrator (93%) and was crying. The authors suggest that these incidents may be impulsive, largely unintended, and result from stress.^[71] A study by Dias et al, suggested that targeted hospital-based education and social service involvement may be effective in reducing these cases.^[72]

Drowning factors

Relevant factors in drowning cases include the following:

• Age of the victim
• Submersion time
• Water temperature
• Water tonicity
• Degree of water contamination
• Symptoms
• Associated injuries (especially cervical spine and head)
• Coincident alcohol or drug use
• Underlying medical conditions
• Type and timing of rescue and resuscitation efforts
• Response to initial resuscitation

Thermal conduction of water is 25-30 times that of air. The temperature of thermally neutral water, in which a nude individual's heat production balances heat loss, is 33°C. Physical exertion increases heat loss secondary to convection/conduction up to 35-50% faster.

A significant risk of hypothermia usually develops in water temperatures less than 25°C, which is the temperature found in most US natural waters during the majority of the year.

During immersion in ice water, a person will become hypothermic in approximately 30 minutes. Cooling at this temperature becomes life-threatening in approximately 60 minutes.^{[73, 74]}

Other important historical factors include the following:

• Shortness of breath, difficulty breathing, apnea
• Persistent cough, wheezing
• In stream, lake, or saltwater immersion, possible aspiration of foreign material or exposure to fungi, bacteria, and other microorganisms
• level of consciousness at presentation, history of loss of consciousness, anxiety, fatigue, changes in usual behavior; Modell suggests that most individuals will have some period of unconsciousness after drowning secondary to cerebral hypoxia^[75]
• Vomiting, diarrhea
• Coincident alcohol or drug use

Pertinent past medical history

Underlying medical conditions that are particularly more likely to lead to drowning include the following:

• Seizure disorder
• Diabetes mellitus
• Psychiatric illness
• Severe arthritis
• Cardiac disease
• Neuromuscular disorder

A United Kingdom study found a 15- to 19-fold increase in the risk of drowning in individuals with epilepsy.^[76]

A number of studies worldwide have documented that drowning is a not infrequent method for suicide, especially among older individuals. Cultural attitudes toward death, water source availability and accessibility, social acceptability of this method, gender, and age may influence drowning as the method of choice.^{[77, 78, 79]}

Cardiac history is important to obtain, especially that of dysrhythmias and syncope. Ion channelopathies and sudden arrhythmic death syndromes, including Brugada syndrome and prolonged QT syndrome, should be considered^[27] ; however, this cause of drowning is probably uncommon. Lunetta et al looked for genetic mutations in 63 drowning victims and failed to document one case of long QT founder gene mutation.^[49]

• References

Physical Examination

The clinical presentations of people who experience submersion injuries vary widely. A drowning victim may be classified initially into 1 of the following 4 groups:

• Asymptomatic
• Symptomatic
• Cardiopulmonary arrest
• Obviously dead

Patients are especially likely to be asymptomatic if they experienced brief, witnessed submersions with immediate resuscitation.

Symptomatic patients may exhibit the following:

• Altered vital signs (eg, hypothermia, tachycardia or bradycardia)
• Anxious appearance
• Tachypnea, dyspnea, or hypoxia: If dyspnea occurs, no matter how slight, the patient is considered symptomatic
• Metabolic acidosis (may exist in asymptomatic patients as well)
• Altered level of consciousness, neurologic deficit
• Cough
• Wheezing
• Hypothermia
• Vomiting, diarrhea, or both

Patients in cardiopulmonary arrest exhibit the following:

• Apnea
• Asystole (55%), ventricular tachycardia/fibrillation (29%), bradycardia (16%)
• Immersion syndrome

In cases of obvious death due to drowning, the following are present:

• Normothermia with asystole
• Apnea
• Rigor mortis
• Dependent lividity
• No apparent CNS function

• References

Approach Considerations

Management of hypoxemia is the key to the management of drowning. A surprising degree of hypoxia may be present in a relatively asymptomatic patient. Obtain continuous pulse oximetry.

Obtain arterial blood gas (ABG) levels in all patients with any history of submersion injury. ABG analysis is probably the most reliable clinical parameter in patients who are asymptomatic or mildly symptomatic. ABG analysis should include co-oximetry to detect methemoglobinemia and carboxyhemoglobinemia.

Remember that cervical spine trauma may be present in any victim of shallow- or rocky-water immersion injury. If the victim is unable to give a clear history of the events, has evidence of head or facial injury, or is found unresponsive in a pool or other shallow body of water, protect the cervical spine until injury is excluded.

Obtain blood for a rapid glucose determination, complete blood count (CBC), electrolyte levels, lactate level, and coagulation profile, if indicated. Collect urine for urinalysis, if indicated. Measure liver enzymes, especially aspartate aminotransferase and alanine aminotransferase. Consider a blood alcohol level and urine toxicology screen for use of drugs. Cardiac troponin I testing may be useful as a marker to predict children who have an elevated risk of not surviving to hospital discharge.

Renal function tests

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 drowning, and, while usually mild (serum creatinine level < 0.3 mmol/L or 3.4 mg/dL), severe renal impairment requiring dialysis may occur.

Radiography

Chest radiography may detect evidence of aspiration, pulmonary edema, or segmental atelectasis suggesting the presence of foreign bodies (eg, silt or sand aspiration). It may also be used for evaluation of endotracheal (ET) tube placement. Extremity, abdominal, or pelvic imaging may be used if clinically indicated.

Computed tomography

A cervical spine radiograph or computed tomography (CT) scan is indicated in individuals with a history of possible cervical trauma or with neck pain or if doubt exists about the circumstances surrounding the submersion injury. Noncontrast head CT scanning is also indicated in an individual with altered mental status and a suggestive or unclear history.

Electrocardiography

Electrocardiography (ECG) should be performed in patients with significant tachycardia, bradycardia, or underlying cardiac disease. Consider ECG if the patient has arrhythmias or if arrhythmias are suspected.^[54]

Monitor the patient with ECG if rewarming is necessary, because dysrhythmias are common when rewarming patients who suffer cold-water immersion injuries.

Catheter monitoring

Arterial and central venous catheters may be useful in monitoring cardiac output and related hemodynamic parameters. Pulmonary artery catheters are less frequently used, yet may prove useful in patients with unstable cardiovascular status or in those who require multiple inotropic and vasoactive medication requirements.

Intracranial pressure monitoring is used in patients with traumatic brain injury or mass lesions (eg, hematomas).

Urinary catheterization for ongoing urine output measurement may be warranted.

• References

Approach Considerations

The most critical role in management is prompt correction of hypoxemia and acidosis. The degree of hypoxemia is often underrecognized. Patients should receive 100% oxygen and should be monitored closely via pulse oximetry, blood gas analysis, or both. Consider intubation and positive end-expiratory pressure (PEEP) with mechanical ventilation in any patient with poor respiratory effort, altered sensorium, severe hypoxemia, severe acidosis, or significant respiratory distress.

Ventricular dysrhythmias (typically, ventricular tachycardia or ventricular fibrillation), bradycardia, and asystole may occur as a result of acidosis and hypoxemia rather than electrolyte imbalance.

Ascertaining whether the drowning occurred in warm or cold water is essential. This depends on the temperature of the water, not of the patient. Maintaining mild hypothermia (core temperature of 32-34ºC) may be indicated for 12-24 hours in patients who remain comatose after a drowning episode.^{[51, 75, 80]}

Seizures should be appropriately treated. Blood glucose concentrations should be frequently monitored and normal glycemic values maintained. Hypotension should be avoided.^{[5, 81]}

• References

Prehospital Care

Optimal prehospital care is a significant determinant of outcome in the management of immersion victims worldwide.^{[82, 83, 84]} Bystanders should call 911 immediately where this service, or similar service, is available. In developing countries, children may be transported more frequently by family members, by taxi or private vehicle, and from a greater distance.^[31]

An individual may be rescued at any time during the process of drowning. No intervention may be necessary, or rapid rescue and resuscitation may be warranted. No two cases are entirely alike. The type of water, water temperature, quantity of water aspirated, time in the water, and individual's underlying medical condition all play a role.

The victim should be removed from the water at the earliest opportunity. Rescue breathing should be performed while the individual is still in the water, but chest compressions are inadequate because of buoyancy issues.^[85] Victims of drowning have most likely suffered asphyxial cardiac arrest; therefore, rescue breathing as well as chest compressions are indicated as opposed to compression-only resuscitation for cardiac arrest.^[51]

The patient should be removed from the water with attention to cervical spine precautions. If possible, the individual should be lifted out in a prone position. Theoretically, hypotension may follow lifting the individual out in an upright manner because of the relative change in pressure surrounding the body from water to air.

Bystanders and rescue workers should never assume the individual is unsalvageable unless it is patently obvious that the individual has been dead for quite a while. If they suspect injury, they should move the individual the least amount possible and begin cardiopulmonary resuscitation (CPR).

As in any rescue initiative, initial treatment should be geared toward ensuring adequacy of the airway, breathing, and circulation (ABCs). Give attention to cervical spine stabilization if the patient has facial or head injury, is unable to give an adequate history, or may have been involved in a diving accident or motor vehicle accident.

In the patient with an altered mental status, the airway should be checked for foreign material and vomitus. Debris visible in the oropharynx should be removed with a finger-sweep maneuver. The abdominal thrust (Heimlich) maneuver has not been shown to be effective in removing aspirated water; in addition, it delays the start of resuscitation and risks causing the patient to vomit and aspirate. In any event, ventilation is achieved even if fluid is present in the lungs.

Supplemental oxygen, fraction of inspired oxygen (FiO₂)100%, should be administered as soon as available. The degree of hypoxemia may be difficult to determine on clinical observation. If available, continuous noninvasive pulse oximetry is optimal. If the patient remains dyspneic on 100% oxygen or has a low oxygen saturation, use continuous positive airway pressure (CPAP) if available. If it is not available, consider early intubation, with appropriate use of positive end-expiratory pressure (PEEP).

Higher pressures may be required for ventilation because of the poor lung compliance resulting from pulmonary edema.

First responders, including emergency medical service (EMS) personnel and professional ocean lifeguards, should be well versed in providing the time-critical institution of advanced interventions, such as airway management. Refresher training in resuscitation is extremely important to strive for excellence in skill maintenance.^{[25, 86]} 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.^{[80, 87]}

More traditional literature proposes that prehospital care providers should begin rewarming. Wet clothing ideally is removed before the victim is wrapped in warming blankets. More recent studies have shown that therapeutic cooling after out-of-hospital ventricular fibrillation cardiac arrest in adults may be beneficial to reduce ischemic brain injury and death.^{[88, 89, 90]} This area needs additional vigorous clinical research to determine the most effective treatment strategy in drowning victims.^{[81, 91, 92]}

• References

Emergency Department Care - Transition to the ICU

The 1960s and 1970s saw a large body of research on drowning pathophysiology, evaluation, and management, including the development of a number of scoring systems to evaluate drowning victims. However, this work, as pointed out in a recent editorial, has not kept pace with work in cardiac and brain resuscitation and has not met the test of large randomized multicenter trials.^[80] As such, while clearly very promising, the use of newer resuscitation methodologies, such as compression-only CPR and therapeutic hypothermia, have not been rigorously studied in drowning patients.

Patients who arrive in the emergency department in cardiopulmonary arrest after a warm-water submersion have a dismal prognosis. The benefit of resuscitative efforts should be continuously assessed. Initial management of near drowning should place emphasis on immediate resuscitation and treatment of respiratory failure. Frequent neurologic assessments should occur; the Glasgow Coma Scale is one modality that has been effectively used. Evaluate associated injuries early, particularly since cervical spine injury may complicate airway management. Initially provide all drowning victims with 100% oxygen, yet be cognizant of the goal to avoid or treat hypoxemia while minimizing hyperoxemia.

Early use of intubation and PEEP, or CPAP/bilevel positive airway pressure (BiPAP) in the awake, cooperative, and less hypoxic individual, is warranted if hypoxia or dyspnea persists despite 100% oxygen.

Endotracheal intubation and mechanical ventilation may be indicated in awake individuals who are unable to maintain adequate oxygenation on oxygen by mask or via CPAP or in whom airway protection is warranted.

Endotracheal intubation

Intubation may be required in order to provide adequate oxygenation in a patient unable to maintain a PO₂ of greater than 60-70 mm Hg (>80 mm Hg in children) on 100% oxygen by facemask. In the alert, cooperative patient, use a trial of BiPAP/CPAP, if available, to provide adequate oxygenation before intubation is performed.

Other criteria for endotracheal intubation include the following:

• Altered level of consciousness and inability to protect airway or handle secretions
• High alveolar-arterial (A-a) gradient: PaO₂ of 60-80 mm Hg or less on 15 L oxygen nonrebreathing mask
• Respiratory failure: PaCO₂ greater than 45 mm Hg

Positive end-expiratory pressure

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 the following:

• Provides distending pressure to improve volume of gas at the end of exhalation (increases functional residual capacity)
• Minimizes atelectasis or alveolar collapse by maintaining pressure above which the lungs collapse (closing pressure)
• Decreases intrapulmonary shunting of blood and improves arterial oxygenation
• Increases intrathoracic pressure, which transmits the applied PEEP to transmural capillary pressure (results in minimizing interstitial lung water)
• Increases the diameter of both small and large airways to improve distribution of ventilation

Extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) has been shown to be beneficial in selected patients.^[93] ECMO may be considered in the following circumstances:

• Respiratory compromise resulting from lack of response to conventional mechanical ventilation or high-frequency ventilation
• A reasonable probability of the patient recovering neurologic function
• Persistent hypothermia from cold-water drowning

• References

Treatment of Volume Depletion and Acidosis

Significant disorders of vascular volume are not common after drowning, although intravascular volume depletion has been attributed secondary to pulmonary edema and intracompartmental fluid shifts, regardless of the type of fluid aspirated. Clinically relevant aberrations in electrolyte concentrations are not usually found. However, hyponatremia and hypernatremia have been reported following the ingestion of large amounts of fresh or salt water. 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 improved oxygenation and correction of volume depletion. Hypothermia may be present and exacerbate hypoxemia, acidosis, and bradycardia.

Normalization of cardiovascular function is ideal for neuroresuscitation. Vasoactive infusions may be efficacious in treating myocardial dysfunction and abnormal peripheral vascular resistance; however, the need for extended cardiovascular support is rare. Overall, treatment goals are aimed at normalization of blood pressure, maintaining organ perfusion, and facilitating gas exchange.

• References

Other Interventions

Nasogastric tube placement can be used for removal of swallowed water and debris. Use the orogastric route if head or facial trauma is suggested.

Bronchoscopy may be needed to remove foreign material, such as aspirated debris or vomitus plugs from the airway.

Efficacy of surfactant therapy has been reported in selected case reports.^{[94, 95]} The routine administration of surfactant is not supported by present evidence. Use should be reserved for those with severe hypoxemic respiratory failure.

The mainstay of neuromonitoring is achieved by frequent neurologic examinations. Deterioration of brainstem function does not bode well for favorable recovery. Continuous EEG monitoring may be helpful in the assessment of subclinical seizures. No evidence supports that intracranial pressure monitoring affects the outcome in drowning victims. One could surmise the potential utility of intracranial pressure monitoring in the case of severe ARDS in order to monitor the impact of permissive hypercarbia and the effect of PEEP.

Therapeutic hypothermia

Hypothermia remains potentially beneficial and its utility has been extrapolated from adults experiencing witnessed out-of-hospital cardiac arrest^{[91, 92]} and asphyxiated newborns.^{[96, 97]} Aggressive resuscitation of drowning in the 1970s was notable for moderate dehydration, controlled hyperventilation, deep hypothermia (30ºC), barbiturate coma, corticosteroids, and continuous neuromuscular blockade.^[98] Retrospective reviews determined a preponderance of survivors who remained in a persistent vegetative state^{[99, 100]} and had increased infectious complications.^[100] Current recommendations propose maintaining core temperature 32-34ºC for 12-72 hours.^[51] This mode of therapy may impede the neurologic examination because of the potential need for neuromuscular blockage to blunt shivering.

• References

Guidelines for Treating Cold-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.

Temperature management

Optimal temperature management in drowning patients is a current topic of significant research and clinical interest. Hypothermic patients with core temperatures less than 86°F who have undergone sudden, rapid immersion in cold water may experience slowing of metabolism and preferential shunting of blood to the heart, brain, and lungs, which may exert a neuroprotective effect during submersion. This is not, however, the case with most immersion victims, who have become hypothermic gradually and are at risk for ventricular fibrillation and neurologic injury.

Many authors have postulated that a primitive mammalian diving reflex may be responsible for survival after extended immersion in cold water. The mechanism for this reflex has been postulated to be reflex inhibition of the respiratory center (apnea), bradycardia, and vasoconstriction of nonessential capillary beds triggered by the sensory stimulus of cold water touching the face.

These responses preserve the circulation to the heart and brain and conserve oxygen, thereby prolonging survival. The sudden temperature drop may depress cellular metabolism significantly, limiting the harmful effects of hypoxia and metabolic acidosis

Traditional studies suggested vigorous rewarming of hypothermic patients to normothermia. In order to rewarm, a number of modalities have been used. A nasogastric tube was placed to assist in rewarming efforts and a urinary catheter was passed to assess urine output.

Core rewarming with warmed oxygen, continuous bladder lavage with fluid at 40°C, and intravenous (IV) infusion of isotonic fluids at 40°C was initiated during resuscitation. Warm peritoneal lavage has been used for core rewarming in patients with severe hypothermia. A cascade unit on the ventilator has been used to warm inspired air.

Thoracotomy, with open heart massage and warm mediastinal lavage, was used in refractory situations. The hypothermic heart is typically unresponsive to pharmacotherapy and countershock. Extracorporeal blood rewarming has been used in patients with severe hypothermia who did not respond to lavage/thoracotomy or who were in arrest.

Central venous access was suggested to be utilized cautiously in hypothermic patients, in order to avoid stimulation of the hypothermic atrium with resultant dysrhythmias.

It was suggested that resuscitation of a submersion victim not be abandoned until the patient has been warmed to a minimum of 30°C. However, newer literature, based on extensive preclinical modeling of cellular response to ischemia and reperfusion injury, as well as analyzing long-term outcome, suggests that therapeutic hypothermia can be effective in reducing ischemic brain injury.^{[80, 91]}  Therapeutic hypothermia improves oxygen supply to ischemic brain areas, decreases cerebral metabolic demand, and decreases increased intracranial pressure.

At least 4 separate case reports of drowning victims who experienced full neurologic recovery after coma and cardiac arrest suggest that therapeutic hypothermia may confer neuroprotection.^{[81, 101, 102]} 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.

The panel of experts at the 2002 World Congress on Drowning^[5] made the following consensus recommendations on drowning management: "The highest priority is restoration of spontaneous circulation, subsequent to this continuous monitoring of core/and or brain (tympanic) temperatures 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 32º-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.

• References

Other Treatment Considerations

Initiation of appropriate management of hypoglycemia and other electrolyte imbalances, seizures, bronchospasm and cold-induced bronchorrhea, dysrhythmias, and hypotension may be necessary in the drowning patient.

Hypoglycemia and hyperglycemia are not only associated with increased mortality and morbidity,^[103] they are especially detrimental in patients with brain injury. The injured brain is exquisitely sensitive to aberrations in serum glucose. Normoglycemia should be the target goal.

• References

Patient Disposition

Patient disposition depends on the history, presence of associated injuries, and degree of immersion injury. Patients can be safely discharged from the ED after 6-8 hours of observation if they meet the following criteria:

• Able to relay a good history of minor immersion injury
• No evidence of significant injury
• No change in mental status or behavior
• No evidence of bronchospasm or tachypnea/dyspnea
• No evidence of inadequate oxygenation (by ABG analysis and pulse oximetry)

Be cautious with early ED discharge in older individuals or in those with underlying medical conditions that might place them at increased risk of hypoxic injury. Victims of mild to moderately severe submersion, who only have mild symptoms that improve during observation and have no abnormalities on ABG analysis or pulse oximetry and chest radiograph, should be observed for a more prolonged period of time in the ED or observation unit.

Instruct discharged patients to return immediately if they develop dyspnea, cough, and/or fever.

Certain patients may display mild to moderately severe hypoxemia that is corrected easily with supplemental oxygen. Admit these patients to the hospital for observation. They can be discharged after resolution of hypoxemia if they have no further complications.

Between 90% and 100% of individuals who arrive in the ED with blunted mental status have been shown to survive without neurologic deficit. However, individuals who were comatose upon arrival in the ED had significantly poorer outcomes. Approximately 34% died after presentation, and an additional 10-23% survived with severe neurologic residua.^{[104, 105]}

Admit patients who require intubation and mechanical ventilation to the ICU. Varying degrees of neurologic as well as pulmonary insults typically complicate their courses. Pulmonary hypertension may result from the release of inflammatory mediators, increasing right ventricular afterload, and decreasing left ventricular preload and pulmonary perfusion. Newer ventilatory modes, including airway pressure release ventilation and high frequency oscillatory ventilation can decrease the risk of ventilator-associated lung injury (VALI). The general ventilator management strategy strives to limit peak pressures to 25 torr, tidal volumes 6-8 mL/kg, fraction of inspired oxygen < 0.6, and optimizing PEEP to improve oxygenation. Use of permissive hypercapnia to decrease barotrauma in many patients with ARDS may not be appropriate in this setting of hypoxic ischemic CNS injury. The elevation in PCO₂ may adversely affect intracranial pressure. High levels of PEEP may be transmitted to the intracranial space and further increase intracranial pressure and additionally decrease cerebral venous return.

Meticulously monitor for evidence of ARDS; multiple organ system failure; nosocomial infection, especially pneumonia; hyperglycemia^[106] ; and/or gastric stress ulceration. Management of ARDS due to submersion is similar to that of ARDS from other causes.

The extent of invasive monitoring needed (eg, arterial catheter, pulmonary artery catheter, central venous pressure catheter) is determined by the degree of hemodynamic or respiratory instability and the presence of renal failure.

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.^{[75, 80]}

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

Monitor closely for bacterial and fungal infection. Evidence is insufficient to support the use of prophylactic antibiotics.

Begin aggressive rehabilitation early (as soon as tolerated) to prevent disuse injury and promote functional improvement.

• References

Transfer

Patients must be treated in a facility capable of providing appropriate, age-related intensive care if they exhibit any of the following:

• Significant hypoxia that requires intubation
• Worsening dyspnea with the potential for intubation
• Evidence of hypoxic cerebral injury
• Evidence of renal insufficiency
• Evidence of hemolysis
• Severe hypothermia requiring cardiopulmonary bypass

Patients who require care for significant cervical spine or head trauma should be managed in a facility capable of sophisticated neurologic monitoring and neurosurgical intervention. Patients with severe neurologic impairment may benefit from transfer to inpatient rehabilitation institutions.

• References

Deterrence/Prevention

A review of 50 cases of drowning that resulted in litigation noted that many of the deaths resulted from preventable omissions of basic safety methods, such as the following^{[75, 107]} :

• Leaving young children unattended at water sites
• Absent or inadequate pool fencing
• Faulty pool design and poor pool maintenance
• Poor lifeguard-to-swimmer ratios
• Poorly trained lifeguards
• Lifeguard distraction and competing duties

In most instances, drowning and near drowning can be prevented with simple safety measures and common sense. Most children younger than 5 years enter a swimming pool directly adjacent to their home or one with inadequate fencing or unlatched gates or doors. Most children who drown in pools are found silently floating with no screaming or splashing having been noted, were last seen in the home, were missing at least 5 minutes, and were in the care of one or both parents at the time of the drowning.^[24]

Children, especially toddlers, should be supervised at all times when they are around water, including a bathtub, toilet, or bucket full of water. Toilet lids should be left closed, or a child-safe fastener device utilized, when not in use. Baby bath seats do not provide additional safety for unsupervised children. Since 1983, at least 104 deaths and 126 nonfatal immersion incidents involving improperly supervised baby bath seats have occurred in the United States.^[24]

Household buckets should be immediately emptied after use and left empty when not in use. Water-containing objects, such as water tanks and cisterns, should have childproof fastenings and solid tops. They should not have items adjacent that afford children easy access.

Adult supervision is essential in the prevention of drowning. Because lapses of supervision are inevitable, other safety precautions must be in place.

All pools should be fenced appropriately. The use of adequate fencing around swimming pools has decreased the number of immersion injuries significantly (by more than one half). The enclosure may be a wall or fence that completely surrounds a pool on all 4 sides, isolating the pool from the remainder of the property. The enclosure must be at least 4 ft tall with no more than 4 in between openings in the fence.

A house or building wall may serve as part of the enclosure only if it does not have any doors or windows through which a child may pass. Doors and gates to the pool should be self-closing and self-latching. Access to the area should be locked when not in use under adult supervision.

Pools, hot tubs, home spas,^[108] and saunas not in use may be made safer with appropriately fitted and maintained covers and alarms, but these have not been shown to prevent drowning. Any doors and windows with access to the pool area should remain closed and locked. Toys and other objects attractive to children should not be left in the pool area.

Parents who own pools or who take their children to pools are encouraged to learn CPR. At least one parent or caretaker should remain focused on children at all times, avoiding other activities that might disturb this concentration, such as using the phone and conversing with others.

Children should wear personal flotation devices in pool areas, but these do not eliminate the need for constant supervision. Air- or foam-filled swimming tools, such as "water wings," inner tubes, and "noodles" are not substitutes for Coast Guard–approved personal flotation devices (PFDs).

Children should be taught to swim, but these lessons should not provide parents with a false sense of security. A 2009 case-controlled study concluded that participation in formal swimming lessons was associated with an 80% reduction in the risk of drowning.^[109]

However, as an astute Florida pediatrician pointed out in an associated letter, swimming programs exist in an unregulated industry and have different objectives, methods, and goals, and these are achieved to varying degrees. Parents should be aware of the qualifications, goals, and limitations of the swimming programs in which they enroll their children.^[110]

Infant swimming or water-adjustment programs do not prevent submersion injuries and are potentially hazardous, providing parents with a false sense of security if they perceive their infant can swim.

The presence of lifeguards at public swimming venues is also a deterrent, but it is not foolproof. Centers for Disease Control and Prevention (CDC) data suggest that 19% of drowning deaths in children occurred in public pools with certified lifeguards present. Nevertheless, trained, professional lifeguards clearly have shown a positive effect on US drowning prevention, including deterring dangerous or risky behavior, determining bathers who appear to be in distress, and determining the presence of hazardous conditions.

The ability of lifeguards to aid in drowning prevention is influenced by a number of factors. Individuals often drown quickly and are unable to call attention to themselves when in distress. As such, overcrowding of pools, lakes, parks, and beaches, as well as assignment of additional distracting duties to the lifeguards, can decrease their effectiveness.^[111]

All individuals involved in boating activities should be able to swim, should use Coast Guard–approved PFDs when on the boat or in the water, and should avoid the use of alcohol or other recreational drugs. Boaters should be taught to anticipate wind, waves, and water temperature and to use protective suits and other insulating garments in cold weather.

Children younger than 14 years should not use personal watercrafts unsupervised by an adult. In 2002, more than 189 children younger than 14 years sustained personal watercraft injuries.^[24] In 2000, only one third of children in this age group were wearing PFDs. As of 2009, 38 states had enacted boating safety statutes, requiring children to wear Coast Guard–approved PFDs at all times when on boats or near open water.

All children should be taught to swim with a buddy, to check for posted danger warnings, and to check the water carefully for depth and possible injurious objects before diving into water. Children should also be taught their swimming limitations and to not play dangerously in natural water areas, in pools, or on the decks surrounding pools.

All individuals should be taught not to drink alcohol or use other recreational drugs when swimming.

Individuals with underlying medical illnesses that may place them at risk when swimming, such as seizure disorders, diabetes mellitus, significant coronary artery disease, severe arthritis, and disorders of neuromuscular function, should swim under the observation of another adult who can rescue them should they get into trouble.

Individuals should not swim alone.

The American Academy of Pediatrics established guidelines for the prevention of drowning in infants, children, and adolescents in 2003,^[112] with an update in 2010.^[69] Recommendations may be found through the Web site: AAP Gives Updated Advice on Drowning Prevention. Prevention and consumer safety tips may be located on the Consumer Product Safety Commission site: Drowning Prevention Toolkit.

• References

Consultations

Neurosurgical, orthopedic, or trauma consultation (institution dependent) is required for patients with concomitant significant head or neck trauma. Early consultation with the intensivist or admitting physician is wise for patients who exhibit pulmonary or CNS insult in order to coordinate ongoing ICU care.

Cardiovascular, intensivist, or trauma surgical consultation may be necessary for patients who require bypass for rewarming or ECMO.

Consider neurology consultation for seizures or persistent neurologic deficit. Consider neurosurgery consultation if associated head or spine trauma, hematoma, aneurysm, or CNS abscess is present.

Consider cardiology consultation for dysrhythmias or myocardial dysfunction, pulmonology consultation for severe or persistent respiratory compromise, and infectious disease consultation for pneumonia or CNS infection.

Physical therapy, occupational therapy, and rehabilitation therapy consultation are needed to help prevent disuse injury and provide early rehabilitation.

• References

Long-Term Monitoring

After initial recovery, drowning patients may develop nonpulmonary infections, including brain abscesses, osteomyelitis, and soft-tissue infections with unusual fungal, amebic, and bacterial pathogens. Because the causative organisms for these infections are rarely seen in other clinical settings, a high index of suspicion must be maintained in patients after acute or subacute injury. Surgical consultation may be required because many of these infections do not respond to antimicrobial therapy alone.

Outpatient care is dictated by the nature and degree of residual functional impairment. With severe neurologic impairment, the patient may benefit from admission to a rehabilitation facility and aggressive rehabilitation. In one case report, neuropsychological testing delineated problems with memory, visuospatial performance, executive function, verbal fluency, flexibility, planning, and abstraction. Visuospatial testing, verbal learning, recall, and logical reasoning showed improvement during a 3-year follow-up period.^[113]

• References

Outcomes

The ideal independent predictor for survival is drowning time.^[114] Poor prognostic signs for recovery include an unwitnessed event, delayed resuscitation, need for CPR at the scene, need for continued CPR in the ED,^[115] and prolonged coma. A multitude of imaging studies (eg, CT, MRI, MR spectroscopy),^{[116, 117]} electrophysiologic studies including brain stem auditory-evoked response (BSAER)^[118] and somatosensory evoked potentials (SSEP),^[119] and biomarkers have been explored to better define prognosis in drowning. At this time, there is no test or assessment that reliably predicts functional neurologic outcome. The most meaningful information with respect to prognosis is derived from an improving neurologic examination over time.^[120]

• References

Medication Summary

Cold-induced bronchorrhea or irritation of the tracheobronchial tree by inhaled water or particulate material can produce cough and bronchospasm. Manage these aggressively because they may worsen hypoxia. The drug of choice is an inhaled beta-agonist bronchodilator.

Corticosteroids have been shown to be of no benefit in the management of submersion injuries. Routine antibiotic prophylaxis is not indicated unless the patient was submerged in grossly contaminated water or sewage.

• References

Albuterol (Proventil HFA, Ventolin HFA, VoSpire)

• Dosing, Interactions, etc.

Clinical Context:  Albuterol relaxes bronchial smooth muscle by action on beta 2-receptors and has little effect on cardiac muscle contractility.

• References

Class Summary

These agents relax bronchial smooth muscle during bronchospasms.

• References