Near-Drowning
Near-drowning
Definition
Near-drowning is the term for survival after suffocation caused by submersion in water or other fluid. Some experts exclude from this definition cases of temporary survival that end in death within 24 hours, which they prefer to classify as drownings.
Description
Drowning is always fatal, but near-drowning may result in survival with no long-lasting effects; survival with permanent damage, usually to the brain; or death after a 24-hour survival period. Near drowning sets into motion a collection of reactions in the body that ultimately can damage the lungs and lead to an absence of oxygen in tissues, even when individuals have been removed from the water and begun breathing either on their own or with mechanical help.
Near-drowning happens very quickly. Within three minutes of submersion, most people are unconscious, and within five minutes the brain begins to suffer from lack of oxygen. Abnormal heart rhythms (cardiac dysrhythmias) often occur in near-drowning cases, and the heart may stop pumping (cardiac arrest). The blood may increase in acidity (acidosis) and, under some circumstances, near drowning can cause a substantial increase or decrease in the volume of circulating blood. If not rapidly reversed, these events cause permanent damage to the brain.
Demographics
About 1,500 children drown every year in the United States. Drowning is the second leading cause of injury-related deaths in children ages one month to 14 years of age in the United States as a whole, and the first leading cause of injury-related deaths in California, Arizona, and Florida. The rate of near drowning is much higher, as not all near drownings are reported. It is estimated that for every drowning, there are four additional hospitalizations and 14 additional emergency room visits due to near drowning.
Children under age four and between 15 and 19 years of age are at highest risk of drowning or near drowning. Most young children drown in swimming pools and bathtubs, while teens drown in natural bodies of water. Teen drownings are often associated with boating accidents, alcohol consumption, and illicit drug use. Boys are 12 times more likely to drown than girls, especially during adolescence , when risk-taking behavior is more pronounced in males. However, even in younger age groups, except in bathtub drownings, substantially more boys drown than girls.
Causes and symptoms
The circumstances leading to near-drownings and drownings are varied. Rarely do they involve nonswimmers accidentally entering deep water. In older children and adults, near-drownings are often secondary to an event such as or a head or spinal injury or (in adults) a heart attack that causes unconsciousness and prevents a diver from resurfacing.
Near-drownings can occur in shallow as well as deep water. Small children have drowned or almost drowned in bathtubs, toilets, industrial-size cleaning buckets, and washing machines. Bathtubs are especially dangerous for infants six months to one year of age, who can sit up straight in a bathtub but may lack the ability to pull themselves out of the water if they slip under the surface. One 2004 study found that 88 percent of children who drowned were under the supervision of another person, usually a family member. Seventy-seven percent of these children were under age ten. The most common occurrence was that the supervising adult knew the child was in or near the water but was distracted long enough for the child to drown.
A reduced concentration of oxygen in the blood (hypoxemia) is common to all near-drownings. When drowning begins, the larynx (a part of the air passage) closes involuntarily, preventing both air and water from entering the lungs. In 10 to 20 percent of cases, hypoxemia results because the larynx spasms and stays closed. This is called "dry drowning," and no water is breathed into the lungs. Hypoxemia also occurs in "wet drowning," when the larynx relaxes and water enters the lungs. Individuals who are close to drowning can also regurgitate their stomach contents and breathe these into the lungs.
The physiological mechanisms that produce hypoxemia in wet drowning are different for freshwater and saltwater, but only a small amount of either kind of water is needed to damage the lungs and interfere with lung's ability to remove oxygen from the air.
The signs and symptoms of near-drowning can differ from person to person depending in part on how long the individual has been submerged, the person's age, and the temperature of the water. Upon rescue, some victims are alert but agitated or disoriented, while others are comatose. Breathing and heartbeat may have stopped, or the victim may be gasping for breath. Bluish skin (cyanosis), coughing, vomiting , and frothy pink sputum (material expelled from the respiratory tract by coughing) are often observed. Rapid breathing (tachypnea) and a rapid heart rate (tachycardia) are common during the first few hours after rescue. The victim may experience hypothermia (drop in core body temperature).
When to call the doctor
Emergency medical aid should be sought with any near drowning incident. Even a child who appears to have recovered should be checked by a physician, since some internal reactions to near drowning can be delayed.
Diagnosis
Diagnosis relies on a physical examination of the victim, reports of observers, and a wide range of tests and other procedures. Blood is taken to measure oxygen levels and to determine electrolyte balances. Pulse oximetry, another way of assessing oxygen levels, involves attaching a device called a pulse oximeter to the patient's finger. An electrocardiograph is used to monitor heart activity. X rays can detect head and neck injuries and fluid in the lungs.
Treatment
Treatment begins with removing the victim from the water and performing cardiopulmonary resuscitation (CPR) as needed to restore heartbeat and provide oxygen until the individual is able to breath without assistance. When emergency medical help arrives, 100 percent oxygen is administered to the victim. If the victim's breathing has stopped or is otherwise impaired, a tube is inserted into the windpipe (trachea) to maintain the airway (endotracheal intubation). The victim is also checked for head, neck, and other injuries, and intravenously fluids may be started. Hypothermia from submersion in very cold water requires special handling to protect the heart.
On arriving at the emergency room, the individual continues receiving oxygen until blood tests show a return to normal. About one-third of near-drowning victims are intubated and initially need mechanical support to breathe. Treatment is administered as needed for cardiac arrest or cardiac dysrhythmias. Slow rewarming is undertaken when hypothermia is present. Individuals are observed for the development of acute respiratory distress syndrome (ARDS) or multi-organ failure, both of which can develop after near drowning. Lung problems can develop 12 or more hours after submersion.
Based on symptoms, individuals may be admitted to the hospital or discharged from the emergency department after four to six hours, if their blood oxygen level is normal and no signs or symptoms of near-drowning are present. Discharged individuals must understand that should complications arise, they must immediately seek additional medical care. Admission to a hospital for at least 24 hours for further observation and treatment is necessary for patients who do not appear to fully recover in the emergency department.
Prognosis
Recovery is directly related to the amount of time the body was without adequate oxygen (hypoxia). Brain damage is the major long-term concern in the treatment of near-drowning victims. Patients who arrive at an emergency department awake and alert usually survive with brain function intact, although they may initially have respiratory complications. Pneumonia is common following near drowning and often develops within the first 24 hours.
Death or permanent neurological damage is very likely when patients arrive at the emergency room comatose or without a heartbeat. Of these patients, 35 to 60 percent die in the emergency department, while almost all of those who survive have permanent disabilities. Early rescue of near-drowning victims (within five minutes of submersion) and prompt CPR (within less than ten minutes of submersion) seem to be the best guarantees of a complete recovery. However, in a phenomenon that is not well understood, extremely cold water (less than 41°F or 5°C) seems to protect individuals from some of the neurological damage that occurs with near drowning. Some hypothermic near-drowning victims have been revived after they appeared dead and have experienced few permanent disabilities.
Prevention
Drowning and near drowning are almost always preventable. Prevention depends on educating adults and children about water safety . Children cannot be left in or near water without adult supervision even for a short time. Unsupervised young children are at risk around swimming pools, bathtubs, toilets, buckets, and natural bodies of water. Pools and spas need to be enclosed with a fence at least 5 ft (1.5 m) high and have a self-closing and self-locking gate. Adults and teens should consider learning CPR. No one should swim alone or play along flooded streams or streets. Teens and adults should be educated to understand that alcohol and illicit drug use substantially increase the chances of a drowning accident. Boat owners need to participate in boat safety classes, and children should wear approved life preservers when boating, water skiing, or riding on a jet ski.
Parental concerns
Parents should be aware that physicians are required to consider the possibility of child abuse in every drowning or near drowning involving a child under the age of one year.
KEY TERMS
Cyanosis —A bluish tinge to the skin that can occur when the blood oxygen level drops too low.
Electrolytes —Salts and minerals that produce electrically charged particles (ions) in body fluids. Common human electrolytes are sodium chloride, potassium, calcium, and sodium bicarbonate. Electrolytes control the fluid balance of the body and are important in muscle contraction, energy generation, and almost all major biochemical reactions in the body.
Hypothermia —A serious condition in which body temperature falls below 95°F (35 °C). It is usually caused by prolonged exposure to the cold.
Hypoxemia —A condition characterized by an abnormally low amount of oxygen in the arterial blood. It is the major consequence of respiratory failure, when the lungs no longer are able to perform their chief function of gas exchange.
Hypoxia —A condition characterized by insufficient oxygen in the cells of the body
Resources
BOOKS
Kallas, Harry J. "Drowning and Near Drowning." In Nelson Textbook of Pediatrics,, 17th ed. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004, pp 425–30.
Piantadosi, Claude A. "Physical, Chemical, and Aspiration Injuries of the Lung." In Cecil Textbook of Medicine, 21st ed. Edited by J. Claude Bennett and Fred Plum. Philadelphia: Saunders, 2000.
WEB SITES
Fiore, Michael, and Sabrina Heidemann. "Near Drowning." September 20, 2004. Available online at <www.emedicine.com/ped/topic2570.htm> (accessed January 14, 2005).
Plantz, Scott H., and Michael E. Zevitz. "Wilderness Near Drowning." December 14, 2004. Available online at <www.emedicine.com/wild/topic34.htm> (accessed January 14, 2005).
Shepherd, Suzanne, and James Martin. "Submersion Injury, Near Drowning." January 12, 2005. Available online at <www.emedicine.com/emerg/topic744.htm> (accessed January 14, 2005).
Tish Davidson, A.M.
Howard Baker
Near-Drowning
Near-drowning
Definition
Near-drowning is the term used for survival after suffocation caused by submersion in water or other fluid or liquid.
Description
An estimated 15,000–70,000 near-drownings occur in the United States each year; insufficient reporting prevents a more precise estimate. A typical person experiencing near-drowning is young and male. Nearly half of all drownings and near-drownings involve children less than four years old. Because home swimming pools are the sites for 60–90% of drownings in the 0–4 age group, they pose the greatest risk for children. Teenage boys are also at heightened risk for drowning and near-drowning; drugs and alcohol are implicated in 40–50% of teenage drownings. Overall, roughly four out of five drowning victims are males.
Causes and symptoms
On many occasions, near-drownings are secondary to an event such as a heart attack that causes unconsciousness or a head or spinal injury that prevents a diver from resurfacing. Near-drownings, moreover, can occur in shallow as well as deep water. Small children have drowned or almost drowned in bathtubs, toilets, industrial-size cleaning buckets, and washing machines. Bathtubs are especially dangerous for infants between six months and one year of age, who can sit up straight in a bathtub but may lack the ability to pull themselves out of the water if they slip under the surface.
A reduced concentration of oxygen in the blood (hypoxemia) is common to all near-drownings. When drowning begins, the larynx (air passage) closes involuntarily, preventing both air and water from entering the lungs . In 10–15% of cases, hypoxemia results because the larynx stays closed; this is called dry drowning. Hypoxemia also occurs in wet drownings, the 85–90% of cases where the larynx relaxes and water enters the lungs. Only a small amount of either freshwater or saltwater is needed to damage the lungs and interfere with the body's oxygen intake. Within three minutes of submersion, most people are unconscious. Within five minutes, the brain begins to suffer from lack of oxygen. Abnormal heart rhythms (cardiac dysrhythmias) often occur in near-drowning cases, and the heart may stop pumping (cardiac arrest). An increase in blood acidity (acidosis) is another consequence of near-drowning and, under some circumstances,
KEY TERMS
Acidosis —An increase in acid content of the blood manifested by a decrease in blood pH below 7.40.
Cardiac arrest —Cessation of heartbeats.
Cardiac dysrhythmias —Abnormal heart rhythms.
Cyanosis —A blue color of the skin caused by inadequate oxygen in the blood.
Dry drowning —Hypoxemia due to closure of the larynx.
Endotracheal intubation —Inserting a tube in the trachea to maintain an open airway.
Hypothermia —A decrease in the internal temperature of the body to a core temperature below 96°F (35.6°C).
Hypoxemia —A reduced concentration of oxygen in the blood.
Tachycardia —Rapid heart rate.
Tachypnea —Rapid breathing.
Trachea —Windpipe.
Wet drowning —Water entering the lungs due to relaxation of the larynx.
near-drowning can cause a substantial increase or decrease in the volume of circulating blood. Many individuals experience a severe drop in body temperature (hypothermia).
The signs and symptoms of near-drowning can differ widely from person to person. Some people are alert but agitated, while others are comatose. Breathing may have stopped in one person, while another may be gasping for breath. Bluish skin (cyanosis ), coughing, and frothy pink sputum (material expelled from the respiratory tract by coughing) are often observed. Rapid breathing (tachypnea), a rapid heart rate (tachycardia), and a low-grade fever are common during the first few hours after rescue. People who have experienced near-drowning but remain conscious may appear confused, lethargic, or irritable.
Diagnosis
Diagnosis relies on a physical examination and on a wide range of tests and other procedures. Blood is taken to measure oxygen levels. Pulseoximetry is another way of assessing oxygen levels. An electrocardiograph is used to monitor heart activity. X rays, computed tomography (CT) scans, or magnetic resonance imaging (MRI) scans can detect head and neck injuries and excess tissue fluid (edema ) in the lungs.
Treatment
Treatment begins with removing the victim from the water and performing cardiopulmonary resuscitation (CPR ). One purpose of CPR is to bring oxygen to the lungs, heart, brain, and other organs by breathing into a person's mouth. When someone's heart has stopped, CPR also attempts to get the heart pumping again by pressing down on the chest. After CPR has been performed and emergency medical help has arrived on the scene, oxygen is administered. If the person's breathing has stopped or is otherwise impaired, a tube is inserted into the windpipe (trachea) to maintain the airway (endotracheal intubation). The person is also checked for head, neck, and other injuries, and intravenous fluids are given. Hypothermia cases require careful handling to protect the heart.
In the emergency department, victims who have experienced near-drowning continue receiving oxygen until blood tests show a return to normal. About one-third of the patients are intubated and initially need mechanical support to breathe. Re-warming is undertaken when hypothermia is present. People may arrive requiring treatment for cardiac arrest or cardiac dysrhythmias. Comatose patients present a special problem. Although various treatment approaches have been tried, none have proved beneficial. Many of these patients die.
People can be discharged from the emergency department after four to six hours if their blood oxygen level is normal, and no signs or symptoms of near-drowning are present. Because lung problems can arise 12 or more hours after submersion, the medical staff must emphasize that the individuals must seek further medical help, if necessary. Admission to a hospital for at least 24 hours for further observation and treatment is a must for people who do not appear to recover fully in the emergency department.
Prognosis
Neurological damage is the major long-term concern in the treatment of people experiencing near-drowning. Those who arrive at an emergency department awake and alert usually survive with brain function intact, as do about 90% of those who arrive mentally impaired (lethargic or confused) but not comatose. Death or permanent neurological damage is very likely when individuals arrive in a comatose condition. Early rescue of people experiencing near-drowning (within five minutes of submersion) and prompt application of CPR (within less than 10 minutes of submersion) seem to be the best predictors of a complete recovery.
Health care team roles
First aid can be administered by anyone with proper training. This may include CPR. Paramedics may provide support during transport to a hospital. Physicians commonly evaluate and provide treatment in an emergency department. Nurses provide emergency and supportive care. Therapists may be called upon to provide follow-up counseling.
Prevention
Prevention depends on educating parents, other adults, and teenagers about water safety.
Parents must realize that young children who are left in or near water without adult supervision, even for a short time, can easily get into trouble. Experts consider putting up a fence around a home swimming pool an essential precaution, and estimate that 50–90% of child drownings and near-drownings could be prevented if fences were widely adopted. The fence should be at least five feet (1.5 m) high, have a self-closing and self-locking gate, and completely surround the pool.
Pool owners and all other adults should consider learning CPR. Everyone should follow the rules for safe swimming and boating. Those who have a medical condition that can cause a seizure or otherwise threaten safety in the water are advised always to swim with a partner. People need to be aware that alcohol and drug use substantially increase the chances of an accident.
Resources
BOOKS
Dix, Jay. Asphyxia and Drowning: An Atlas. Boca Raton, FL: CRC Press, 2000.
Fletemeyer, John A., and Samuel J. Freas. Drowning: New Perspectives on Intervention and Prevention. Boca Raton, FL: CRC Press, 1999.
Kallas, Harry J. "Drowning and Near Drowning." In Nelson Textbook of Pediatrics, 16th ed., edited by Richard E. Behrman et al. Philadelphia: W. B. Saunders, 2000, 279-87.
Modell, Jerome H. "Drowning and Near Drowning." In Harrison's Principles of Internal Medicine, 14th ed., edited by Anthony S. Fauci et al. New York: McGraw-Hill, 1998, 2555-56.
Piantadosi, Claude A. "Physical, Chemical, and Aspiration Injuries of the Lung." In Cecil Textbook of Medicine, 21st ed., edited by Lee Goldman and J. Claude Bennett. Philadelphia: W. B. Saunders, 2000, 425-33.
PERIODICALS
Blum, C., and J. Shield. "Toddler Drowning in Domestic Swimming Pools." Injury Prevention 6 no. 4 (2000): 288-90.
Frison, Y. M. "Pediatric Near-Drownings." Nursing Spectrum 8 no. 16 (1998): 11, 24, 1998.
Gheen, K. M. "Near-Drowning and Cold Water Submersion."Seminars in Pediatric Surgery 10 no. 1 (2001): 26-7.
Giesbrecht, G. G. "Cold Stress, Near Drowning and Accidental Hypothermia: A Review." Aviation, Space and Environmental Medicine 71 no. 7 (2000): 733-52.
Zuckerman, G. B, and E. E. Conway. "Drowning and Near Drowning: A Pediatric Epidemic." Pediatric Annuals 29 no. 6 (2000): 360-66.
ORGANIZATIONS
American College of Emergency Physicians. P.O. Box 619911, Dallas, TX 75261-9911. (800) 798-1822. (972) 550-0911. (972) 580-2816. <http://www.acep.org/>. info@acep.org.
American College of Osteopathic Emergency Physicians. 142 E. Ontario Street, Suite 550, Chicago, IL 60611. (312) 587-3709. (800) 521-3709. (312) 587-9951. <http://www.acoep.org>.
National Safe Kids Campaign. 1301 Pennsylvania Avenue, Suite 1000, Washington, D.C. 20004-1707. <http://pedsccm.wustl.edu/AllNet/english/neurpage/protect/drown.htm>.
Search and Rescue Society of British Columbia. P.O. Box 1146, Victoria, BC Canada V8W 2T6. (250) 384-6696. <http://www.sarbc.org/homepage.html>. sarbc@sarbc.org.
OTHER
Columbia Presbyterian Medical Center. <http://cpmcnet.columbia.edu/texts/guide/hmg13_0005.html>.
Consumer Products Safety Commission. <http://www.lifesaver.com/stats.htm>.
Diving Medicine Online. <http://www.gulftel.com/~scubadoc/hypoth.htm>.
Merck Manual. <http://www.merck.com/pubs/mmanual_home/sec24/283.htm>.
National Library of Medicine. <http://medlineplus.adam.com/ency/article/000046.htm>.
L. Fleming Fallon, Jr., M.D., Dr.P.H.
Near-Drowning
Near-Drowning
Definition
Near-drowning is the term used for survival after suffocation caused by submersion in water or other fluid or liquid.
Description
An estimated 15,000-70,000 near-drownings occur in the United States each year; insufficient reporting prevents a more precise estimate. A typical person experiencing near-drowning is young and male. Nearly half of all drownings and near-drownings involve children less than four years old. Because home swimming pools are the sites for 60-90% of drownings in the 0-4 age group, they pose the greatest risk for children. Teenage boys are also at heightened risk for drowning and near-drowning; drugs and alcohol are implicated in 40-50% of teenage drownings. Overall, roughly four out of five drowning victims are males.
Causes and symptoms
On many occasions, near-drownings are secondary to an event such as a heart attack that causes unconsciousness or a head or spinal injury that prevents a diver from resurfacing. Near-drownings, moreover, can occur in shallow as well as deep water. Small children have drowned or almost drowned in bathtubs, toilets, industrial-size cleaning buckets, and washing machines. Bathtubs are especially dangerous for infants between six months and one year of age, who can sit up straight in a bathtub but may lack the ability to pull themselves out of the water if they slip under the surface.
A reduced concentration of oxygen in the blood (hypoxemia) is common to all near-drownings. When drowning begins, the larynx (air passage) closes involuntarily, preventing both air and water from entering the lungs. In 10-15% of cases, hypoxemia results because the larynx stays closed; this is called dry drowning. Hypoxemia also occurs in wet drownings, the 85-90% of cases where the larynx relaxes and water enters the lungs. Only a small amount of either freshwater or saltwater is needed to damage the lungs and interfere with the body's oxygen intake. Within three minutes of submersion, most people are unconscious. Within five minutes, the brain begins to suffer from lack of oxygen. Abnormal heart rhythms (cardiac dysrhythmias) often occur in near-drowning cases, and the heart may stop pumping (cardiac arrest). An increase in blood acidity (acidosis) is another consequence of near-drowning and, under some circumstances, near-drowning can cause a substantial increase or decrease in the volume of circulating blood. Many individuals experience a severe drop in body temperature (hypothermia).
The signs and symptoms of near-drowning can differ widely from person to person. Some people are alert but agitated, while others are comatose. Breathing may have stopped in one person, while another may be gasping for breath. Bluish skin (cyanosis ), coughing, and frothy pink sputum (material expelled from the respiratory tract by coughing) are often observed. Rapid breathing (tachypnea), a rapid heart rate (tachycardia), and a low-grade fever are common during the first few hours after rescue. People who have experienced near-drowning but remain conscious may appear confused, lethargic, or irritable.
Diagnosis
Diagnosis relies on a physical examination and on a wide range of tests and other procedures. Blood is taken to measure oxygen levels. Pulseoximetry is another way of assessing oxygen levels. An electrocardiograph is used to monitor heart activity. X rays, computed tomography (CT) scans, or magnetic resonance imaging (MRI) scans can detect head and neck injuries and excess tissue fluid (edema ) in the lungs.
Treatment
Treatment begins with removing the victim from the water and performing cardiopulmonary resuscitation (CPR). One purpose of CPR is to bring oxygen to the lungs, heart, brain, and other organs by breathing into a person's mouth. When someone's heart has stopped, CPR also attempts to get the heart pumping again by pressing down on the chest. After CPR has been performed and emergency medical help has arrived on the scene, oxygen is administered. If the person's breathing has stopped or is otherwise impaired, a tube is inserted into the windpipe (trachea) to maintain the airway (endotracheal intubation). The person is also checked for head, neck, and other injuries, and intravenous fluids are given. Hypothermia cases require careful handling to protect the heart.
In the emergency department, victims who have experienced near-drowning continue receiving oxygen until blood tests show a return to normal. About one-third of the patients are intubated and initially need mechanical support to breathe. Re-warming is undertaken when hypothermia is present. People may arrive requiring treatment for cardiac arrest or cardiac dysrhythmias. Comatose patients present a special problem. Although various treatment approaches have been tried, none have proved beneficial. Many of these patients die.
People can be discharged from the emergency department after four to six hours if their blood oxygen level is normal, and no signs or symptoms of near-drowning are present. Because lung problems can arise 12 or more hours after submersion, the medical staff must emphasize that the individuals must seek further medical help, if necessary. Admission to a hospital for at least 24 hours for further observation and treatment is a must for people who do not appear to recover fully in the emergency department.
Prognosis
Neurological damage is the major long-term concern in the treatment of people experiencing near-drowning. Those who arrive at an emergency department awake and alert usually survive with brain function intact, as do about 90% of those who arrive mentally impaired (lethargic or confused) but not comatose. Death or permanent neurological damage is very likely when individuals arrive in a comatose condition. Early rescue of people experiencing near-drowning (within five minutes of submersion) and prompt application of CPR (within less than 10 minutes of submersion) seem to be the best predictors of a complete recovery.
Health care team roles
First aid can be administered by anyone with proper training. This may include CPR. Paramedics may provide support during transport to a hospital. Physicians commonly evaluate and provide treatment in an emergency department. Nurses provide emergency and supportive care. Therapists may be called upon to provide follow-up counseling.
Prevention
Prevention depends on educating parents, other adults, and teenagers about water safety.
Parents must realize that young children who are left in or near water without adult supervision, even for a short time, can easily get into trouble. Experts consider putting up a fence around a home swimming pool an essential precaution, and estimate that 50-90% of child drownings and near-drownings could be prevented if fences were widely adopted. The fence should be at least five feet (1.5 m) high, have a self-closing and self-locking gate, and completely surround the pool.
Pool owners and all other adults should consider learning CPR. Everyone should follow the rules for safe swimming and boating. Those who have a medical condition that can cause a seizure or otherwise threaten safety in the water are advised always to swim with a partner. People need to be aware that alcohol and drug use substantially increase the chances of an accident.
KEY TERMS
Acidosis— An increase in acid content of the blood manifested by a decrease in blood pH below 7.40.
Cardiac arrest— Cessation of heartbeats.
Cardiac dysrhythmias— Abnormal heart rhythms.
Cyanosis— A blue color of the skin caused by inadequate oxygen in the blood.
Dry drowning— Hypoxemia due to closure of the larynx.
Endotracheal intubation— Inserting a tube in the trachea to maintain an open airway.
Hypothermia— A decrease in the internal temperature of the body to a core temperature below 96 °F (35.6 °C).
Hypoxemia— A reduced concentration of oxygen in the blood.
Tachycardia— Rapid heart rate.
Tachypnea— Rapid breathing.
Trachea— Windpipe.
Wet drowning— Water entering the lungs due to relaxation of the larynx.
Resources
BOOKS
Dix, Jay. Asphyxia and Drowning: An Atlas. Boca Raton, FL: CRC Press, 2000.
Fletemeyer, John A., and Samuel J. Freas. Drowning: New Perspectives on Intervention and Prevention. Boca Raton, FL: CRC Press, 1999.
Kallas, Harry J. "Drowning and Near Drowning." In Nelson Textbook of Pediatrics, 16th ed., edited by Richard E. Behrman, et al. Philadelphia: W. B. Saunders, 2000, 279-87.
Modell, Jerome H. "Drowning and Near Drowning." In Harrison's Principles of Internal Medicine, 14th ed., edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1998, 2555-56.
Piantadosi, Claude A. "Physical, Chemical, and Aspiration Injuries of the Lung." In Cecil Textbook of Medicine, 21st ed., edited by Lee Goldman and J. Claude Bennett. Philadelphia: W. B. Saunders, 2000, 425-33.
PERIODICALS
Blum, C., and J. Shield. "Toddler Drowning in Domestic Swimming Pools." Injury Prevention 6 no. 4 (2000): 288-90.
Frison, Y. M. "Pediatric Near-Drownings." Nursing Spectrum 8 no. 16 (1998): 11, 24, 1998.
Gheen, K. M. "Near-Drowning and Cold Water Submersion." Seminars in Pediatric Surgery 10 no. 1 (2001): 26-7.
Giesbrecht, G. G. "Cold Stress, Near Drowning and Accidental Hypothermia: A Review." Aviation, Space and Environmental Medicine 71 no. 7 (2000): 733-52.
Zuckerman, G. B, and E. E. Conway. "Drowning and Near Drowning: A Pediatric Epidemic." Pediatric Annuals 29 no. 6 (2000): 360-66.
ORGANIZATIONS
American College of Emergency Physicians. P.O. Box 619911, Dallas, TX 75261-9911. (800) 798-1822. (972) 550-0911. (972) 580-2816. 〈http://www.acep.org/〉. info@acep.org.
American College of Osteopathic Emergency Physicians. 142 E. Ontario Street, Suite 550, Chicago, IL 60611. (312) 587-3709. (800) 521-3709. (312) 587-9951. 〈http://www.acoep.org〉.
National Safe Kids Campaign. 1301 Pennsylvania Avenue, Suite 1000, Washington, D.C. 20004-1707. 〈http://pedsccm.wustl.edu/All-Net/english/neurpage/protect/drown.htm〉.
Search and Rescue Society of British Columbia. P.O. Box 1146, Victoria, BC Canada V8W 2T6. (250) 384-6696. 〈http://www.sarbc.org/homepage.html〉. sarbc@sarbc.org.
OTHER
Columbia Presbyterian Medical Center. 〈http://cpmcnet.columbia.edu/texts/guide/hmg13_0005.html〉.
Consumer Products Safety Commission. 〈http://www.life-saver.com/stats.htm〉.
Diving Medicine Online. 〈http://www.gulftel.com/∼scubadoc/hypoth.htm〉.
Merck Manual. 〈http://www.merck.com/pubs/mmanual_home/sec24/283.htm〉.
National Library of Medicine. 〈http://medlineplus.adam.com/ency/article/000046.htm〉.
Near-Drowning
Near-Drowning
Definition
Near-drowning is the term for survival after suffocation caused by submersion in water or another fluid. Some experts exclude from this definition cases of temporary survival that end in death within 24 hours, which they prefer to classify as drownings.
Description
An estimated 15,000-70,000 near-drownings occur in the United States each year (insufficient reporting prevents a better estimate). The typical victim is young and male. Nearly half of all drownings and near-drownings involve children less than four years old. Home swimming pools pose the greatest risk for children, being the site of 60-90% of drownings in the 0-4 age group. Teenage boys also face a heightened risk of drowning and near-drowning, largely because of their tendency to behave recklessly and use drugs and alcohol (drugs and alcohol are implicated in 40-50% of teenage drownings). Males, however, predominate even in the earliest age-groups, possibly because young boys are often granted more freedom from supervision than young girls enjoy, making it more likely that they will stumble into danger and less likely that they will attract an adult's attention in time for a quick rescue. Roughly four out of five drowning victims are males.
Causes and symptoms
The circumstances leading to near-drownings (and drownings also) cannot be reduced to a single scenario involving nonswimmers accidentally entering deep water. On many occasions, near-drownings are secondary to an event such as a heart attack that causes unconsciousness or a head or spinal injury that prevents a diver from resurfacing. Near-drownings, moreover, can occur in shallow as well as deep water. Small children have drowned or almost drowned in bathtubs, toilets, industrial-size cleaning buckets, and washing machines. Bathtubs are especially dangerous for infants six months to one year old, who can sit up straight in a bathtub but may lack the ability to pull themselves out of the water if they slip under the surface.
A reduced concentration of oxygen in the blood (hypoxemia) is common to all near-drownings. Human life, of course, depends on a constant supply of oxygen-laden air reaching the blood by way of the lungs. When drowning begins, the larynx (an air passage) closes involuntarily, preventing both air and water from entering the lungs. In 10-15% of cases, hypoxemia results because the larynx stays closed. This is called "dry drowning." Hypoxemia also occurs in "wet drowning," the 85-90% of cases where the larynx relaxes and water enters the lungs. The physiological mechanisms that produce hypoxemia in wet drowning are different for freshwater and saltwater, but only a small amount of either kind of water is needed to damage the lungs and interfere with the body's oxygen intake. All of this happens very quickly: within three minutes of submersion most people are unconscious, and within five minutes the brain begins to suffer from lack of oxygen. Abnormal heart rhythms (cardiac dysrhythmias) often occur in near-drowning cases, and the heart may stop pumping (cardiac arrest). An increase in blood acidity (acidosis) is another consequence of near-drowning, and under some circumstances near-drowning can cause a substantial increase or decrease in the volume of circulating blood. Many victims experience a severe drop in body temperature (hypothermia ).
The signs and symptoms of near-drowning can differ widely from person to person. Some victims are alert but agitated, while others are comatose. Breathing may have stopped, or the victim may be gasping for breath. Bluish skin (cyanosis ), coughing, and frothy pink sputum (material expelled from the respiratory tract by coughing) are often observed. Rapid breathing (tachypnea), a rapid heart rate (tachycardia), and a low-grade fever are common during the first few hours after rescue. Conscious victims may appear confused, lethargic, or irritable.
Diagnosis
Diagnosis relies on a physical examination of the victim and on a wide range of tests and other procedures. Blood is taken to measure oxygen levels and for many other purposes. Pulse oximetry, another way of assessing oxygen levels, involves attaching a device called a pulse oximeter to the patient's finger. An electrocardiograph is used to monitor heart activity. X rays can detect head and neck injuries and excess tissue fluid (edema ) in the lungs.
Treatment
Treatment begins with removing the victim from the water and performing cardiopulmonary resuscitation (CPR). One purpose of CPR—which, of course, should be attempted only by people trained in its use—is to bring oxygen to the lungs, heart, brain, and other organs by breathing into the victim's mouth. When the victim's heart has stopped, CPR also attempts to get the heart pumping again by pressing down on the victim's chest. After CPR has been performed and emergency medical help has arrived on the scene, oxygen is administered to the victim. If the victim's breathing has stopped or is otherwise impaired, a tube is inserted into the windpipe (trachea) to maintain the airway (this is called endotracheal intubation). The victim is also checked for head, neck, and other injuries, and fluids are given intravenously. Hypothermia cases require careful handling to protect the heart.
In the emergency department, victims continue receiving oxygen until blood tests show a return to normal. About one-third are intubated and initially need mechanical support to breathe. Rewarming is undertaken when hypothermia is present. Victims may arrive needing treatment for cardiac arrest or cardiac dysrhythmias. Comatose patients present a special problem: although various treatment approaches have been tried, none have proved beneficial. Patients can be discharged from the emergency department after four to six hours if their blood oxygen level is normal and no signs or symptoms of near-drowning are present. But because lung problems can arise 12 or more hours after submersion, the medical staff must first be satisfied that the patients are willing and able to seek further medical help if necessary. Admission to a hospital for at least 24 hours for further observation and treatment is a must for patients who do not appear to recover fully in the emergency department.
Prognosis
Neurological damage is the major long-term concern in the treatment of near-drowning victims. Patients who arrive at an emergency department awake and alert usually survive with brain function intact, as do about 90% of those who arrive mentally impaired (lethargic, confused, and so forth) but not comatose. Death or permanent neurological damage is very likely when patients arrive comatose. Early rescue of near-drowning victims (within five minutes of submersion) and prompt CPR (within less than 10 minutes of submersion) seem to be the best guarantees of a complete recovery. An analysis of 715 patients admitted to emergency departments in 1971–81 revealed that 69% recovered completely, 25% died, and 6% survived but suffered permanent neurological damage.
Prevention
Prevention depends on educating parents, other adults, and teenagers about water safety. Parents must realize that young children who are left in or near water without adult supervision even for a short time can easily get into trouble, not just at the beach or next to a swimming pool, but in bathtubs and around toilets, buckets, washing machines, and other household articles where water can collect. Research on swimming pool drownings involving young children shows that the victims have usually been left unattended less than five minutes before the accident. Experts consider putting up a fence around a home swimming pool an essential precaution, and estimate that 50-90% of child drownings and near-drownings could be prevented if fences were widely adopted. The fence should be at least five feet high and unclimbable, have a self-closing and self-locking gate, and completely surround the pool.
Pool owners—and, indeed, all other adults—should consider learning CPR. Everyone, of course, should follow the rules for safe swimming and boating. Those who have a medical condition that can cause a seizure or otherwise threaten safety in the water are advised always to swim with a partner. And of course, people need to be aware that alcohol and drug use substantially increase the chances of an accident.
The danger of alcohol and drug use around water is a point that requires special emphasis where teenagers are concerned. Teenagers can also benefit from CPR training and safe swimming and boating classes.
Resources
BOOKS
Modell, Jerome H. "Drowning and Near-Drowning." In Harrison's Principles of Internal Medicine, edited by Anthony S. Fauci, et al. New York:McGraw-Hill, 1997.
near-drowning
Certain tissues of the body are much less sensitive to oxygen starvation than others. For example, blood (which carries the oxygen) can be shut off from an arm or leg, and, provided the limb is being rested, the muscle can survive without its blood supply (and therefore without oxygen) for well over half an hour. It does so by drawing on its store of glucose, which it converts to lactic acid. This is known as anaerobic respiration, and muscle has a large anaerobic reserve. The brain, though, has no such reserve, and any interruption to blood running up the carotid arteries results in unconsciousness almost at once, with permanent damage occurring after 2–3 minutes. The heart is also vulnerable to oxygen starvation, because, unlike the muscles of the arms or legs, it can't be rested, and must go on beating, rapidly using up its anaerobic reserve.
So the strategy for a diving mammal is clear: its precious oxygen pool (carried by the red blood cells) must remain the sole preserve of the brain and heart, while the rest of the body can do without. This is achieved by reflex constriction, all blood vessels with the exception of the carotid and coronary arteries, stimulated by the effect of cold water touching the nose and face, and also by the very act of breath-holding. With only the brain and heart arteries to supply, the heart rate can slow right down, and drops to around 10 beats per minutes.
Evolution has robbed terrestrial mammals of the diving reflex, of which just a vestige remains, detectable only in the first few months of infancy. So, if, it is not the diving reflex influencing survival, then what? The answer lies with the temperature of the water. This is best explained by reflecting on the history of surgery. With the discovery of anaesthesia, surgeons found that they could operate on almost any part of the body, but they couldn't operate on the heart while it was beating. To stop the heart for anything more than a few minutes meant risking brain damage, so there was insufficient time for surgery.
However, animals appeared to recover fully from heart surgery with the circulation stopped, provided that their bodies had been cooled down a little first — the theory being that reduced body temperature meant a lower metabolic rate and so less oxygen consumption by the brain. The cooler the animal, the longer the circulation could be stopped without obvious harm. The first heart surgery to be performed on a human subject took place in 1954. The patient was a child with a hole in the heart. Circulation was stopped for 15 minutes while surgeons repaired the defect. The operation was a complete success.
Of course, now that the work of circulation and breathing can be done by heart/lung machines, the cooling process can be controlled much more easily, and it is possible to take body temperature as low as 18°C. At that temperature, blood flow to the brain can be stopped for up to 60 minutes before tissue damage (such as a stroke) begins to show itself, though re-warming must be taken very slowly.
The analogy between cerebral protection with deep hypothermia, and cold water submersion, now becomes obvious. The chance of survival is increased in those whose brains have become coolest before the heart stops beating. It would be expected that very small children or infants submerged in ice cold water should have the best chance of all, because their rate of cooling is highest: this is indeed the case. So the clinical approach to resuscitation of these very cold individuals might logically be to reverse the cooling procedure used in heart surgery, and use the heart/lung machine to support circulation while re-warming. And remarkable results have indeed been achieved at centres where these facilities are available.
To summarize; experience in the use of deep hypothermia in cardiac surgery has provided insight into the physiological principles governing survival after very long periods spent under water. Furthermore, these principles have been applied to the techniques used to resuscitate victims of near-drowning.
Mark Harries
See also cold exposure; drowning; hypothermia; resuscitation; survival at sea.