Ascending too quickly from a dive introduces substantial risks due to rapid pressure changes. This can lead to serious health complications for divers, potentially resulting in injuries that range from mild discomfort to life-threatening conditions. Understanding these potential outcomes is fundamental for anyone engaging in underwater activities to ensure safety and well-being.
How Pressure Affects the Body
The behavior of gases under varying pressures is governed by fundamental scientific principles, primarily Boyle’s Law and Henry’s Law. Boyle’s Law states that at a constant temperature, the volume of a gas is inversely proportional to the pressure exerted on it. This means that as a diver descends and pressure increases, gases in the body’s air spaces, such as the lungs and sinuses, compress. Conversely, during ascent, as pressure decreases, these gases expand.
Henry’s Law explains how gases dissolve into liquids. It posits that the amount of gas dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid. In diving, this applies to the nitrogen in the air divers breathe.
As a diver descends, the increased pressure causes more nitrogen from the breathing gas to dissolve into the body’s tissues and bloodstream. During a controlled ascent, this dissolved nitrogen is gradually released from the tissues and expelled through respiration. However, if ascent is too rapid, the nitrogen cannot be released slowly enough, leading to the formation of bubbles within the body.
Decompression Sickness
Decompression sickness (DCS), commonly known as “the bends,” occurs when nitrogen absorbed into the body’s tissues and blood during a dive forms bubbles as the surrounding pressure rapidly decreases during ascent. These bubbles can disrupt normal physiological functions by blocking blood flow or directly damaging tissues. The severity and manifestation of DCS vary widely depending on where these gas bubbles form and migrate within the body.
DCS has two main types. Type I DCS is less severe, affecting the musculoskeletal system and skin. Common symptoms include persistent joint pain, skin manifestations like itching, rashes, or mottling, and general fatigue or malaise.
Type II DCS impacts vital systems such as the central nervous system, respiratory system, and circulatory system. Neurological symptoms range from numbness, tingling, and muscle weakness to paralysis, seizures, or confusion. Respiratory involvement, sometimes referred to as “the chokes,” can lead to chest pain and breathing difficulties due to bubbles affecting the lungs.
Type II DCS can lead to significant functional impairment or be life-threatening. Symptoms of DCS can appear immediately or be delayed for hours.
Barotrauma
Barotrauma refers to physical tissue damage caused by pressure differences between gas-filled spaces within the body and the surrounding environment. In diving, this commonly occurs when a diver ascends too quickly, causing trapped air to expand rapidly. Several types of barotrauma can affect divers, each with distinct mechanisms and symptoms.
Pulmonary barotrauma, or lung overexpansion injury, is a serious type. This occurs if a diver holds their breath during ascent, preventing expanding air from escaping the lungs. Trapped air can overstretch and rupture lung tissues.
Such an injury can lead to air entering the bloodstream, causing an arterial gas embolism (AGE), where bubbles block blood flow to vital organs like the brain or heart. Symptoms of pulmonary barotrauma may include chest pain, shortness of breath, or coughing, sometimes with frothy or bloody sputum.
Ear barotrauma, particularly middle ear squeeze or reverse block, results from the inability to equalize pressure in the middle ear during ascent. This imbalance can cause pain, fullness, or even rupture the eardrum.
Sinus barotrauma occurs when air trapped in the sinuses cannot equalize, leading to pain, pressure, or a nosebleed. These types of barotrauma are characterized by localized pain corresponding to the affected air space.
Responding to Diving Injuries
If a diver shows symptoms of decompression sickness or barotrauma after rapid ascent, immediate and decisive action is important. The primary step involves seeking prompt medical attention, ideally from a medical professional specializing in dive medicine. Delaying treatment can worsen outcomes.
While awaiting professional help, certain first aid measures can be administered. The injured diver should be laid down, ideally in a horizontal position. Administering 100% oxygen through a tight-fitting mask is important if trained personnel and oxygen equipment are available.
Oxygen helps reduce the size of gas bubbles and supports tissue oxygenation. Keeping the diver warm and hydrated is also beneficial, provided they are conscious and able to drink fluids without difficulty.
Self-treatment is not an option, and professional medical evaluation is essential for diagnosis and appropriate care. Definitive treatment for serious diving injuries, particularly decompression sickness, typically involves hyperbaric oxygen therapy, where the patient breathes pure oxygen in a pressurized chamber to reduce bubble size and facilitate their reabsorption.