NEAR-DROWNING
Near-drowning is
survival for at least 24 hours after submersion. The most common consequence is
hypoxemia. Drowning is one of the leading causes of unintentional death in
children younger than 14 years of age. An estimated 7000 drownings and 90,000
near-drownings occur yearly in the United States. There are ap-proximately 1000
deaths by drowning of children every year. Children younger than 4 years of age
account for 40% of drown-ings (Suominen et al., 2002).
Factors associated with
drowning and near-drowning include alcohol ingestion, inability to swim, diving
injuries, hypothermia, and exhaustion. Efforts to save the victim should not be
aban-doned prematurely. Successful resuscitation with full neurologic recovery
has occurred in near-drowning victims after prolonged submersion in cold water.
This is possible because of a decrease in metabolic demands or the diving
reflex.
After resuscitation,
hypoxia and acidosis, the primary problems of a victim who has nearly drowned,
require immediate inter-vention in the ED. Resultant pathophysiologic changes
and pul-monary injury depend on the type of fluid (fresh or salt water) and the
volume aspirated. Fresh water aspiration results in a loss of surfactant, hence
an inability to expand the lungs. Salt water aspiration leads to pulmonary
edema from the osmotic effects of the salt within the lung. After a person
survives submersion, acute respiratory distress syndrome resulting in hypoxia,
hypercarbia, and respiratory or metabolic acidosis can occur.
Therapeutic goals
include maintaining cerebral perfusion and adequate oxygenation to prevent
further damage to vital organs. Immediate cardiopulmonary resuscitation is the
factor with the greatest influence on survival. The treatment goal, prevention
of hypoxia, is accomplished by ensuring an adequate airway and res-piration,
thus improving ventilation (which helps to correct res-piratory acidosis) and
oxygenation. Arterial blood gas analyses are performed to evaluate oxygen,
carbon dioxide, and bicarbonate levels and pH. These parameters determine the
type of ventilatory support needed. Use of endotracheal intubation with positive-pressure
ventilation (with PEEP) improves oxygenation, prevents aspiration, and corrects
intrapulmonary shunting and ventilation– perfusion abnormalities (caused by
aspiration of water). If the pa-tient is breathing spontaneously, supplemental
oxygen may be administered by mask. However, an endotracheal tube is neces-sary
if the patient does not breathe spontaneously.
Because of submersion,
the patient is usually hypothermic. A rectal probe is used to determine the
degree of hypothermia. Prescribed rewarming procedures (eg, extracorporeal
warming, warmed peritoneal dialysis, inhalation of warm aerosolized oxy-gen,
torso warming) are started during resuscitation. The choice is determined by
the severity and duration of hypothermia and available resources. Intravascular
volume expansion and inotropic agents are used to manage hypotension and
impaired tissue per-fusion. ECG monitoring is initiated, because dysrhythmias
fre-quently occur. An indwelling urinary catheter is inserted to measure urine
output. Hypothermia and accompanying metabolic acidosis may compromise renal
function. Nasogastric intubation is used to decompress the stomach and to
prevent the patient from aspi-rating gastric contents.
In case the patient appears deceptively healthy, close
moni-toring continues with serial vital signs, serial arterial blood gas
values, ECG monitoring, intracranial pressure assessments, serum electrolyte
levels, intake and output, and serial chest x-rays. After a near-drowning, the
patient is at risk for complications, such as hypoxic or ischemic cerebral
injury, acute respiratory distress syndrome, pulmonary damage secondary to
aspiration, and life-threatening cardiac arrest.
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