Drowning and non-fatal immersion in water

Non-fatal submersion (partial drowning) is asphyxia in water that does not result in death; partial drowning causes hypoxia due to aspiration or laryngospasm. Sequelae of hypoxia may include brain damage and multiple organ failure. Patients are evaluated with chest radiography, oximetry, or blood gas measurements. Treatment is supportive, including reversal of heart block, restoration of respiration, and management of hypoxia, hypoventilation, and hypothermia.

Drowning, or fatal water asphyxia, is the 7th leading cause of accidental death in the United States and the 2nd leading cause among children ages 1–14. Drowning occurs most often in children younger than 4 years of age and in disadvantaged and immigrant children. Risk factors for people of all ages include alcohol or drug use and conditions that cause temporary incapacitation (e.g., seizures, hypoglycemia, stroke, MI). Near drowning occurs most often in swimming pools, hot tubs, natural bodies of water, and, among infants and toddlers, in toilets, bathtubs, buckets of water, or cleaning solutions. For every drowning death, approximately 4 near drownings result in hospitalization.

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Pathophysiology of drowning and non-fatal submersion

Hypoxia is a major factor in partial drowning, causing damage to the brain, heart, and other tissues. Cardiac arrest may follow respiratory arrest. Cerebral hypoxia may cause cerebral edema and, often, permanent neurologic sequelae. Generalized tissue hypoxia may cause metabolic acidosis. Initial hypoxia results from aspiration of water or gastric contents and acute reflex laryngospasm, or both. Lung injury from aspiration or hypoxia may itself cause subsequent secondary hypoxia. Aspiration, particularly of particulate matter or chemicals, may result in aspiration pneumonitis (sometimes primary or secondary to bacterial pneumonia) and may impair alveolar secretion of surfactant, usually resulting in focal pulmonary atelectasis. Extensive atelectasis can make the injured areas of the lung rigid and poorly ventilated, potentially causing respiratory failure with hypercapnia and respiratory acidosis. Perfusion of poorly ventilated areas of the lung (ventilation/perfusion imbalance) worsens the hypoxia. Alveolar hypoxia can cause noncardiogenic pulmonary edema.

Laryngospasm often limits the volume of fluid aspirated; but in some cases, large volumes of fluid aspirated during partial drowning may alter electrolyte concentrations and blood volume. Seawater may slightly increase Na ⁺ and Cl". In contrast, large quantities of fresh water may significantly decrease electrolyte concentrations, increase circulating blood volume, and cause hemolysis. Bone, soft tissue, head, and visceral injuries may occur. Cervical and other spinal fractures (which may lead to drowning) may occur in shallow-water divers. Cold water exposure causes systemic hypothermia, which can be a serious problem. However, hypothermia may also be protective by stimulating the diving reflex, slowing the heart rate, constricting peripheral arteries, and thus redistributing oxygenated blood from the extremities and intestines to the heart and brain. Hypothermia also reduces tissue O2 requirements _, prolonging survival and delaying the onset of hypoxic tissue injury. The diving reflex and the protective clinical effects of cold water are generally greater in young children.

Symptoms of Drowning and Non-Fatal Submersion

Children who cannot swim can go underwater in less than a minute, much faster than adults. After rescue, agitation, vomiting, wheezing, and impaired consciousness are typical. The patient may have respiratory failure with tachypnea and cyanosis. Sometimes, symptoms of respiratory failure develop several hours after immersion.

The diagnosis of most people found in or near water is based on obvious clinical findings. The first step is to revive the person, then conduct diagnostic tests. If cervical spine injury is suspected, it should be immobilized, including unconscious victims and people whose mechanism of injury is likely related to diving. Attempts to remove water from the lungs are of little help. It is necessary to consider the possibility of secondary craniocerebral injury and conditions that may have contributed to drowning (e.g., hypoglycemia, stroke, acute myocardial infarction).

All patients should have their blood oxygenation assessed by oximetry; if respiratory symptoms are present, chest radiography and blood gas analysis should be performed. Because respiratory symptoms may take some time to develop, patients who do not have them are nevertheless transported to the hospital for observation for several hours. Patients with symptoms or a history of prolonged underwater exposure should have their temperature measured, an ECG taken, plasma electrolytes determined, and continuous oximetry and cardiac monitoring initiated. Patients with possible cervical spine injury should have imaging studies. Patients with impaired consciousness should have a CT scan of the head. If any other pathological conditions are suspected, appropriate studies should be performed (e.g., blood glucose concentration, ECG, etc.). Patients with pulmonary infiltrates, bacterial pneumonia should be differentiated from aspiration pneumonitis by blood culture and sputum culture and Gram stain.

Prognosis and treatment of drowning and non-fatal submersion

Factors that increase a drowning person's chance of surviving without permanent consequences include:

• short duration of immersion;
• colder water temperature;
• younger age;
• absence of concomitant diseases, secondary trauma and aspiration of solid impurities or chemicals;
• and, most importantly, starting resuscitation as quickly as possible.

In cold water, survival is possible even after more than an hour, especially in children. Therefore, the patient must be actively resuscitated even after a long stay under water.

Treatment is aimed at correcting cardiac arrest, hypoxia, hypoventilation, hypothermia and other pathological conditions. If the patient is not breathing, breathing should be restored immediately, if necessary, while still in the water. If spinal immobilization is necessary, it is carried out in a neutral position, while artificial respiration is performed, pushing the lower jaw forward without throwing the head back or raising the lower jaw. If necessary, closed cardiac massage is started, followed by a transition to extended cardiac resuscitation; oxygenation is provided, intubating the trachea as soon as possible. Patients with hypothermia should be warmed up as quickly as possible.

Patients with signs of hypoxia or moderate symptoms are hospitalized. In the hospital, treatment is continued to achieve acceptable arterial O2 and CO2 levels. Artificial ventilation may be required. 100% O2 is given; the concentration is reduced depending on the results of blood gas analysis. Positive end-expiratory pressure or positive variable pressure ventilation may be required to expand and maintain alveolar patency, which in turn maintains oxygenation; respiratory support may be necessary for many hours or days. Inhaled beta-adrenergic agonists administered via a nebulizer relieve bronchospasm and reduce wheezing. Patients with bacterial pneumonia are given antibiotics directed at microorganisms identified or suspected on the basis of the results of bacteriological examination of sputum or blood. Glucocorticoids are not used.

Fluid or electrolyte replacement to correct electrolyte imbalances is rarely necessary. Fluid restriction is usually not indicated, even in the presence of pulmonary or cerebral edema. Treatment for prolonged hypoxia is the same as that following cardiac arrest.

Patients with moderate symptoms and normal oxygenation may be observed in the emergency department for several hours. If symptoms resolve and oxygenation remains normal, they may be discharged with instructions to return if symptoms recur.

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Prevention of Drowning and Non-Fatal Submersion

Consumption of alcohol or medications, major risk factors, should be avoided before swimming, boating or supervising children near water.

Less experienced swimmers should always be accompanied by someone who can swim well, or the swimming area should be safe. Swimming should be stopped if a person feels cold, because hypothermia can lead to poor self-esteem later on. When swimming in the ocean, it is important to learn to avoid breaking waves by swimming parallel to the shore, not towards it.

Children should wear buoyancy aids both while swimming and near water. Children should be supervised by an adult near water, regardless of the location - beach, pool or pond. Babies and toddlers should also be supervised, ideally at arm's length, near toilets or containers (buckets, basins) with water, which is best poured out immediately after use. Swimming pools should be surrounded by a fence at least 1.5 m high.

In boats, it is best for everyone to wear life jackets, especially those who cannot swim and small children. The exhausted, elderly, and those with seizure disorders or other illnesses that could cause loss of consciousness while in the water or on a boat trip require special attention.

Trained lifeguards should be available at public swimming areas. Comprehensive public prevention programs should target at-risk groups, teach children to swim as early as possible, and, where possible, introduce adolescents and adults to basic CPR.