Critical Care Clinics
Volume 15 • Number 2 • April 1999
Copyright © 1999 W. B. Saunders Company

ENVIRONMENTAL EMERGENCIES

NEAR DROWNING

Ramesh C. Sachdeva MD, PhD

 

Address reprint requests to
Ramesh C. Sachdeva, MD, PhD
Critical Care Section
Texas Children's Hospital
6621 Fannin, MC2-3450
Houston, TX 77030

Department of Pediatrics and the Center for Medical Ethics and Health Policy, Baylor College of Medicine; the Critical Care Section, Texas Children's Hospital, Houston, Texas

Despite efforts at prevention and availability of life-sustaining technologies in intensive care units (ICUs), near drowning continues to be associated with high mortality and morbidity in both children and adults.

 

Attempts at providing interventions to improve the outcomes of victims of near drowning date back 400 years when Paracelus, a Swiss physician, demonstrated the importance of ventilating individuals who were nearly drowned by inserting fireplace bellows into the victim's mouth or nostril to inflate the lungs. [59] [63] In the eighteenth century, Humane Societies were established in England, Scandinavia, and United States with increasing interest in treating victims of near drowning. [59] [63] Tilting boards were used not too long ago in this century with the goal of moving the victim's diaphragm by shifting the weight of the abdominal contents. [59] [63]

 

With the availability of sophisticated technologies in adult and pediatric ICUs, victims of near drowning are now more likely to survive. However, this improvement in short-term survival of near-drowning victims after an acute submersion episode has also resulted in an increase in major complications, including the development of acute respiratory distress syndrome (ARDS) during the ICU stay and persistent hypoxic-ischemic central nervous system (CNS) injury. Therefore, it is important for the critical care physician to be not only familiar with the acute ICU management of victims of near drowning, but also to understand the pathophysiologic mechanisms of near drowning, including the cellular mechanisms of CNS injury, because many of the advances in optimizing outcomes of near-drowning victims depend on the success of CNS resuscitation.

DEFINITIONS

In the past three decades, a number of different terminologies have replaced the term drowning, which referred to a submersion accident resulting in death. [11] [22] These definitions and the course of submersion accidents are summarized in Figure 1 . Outcomes of an individual who has a submersion accident may include (1) immersion syndrome, which is sudden death after contact with cold water, or (2) submersion injury, which is submersion resulting in death within 24 hours of submersion (drowning), at least temporary survival (near drowning), or water rescue or removal of victim from water (save). Secondary drowning refers to death from complications of submersion, 24 hours after submersion.

Text Box: Figure 1. Submersion accident flowchart. EPIDEMIOLOGY

Drowning represents the third most common cause of all accidental deaths and is the second most common cause of death in individuals under 44 years. [5] Of the estimated 140,000 to 150,000 deaths worldwide caused by drowning, 6000 to 8000 deaths occur in the United States. Figure 2 shows that drowning is one of the leading causes of accidental deaths among children and adolescents. [5] Of all drowning deaths, 55% to 60% are seen in individuals less than 20 years of age, with the largest proportion occurring in children younger than 5 years. African American children have an almost twofold higher rate of drowning than Caucasians, and drowning is more common in males then in females. [9] [51] In males, there appears to be a bimodal increase in peak at an age of approximately 5 years and again at an age of approximately 20 years. [9]

 

Risk factors associated with submersion accidents are summarized in Table 1 . The typical profile of the pediatric drowning victim is a preschool male swimmer who has the submersion accident in a home swimming pool while under adult supervision. [47] [51]

PATHOPHYSIOLOGY

Aspiration of Freshwater or Saltwater Fluid

Karpovich [18] has described the sequence of events after submersion in animal models. There is an initial phase of panic and struggle that is followed by breatholding and swallowing of large amounts of water. With further attempts at breathing, water is aspirated into the lung.

 

Animal studies support that there are physiologic and biochemical differences between freshwater and saltwater drowning. [45] [56] Freshwater is more hypotonic compared with plasma and is absorbed from alveoli into capillaries, resulting in hemodilution (hyponatremia, hypokalemia) and in secondary hemolysis. [45] In contrast, saltwater drowning results in hemoconcentration, because saltwater has a higher osmolality compared with plasma. Additionally, aspiration of freshwater results in the dilution of a pulmonary surfactant that contributes to the development of alveolar collapse, atelectasis, hypoxemia, and ventilation-perfusion mismatch. In contrast, saltwater drowning predisposes fluid movement from the intravascular compartment into the alveoli. Hypoxemia occurs along with physiologic shunting, secondary to perfusion of fluid-containing alveoli.

TABLE 1 -- RISK FACTORS FOR SUBMERSION ACCIDENTS

1. Age: Less than 20 y, with a higher risk for age less than 5 y.

2. Gender: Males greater than females.

3. Race: African Americans more than Caucasians.

4. Time of day: Toddler drownings tend to occur around meal preparation times (when there may be less adult supervision) i.e., in afternoon and early evenings.

5. Preexisting illnesses: Fourfold increase for submersion accidents in individuals who have a history of seizure disorders.

6. Climate: In warmer climates in industrialized nations, the majority of drownings occur in family swimming pools, whereas, in colder climates in industrialized nations, the majority of drownings occur in natural bodies of freshwater.

7. Use of equipment: Solar blankets in pools, for example.

8. Use of intoxicants: Alcohol, for example.

9. Hyperventilation: Before underwater swimming (shallow-water blackout syndrome).

10. Breakdown of safety precautions: Unlocked or malfunctioning safety fences, for example.

Text Box: Figure 2. Percentage of fatal injuries in children under 19. MVA = motor vehicle accidents. ( Data from Centers of Disease Control, MMWR 39:442-452, 1990.)
There appears to be a controversy in results from animal models compared with observations from clinical practice. Despite the significant electrolyte aberrations seen in animal models of freshwater and saltwater drowning, these may not be as prominent in clinical practice, because more than 11 mL of fluid per kg body weight needs to be aspirated for significant alterations in blood volume. [26] [51] Similarly, aspiration in excess of 22 mL fluid per kg body weight needs to take place for clinically significant electrolyte changes to be seen. [25] [28] However, certain unusual circumstances such as submersion accidents in the Dead Sea or in industrially polluted waters may predispose victims to serious electrolyte abnormalities. [61] These include hypercalcemia and hypermagnesemia observed in victims of submersion accidents in the Dead Sea and hypercalcemia reported in victims of submersion accidents in calcium-rich waste water from offshore oil rigs. [12] [61]

Effects on the Respiratory System

Approximately 10% to 15% of victims of submersion accidents have acute laryngospasm that results in dry drowning, because there is no aspiration of water into the lungs and death typically occurs owing to profound obstructive asphyxia. Since even a small amount of fluid (1 to 3 mL fluid per kg body weight) can lead to severe abnormalities in gas exchange, hypoxemia has been described as the single most important consequence of near drowning. Table 2 compares differences between freshwater and saltwater aspiration based on evidence from animal studies. [11] [13] [29] [35] It has been suggested that the hypoxemia in freshwater drowning is caused by the inactivation of pulmonary surfactant, resulting in worsening of lung compliance and atelectasis. [13] [35] Increased capillary leaks predispose the individual for development of pulmonary edema. Perfusion of poorly ventilated areas of the lung results in intrapulmonary shunting and may lead to ventilation-perfusion mismatch. [35] Similarly, it has also been suggested that hypoxemia in saltwater drowning is secondary to fluid movement into the alveoli caused by the establishment of an osmotic gradient between the capillary-alveolar membrane; this results in intrapulmonary shunting and ventilation-perfusion mismatch. Individuals who survive the initial course of near drowning are at risk for the development of secondary drowning: the development of ARDS. [22] [23] These individuals are also at risk for pneumonia which may worsen further the hypoxemia. [23]

 

TABLE 2 -- COMPARISON OF EFFECTS OF FRESHWATER AND SALTWATER ASPIRATION ON THE RESPIRATORY SYSTEM

Effect

Freshwater Aspiration

Saltwater Aspiration

1. Pulmonary surfactant

Altered

Not altered

2. Arterial oxygen content

Lowered

Significantly lowered

3. Periodic hyperinflation of lung resulting in significant and lasting improvement in blood gases (improvement in Pa O2 )

Improvement

No improvement

Effects on the Cardiovascular System

Effects of the submersion accident on the respiratory system resulting in hypoxemia can lead to an increased risk for development of arrhythmias, including ventricular tachycardia, ventricular fibrillation, and asystole. The presence of metabolic acidosis may further lower the threshold for development of arrhythmias. Myocardial dysfunction and cardiogenic shock can occur because of persistent hypoxemia.

Central Nervous System Effects

CNS dysfunction may be secondary to the initial hypoxic injury and may be caused by progressive CNS injury because of postresusitation cerebral hypoperfusion. Postresusitation cerebral hypoperfusion is caused by a variety of mechanisms, including increased intracranial pressure, cytotoxic cerebral edema, cerebral arteriolar spasm caused by calcium entry into the vascular smooth muscle, and by oxygen-derived free radicals.

 

There may be differences between children and adults with respect to the pathophysiologic responses after submersion accidents. Because of the larger surface area and proportionately smaller amounts of subcutaneous fat in children compared with adults, children are more likely to develop hypothermia than adults. [62] It has also been suggested that the diving reflex is more prominent in children than in adults, resulting in bradycardia, redistribution of blood to the heart, and CNS. [4] [7] [14] Hypothermia affects cerebral metabolic rate, and it has been shown that severe hypothermia to 28°C (82.4°F) can lower energy utilization by 50%. [46] Although the role of the diving reflex in children has been questioned by some, it does appear that after submersion accidents that may be secondary to the diving reflex or hypothermia, [15] [44] there is theoretically a greater level of CNS protection in children than in adults.

 

Hypothermia appears to offer some degree of protection for the CNS. [2] It has been suggested that rapid cooling in icy water <5°C (41°F) is necessary to offer potential protective benefits. [34] However, severe hypothermia itself can cause significant depression of sensorium and an increased risk of mortality. Very young children and elderly individuals are at higher risk for developing hypothermia.

Pathophysiologic Basis of Neurologic Injury

It is important for critical care physicians and other clinicians taking care of victims of submersion accidents to understand the pathophysiologic basis of neurologic injury, [19] particularly since this is an area of growing research and is likely to form the basis of many interventions in future years. Ischemia results in the release of neurotransmitters such as glutamate, which, in turn, stimulates phospholipase-C-induced hydrolysis of phosphatidylinositol biphosphate to inositol triphosphate and diacylglycerol. Arachidonic acid is produced by two ways: from diacylglycerol and also by the action of inositol-triphosphate-generated calcium on phospholipase A2 . Arachidonic acid in the presence of reperfusion participates in three metabolic pathways: cyclooxygenase, lipooxygenase, and cytochrome p-450. Some of the actions of these pathways include vasoactive effects, injury to the blood-brain barrier, and platelet aggregation, leading to thrombosis. The cyclooxygenase pathway also contributes to the production of oxygen radical formation. Oxygen radical formation is also mediated by other mechanisms, including neutrophils, xanthine oxidase, and quinone reactions. These radicals are highly reactive, and the CNS is particularly sensitive to them because of the presence of polyunsaturated fatty acids (like arachidonic acid).

MANAGEMENT

There may be inadequate information at the scene of the submersion accident, and since the aggressiveness and success of the initial resuscitation is a strong determinant of long-term prognosis, it is important to initiate basic and advanced cardiac life support measures promptly. Note that submersion time is a strong predictor of outcomes. [33] [38] [43] There are several excellent reviews summarizing the clinical approach and management of victims of submersion accidents; many of these reviews also provide algorithms to aid the clinician in developing management strategies for these patients. *

Resuscitation at the Scene

Similar to any resuscitative effort, restoration of airway patency, breathing, and circulation must be ensured. Mouth-to-mouth breathing even while the victim is in the water should be attempted. [22] [51] [54] Efforts to remove the submersion accident victim out of the water should be made as quickly and safely as possible, and time should not be wasted in attempting chest compressions while in the water since this has not been shown to be effective. Heimlich and Patrick have recommended using subdiaphragmatic pressure in an attempt to remove water from the airway. However, since most victims of submersion accidents aspirate small quantities of water but may swallow larger amounts of water, and since attempting subdiaphragmatic pressure may increase the risk of aspiration, this maneuver is not recommended. [35] [36] [37] However, subdiaphragmatic thrust may be extremely important if there is airway obstruction caused by foreign bodies or debris. Victims of submersion accidents may have other ongoing conditions like seizures, head injuries, neck injuries, and trauma, and these should be kept in mind during the initial resuscitation at the scene and during transport to an emergency center.

* References [8] [9] [10] [11] [22] [32] [35] [37] [38] [41] [42] [46] [50] [51] [54] [63]

Management in the Emergency Center

A systematic approach to the victims of the submersion accident should be used. An adequate airway needs to be maintained. Elective intubation may need to be considered, even in the absence of respiratory depression, with the goal of protecting the airway, particularly in individuals who have a depressed neurologic status. Attention should be paid to ensure adequate breathing to achieve satisfactory oxygenation and ventilation. Individuals who have hypoxemia may benefit with the application of positive and expiratory pressure (PEEP), but diuretics may not be very useful in this initial phase of stabilization. Pulse oximetry, capnography, and blood gases should be monitored, particularly in the child who is intubated to monitor for the development of hypoxemia and hypercarbia, both of which would be detrimental to the goal of achieving successful CNS resuscitation. Hemodynamic assessment should include clinical evaluation of both cardiac status (including function and the presence of arrhythmias) and peripheral perfusion. Many patients may be acidemic, which may further worsen myocardial function. Sodium bicarbonate along with fluids may be necessary to correct the metabolic acidosis. Hypovolemia is not uncommon and fluid resuscitation may be necessary with isotonic crytalloids or colloids. Remember that these patients have an increased risk for developing cerebral edema and that fluids should be used judiciously. However, the basic paradigm of ensuring adequate hemodynamic stability to ensure optimal cerebral perfusion as a priority remains the goal of any CNS resuscitation and also applies to the victim of a submersion accident. Basic cardiopulmonary resuscitation in children and adults may be necessary in the victim of a submersion accident and is essentially similar to any other individual needing resuscitation. Management in the emergency department would of course include the basic management standards for any critically ill child, including the evaluation of signs of trauma (including evaluation of the cervical spine for injuries), monitoring, and prompt attention to changes in clinical status. Victims of submersion accidents who are hypothermic need rewarming, which can be achieved with external devices described elsewhere in this issue and core-rewarming techniques. Close attention needs to be paid to electrolytes, blood gases, and acid-base status as the individual is being rewarmed. Since rewarming is associated with an increased risk for the development of cardiac arrhythmias, many centers use extracorporeal circulation techniques to rewarm victims of cold-water submersion accidents. [4] Laboratory diagnostic studies in an individual who had nearly drowned include electrolytes, blood urea nitrogen (BUN), creatinine, blood gases (to evaluate the extent of hypoxemia, status of ventilation, and acidosis), and hemoglobin levels. Toxicology studies, including alcohol levels, may be considered based on the clinical situation. If there is a underlying history of seizure disorder, anticonvulsant drug levels should be obtained. To look for any arrhythmias and also to evaluate the QT C interval, the clinician should obtain a baseline electrocardiogram. It has been suggested that routine CT imaging of the head is not necessary at this stage unless an associated head injury is suspected based on the patient's history or the clinical examination.

Management in the Intensive Care Unit

Monitoring

Since victims of submersion accidents may have multiple organ system involvement, monitoring strategies need to be individualized to the patient and to have the assessment of the potential risk-benefit ratio of the monitoring intervention planned. Typically, monitoring of patients needing admission to the ICU will include noninvasive techniques like continuous cardiorespiratory monitoring, pulse oximetry, capnography in intubated patients, with close assessment of fluids and intake and output. Invasive monitoring, including arterial catheterization (for frequent blood gases measurements and continuous blood pressure assessment) and central venous catheterization (to monitor filling pressures particularly in patients in shock) will likely be needed. Thermodilution pulmonary artery catheterization may be indicated; however, its use in the pediatric population has continued to decrease in most centers in the United States and has been substituted with the use of serial echocardiography. It cannot be emphasized enough that meticulous attention to frequent clinical neurologic examinations and assessment of Glasgow Coma Scale scores by physicians and nurses in the ICU are key in the patient's management.

 

Management of Short-Term Issues of Patients Who Have Submersion Accidents and Who Are in the Intensive Care Unit

 

Besides the initial management of establishing a stable airway and achieving satisfactory oxygenation and ventilation, strategies aimed at minimizing the risk for developing ARDS should be employed. Pressure-control ventilation with low-peak airway pressure and prolonged inspiratory time may be considered. As longer inspiratory times are used, it is crucial that the clinician carefully evaluates for the development of auto-PEEP secondary to inadequate time for expiration. Although permissive hypercapnia is frequently used in minimizing barotrauma in patients who are in the ICU, this may not be suitable in the individual who has CNS injury, because the resulting hypercarbia can adversely affect intracranial pressure and can be extremely detrimental to a successful CNS resuscitation. Other strategies, including high-frequency ventilation and extracorporeal membrane oxygenation (ECMO), have also been attempted in patients who had nearly drowned and who develop secondary severe lung injury. [51] [53]

 

The optimal neurologic care for individuals who have submersion accidents remains controversial with variations between centers. Earlier studies supported the use of HYPER therapy (including treatment for hyperhydration by diuretics, hyperventilation, hypothermia to treat hyperpyrexia, barbiturates to treat hyperexcitability, and neuromuscular blockade to treat hyperrigidity) for patients who had nearly drowned. [3] [6] [7] However, subsequent studies did not demonstrate improved outcomes among patients receiving the HYPER therapy. [3] [8] [24] [30] Therefore, most centers currently employ supportive care and do not use barbiturates, steroids, hypothermia, hyperventilation, intracranial pressure monitoring, or neuromuscular blockade routinely in the management of patients who have nearly drowned. [3] [8] [30] Although using pharmacologic agents such as pentobarbital has the potential advantage of decreasing cerebral oxygen demand, its use has not been shown to improve CNS outcomes among children. Routine use of intracranial pressure monitoring is not employed by most centers despite the fact that high intracranial pressures after 72 hours of the injury is usually associated with poor outcomes. [52]

 

Many pediatric ICUs in the United States continue to use techniques like head elevation and midline position and the avoidance of internal-jugular catheters with the aim of minimizing any mechanical obstruction for cerebral blood return. The use of PEEP may be necessary to improve the underlying hypoxemia; however, note that many centers avoid the use of PEEP (unless clearly needed for the pulmonary status) in an attempt to enhance cerebral blood outflow and in turn decrease intracranial pressure. To optimize CNS resuscitation, it is important to ensure that the patient does not become hypercarbic or hyperglycemic. Seizures should be promptly recognized and treated. In addition to cardiorespiratory support and efforts at maximizing neurologic recovery, it is important to address other associated injuries and underlying medical conditions.

 

Management of Long-Term Issues of Patients Who Have Submersion Accidents and Who Are in the Intensive Care Unit

Patients who have submersion accidents are at risk to develop multiple organ system involvement, including myocardial dysfunction, renal failure, and disseminated intravascular coagulation, and supportive care needs to be provided for these conditions. [16] [41] [55] ARDS can be a significant cause of morbidity and mortality in the patient who has nearly drowned. [49] Note that based on the American-European Consensus Conference on ARDS, the definition of ARDS includes the presence of (1) impaired oxygenation (Pa O2 /Fi O2 ratio < 200); (2) bilateral pulmonary infiltrates on roentgenographic examination; and (3) pulmonary artery occlusion pressure (wedge pressure) < 18 mm or no clinical findings suggestive of increased left atrial pressure. [57] Management of ARDS is largely supportive in nature and is also similar in the patient who has had a submersion accident. [27] PEEP has been used for several years in the management of patients who have ARDS. By restoring functional residual capacity (FRC) to more than closing capacity, PEEP decreases the risk of atelectasis. The optimal amount of PEEP used needs to be individualized to the patient. In general, early use of PEEP up to at least 8 cm of water is needed in most cases of ARDS. Accordingly, after using an adequate tidal volume (5 to 10 mL/kg) and I:E ratio (I-cycle < E-cycle), the clinician rapidly increases PEEP in increments of 2 to 3 cm H2 O to achieve Fi O2 levels < 0.6. Currently, most pediatric centers have adopted a fairly aggressive use of PEEP up to a level of approximately 20 cm of H2 O. Most centers use a very conservative approach for weaning PEEP, with the aim of minimizing alveolar derecruitment. [49] Thus, PEEP is weaned in small decrements every few hours. Once PEEP has been weaned to a range of approximately 5 to 7 cm of H2 O, then Fi O2 is decreased to lower levels. To minimize barotrauma, many centers would use neuromuscular blockade in patients requiring PEEP levels in excess of 12 cm of Hg especially in children. In situations where neuromuscular blockade is needed and the patient has a risk for developing seizures, continuous electroencephalographic (EEG) monitoring may be necessary. [49] In contrast, some adult centers use increasing amounts of sedation and do not routinely neuromuscularly block adults requiring PEEP levels in excess of 12 cm of Hg. [49]

 

Many of the new approaches in the management of ARDS remain mostly supportive in nature. It is noteworthy that a randomized study in children did show the potential benefits of using high-frequency ventilation in the management of ARDS, and in small clinical studies in which nitric oxide was used in children and adults who have ARDS, improved outcomes have been shown. [1] [49]

Since many patients who have nearly drowned will have a long length of stay in the ICU, they are always at increased risk for nosocomial infections. Although routine use of prophylactic antibiotics has not been shown to be effective, the clinician needs to have a high degree of suspicion for the development of nosocomial infections. Patients who develop fever and other clinical changes suggesting infection would need cultures and prompt institution of broad-spectrum antibiotics. [60]

 

Other Management Considerations and Role of the Intensive Care Unit Physician to Provide Support for the Family

 

Submersion accidents are sudden and unexpected. Many victims of near drowning end up staying for long periods in the ICU and in the hospital, leading to significant associated costs. Survivors may have severe neurologic injury, needing rehabilitation and long-term care. All these issues can place a tremendous emotional and financial burden on the family. [31] The ICU physician needs to be compassionate but realistic in his interactions with the family. It is not uncommon for nursing staff and trainees to get emotionally attached, particularly to children in pediatric ICUs, and it remains important for ICU physicians to remain objective in their decision making and to support the family as well as other members of the ICU team through the process.

PROGNOSIS AND OUTCOMES

In general, studies indicate that 90% of children who survive submersion accidents and 68% of patients needing cardiopulmonary resuscitation (CPR) have good outcomes. [39] [42] The success of resuscitation at the site of submersion accidents is the major determinant of a good outcome. It has been shown that individuals who are conscious on arrival to the hospital after being successfully resuscitated have an excellent chance of intact survival. Most studies support that the longer the duration of submersion, the poorer the likely outcome. Also, cold-water submersion is associated with better outcomes compared with warm-water submersion accidents.

 

Results of some studies indicate that demographic characteristics (age and gender; clinical factors like duration of submersion, core temperature, respiratory effort, response to painful stimuli, and pupillary reaction; and laboratory parameters like pH) are unreliable predictors of outcome in victims of submersion accidents. [30] Other studies have results that suggest that pupillary unresponsiveness in the emergency department and an initial Glasgow Coma Scale score of less than 5 on arrival to the ICU are associated independently with poor CNS outcomes. [20] As more research efforts are directed to developing identifying prediction models, it is important to appreciate that clinical decision making will always need to take the trade-offs between sensitivity and specificity into account. An approach with evidence-based medicine should be employed by the clinician. Clinicians and researchers need to keep the relative importance of sensitivity and specificity in mind while interpreting prediction studies for application in their clinical practice, which, in turn, needs to be based on how they plan to use the results from the prediction model. Specificity should be maximized if false-positive rates are to be avoided. [17] Similarly, sensitivity should be maximized if false-negative rates are to be avoided. [17] Therefore, prognostic tests that may lower the threshold for the physician to consider withdrawal of care in the emergency department and the ICU should be highly specific in nature. Given the high likelihood of obtaining imprecise information on the duration of submersion and the lack of specific predictors that can be used with a high degree of accuracy, it has been suggested that all near-drowning victims should be treated aggressively initially in the emergency department setting. Using this approach also provides families a better opportunity to cope with the catastrophe at hand. However, note that the need for CPR in the emergency center after a warm-water submersion accident has been shown to be associated with largely poor outcomes, whereas cold-water submersion accidents are associated with better outcomes. [30] [35] [43] Therefore, it has been suggested that CPR should be continued, particularly in individuals who have been victims of cold-water submersion accidents until the patient has been rewarmed in a satisfactory manner. [35] [58]

 

Prediction of outcome of victims of near drowning after they arrive in the ICU has remained challenging. Frequently, the ICU physician may be faced with questions related to the likely outcome of the near-drowning patient in the ICU and may have to address issues raised by nurses, trainees, and families as to if and when withdrawal of care should be considered. It is important for ICU physicians to individualize each case and develop a decision framework based on the ethical and the legal foundations of the community and country in which they practice. However, there are several clinical studies that may facilitate the physician's discussions with the family while discussing prognosis. Table 3 provides a classification system that can be related to outcome. Studies performed by Conn showed that patients in Group A survived intact, patients in Group B had a mortality rate of 10%, and patients in Group C had mortality rates of 34%. [6] It has also been shown that Glasgow Coma Scale scores of less than 5 are associated with high mortality, or severe CNS damage. Scoring systems and predictors of outcomes in which patient clinical information is used and techniques such as brain-stem-evoked potentials and cerebral blood flow measurement have also been suggested for use in selected cases.

 

Based on clinical experiences from many centers in the United States, it appears that the absence of cognitive function and the absence of some degree of neurologic recovery by 48 to 72 hours after the initial submersion accident is likely to be associated with a poor long-term outcome. [51] Additionally, the presence of seizures persisting beyond 12 hours is also associated with a poor outcome.

 

TABLE 3 -- CONN'S NEUROLOGIC CLASSIFICATION SYSTEM

A: Awake

B: Blunted

C: Comatose

  C1: Decorticate

   C2: Decerebrate

  C3: Flaccid

 

The discussion above relates to the prognosis of neurologic function. However, it is important to mention that many individuals who have nearly drowned and who are admitted to the ICU may need prolonged ventilatory support, including the need for high pressures, and are at risk for developing barotrauma, volutrauma, and ARDS. Also, these individuals frequently have a long duration of ICU stay with an increased risk of developing nosocomial infections. Many individuals who have nearly drowned may have a good short-term outcome only to succumb to secondary drowning in the ICU or to result in a vegetative state. [40]

ETHICAL BASIS OF DECISION MAKING FOR PHYSICIANS PROVIDING CARE FOR VICTIMS OF SUBMERSION ACCIDENTS

The ethical role of physicians providing initial care for patients in the emergency center or subsequent care in the ICU is based on the fundamental ethical foundations of the society and country in which the physician practices. Social norms dictate public policy and in turn the legal system. The current health care system in the United States is a blend between three concepts of distributive justice: egalitarian, libertarian, and utilitarian. [21] Egalitarian theories emphasize concepts of equal access and distribution of social benefits; libertarian theories emphasize liberty, procedural justice, and free markets; and utilitarian theories emphasize maximizing the utility for overall good. Current triage decisions and policies to admit patients to ICUs in the United States are based on the individual patient and not on society as the primary stakeholder. [48] Therefore, given the lack of robust long-term prognostic determinants and their lack of specificity for predicting outcomes in individual patients, physicians in the United States are likely to provide aggressive support and interventions even for potentially small probabilities of good outcomes for the individual patient who has nearly drowned. Finally, since patients who have nearly drowned may be unable to communicate their wishes, physicians must always remain an advocate for their patient's rights.

PREVENTION

The key to minimizing morbidity and mortality secondary to submersion accidents is successful prevention. The American Academy of Pediatrics Committee on Injury and Poison Prevention has developed a list of 23 recommendations to decrease the incidence of near drowning. Successful prevention programs can only be implemented in a proactive manner. This would include an emphasis on educational efforts and increased awareness not only in the community in general with a special focus to target those at higher risk but also for providers, including emergency medical response teams, community primary care physicians to provide anticipatory guidance, and in-hospital medical teams. It has been shown that both children and adults benefit from water-safety prevention programs. Appropriate applications of barriers, including four-sided fencing with self-closing and self-latching gates and doors, pool safety covers, and house alarms may prevent a large number of submersion accidents, particularly in children under 5 years. [39] It is important to remember that placing appropriate barriers does not replace the need for supervision of children while in water by responsible adults. [11]

SUMMARY

Submersion accidents continue to be a significant cause of morbidity and mortality in children and adults. The key to successful management is prevention of these accidents. Proactive efforts to minimize submersion accidents in the community should be made by medical and legislative groups. Anticipatory guidance by primary care physicians, particularly for families and individuals at increased risk, should be performed.

 

Outcomes of individuals who have become victims of submersion accidents can be optimized by the development of a rapid response system, because successful initial resuscitation efforts clearly improve outcomes. For individuals who have nearly drowned and who have arrived in the emergency department, a systematic and aggressive approach needs to be followed with particular emphasis on cardiorespiratory support to optimize neurologic outcome. Despite many studies aimed at developing predictors of outcomes, there is limited information that can be used in a prospective manner to guide the emergency-room physician in limiting the level of interventions. Thus, all aggressive supportive care and resuscitation should be performed at this stage, except in clearly futile situations.

 

Once patients arrive in the ICU, meticulous care, including monitoring of cardiorespiratory and neurologic status and attention to electrolytes and acid-base status, needs to be continued. Besides providing basic supportive measures, the ICU physician should investigate for other associated trauma and medical conditions that may need to be addressed once the patient is stabilized. Patients who have nearly drowned are likely to have long ICU stays, predisposing them to nosocomial infections. Despite efforts at minimizing barotrauma and volutrauma, many patients who have nearly drowned and who need ventilatory support may develop ARDS. The management of these patients is similar to other patients who have ARDS. However, strategies like permissive hypercapnia that are used commonly in patients who have ARDS may not be suitable in patients who have CNS injury.

 

Despite aggressive care, neurologic injury with long-term sequelae secondary to hypoxic ischemic injury remains a major problem in the management of victims of submersion accidents. It is important for the clinician to keep the pathophysiologic and cellular mechanisms of CNS injury in mind, because future interventions are likely to be based on these pathways. Besides providing care for the patient, it is important for the ICU physician to be sensitive to the needs of the family and to support them through this catastrophe that is likely to place a tremendous financial and emotional burden on most of them.

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