Pediatric Submersion Injuries
Pediatric Submersion Injuries
Author: Charles Stewart, MD, Emergency Physician, Colorado Springs, CO.
Peer Reviewer: Steven Winograd, MD, FACEP, Attending Physician, Department of Emergency Medicine, Allegan General Hospital, Allegan, MI.
Death from submersion incidents is the second leading cause of accidental death in children, with one-third of all survivors sustaining significant neurological damage.1-3 The exact percentage of the vast number of minor submersion incidents that result in a lethal outcome is controversial. A 1977 study in South Carolina reported that at least 15% of school children had at least one submersion incident during the prior year.4 With a reported drowning rate of 7.4 per 100,000 in that state, the authors calculated that at least one-half million incidents per year occurred that presented a serious risk of drowning in South Carolina alone. This article presents a review of the types of submersion injuries, management strategies, and ways to prevent these occurrences.
— The Editor
Introduction
Every year, drowning claims between 6000 and 8000 people in the United States.5 Most of these victims are young, under the age of 24.6 (See Table 1.) Drowning is the second largest cause of injury-related death in people of this age group, and it is the third leading cause of death for 1- to 15-year-olds. At all ages, boys will drown three times more often than girls. Most drownings occur within 10 feet of safety, and two-thirds of the victims cannot swim.7 Boating accidents and floods are other well-known scenarios of drowning.
Table 1. Statistical Risk Factors |
• Age (40% of victims are younger than 4 years) |
• Location (home swimming pools or bathtubs) |
• Sex (Boys drown three times more often than girls) |
• Drugs (particularly alcohol) |
• Trauma (diving or falls) |
• Predisposing illnesses (particularly epilepsy)21-23 |
• Warm weather (50% occur between May and August) |
Adolescents (or parents) using alcohol and drugs not only are at increased risk of drowning themselves, they also increase the risk of those around them.8 Whether impaired judgment or loss of self-protective reflexes is at fault is moot. The use of other, more illicit drugs is thought to play a relatively major role in drownings, but again, the true incidence is not known.
Since all water-related activities increase with warm weather, the incidence of drownings will naturally increase in warmer climates and weather. Drowning is a problem in all states, including the arid desert states.9 The most common sites of drownings include home swimming pools, bathtubs, and open bodies of water.
About 6% of drownings may represent child abuse or neglect.10-12 In one study, as many as 67% of bathtub submersion incidents were found to have a history consistent with abuse or neglect.13 Bathtubs are the usual site of drowning in children younger than 1 year of age.14
Definitions
In order to discuss the circumstances of submersion injuries, a uniform terminology is needed. The following terms are frequently used and have been adapted from Modell and others.15
Drowning. Drowning is suffocation by submersion in a fluid, whether or not the fluid is aspirated into the lungs. This is considered the cause of death if the death occurs within 24 hours of the insult.16
Near Drowning. Near drowning is survival beyond 24 hours after suffocation by submersion and implies that recovery has occurred after the insult. This may be termed a submersion injury or submersion incident in some of the literature. Note that this definition has been challenged and some feel that near drowning should be redefined as "survival, at least temporarily, after aspiration of fluid into the lungs." These authors feel that aspiration of fluid may lead to complications even without a history of loss of consciousness.17
Secondary Drowning. Secondary drowning implies that the victim is initially resuscitated but death occurs minutes to days after the initial resuscitation. The definition of secondary drowning is controversial, and the term probably is inappropriate. This condition also is termed delayed death subsequent to near drowning. Death may result from either the respiratory insult or any other cause. Since the cause of death does not matter in this definition, many of these patients die from severe neurologic dysfunction related to the initial insult. Patients with respiratory causes for secondary drowning usually have clear symptoms of respiratory compromise immediately after submersion.18
Immersion Syndrome. The immersion syndrome is a form of drowning caused by sudden exposure to very cold water (< 20°C or 68°F). This may be due to a vagally induced dysrhythmia. The two most commonly proposed arrhythmias are asystole and ventricular fibrillation.19,20 Ingestion of alcohol and other intoxicants is thought to be a predisposition to this syndrome.
Immersion Hypothermia. Drowning can also result from hypothermia due to prolonged immersion. When the core body temperature reaches about 32-33°C (89.6-91.4°F), the victim will lose purposeful activity. At that point, swimming and other self-protective action ceases, and drowning may occur. If the patient becomes sufficiently hypothermic (e.g., in arctic waters), death may occur from hypothermia alone.
Problems with Definitions. The definitions of near drowning and drowning are, of course, retrospective. There is no prognostic import to any of the definitions. The emergency physician should treat all patients as near-drowning casualties, unless there is an obvious injury that is incompatible with life. Only after documented submersion times are greater than 1 hour should the emergency department (ED) consider that the patient is non-resuscitatable. These times may be shortened considerably if the water is warm.
Pathophysiology: Mechanism of Drowning
The sequence of events that follows submersion has been abundantly described in animal studies, providing us with a model of drowning.
Stage I: Panic and Struggle. In most drownings, a period of panic and struggle followed by exhaustion are the initial events.24 During the 1890s, Brouardel described this as the "stage of surprise" and described it as lasting about 5-10 seconds.25 Another researcher noted that this stage lasts 20-60 seconds in humans. During this stage, the victim will attempt to reach or remain at the water’s surface. Frantic hyperventilation occurs as long as the head can be held above water. Other clues that identify potential drowning victims are an open but not vocalizing mouth and a rolled back (far hyperextended) head. Modell noted that some victims are swimming and calmly become motionless or quietly disappear below the water after diving.26
Stage II: Breath Holding. Breath-holding apnea begins with submersion and lasts about 60 seconds. The mouth is shut and respirations voluntarily are stopped.
Stage IIIA: Aspiration. Brouardel also described a stage where agitation ceases, and the victim may swallow water and begin to vomit. Approximately 90% of drowning victims aspirate the water and vomitus, cough violently, and then gasp involuntarily, flooding the lungs and air passages with water.
Stage IIIB: Laryngospasm. The other 10% die of asphyxia thought to be secondary to laryngospasm. No evidence of aspiration is found in these victims. This entity is also called "dry drowning" or "drowning without aspiration." Fluid in the larynx in humans can result in severe and prolonged laryngospasm. This suggests that in humans, breath holding may be followed by laryngospasm of variable duration. Ultimately, of course, asphyxia relaxes the glottis, and the lungs will flood with water. Although only about 15% of victims fit into this category, 90% of the successfully resuscitated patients come from this subset.
Stage IV: Respiratory Arrest. Brouardel then described the "second stage of respiratory arrest" where no thoracic movements occurred and the animals became unconscious.
Stage V: Agonal Movements and Death. Agonal respiratory movements, cardiac arrest, and death then ensue in both types of drowning.
Mitigating Circumstances
There are several exceptions to this sequence of events:
Hypothermia. In very cold water, as noted previously, hypothermia may rapidly disable a victim, and little or no exhaustion, panic, or struggle may occur before the victim ceases to swim and aspirates water.
Unconsciousness. Events that render the victim unconscious, such as use of drugs or alcohol, seizures, or head trauma will also prevent a struggle and exhaustion prior to aspiration.27-30 Divers who sustain neck injuries may be conscious but unable to resurface. Children with seizure disorders have a far greater risk of drowning, particularly in a bathtub, when compared with children without seizure disorders.31
Voluntary Hyperventilation. Another cause is hyperventilation prior to swimming underwater. By hyperventilation, swimmers can rapidly lower their PaCO2 to 20 mmHg, but the PaO2 will be only modestly increased. As the victim exercises, his PaCO2 will return to between 40 and 47 mmHg, which is not sufficient to trigger the urge to breathe. Simultaneously, the PaO2 will fall to 30-40 mmHg, causing unconsciousness, with subsequent drowning.32,33
Rapidly Moving Water. It is unknown whether the same struggles take place in rapidly moving water. It is conceivable that the force of the moving water and objects struck underwater may cause rapid loss of consciousness due to trauma. In surf and in mountain streams, both drowning and near drowning often are associated with physical evidence of multiple trauma.
Type of Aspirated Fluid
Aspiration of even small quantities of fluid can lead to a drastic change in PO2. The differentiation between aspiration of salt or fresh water is often emphasized in some medical texts, but the presence of contaminants (i.e., silt, mud, sewage, bacteria, and diatoms) is probably of more consequence in actual practice. Aspiration of acidic stomach contents and other debris (i.e., sewage, sand, mud, diatoms, or algae) profoundly contribute to the pulmonary injury and the development of aspiration chemical pneumonitis.
Theoretically, there should be electrolyte and blood volume differences between fresh and salt-water submersion victims if a significant amount of fluid has been aspirated. Few survivors of submersion incidents aspirate enough water to cause any significant changes in either blood volume or serum electrolytes. Experimental studies show that if less than 20 mL/kg of body weight is aspirated, no life-threatening electrolyte abnormalities occur, and at least 11 mL/kg is necessary to cause changes in blood volume. This means that a 20 kg child must aspirate 400 mL of solution in order to have significant electrolyte disturbances. Although the lungs can hold far more than that, most adults have somewhat less than 150 mL of solution in the lungs at the time of death by drowning. The main reason for the lower volume of aspiration in human vs. animal studies appears to be the previously described laryngospasm that is induced in humans by fluid in the posterior pharynx.
Clinical information on submersion patients indicates that there is no significant difference in serum electrolytes and hematocrit values among fresh, salt, and brackish water aspiration. Following fresh and salt-water submersion in experimental models, the ultrastructure and light microscopy findings of the lungs are remarkably similar.
Profound electrolyte changes can be found in Dead Sea submersion victims, even with aspiration of only modest amounts of fluid.34 One might expect similar results for submersion victims from the Great Salt Lake, but no cases have been reported in the literature. Hypernatremia from seawater ingestion is thought to be due to swallowed water rather than aspiration.35
There are important differences in aspiration of fresh and seawater that do not involve electrolyte imbalance, however. Aspiration of seawater is twice as lethal as fresh water per unit volume because of the impurities and bacteria it contains. Seawater contains more than 20 known pathogenic bacteria, including Pseudomonas putrefaciens, Staphylococcus aureus, and Vibrio parahaemolyticus.36
Salt water also appears to produce a larger direct insult to the lung than fresh water.37 When a significant amount of seawater is aspirated, the salt diffuses into the blood, with rapid elevation of the plasma sodium. Osmotic forces pull protein-rich fluid from the circulation into the pulmonary interstitium. The result is a fulminant pulmonary edema with direct parenchymal damage. With salt-water aspiration, hypovolemia may develop, especially if a large volume of water has been swallowed.
Immediate Sequelae of Aspiration
The most important abnormality from a submersion incident is a profound hypoxemia resulting from asphyxia. The immediate effect of asphyxia is a rapidly decreasing arterial PO2 with a concomitant increase in the pCO2 that leads to a combined respiratory and metabolic acidosis. The sequelae of this hypoxia may affect the brain, heart, and kidneys.
As previously noted, about 15% of patients have asphyxia from the laryngospasm without significant aspiration at the time of resuscitation. These patients rapidly recover from asphyxia if they are successfully resuscitated before cardiac arrest or irreversible brain damage occurs.
Aspiration of as little as 1-3 mL of fluid per kg of body weight results in persistently abnormal pulmonary functions from a combination of several mechanisms. (See Table 2.) Immediate vagal reflexes cause pulmonary vasoconstriction and a pulmonary hypertension after the aspiration of the fluid. Passage of water through the alveolar epithelium, the basement membrane, and the endothelial capillary lining causes a rapid disruption of the pulmonary ultrastructure.38,39 Loss or inactivation of pulmonary surfactant causes an alveolar collapse, with a subsequent decrease in pulmonary compliance.
Table 2. Potential Consequences of Aspiration of Fluids |
• Pulmonary edema |
• Increasing shunt |
• Direct toxicity of aspirated fluid |
• Washout of surfactant |
• Inactivation of surfactant |
• Direct alveolar membrane injury |
This combination of mechanisms results in increased membrane permeability, exudation of proteinaceous material into the alveoli, and pulmonary edema. The other result of these mechanisms is a profound ventilation/perfusion mismatch and subsequent hypoxemia. These abnormalities cause a rapid elevation of the PaCO2 and a fall of the PaO2.
Hypothermia
Hypothermia is a more frequent cause of death in the water than formerly realized. When the Titanic sank in 1°C water, 1500 people died within 90 minutes, yet there were ample life preservers to go around.40 Unconsciousness occurs when the core body temperature reaches about 32-33°C (89.6-91.4°F); in the water, swimming efforts cease, and the unprotected person will drown.
In cold water, hypothermia will develop in a short time in unprotected adults.41 If the water is not only cold, but also moving quickly, hypothermia may develop at an incredibly rapid rate. A child’s temperature drops even more quickly because of the relatively large surface-area-to-mass ratio and the lack of subcutaneous fatty insulation.
Studies on human subjects in cold water (as low as 4.5°C or 40.1°F) show that the maximum heat loss occurs from the head, the neck, the sides of the chest, and the groin.42 Swimming and other motion enhances this loss, increasing the risk of hypothermia.
Since movement enhances the cooling process, the better swimmers often die first because they are more likely to try to tread water or swim rather than just float. Likewise "drown proofing," a technique of bobbing in the water, will markedly increase the heat loss as water circulates about the head. Based upon these studies, a heat escape lessening posture (the HELP position) was devised in which the victim draws the knees up close to the chest, presses the arms to the sides, and remains as quiet as possible. For three or more persons, huddling quietly and closely together will decrease the heat loss from the groin and front areas of the body.
Detrimental Effects. Hypothermia presents a therapeutic dilemma in the management of the near-drowning victim. On one hand, the cardiovascular complications of hypothermia include hypotension, bradycardia, conduction deficits, and ventricular fibrillation. Electrical defibrillation of the heart is difficult at low core body temperatures. Drugs, such as antiarrhythmics and insulin, may be ineffective and accumulate, reaching toxic levels due to the slowed metabolism and excretion.
Protective Effects. On the other hand, it should be emphasized that the development of hypothermia prior to the final anoxic insult protects the brain for a considerable period following a cardiopulmonary arrest. The combination of hypothermia (no matter what means of induction) and the diving reflex probably plays a major role in salvage after prolonged submersion.
The development of hypothermia protects the brain by decreasing metabolic demands and slowing the development of cerebral hypoxia. This process has been confirmed by extensive clinical experience in cardiovascular surgery. Since the late 1950s, physicians have been extending cerebral hypoxic survival times for neurosurgical and cardiovascular procedures by profound hypothermia. Of course, the submersion victim is not a well-controlled, well-oxygenated operative patient.
To protect the brain from hypoxic damage, it is necessary to cool the brain very rapidly, at least 7°C in 10 minutes. This rate of cooling will double survival times during cerebral hypoxia.43 Unfortunately, surface cooling rates associated with immersion are too slow to cool the brain sufficiently to protect it from anoxia caused by drowning, even in children. If cerebral hypoxia is the mechanism for survival in protracted submersion, then an alternative metabolic method of rapid brain cooling must be evoked.
The Diving Reflex
The diving reflex is found in all mammals and consists of bradycardia, profound systemic vasoconstriction, and suppression of respiratory activity.
The diving reflex is evoked by the presence of cold water on the victim’s face or nose. Anxiety and very cold water enhance the response. A "dry" suit that prevents rapid cooling of the cutaneous thermal receptors but leaves the face exposed to the environment also enhances it.44-46
The diving reflex plays a powerful role in oxygen conservation in diving animals and allows some to remain submerged for as long as 30 minutes. The inhibition of respirations apparently continues until the brain shuts down due to hypoxia. The reflex is strongest in young animals and with colder water. It is present but not particularly strong in adult humans. The diving reflex, which is most active in infants and small children, may drop a child’s heart rate to about 8-10 beats per minute, while core body temperature rapidly falls to about 28-30°C (82.4-86°F).
Aspiration of Water. Recent canine studies suggest that swallowing and aspiration of icy water will enhance the cooling rate.47,48 Indeed, this aspiration of cold water and rapid induction of hypothermia may play a role in cases where preservation of neurologic function occurs despite prolonged anoxia.
It should be emphasized that the simultaneous onset of anoxia with hypothermia carries a less favorable prognosis than when the hypothermia precedes the anoxia. When cardiac arrest finally occurs, there may be only an additional 10- to 15-minute period before the brain is irreversibly damaged in the anoxic hypothermic patient. Even with this understanding, the prolonged periods of submersion that have a subsequent good outcome and total recovery are not quite so miraculous as they appear.
Studies of submersion victims in warmer climates show lower survival and higher morbidity. This is probably due to the loss of protective reflexes and protective hypothermia. The difference is so marked that practitioners who see warm-water submersion patients from the Southern states have an entirely different outlook on this disease than Northerners who deal with cold-water submersion victims. Indeed, the worst outcome appears to be in victims of hot tub submersion incidents.
Emergency Management: Rescue and Initial Resuscitation
Submersion Times. Time is crucial in the management of the submersion victim. Full neurologic recovery is not likely if the victim has been submerged for longer than 30 minutes in cold, fresh water or longer than 15 minutes in warm, fresh water. In hot springs and hot tubs, successful resuscitations are unlikely after even shorter times.49 In very cold water, victims of submersion have had documented survival times of up to 66 minutes with little or no neurologic deficit.50
Submersion time is often inaccurate and should serve only as a rough estimate. The emotional excitement at the time of submersion is so intense that few observers are able to reliably document the duration of submersion. Unless the immersion time exceeds 1 hour in cold water and is unquestionably documented, it is best to attempt resuscitation on all victims. The times at which rescuers were called and help arrived are often known, and in extreme cases, may be used to approximate the submersion time.
Rescue. The attempt to rescue a drowning child has claimed many a rescuer’s life. Although a poor swimmer or untrained rescuer should not attempt an in-water rescue, most victims are well within reach of a moderately trained rescuer. The American Red Cross and the YMCA provide abundant courses in proper water rescue techniques for simple water rescue. This material is easily available, and thus, will not be repeated here. Complex water rescue, such as at the foot of dams and in floodwaters, is well beyond the scope of this article.
Mechanisms of Injury
All patients who are involved in boating accidents; fall into rapidly moving water, rapids, or surf; fall from a height greater than 10 feet; or are involved in head-first diving accidents should be considered to have multiple trauma and potential cervical spine injuries.51 The easiest and quickest splint that can be used for these critical submersion victims is the long backboard. No time should be wasted in meticulous splinting techniques for the patient who is not breathing or who is in respiratory distress from a submersion injury. Likewise, the patient should not be subjected to any movement without appropriate cervical splinting precautions. Once on shore, the long backboard will provide a surface suitable for CPR if needed.
Injuries are likely in rapidly moving water, falls from heights into the water, and ice rescues. Fractures to the lower extremities are more likely in ice accidents and falls from a height, but spinal injuries are common with any head-first entrance into water. Falls into fast-moving water may have any combination of injuries, as the victim may tumble and smash into rocks and other debris. Cervical spine precautions should be taken for all of these patients.
Airway Maneuvers. Since the primary mechanism of injury for this disease is hypoxia, maneuvers to restore ventilation are of paramount importance. If the victim is apneic, mouth-to-mouth breathing should be initiated as soon as possible. It can be started as soon as the patient can be placed on a flotation device or the rescuer can stand. If neck injury is suspected, the head-tilt method should not be used, as it markedly flexes the neck. Use of the jaw-thrust method of airway management will give better protection for the cervical spine and should open the airway sufficiently.
Except for placing the victim in a relatively head down position, most clinicians do not recommend maneuvers designed to expel water from the chest.52,53 Because of the higher rate of complications from seawater aspiration, some authors advocate postural maneuvers for draining seawater out of the lungs but never at the expense of expeditious CPR.
There are no data to support the use of a Heimlich maneuver in a submersion victim who does not have a particulate matter foreign body obstruction.54,55 Care must be taken to prevent aspiration of gastric contents since vomiting is very common with this maneuver.
It is imperative that no time be wasted with this or other maneuvers. Since animal studies and human post-mortem studies show that most victims do not aspirate significant amounts of liquid, the overall clinical significance of this or any other maneuver designed to "clear the water out of the lungs" is open to many questions.
Suction. Suction equipment must be available since many of these patients will vomit, which may result in aspiration. If vomiting occurs or seems imminent, the lateral decubitus position is recommended. Early intubation of the patient will protect the patient from further aspiration and allow both suctioning and administration of high-flow oxygen.
Supplemental Oxygen. Supplemental oxygen is a mainstay in the prehospital care of the near-drowning victim. Early efforts should include 100% oxygen, which should be administered immediately by bag-valve-mask, and followed by rapid intubation in the unconscious patient. Field intubation techniques should be modified to protect the spine if trauma is suspected.
Cardiopulmonary Resuscitation. Immediate and adequate resuscitation is of paramount importance and is the single most important factor influencing survival. The immediate actions of the primary responder have the potential to significantly affect the outcome for the near-drowning victim.
If the patient has no pulse or is not breathing, CPR should be initiated. It is difficult to provide effective chest compressions while the patient is still in the water, but ventilations can be instituted immediately. The patient may be extricated from the water on a backboard or a Stokes’ basket litter. Chest compression may be started as soon as the backboard can be supported. Initial advanced cardiac life support (ACLS) measures do not otherwise differ from those used in other patients.
Post-Resuscitation Management. If the patient responds to initial management, oxygen must be started at high flow with a non-rebreathing facemask. An intravenous line should be started if available and within the rescuer’s ability and training. Wet clothing should be removed, if possible, and the patient covered with blankets. Constant attention should be paid to vital signs, the potential of vomiting, and the possibility of deterioration of the patient during transport. Potential problems include pulmonary edema and shock from associated trauma. The potential for cervical spine trauma in diving accidents cannot be overemphasized.
Emergency Department Management
Initial management of the victim in the ED involves three priorities: 1) assessment of the ABCs; 2) treatment of the hypoxia; and 3) protection of the cervical spine.
Assessment of the ABCs. Airway management and restoration of ventilation and circulation are the first priority tasks. These tasks should not be delayed in an ED to drain the lungs of fluid. As noted above, most patients aspirate only small quantities of fluid. Better survival is found with rapid restoration of ventilation and circulation.
If the patient is not receiving 100% oxygen, this should be instituted immediately, followed by rapid intubation of the unconscious victim. If the child is combative, then rapid sequence intubation should be used. If the child is completely alert, awake, and appropriately mentating on arrival to the ED, then observation with 100% oxygen by facemask is appropriate. If there is any question, the error should be on aggressive management of the airway.
Cardiac monitoring is needed for all patients, as both the acidosis and the hypoxia will decrease the fibrillation threshold. An intravenous line for medications should be started at this time if it is not already present. Core body temperature should be measured, and measures to dry off the patient and conserve the patient’s body temperature should be undertaken. Warming lights or warming blankets are always appropriate for unclothed, wet children.
Defibrillation of the patient in ventricular fibrillation should be accomplished in the field if possible. If hypothermia is found, successful defibrillation may be possible only after core rewarming is accomplished. A cold heart is always difficult to restart, so it is important to not give up too soon. There have been reports of complete recovery after CPR times of up to two hours following a cold-water submersion, particularly in small children. Resuscitation efforts should be continued until circulation and respiration are re-established or cerebral death has occurred.56 The rescuers and clinicians should be reminded that a dry environment is safer during attempts at defibrillation.
Treatment of Hypoxia. Management of the pulmonary system abnormalities of near drowning begins with airway management and continues until final disposition of the patient.
Oxygen should be administered at the highest FiO2 available. Immediate arterial blood gas (ABG) determinations and an initial chest x-ray are necessary. The goal of routine respiratory management is to achieve a PaO2 of 70-100 mmHg. Although some patients will be able to maintain this PaO2 with supplemental oxygen alone, more than 70% of patients will require more aggressive therapy. The initial ABG should be correlated with pulse oximetry and end title CO2 if the child is intubated.
Rapid intubation allows both protection of the airway and administration of higher oxygen concentrations. Positive end expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) with intermittent mandatory ventilation (IMV) can be used easily on the intubated patient. Ideally, PEEP should be started in the ED and the patient’s oxygenation monitored by blood gases as the patient’s course progresses. Nasal CPAP also may be used in the conscious and unintubated patient with respiratory distress.57
In experimental near drowning in pigs, 5 cm of PEEP increased arterial oxygen tension, even when instituted 20 minutes after the insult.58 The addition of PEEP will decrease the degree of intrapulmonary shunting, decrease the V/Q mismatch, and increase the functional residual capacity. The increased PaO2 from the use of PEEP and CPAP will occur regardless of whether the patient has suffered fresh water or seawater submersion. Fresh water submersion victims may require the use of either PEEP or CPAP to maintain the patency of the surfactant-deficient small airways.
Bronchospasm may be treated with a variety of bronchodilators that are administered by nebulizer. The standard dosages of these agents should be used.
Fiberoptic or rigid bronchoscopy may be indicated in patients who have aspirated particulate matter or contaminated fluids. It is particularly noteworthy that a high percentage of patients have had silt or sand in the trachea and lungs after falling in rapidly moving streams or in surfing accidents. These densities may be seen as "sand bronchograms" on plain films of the chest. Chest CT may be indicated for patients who have possible aspiration of sand or other particulate matter. Imaging of the sinuses also is indicated to assess possible nasal inhalation of foreign material.
Protection of the Cervical Spine. The cervical spine should be evaluated rapidly in all submersion victims. This is particularly important if there are signs of trauma or if the patient is unconscious. The cervical spine should be protected by a cervical collar and long spine board, and cervical spine x-rays should be obtained as soon as possible. An appropriate exception to this would be if the incident had been witnessed and there was obviously no trauma involved.
Adjunctive Immediate Therapy. Victims of submersion exhibit a combined respiratory and metabolic acidosis. The respiratory component should be corrected with prompt airway control and ventilation. Severe metabolic acidosis is common and may require correction with sodium bicarbonate. ABG results can be used to guide therapy.
Rewarming Methods. The evaluation and treatment of hypothermia, whether wet or dry, on land or in the water, is essentially the same.59 The most basic method of prevention of heat loss should be used from the very start of the resuscitation; the patient should be dried. Evaporation causes rapid heat losses, and wet clothes rarely protect sufficiently from heat losses. Wet clothing should be removed as soon as possible in the resuscitation, and the patient should be covered with warmed, dry blankets.
The rewarming method of choice in the hypothermic non-breathing, cold-water submersion victim is probably cardiopulmonary bypass with in-line heat exchanger. This method has the very practical advantage of rewarming the core and oxygenating the brain at the same time.
Water baths for rewarming are dangerous for both patient and staff if cardiovascular monitoring is employed. Other methods (i.e., peritoneal dialysis and hemodialysis) may be used for rapid rewarming. For the conscious patient without significant respiratory embarrassment, active external heating may suffice. Although heated, moistened oxygen and warmed intravenous fluids do not contribute significant heat calories to the resuscitation, this form of adjunctive warming will often balance heat losses.
History. After all of the immediate resuscitative efforts are underway, it is appropriate to obtain as much medical history as is available, paying particular attention to those factors that will influence the prognosis and possible complications. The physician should attempt to document what kind of fluid the patient was submerged in, the temperature of the solution, a rough approximation of duration of submersion, what resuscitative efforts were made at the scene, and the response to these efforts. The patient’s age should be estimated, if not readily available, and any pre-existing diseases that are known should be identified. In many cases, these data will be readily available from friends or family, but some victims are never identified. If possible, obtain details of the accident while questioning the patient or those accompanying him. The details may provide clues to other injuries, such as fractures or intra-abdominal injuries, which may go unrecognized temporarily during the excitement of the resuscitation.
If the victim is an infant or a child, the possibility of child abuse must be considered. Children may be forcibly submerged under water as a form of punishment. If other evidence of trauma or child abuse is noted, or the examination is not consistent with the given story, this should be carefully documented.
In the majority of child submersion incidents, at least one parent is near the scene of the accident.60 Most parents are emotionally distressed, devastated, and remorseful. The parents often relate that the child was playing, and they momentarily lost sight of the child, only to find him floating face down or submerged in the backyard pool. Another classic story is that the child was left playing in the bathtub for a few moments and the caretaker returned to find the child face down in the tub. If the parents are not reacting appropriately or give an overly detailed or unusual story, the examiner’s suspicions should be heightened.
Cessation of Resuscitation. After rescue, the victim may appear to be clinically dead, either because a true cardiac arrest has occurred or because the bradycardic weak pulse is not palpable. The development of immersion hypothermia prior to the anoxic insult may be protective for the brain. All cold-water submersion victims should have a trial of resuscitation with immediate ventilation and closed chest massage. Brain death is difficult to determine at lower body temperatures, so rewarming the patient to at least 30°C. is required before abandoning CPR. CPR exceeding two hours has been successful, and victims have survived submersion times as long as 40 minutes.
Adjuvant Hospital Therapy
Antibiotics. The mortality of pneumonia associated with near drowning is 60%.61 There is little evidence for, and substantial logic against, the use of prophylactic antibiotics. In one study where 21 patients were given prophylactic antibiotics, 16 developed pneumonia from an organism resistant to the antibiotic used.62 No reduction in pneumonia or mortality was noted when prophylactic antibiotics have been used.
Less controversy exists over the use of prophylactic antibiotics when the patient aspirates grossly contaminated water such as from sewers or septic tanks. With such contamination of the lungs, most authorities recommend antibiotics.
Glucose. Hypothermia and alcohol, alone or in combination, may cause hypoglycemia, and all drowning victims should have their glucose checked and hypoglycemia corrected.
Steroids. Corticosteroid therapy for pulmonary injury of drowning has not been demonstrated to be helpful in either canine or human studies.63,64 They should probably not be used for treatment of the pulmonary injury.
Surfactant. Surfactant is washed out or destroyed by both salt water and fresh water aspiration. Addition of artificial surfactant will theoretically improve the gas exchange in submersion survivors. Artificial surfactant has been used in the treatment of submersion victims with some success.65,66 Animal studies have conflicting results, and this treatment will need additional study before it can be routinely recommended.
Cardiopulmonary Bypass. Cardiopulmonary bypass provides fast rewarming, maintains tissue perfusion and oxygenation, and assists the cold and inefficient heart during the resuscitation. It may have a significant adjuvant role beyond rewarming in the treatment of the cold-water submersion victim in cardiac arrest.
Central Nervous System Protection. Early studies advocated the use of hypothermia, intracranial perfusion monitoring, and barbiturates to improve outcome.67,68 There is now a general consensus that early barbiturate loading, mild hypothermia, and control of intracranial pressure (ICP) does not improve the overall outcome. Currently, ICP monitoring is not recommended, but if it is done, an elevated ICP bodes a poor prognosis for the patient.
Prognosis
The prognosis of a submersion patient may be difficult to estimate. (See Tables 3 and 4.) If the patient has made a first respiratory effort within 30 minutes of rescue, the prognosis is good.69 The adult patient who arrives at the hospital with a beating heart has a good chance of recovering all neurologic function. Survival after the submersion event appears to depend upon a number of interrelated factors.
Table 3. Factors Affecting Prognosis* |
• Duration of the submersion |
• Duration and degree of hypothermia (water temperature) |
• Age of the patient |
• Water contaminants |
• Duration of respiratory arrest |
• Duration of cardiac arrest |
• Rapidity and effectiveness of resuscitation |
• The diving reflex |
*Without controlled studies, it is difficult to determine which factors have the greatest effect on the outcome of the patient after a submersion incident. |
Table 4. Good Prognostic Factors Following a Submersion Incident |
• Alert and awake on arrival to ED |
• Cold, fresh water |
• Short submersion |
• Older child or young adults |
• On-scene advanced cardiac life support or basic life support |
• Healthy |
In warm water submersion, a clinical picture that includes one or more of the following features will imply a severe neurologic impairment or mortality, even in children:70-72
• Submersion for greater than 5 minutes;
• Absence of pupillary light reflex (in the ED);
• Pulseless on arrival in ED;
• No CPR for 10 minutes or more;
• Rural location of incident;
• CPR longer than 25 minutes;
• pH less than 7.1 on arrival at the hospital;
• Need for in-hospital resuscitation or ventilation;
• High initial blood glucose concentration;
• Male sex;
• Abnormal chest radiograph findings; and/or
• History of epinephrine administration in field or ED.
Many investigators have proposed predictive rules incorporating one or more of these variables. Most of these predictive rules are more appropriately applied in the ICU after initial resuscitation than in the ED. An interesting exception is a tool designed for the ICU — the Pediatric Risk of Mortality Score (PRISM).73 This tool appeared to be more effective when used in the ED than in the ICU.74
In the absence of any unusual circumstance, such as cold water immersion or barbiturate use, a reasonable guideline is to continue resuscitation for 30-40 minutes. After that time, consider stopping all efforts if no effective cardiac activity has been restored.
The same prognostic factors cannot be applied to submersion in cold water. As has been noted before, there is a profound protective effect of hypothermia on cerebral survival.
There is some controversy about what to do when the victim arrives in the ED awake, alert, and without significant signs of aspiration. As noted earlier, pulmonary edema can have a delayed onset (secondary drowning). Observation of the patient with a history of submersion is commonly recommended. Any child with tachypnea, oxygen requirements, or an abnormal chest radiograph should be admitted. Children who have no pulmonary symptoms may be observed for a period of time. At least one study suggests that these patients may be safely sent home.75,76 An observation period of several hours is a reasonable compromise in low-risk patients with good parental supervision and close medical follow-up.
Prevention
Like all diseases, it is much easier to prevent a submersion incident than it is to treat one. Many of the major factors that contribute to a submersion incident are preventable, such as an inability to swim, failure to wear proper protective gear, consumption of drugs or alcohol, and stunts. Because the greatest proportion of drownings occur in non-swimmers, the protection afforded by swimming lessons is easy to support and has been known for ages.
Children require special preventative measures.77 A child with "water wings" or in a floating support, without adequate supervision immediately available, is a fatality waiting for a place to happen. Overestimation of swimming skills and trauma associated with horseplay may contribute to a child’s demise.
Fences around pools markedly reduce the incidence of submersion injuries in those areas where they are required.78-80 Because fencing requires no training or action on the part of the child or the parent, it deserves a very high priority in prevention efforts. The fencing should be at least 4 feet high and include self-locking gates. Immersion alarm systems for unattended pools will further decrease deaths but should not be used as a primary means of drowning prevention.
The adult who is intoxicated not only cannot supervise a child, he or she also cannot supervise personal actions. To reach the "legally drunk" 100 mg/dL level, the average 70 kg person needs to consume only four beers or two mixed drinks in the space of an hour. Any steps that reduce intoxication among swimmers will reduce the frequency of injury and death.
Patients with seizure disorders or other handicaps must be properly supervised, as their risk is higher.81 For these patients, buddy swimming and proper supervision is mandatory. For these parents, cardiopulmonary resuscitation training should be strongly advocated.82
For those who are exposed to the elements, particularly at sea in the higher latitudes, instructions in methods of conserving the body heat during immersion should be mandatory. Proper protective gear should be worn at all times in these areas, including both survival suit and approved flotation devices.
Conclusion
Between 6000 and 8000 drownings occur each year in the United States, and there is a similar number of near-drownings that are reported.
The single most important factor in recovery of the patient is the time from submersion until definitive airway management.
Younger victims in cold water have the best prognosis for long-term survival. Those who are submersed in hot tubs have the worst prognosis. All patients deserve a full and aggressive resuscitation. Unfortunately, there is no proven way to predict which person will survive intact, which will die, or which will survive with neurologic damage.
Finally, the best treatment for this disease is prevention. Age-specific swimming lessons, water safety, and adequate supervision should be stressed for children. Liquor and other intoxicants should be banned from swimming areas.
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