Drowning
is the fifth leading cause of accidental death in
the USA. The number of deaths due to drowning could
undoubtedly be significantly reduced if adequate preventive
and first aid instruction programs were instituted.
The asphyxia of drowning is usually due to aspiration
of fluid, but it may result from airway obstruction
caused by laryngeal spasm while the victim is gasping
under water. About 10% of victims develop laryngospasm
after the first gulp and never aspirate water. The
rapid sequence of events after submersion - hypoxemia,
laryngospasm, fluid aspiration, ineffective circulation,
brain injury, and brain death - may take place within
5 - 10 minutes. This sequence may be delayed for longer
periods if the victim, especially a child, has been
submerged in very cold water or if the victim has
ingested significant amounts of barbiturates. Immersion
in cold water can also cause a rapid full in the victim's
core temperature, so that systemic hypothermia and
death may occur before actual drowning.
The primary effect is hypoxia due to perfusion of
poorly ventilated alveoli, intrapulmonary shunting,
and decreased compliance. The first requirement of
rescue is immediate cardiopulmonary resuscitation.
A number of circumstances or primary events may precede
near drowning and must be taken into consideration
in management: (1) use of alcohol or other drugs,
(2) extreme fatigue, (3) intentional hyperventilation,
(4) sudden acute illness, (5) head or spinal cord
injury sustained in diving, (6) venomous stings by
aquatic animals, and (7) decompression sickness in
deep water diving.
When first seen, the near-drowning victim may present
with a wide range of clinical manifestations. Spontaneous
return of consciousness often occurs in otherwise
healthy individuals when submersion is very brief.
Many other patients respond promptly to immediate
ventilation. Other patients, with more severe degrees
of near drowning, may have frank respiratory failure,
pulmonary edema, shock, anoxic encephalopathy, cerebral
edema, and cardiac arrest. A few patients may be deceptively
asymptomatic during the recovery period - only to
deteriorate or die as a result of acute respiratory
failure within the following 12 - 24 hours.
Clinical
Findings
A.
Symptoms and Signs
The
patient may be unconscious, semiconscious, or awake
but apprehensive, restless, and complaining of headaches
or chest pain. Vomiting is common, Examination may
reseal cynaosis, trismus, apnea, tachypnea, and wheezing.
A pink froth from the mouth and nose indicates pulmonary
edema. Cardiovascular manifestations may include tachycardia,
arrhythmias, hypotension, cardiac arrest, and circulatory
shock. Hypothermia may be present.
B.
Laboratory Findings :
Urinalysis
shows proteinuria, hemoglobinuria, and acetonuria.
Leukocytosis is usually present. The Pao2 is usually
decreased and the Paco2 is increased or decreased.
The blood pH is decreased as a result of metabolic
acidosis. Chest X-rays may show pneumonitis or pulmonary
edema.
Prevention
Prevention consists of avoidance of alcohol during
recreational swimming or boating, close supervision
of toddlers, swimming lessons early in life, and use
of personal flotation devices when boating. All swimming
pools should be fenced.
Treatment
A.
First Aid :
Immediate
measures to combar hypoxemia at the scene of the incident
- with sustained effective ventilation, oxygenation,
and circulatory support - are critical to survival
with complete recovery. Hypothermia and cervical spine
injury should always be suspected.
1.
Standard CPPR is initiated if pulse and respiration
are absent.
2. Do not waste time attempting to drain water from
the victim's lungs, since this measure is most often
in no value. The Heimlich maneuver should be used
only if airway obstruction by a foreign body is suspected.
The cervical spine should be immobilized if neck injury
is possible.
3. Do not discontinue basic life support for seemingly
"hopeless" patients until core temperature
reaches 32 C. Complete recovery has been reported
after prolonged resuscitation of hypothermic patients.
B.
Hospital Care :
Careful
observation of the patient; continuous monitoring
of cardiorespiratory function; serial determination
of arterial blood gases, pH, renal function, and electrolytes;
and measurement of urinary output are required. Pulmonary
edema may not appear for 24 hours.
1.
Ensure optimal ventilation and oxygenation
The danger of hypoxemia exists even in the alert,
conscious patient who appears to be breathing normally.
Oxygen should be administered immediately at the highest
available concentration. Endotracheal intubation and
mechanical ventilation are necessary for patients
unable to maintain an open airway or normal blood
gases and pH. Nasogastric intubation will allow removal
of swallowed water and prevention of aspiration. If
the victim does not have spontaneous respirations,
intubation is required. Oxygen saturation should be
maintained at 90% or higher. Continuous positive airway
pressure is the most effective means of reversing
hypoxia in patients with spontaneous respirations
and patients airways. Positive end expiratory pressure
is also effective for treating respiratory insufficiency.
Assisted ventilation may be necessary with pulmonary
edema, respiratory failure, aspiration, pneumonia,
or severe central nervous system injury. Serial physical
examinations and chest X-rays should be carried out
to detect possible pneumonitis, atelectasis, and pulmonary
edema. Bronchospasm due to aspirated material may
require use of bronchodilators. Antibiotics should
be given only when there is clinical evidence of infection
- not prophylactically.
2.
Cardiovascular support - Central venous pressure may
be monitored as a guide to determining whether vascular
fluid replacement and pressors or diuretics are needed.
If low cardiac output persists after adequate intravascular
volume is achieved, pressors should be given. Otherwise,
standard therapy for pulmonary edema, cardiogenic
or not, is administered.
3.
Correction of blood pH and electrolyte abnormalities
- Metabolic acidosis is present in 70% of near-drowning
victims, but it is usually of monitor importance and
corrected through adequate ventilation and oxygenation.
While controversial, bicarbonate administration has
been recommended for comatose patients.
4.
Cerebral injury - Some near-drowning patients may
progress to irreversible central nervous system damage
despite apparently adequate treatment of hypoxia and
shock. Mild hyperventilation to achieve a PaCo2 of
approximately 30 mm Hg is recommended to lower intracranial
pressure.
5.
Hypothermia - Core temperature should be measured
and managed as appropriate.
Course
& Prognosis
Victims of near drowning who have had prolonged hypoxemia
should remain under close hospital observation for
2 - 3 days after all supportive measures have been
withdrawn and clinical and laboratory findings have
been stable. Residual complications of near drowning
may include intellectual impairments, convulsive disorders,
and pulmonary or cardiac disease.
