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Physiology Related to Special Environments
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Decompression sickness occurs on ascent from a dive. The inspired gas pressures decrease as the diver ascends, and a partial pressure gradient for gases develops between the tissues and the alveoli. If the rate of ascent is rapid, the gases come out of solution in the tissues and form bubbles. The signs and symptoms of decompression sickness usually occur within 6 hours of decompression. Joint pain in the limbs is due to bubble formation in ligaments, tendons and joints. Large intravascular bubbles trapped in the pulmonary circulation cause dyspnoea and cough (‘chokes’). Bubbles may form in the spinal cord, leading to motor and sensory deficits. Bubbles in the vestibular apparatus produce vertigo (‘staggers’). Avascular necrosis of the head and neck of humerus, femur and upper tibia is a long-term adverse effect of decompression sickness. The process of ascending in several stages, with stops at depths where the ambient pressure is half that at the depth of the previous stop, can prevent decompression sickness. Breathing helium–oxygen mixtures rather than compressed air also reduces this risk.
Pathophysiology of Spinal Cord Injury in a Rat Model of Decompression Sickness
Published in John J. Lemasters, Constance Oliver, Cell Biology of Trauma, 2020
Decompression sickness, a disease that affects divers and high-altitude fliers, is induced by a rapid decrease in ambient pressure. During decompression the difference in partial pressure of gas between body tissues and the environment causes the gas dissolved in the tissues to diffuse out into the blood. In the pulmonary microcirculation the gas diffuses from the blood to the air. Eventually the partial pressure of gas in body tissues equilibrates with the alveolar partial pressure of gas. During decompression, the decrease in ambient pressure diminishes the solubility of the gas in tissues. If the decrease in pressure occurs too rapidly to allow equilibration of the gas tension in the tissue with the ambient pressure, large amounts of free gas form. Formation of gas bubbles further retards the elimination of gas from tissues; the elimination of nitrogen is affected the most because this gas is metabolically inert and can be eliminated only by the circulation.1
The cardiovascular system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Mary N Sheppard, C. Simon Herrington
Decompression sickness occurs particularly in the context of deep sea diving, when divers breathe air at higher than atmospheric pressure. The inhaled gases are dissolved in blood and tissue in proportion to the pressure. Rapid ascent with an accompanying fall in pressure results in the gases coming out of solution, leading to blockage of small vessels, particularly in the legs, lung, and more severely the cerebral circulation. This can also occur in rapid aircraft decompression at high altitude. Recompression and slow decompression in a special decompression chamber are the only treatment. Chronic decompression sickness (Caisson disease) results in necrosis of the intra-articular bone, especially of the hip and shoulder (see Chapter 13).
Discovery of caisson disease: a dive into the history of decompression sickness
Published in Baylor University Medical Center Proceedings, 2022
Scott Ninokawa, Kristen Nordham
Decompression sickness, or decompression illness, is the result of rapid decompression causing bubbles to form in the body’s blood and vital tissues. It is commonly referred to in the context of SCUBA diving accidents, but can affect pilots, parachutists, miners, and anyone who is exposed to rapid reductions in barometric pressure. Inert gases, such as nitrogen, are dissolved in the blood and absorbed by various tissues throughout the body in proportion to the surrounding environmental pressures. If this pressure is reduced quickly, termed decompression, the nitrogen can form bubbles, which wreak havoc on various tissues of the body, causing arthralgias, dyspnea, pruritus, confusion, seizures, and paralysis. If left untreated, most minor cases resolve on their own, but severe cases can cause death if not managed emergently.4 This disease was a mysterious ailment faced by miners in France in the early 1800s, but today it is well described with scientific tables and complex physics calculations that allow for its prevention. This disease resulted in numerous deaths of industrial laborers, caused disability of physicians, and was the source of many myths and homeopathic remedies.
A literature review of immersion pulmonary edema
Published in The Physician and Sportsmedicine, 2019
Manish Kumar, Paul D. Thompson
Underwater diving has been associated with several well-established medical complications including barotrauma, decompression sickness, and nitrogen narcosis. Immersion pulmonary edema (IPE) is a lesser known phenomenon that is seen with surface swimming and deep diving. It can occur in individuals without having pre-existing cardiac conditions such as coronary artery stenosis or valvular heart disease. Most of the evidence and discussion of IPE has been presented through case reports and smaller studies. Little is written about IPE in the cardiac literature. Consequently, we performed a systematic review of immersion pulmonary edema to describe the condition and provide guidelines for its management.
Is it safe to SCUBA dive with asthma?
Published in Expert Review of Respiratory Medicine, 2019
Megan Dp Gore, Giles Dixon, Andrew E Stanton
Decompression sickness, colloquially known as ‘the bends’, can present with joint pain, numbness or paraesthesia, headache, unexplained fatigue, dizziness or weakness [53]. Other symptoms and signs include diffuse reticular rash (cutaneous DCS), itch, impaired mental status and co-ordination. Symptoms and signs are often idiosyncratic with no definitive ‘typical’ pattern which can be applied to all cases.