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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
Nitrogen narcosis can occur because the partial pressure of nitrogen increases when compressed air is used for breathing. At high pressures, nitrogen may be soluble in lipids, leading to membrane expansion and interference with neural transmission by modulating ion channels. At a depth of 30 msw, divers develop euphoria and reduced dexterity and mental agility. At 50 msw, there may be loss of concentration and decreased neuromuscular coordination. Beyond 50 msw, the symptoms become severe, and divers may become unconscious at depths beyond 90 msw.
Body Composition in Perspective
Published in Henry C. Lukaski, Body Composition, 2017
Concurrently, Behnke (1942) reported that retention of inhaled nitrogen by experienced undersea divers depended on body fatness. Because inhaled nitrogen is nearly five times more soluble in fat than water or blood, this finding provided a physiological explanation for the debilitating condition of nitrogen narcosis afflicting some Navy divers. This important finding provided the first indication of an association between body composition (body fatness) and physiological function (excess nitrogen retention), albeit adverse.
Special environments
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2015
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Nitrogen narcosis can occur because the partial pressure of nitrogen increases when compressed air is used for breathing. At high pressures nitrogen may be soluble in lipids, leading to membrane expansion and interference with neural transmission by modulating ion channels. At a depth of 30 msw, divers develop euphoria, and reduced dexterity and mental agility. At 50 msw, there may be loss of concentration and decreased neuromuscular coordination. Beyond 50 msw, the symptoms become severe, and divers may become unconscious at depths beyond 90 msw.
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.
“It didn't bring back the old me but helped me on the path to the new me”: exploring posttraumatic growth in British veterans with PTSD
Published in Disability and Rehabilitation, 2022
Petra Ann Walker, Hanna Kampman
The calm found underwater by the divers brings to mind Straughan’s [14] findings on touch and changes in auditory perceptions. The calm appears to help individuals to approach their challenges purposefully after the respite from their physical symptoms. This connects to the process of PTG, as an individual starts to manage their emotional distress and engage in coping mechanisms to deal with their challenges [7]. It is not clear what the process of The Calm involves. Unlike mindfulness or meditation, it is instantaneous: occurring the moment the head submerges, almost akin to a state of flow [56]. Similar findings have risen from Caddick et al.’s [5] exploration into surfing and veterans, where the surfing appeared to offer “temporary absence of trauma-related thoughts and feelings” [5,p.79] which they experienced through embodied sensations of being immersed in the ocean environment. The concept of flow, which is described as when you are fully emerged into an activity, purely from enjoyment of the activity, and which often entails a changed perception of time [56], fits with the descriptions of participants mentioning the calm occurring even on the first dive. It may be also that different sensory properties underwater play a part here. It is worth noting that despite breathing being identified as a route to stress reduction in divers [49], with the role of breath in maintaining buoyancy and speed of air consumption drawing parallels with meditation, no participant mentioned the breath. This could be because the primary researcher is an experienced diver and participants took it for granted. Finally, previous suggestions explaining relief of stress underwater includes nitrogen narcosis. However, these effects are rarely felt at shallow depths [15], whereas The Calm occurs even in shallow water, so it is unlikely to be a major factor. One thing is certain, like the relief of pain, The Calm leads to hope and optimism, identified as a correlates of PTG [57].