Drowning
(Fatal Drowning;
Nonfatal Drowning)
By
, MD, Department
of Emergency Medicine, University of Colorado School of Medicine
Drowning is
respiratory impairment resulting from submersion in a liquid medium. It can be
nonfatal (previously called near drowning) or fatal. Drowning results in
hypoxia, which can damage multiple organs, including the lungs and brain.
Treatment is supportive, including reversal of respiratory arrest and cardiac arrest,
hypoxia, hypoventilation, and hypothermia.
Drowning is
among the top 10 causes of mortality for children and young people worldwide.
In the United States, drowning is the 10th most common cause of unintentional
death. In 2013 in the US, drowning was the leading cause of injury mortality in
children ages 1 to 4 yr and was second only to motor vehicle collisions for
children ages 5 to 14 yr (1). Other groups
at higher risk of drowning death include the following:
·
Males (80% of
victims over age 1 yr)
·
People who have
used alcohol or sedatives
·
People with
conditions that cause temporary incapacitation (eg, epilepsy (3), with a twenty
times increased chance of drowning among children and adolescents)
·
People with
a long QT syndrome (swimming can trigger arrhythmias that cause
unexplained drowning in people with a long QT syndrome, particularly LQT1)
Drowning is common in pools, hot tubs,
and natural water settings, and, among infants and toddlers, in toilets,
bathtubs, and buckets of water or cleaning fluids. About 4 times as many people
are hospitalized for nonfatal drowning as die as a result of drowning.
Pathophysiology
Hypoxia
Hypoxia is the
major insult in drowning, affecting the brain, heart, and other tissues;
respiratory arrest followed by cardiac arrest may occur. Brain hypoxia may
cause cerebral edema and, occasionally, permanent neurologic sequelae.
Generalized tissue hypoxia may cause metabolic acidosis. Immediate hypoxia results from aspiration of fluid or
gastric contents, acute reflex laryngospasm (previously called dry drowning),
or both. Lung injury due to aspiration or hypoxia itself may cause delayed
hypoxia (previously called secondary drowning). Aspiration, especially with
particulate matter or chemicals, may cause chemical pneumonitis or secondary bacterial pneumonia and may impair alveolar secretion of surfactant,
resulting in patchy atelectasis. Extensive atelectasis may make
the affected areas of the lungs stiff, noncompliant, and poorly ventilated,
potentially causing respiratory failure with hypercapnia and respiratory acidosis. Perfusion of poorly ventilated areas of the lungs (V/Q
mismatch) worsens hypoxia. Alveolar hypoxia may cause noncardiogenic pulmonary
edema.
Hypothermia
Exposure to cold
water induces systemic hypothermia, which can be a significant problem. However, hypothermia can be
protective by stimulating the mammalian diving reflex, slowing the heart rate,
and constricting the peripheral arteries, shunting oxygenated blood away from
the extremities and the gut to the heart and brain. Also, hypothermia decreases
the oxygen needs of tissues, possibly prolonging survival and delaying the
onset of hypoxic tissue damage. The diving reflex and overall clinically
protective effects of cold water are usually greatest in young children.
Fluid aspiration
Laryngospasm
often limits the volume of fluid aspirated. Distinction between freshwater and
seawater drowning was once considered important due to the potential
electrolyte shifts, hemolysis, and fluid compartment shifting that possibly
could occur. However, studies have shown that in most patients, too little
liquid is aspirated to have these effects. Aspiration can lead to pneumonia, sometimes with anaerobic or fungal pathogens, and pulmonary edema.
Dangerous underwater breath-holding behaviors (DUBBs)
Dangerous
underwater breath-holding behaviors (DUBBs) are practiced mostly by healthy
young men (often good swimmers) trying to prolong their capacity to remain
submerged. There are 3 described types of DUBB:
·
Intentional
hyperventilation—blowing off carbon dioxide before submerged swimming, thereby
delaying central hypercarbic ventilatory responses
·
Hypoxic
training—extending capacity for underwater distance swimming or breath-holding
·
Static
apnea—breath-holding for as long as possible while submerged and motionless,
including as a game
In DUBB, while
submerged, hypoxia occurs first, followed by loss of consciousness (hypoxic
blackout, breath-hold blackout) and then drowning.
Associated injuries
Skeletal,
soft-tissue, head, and internal injuries may occur, particularly among surfers,
water skiers, boaters, flood victims, and occupants of submerged vehicles.
People who dive into shallow water may sustain cervical and other spine
injuries (which may be the cause of drowning).
General references
1.
Centers for Disease Control and Prevention. National Center for Injury
Prevention and Control: WISQARS (Web-based Injury Statistics Query and
Reporting System) [database].The cost on injury in the U.S. Accessed September 6, 2017.
2.
Centers for Disease Control and Prevention. Morbidity and Mortality
Weekly Report.Racial/Ethnic
disparities in fatal unintentional drowning among persons aged <=29 years –
United States 1999-2010. MMWR 63:421-426, 2014.
3.
Sillanpää M, Shinnar S. SUDEP and other causes of mortality in
childhood-onset epilepsy. Epilepsy Behav 28(2):249-255, 2013. doi:
10.1016/j.yebeh.2013.04.016.
Symptoms and Signs
During drowning,
panic and air hunger occur. Children who are unable to swim may become
submerged in < 1 min, more rapidly than adults. After rescue,
anxiety, vomiting, wheezing, and altered consciousness are common. Patients may
have respiratory failure with tachypnea, intercostal retractions, or cyanosis.
Respiratory symptoms are sometimes delayed for up to 6 hours after submersion.
Patients may have symptoms due to injuries or exacerbations of underlying
disorders.
Pearls & Pitfalls
|
·
Sometimes respiratory symptoms and hypoxia are delayed for up to 6
hours after submersion.
|
Diagnosis
·
Clinical
evaluation
·
For concomitant
injuries, imaging studies as indicated
·
Pulse oximetry
and, if results are abnormal or if respiratory symptoms and signs are present,
ABG and chest x-ray
·
Core temperature
measurement to rule out hypothermia
·
Evaluation for
causative or contributing disorders (eg, seizure, hypoglycemia, MI,
intoxication, injury)
·
Ongoing
monitoring as indicated for delayed respiratory complications
Most people are
found in or near water, making the diagnosis obvious clinically. Resuscitation, if indicated, should precede completion of the diagnostic assessment.
Cervical spine injury is considered, and the spine is immobilized in patients
who have altered consciousness or whose mechanism of injury involves diving or
trauma. Secondary head injury and conditions that may have contributed to
drowning (eg, hypoglycemia, MI, stroke, intoxication, arrhythmia) are
considered.
All patients
undergo assessment of oxygenation by oximetry or, if results are abnormal
or if there are respiratory symptoms or signs, ABG and chest x-ray. Because
respiratory symptoms may be delayed, even asymptomatic patients are transported
to the hospital and observed for several hours.
In patients with
symptoms or a history of prolonged submersion, core body temperature is
measured, ECG and serum electrolytes are obtained, and continuous oximetry and
cardiac monitoring are done. Patients with possible cervical spine injury
undergo cervical spine imaging.
Patients with
altered consciousness undergo head CT. Any other suspected predisposing or
secondary conditions are evaluated with appropriate testing (eg, fingerstick
glucose for hypoglycemia, ECG for MI, cardiac monitoring for arrhythmia,
evaluation for intoxication). Patients who drown without apparent risk factors
are evaluated for long QT syndrome and torsades de points ventricular
tachycardia. In patients with pulmonary infiltrates, bacterial or fungal
pneumonia is differentiated from chemical pneumonitis and pulmonary edema using
blood cultures and sputum Gram stain and culture. If indicated (eg, bacterial
or fungal pneumonia is suspected but the pathogen cannot be otherwise
identified), bronchial washings are obtained for testing, including culture.
CLINICAL CALCULATOR:
QT Interval
Correction (EKG)
Prognosis
Factors that
increase the chance of surviving submersion without permanent injury include
the following:
·
Rapid
institution of resuscitation (most important)
·
Brief duration
of submersion
·
Cold water
temperature
·
Young age
·
Absence of
underlying medical conditions, secondary trauma, and aspiration of particulate
matter or chemicals
Survival may be
possible in cold water submersion that lasts > 1 h, especially
among children; thus, even patients with prolonged submersion are vigorously
resuscitated.
Treatment
·
Resuscitation
·
Correction of
oxygen and carbon dioxide levels and other physiologic abnormalities
·
Intensive
respiratory support
Treatment aims
to correct cardiac arrest, hypoxia, hypoventilation, hypothermia, and other physiologic
insults.
Resuscitation after drowning
In apneic
patients, rescue breathing is started immediately—in the water, if necessary.
If spinal immobilization is necessary, it is done in a neutral position, and
rescue breathing is done using a jaw thrust without head tilt or chin lift.
Emergency medical services are called. If the patient does not respond to
rescue breathing, cardiac compression is started, followed by advanced cardiac life support. Although the 2015 American Heart Association Guidelines
for CPR recommend chest compressions as the first step in resuscitation of
patients in cardiac arrest, drowning is an exception to this recommendation.
Attempts to remove water from the lungs are avoided because they delay
ventilation and increase the risk of vomiting. Oxygenation, endotracheal intubation, or both should
proceed as soon as possible. Hypothermic patients are warmed as soon as
possible. Immediate treatment measures may include removing
clothing, drying, and insulation.
Pearls & Pitfalls
|
·
Avoid attempts to remove water from the lungs; this only delays
ventilation and increases risk of vomiting.
|
Hospital care for drowning patients
All hypoxic or
moderately symptomatic patients are hospitalized. In the hospital, supportive
treatment continues, aimed primarily at achieving acceptable arterial oxygen
and carbon dioxide levels. Mechanical ventilation may be
necessary. Patients are initially given 100% oxygen; the concentration is
titrated lower based on ABG results. Positive end-expiratory pressure
ventilation is usually necessary to help expand or maintain patency of
alveoli to maintain adequate oxygenation. Pulmonary support may be necessary
for hours or days. If adequate oxygenation is impossible despite maximizing
ventilator settings, extracorporeal membrane oxygenation may be considered.
Nebulized β2-agonists may help reduce bronchospasm and
wheezing. Surfactant administration may be helpful in critically ill patients
with significant lung compliance issues after drowning, although no clinical
trials have addressed this. Patients with pneumonia are
treated with antibiotics targeting organisms identified or suspected based on
results of sputum testing and/or blood cultures. Corticosteroids are not used.
Core body temperature is monitored, and hypothermia is
treated.
Fluids or
electrolytes are rarely required to correct significant electrolyte imbalances.
Fluid restriction is rarely indicated, unless pulmonary or cerebral edema
occurs. Concomitant injuries and disorders (eg, head or cervical injury,
seizure, arrhythmia) may also require treatment.
Discharge of drowning patients
Patients with
mild symptoms, clear lungs, and normal oxygenation should be observed in the
emergency department for at least 6 hours. If symptoms resolve and the
examination and oxygenation remain normal, patients can be discharged with
instructions to return if symptoms recur. Reports in social media and other
sources of patients dying after such evaluations (sometimes called "dry
drowning" or "secondary drowning") are unfounded.
Prevention
Drugs, alcohol, and drowning
Use of alcohol
or drugs, a major risk factor, should be avoided before and during swimming and
boating and when supervising children around water.
Swimming safety
Swimmers should
use common sense and be aware of weather and water conditions. Swimmers should
be accompanied by an experienced swimmer or swim only in guarded areas.
Swimming should stop if the swimmer looks or feels very cold, because hypothermia
may impair judgment. Ocean swimmers should learn to escape rip currents by
swimming parallel to the beach rather than toward the beach. Swimmers should be
discouraged from DUBBs. If they practice them, they should be supervised and
should know their dangers. Swimmers should avoid swimming near a boat exhaust
port, which can cause carbon monoxide poisoning.
Public swimming
areas should be supervised by lifeguards trained in water safety and
resuscitation as well as rescue techniques. Life preservers, life jackets, and
a shepherd's crook should be available close to poolside. Emergency airway
equipment, automated external defibrillators (AEDs), and immediate telephone access
to emergency medical services should be available. Comprehensive community
prevention programs should target high-risk groups, teach children to swim as
early as possible, and teach CPR to as many adolescents and adults as possible.
Owners of private pools should also have immediate telephone access to
emergency medical services and know about resuscitation after drowning.
Water safety for children
Children should
wear US Coast Guard–approved flotation devices when in or around water.
Air-filled swimming aids and foam toys (water wings, noodles, etc) are not
designed to keep swimmers from drowning and should not be used as a substitute
for US Coast Guard–approved equipment. Children must be constantly supervised
by an adult when around water, including beaches, pools, and ponds. Infants and
toddlers should also be supervised, ideally within arm’s length, when near
toilets, bathtubs, or any collection of water. Studies in the US and China have
shown that formal swimming lessons reduce the risk of fatal drowning among
children ages 1 to 4; however, even children who have been taught how to swim
require constant supervision when in or around water. Adults should remove
water from containers such as pails and buckets immediately after use. Swimming
pools should be surrounded with a locked fence ≥ 1.5 m in height.
Boating safety
Before
embarking, boaters should wear US Coast Guard–approved life jackets and should
check weather and water conditions. Nonswimmers and small children in a boat
should wear US Coast Guard–approved life jackets at all times. Because
consuming any quantity of alcohol increases the risk of drowning, operators and
passengers on recreational boats should generally avoid consuming alcohol.
Special populations at risk for drowning
People who are
debilitated or elderly or have seizure disorders or other medical conditions
that can alter consciousness require constant supervision when they are boating
or swimming and when in bathtubs.
People with a
personal or family history of unexplained drowning not attributable to alcohol
use, drug use, or a seizure disorder merit evaluation for long QT syndrome.
Key Points
·
Evaluate patients for suspected or feasible causes of drowning (eg,
cervical spine injury, head injury, seizure arrhythmias, hypoglycemia) as well
as injuries or consequences of drowning (eg, head or cervical spine injury,
aspiration).
·
Vigorously resuscitate cold water drowning victims even if submersion was
prolonged; survival is possible even after 1 h of submersion, particularly in
young children.
·
Resuscitation begins with rescue breathing, not chest compressions.
·
Preventive measures (e.g., swimming lessons, child supervision, use of US
Coast Guard–approved flotation devices or life jackets, avoiding alcohol,
access to trained lifeguards and emergency medical services) can have
significant public health benefits.
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