Decompression Sickness and Diving Barotrauma

Decompression sickness and diving barotrauma are the pressure-related injuries of underwater diving. Decompression sickness arises when inert gas dissolved in tissues under raised ambient pressure forms bubbles during ascent, while barotrauma is the mechanical injury that occurs when gas-filled body spaces fail to equalize as pressure changes. Together with arterial gas embolism, they constitute decompression illness, a hazard of recreational, occupational, and travel-related diving.

Definition

Decompression sickness is the disorder caused by inert gas coming out of solution as bubbles in blood and tissue during or after ascent from a hyperbaric exposure, and diving barotrauma is the tissue injury produced when gas-filled spaces cannot equalize pressure during descent or ascent; the term decompression illness groups decompression sickness with pulmonary barotrauma-related arterial gas embolism.

Scope

This topic covers the pressure-change injuries of diving: decompression sickness from inert-gas bubble formation, the barotrauma of gas-filled spaces such as the ear, sinuses, and lungs, and the related arterial gas embolism. It addresses the underlying gas physics, recognized risk factors, and clinical spectrum. It is a reference account of how these disorders are conceptualized and studied, not clinical or dive-safety guidance.

Core questions

• How does dissolved inert gas form damaging bubbles during ascent?
• Why do gas-filled body spaces sustain injury when ambient pressure changes?
• How do decompression sickness, pulmonary barotrauma, and arterial gas embolism relate under the umbrella of decompression illness?
• Which dive and host factors govern the risk of pressure injury?

Key concepts

• Boyle's law and gas behavior under pressure
• Inert gas saturation and supersaturation
• Bubble formation on ascent
• Barotrauma of descent and ascent
• Pulmonary barotrauma and arterial gas embolism
• Decompression illness as an umbrella term
• Ascent rate and decompression stops

Mechanisms

Under increased ambient pressure during a dive, inert gas (typically nitrogen) dissolves into tissues in proportion to the partial pressure breathed. On ascent the ambient pressure falls, and if it falls faster than the gas can be eliminated through the lungs the tissues become supersaturated and gas comes out of solution as bubbles, producing decompression sickness with effects ranging from joint pain to neurological injury (Vann et al., 2011). Barotrauma reflects the behavior of gas-filled spaces under changing pressure, as described by Boyle's law: failure to equalize the middle ear, sinuses, or lungs causes mechanical injury, and overexpansion of trapped pulmonary gas on ascent can rupture alveoli and force gas into the arterial circulation as arterial gas embolism (Vann et al., 2011; Lynch & Bove, 2009). Decompression illness is used as an umbrella term spanning bubble disease and pulmonary barotrauma because they can be clinically indistinguishable (Vann et al., 2011).

Clinical relevance

Diving injuries are relevant to travel and primary-care medicine because recreational diving is a common travel activity and presentations may occur after return from a destination. Understanding the pressure physics clarifies why ascent rate, depth, and equalization matter. This entry describes how these conditions are defined and understood; it does not provide dive tables, recompression protocols, or individualized treatment advice.

Epidemiology

Pressure injuries are hazards of compressed-gas diving in recreational, occupational, and military settings, with risk influenced by dive depth and duration, ascent rate, repetitive dives, and individual factors (Vann et al., 2011). Ear and sinus barotrauma are among the most common diving complaints, while serious decompression sickness and arterial gas embolism are less frequent but potentially severe (Lynch & Bove, 2009).

Evidence & guidelines

The clinical and physiological basis of decompression illness is synthesized in the widely cited review by Vann and colleagues (2011), which integrates the gas-bubble mechanism with the clinical spectrum and the rationale for recompression. A primary-care-oriented review by Lynch and Bove (2009) summarizes the evidence on diving medicine, including barotrauma and fitness-to-dive considerations. Dive-medicine organizations maintain operational guidance, summarized here only at the level of underlying principles.

History

Decompression sickness was first recognized in nineteenth-century caisson and tunnel workers as caisson disease, and naval research on submarine escape and diving established the gas-bubble model and the use of staged decompression and recompression. The growth of recreational scuba diving in the later twentieth century extended these hazards to travelers and the general population, and the modern umbrella concept of decompression illness emerged to unify bubble disease and pulmonary barotrauma (Vann et al., 2011).

Key figures

• Richard Vann
• Richard Moon
• Simon Mitchell
• Alfred Bove
• Frank Butler

Seminal works

• vann-2011
• lynch-bove-2009

Frequently asked questions

What is the difference between decompression sickness and barotrauma?

Decompression sickness results from inert gas forming bubbles in tissues during ascent, whereas barotrauma is mechanical injury to gas-filled spaces such as the ear, sinuses, or lungs when pressure changes and the space cannot equalize; the two can occur in the same dive and are grouped clinically as decompression illness.

Why does ascending slowly matter in diving?

A slow, staged ascent lets dissolved inert gas leave the tissues through the lungs before it can come out of solution as bubbles, and it reduces the risk of overexpanding trapped lung gas, lowering the chance of decompression sickness and pulmonary barotrauma.