Drowning is the process of experiencing respiratory impairment from submersion or immersion in liquid. This physiological event involves a complex cascade of responses within the body. This article explains the physiological changes that occur when the body is deprived of oxygen during a drowning incident.
The Body’s Immediate Reactions to Submersion
Upon sudden submersion, the body’s initial response is often intense panic and an involuntary struggle to reach the surface. This reaction can lead to rapid, inefficient movements that quickly deplete energy and oxygen reserves. Following this, a person will instinctively hold their breath to prevent water from entering the lungs. This voluntary breath-holding can last for a short period, but the urge to breathe eventually becomes overwhelming.
As water enters the upper airway, a reflex known as laryngospasm often occurs. This involves the involuntary closing of the vocal cords, which effectively seals off the airway and prevents significant water from reaching the lungs. While laryngospasm offers a temporary protective mechanism, it also prevents air from entering the lungs, leading to asphyxia. This sealed airway can contribute to “dry drowning,” where little to no water is aspirated. The struggle and lack of oxygen eventually lead to a loss of consciousness, typically within a few minutes.
The Physiological Cascade of Oxygen Deprivation
The progressive lack of oxygen, known as hypoxemia, and eventually the complete absence of oxygen, or anoxia, profoundly impacts the body’s systems. The brain is highly sensitive to oxygen deprivation, with damage potentially beginning after approximately five minutes. As oxygen levels decline, brain function rapidly deteriorates, leading to altered consciousness, potential seizures, and irreversible brain injury.
The heart also responds significantly to oxygen deprivation. Initially, the heart rate may increase as the body attempts to compensate and deliver oxygen to vital organs. However, as hypoxemia worsens, the heart rate slows significantly, a condition called bradycardia. Without adequate oxygen, the heart’s ability to pump blood effectively diminishes, eventually leading to cardiac arrest.
In many drowning incidents, water is aspirated into the lungs after laryngospasm relaxes due to oxygen deprivation. This inhaled water can damage lung tissue and wash away surfactant, a substance that keeps the air sacs open. This leads to impaired gas exchange, where oxygen cannot enter the bloodstream and carbon dioxide cannot be expelled, resulting in pulmonary edema. Prolonged oxygen deprivation prevents cells from producing energy efficiently, causing widespread cellular damage and the accumulation of toxic byproducts.
Understanding Near Drowning and Subsequent Effects
Near drowning refers to surviving, at least temporarily, after experiencing respiratory impairment from submersion or immersion in liquid. Even if rescued and appearing to recover quickly, immediate medical attention is essential due to potential delayed complications. Resuscitative efforts, such as cardiopulmonary resuscitation (CPR) and ventilation, are important interventions.
Survivors of a drowning incident can face a range of health issues. One common complication is Acute Respiratory Distress Syndrome (ARDS), a lung injury where fluid builds up in the air sacs, further impairing oxygen exchange. Aspiration of water can also lead to pneumonia, an infection of the lungs. Even after rescue, brain swelling (cerebral edema) can develop, contributing to persistent neurological deficits such as memory problems, motor impairment, or a persistent vegetative state. Cardiac complications, including arrhythmias and myocardial injury, can also manifest, highlighting the need for comprehensive medical evaluation even if they initially seem fine.