Near Drowning - An Overview

What Is Near Drowning?

It is defined as an impairment in respiratory function due to drowning. It accounts for nearly 400,000 deaths annually worldwide; however, this number could be higher if non-fatal drownings are also included.

The highest incidence of drowning occurs in children (due to inadequate supervision), persons of low socioeconomic status, and residents living close to water bodies. Approximately 7 % of drowning incident in children happen due to neglect or abuse. Adult drownings are mostly accidental and common during the summer months.

Drowning victims are often alone with preexisting conditions like cardiovascular diseases, seizures, neurocognitive disorders, and physical disability. Apart from this, some of the risk factors for drowning are:

1. Inability to swim or overestimation of swimming capabilities.

2. Risk-taking behavior.

3. Alcohol consumption.

4. Hypothermia (drop in body temperature) can lead to cardiac arrhythmias and rapid exhaustion.

5. Concomitant trauma or stroke.

6. Developmental disorders in children.

7. Undetected primary cardiac arrhythmia. Studies have shown that a known or unknown family history of ischemic heart disease increases the risk of drowning threefold.

8. Hyperventilation (rapid or deep breathing) before a shallow drive increases the chances of drowning. Hyperventilation is part of a normal swimming routine, and swimmers practice hyperventilating to reduce the arterial pressure of carbon dioxide (PaCO2). If submerged for a prolonged duration, the partial pressure of oxygen (PaO2) will drop before the PaCO2. This will lead to cerebral hypoxia, loss of consciousness, and other associated drowning symptoms.

What Are the Symptoms of Drowning?

This can be divided into two categories for easy understanding. They are as follows:

• Generalized Symptoms - It typically starts with panic, loss of normal breathing pattern, breath-holding, and struggling to stay above water. Then, inspiratory reflexes kick in, leading to water aspiration (inhaling water), coughing, hypoxemia (low level of oxygen in the blood), loss of consciousness, and apnea (temporary cessation of breathing).

Hypoxia (specifically cerebral hypoxia) is the main cause of morbidity and mortality in drowning victims. The quantity and quality of the aspirated fluid play an important role in the severity and type of symptoms.

An average of 1ml/kg to 3 ml/kg (milliliter per kilogram) can compromise the function of the pulmonary surfactant leading to respiratory compromise and hypoxia. A few examples of fluid composition that can affect the outcome are:

1. Ventricular dysrhythmia (abnormal heart rhythms) is always associated with the aspiration of cold water.

2. Salt water, on the other hand, increases the chances of cardiac arrest.

3. Contaminated water can cause infection and sepsis.

Organ-Specific Symptoms - The effect of hypoxia on the three most important organ systems is discussed below:

1. Pulmonary - Normal lungs are coated with a thin layer of lipoprotein (fat and proteins) known as pulmonary surfactant. Its selective permeability allows exchange of gases and maintains the structural integrity of the lungs. In drowning victims, the aspirated water (salt or fresh) washes out and destroys the pulmonary surfactant, which makes the lungs susceptible to increased permeability. As a result, water enters the lungs, resulting in pulmonary edema and acute respiratory distress syndrome (ARDS). Patients with ARDS have hypoxia due to decreased lung compliance, pulmonary insufficiency, and intrapulmonary shunting, which are often life-threatening.

2. Neurological - Hypoxia in drowning also affects the brain by causing ischemia (reduced oxygen at tissue level) through hypoxemia (below-normal level of oxygen in the blood) and hypoperfusion (reduced blood flow). Symptoms based on severity include involuntary jerks, seizures, and coma, lacking brainstem reflexes (brain death). In addition, nearly 20 % of the drowning victims sustain neurological damage, which limits functional recovery leading to long-term sequelae.

3. Cardiovascular - Hypoxia causes a wide variety of dysrhythmias (abnormal rhythms) in the cardiovascular system, which leads to symptoms like hypothermia, coronary artery spasm, myocardial ischemia, etc.

Other symptoms include metabolic and respiratory acidosis, multiorgan dysfunction syndrome (due to systemic inflammatory response), renal failure, hemolysis, etc.

How Is a Drowning Victim Treated?

The treatment can be divided into two stages.

Prehospital Care: Bystanders and emergency medical personnel play a vital role in the outcome of a drowning victim. CPR (cardiopulmonary resuscitation) by bystanders improves outcomes but should be done without compromising the rescuer's safety. Before CPR, the following steps should be performed:

1. Check for pulse.

2. Start rescue breathing. This provides ventilation which is detrimental for drowning victims with cardiac and pulmonary arrest. Therefore, rescue breaths are given primary importance in patients with drowning cardiac arrest instead of chest compressions given in patients with non-drowning cardiac arrest.

Trained professionals undertake the next steps with the help of the necessary equipment.

1. High-quality chest compressions are given next.

2. Defibrillation is the next obvious step and is done in victims with dysrhythmias with an automated external defibrillator (if available).

3. Depending on the severity, the airway should be managed in victims with respiratory distress with the help of big-mask ventilation or tracheal intubation.

4. Patients with core temperatures less than 33 degrees should be kept warm.

In the Emergency Department: This includes:

1. CPR is continued in patients with cardiac arrest until the patient is warm.

2. If conventional CPR fails, it is replaced with extracorporeal cardiopulmonary resuscitation (ECPR) - It is a method of CPR that passes the patient's blood through a machine to oxygenate the blood.

The following steps are undertaken in patients with respiratory arrest:

1. The ABCs (airway, breathing, and circulation) must be addressed with the help of mechanical ventilation and other supportive measures.

2. Symptomatic patients should be continuously monitored for oxygen saturation and cardiac telemetry.

3. Patients should also be treated for associated drowning symptoms like hypoxia, pneumonia, and altered mental status.

4. Hypoxia can be managed with oxygenation and ventilation.

5. Pneumonia should be treated with antibiotics.

6. Altered mental status can be addressed with sedation, anticonvulsants, diuretics (to reduce intracranial pressure), etc., depending on the severity.

7. Non-fatal drowning victims should be prescribed prophylactic antibiotics (to prevent infection from contaminated water) and beta-adrenergic agonists (if bronchospasm is observed).

8. Symptomatic patients with normal oxygen saturation should be observed for at least eight hours. They must be discharged only when there is normal mentation, no (new or worsening) respiratory symptoms, normal vital signs, and normal auscultation.

9. The asymptomatic victims can be discharged under the care of a responsible adult who can provide home monitoring. However, instructions should be given to return to an emergency if they develop any of the symptoms mentioned above.

Conclusion

Drowning is a preventable medical condition; it has been observed that secure fencing and gated swimming pools reduce the incidents of drowning in children by 80 %. Drowning in adults can also be prevented with the help of appropriate floatation devices and avoidance of alcohol and drugs. If the accident does occur, bystander intervention and emergency medical services increase the victims' chances of survival apart from the in-hospital care.