The force of pressure was revealed when the Titan sank it apparently exploded on descent to explore the wreckage of the Titanic at 3,800 m below sea level, where the ambient pressure is 380 times higher than at the surface of the water.
Without a boat to protect them, people can only dive for recreational purposes to a depth of about 50m by breathing pressurized air from a tank carried on their backs. Even at this depth, atmospheric pressure is about 5 times higher than on land, and sudden changes can be detrimental to health.
Also read: Juan Valdivia, 69 meters underwater in one breath
Extreme conditions are defined primarily in terms of temperature and pressure, explained in an editorial published in Frontiers in psychology.(1) Research under these conditions “has expanded the knowledge of physiology by highlighting new pathways of regulation, breaking down old concepts, and proposing new models for some of the pathophysiological problems in patients,” the authors write.
From the depths of the water surface to the highest mountain peaks, the body’s response to hyperbaric and hypobaric conditions is summed up by the expansion or contraction of the gases present in the body. “The effects are primarily related to changes in oxygen partial pressure,” explained Dr. Richard Moon, medical director of the Center. Center for Hyperbaric Medicine and Environmental Physiology and teacher ducal university in Durham, USA, in an interview Univadis.
Under these extreme conditions fundamental physics meets physiology.
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An injury caused by pressure changes is known as barotrauma.(2) Barotrauma often occurs when recreational and professional divers have difficulty recalibrating their middle ear or sinus pressure. Middle ear barotrauma can be prevented with proper diving technique and speed, and often resolves without medical intervention.
Changes in atmospheric pressure, more dangerous but less common, can also cause pulmonary barotrauma, which affects the lungs and can lead to rupture. This can happen if divers thoughtlessly hold their breath during their ascent to the surface.
Barotrauma also occurs in healthcare settings. A systematic review found that barotrauma was reported in 4.2% of patients hospitalized for COVID-19.(3) A significantly higher rate was observed in those who received mechanical ventilation, suggesting the need for safer methods.
Another diving hazard occurs about 30 m below the surface, where the excessive concentration of nitrogen begins to have an anesthetic effect, causing a condition similar to intoxication called nitrogen narcosis.(4) The effect gets progressively worse in deeper water, and at about 50 meters, “a person is pretty drunk,” Moon says. Other neurological symptoms may follow.
For divers, the most common problem is decompression sickness, in which inert gases such as nitrogen expand, creating bubbles in body tissues and the bloodstream.(5) “This is very similar to the discovery of a carbonated drink,” explained Dr. Moon.
The severity of decompression sickness ranges from numbness and mild arthralgia to paralysis and death in rare cases. The risk of this disease is greatly reduced when you get up slowly, using a table or computer to determine the correct time to get up.
Treatment for decompression sickness usually consists of administering oxygen through a mask or in a pressure chamber where patients breathe 100% oxygen at two to three times normal pressure.
Hyperbaric oxygen has several therapeutic uses, such as the treatment of carbon monoxide poisoning or gangrene. In addition, researchers have found that improved oxygenation at higher atmospheric pressure in places like the Dead Sea, located 430 meters below sea level, may have physiological benefits for people with moderate to severe lung disease caused by cystic fibrosis.(6)
Decompression sickness is not limited to divers. Outside the Earth’s atmosphere, this condition worries astronauts, who experience lower environmental pressures during spacewalks compared to spacecraft conditions. Recent research is focused on developing new spacesuit technology that helps reduce the risk of decompression sickness.(7)
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Climbing to high altitudes presents a similar problem, as hypoxia can cause “altitude sickness”. This disorder usually presents with nausea, vomiting, and headache when the person has not acclimatized to an altitude where the air is less dense and there is little oxygen.
For mild cases of acute mountain sickness, “you can usually get relief with acetaminophen or some other medication,” Dr. Moon said. For more serious conditions at altitude, such as pulmonary and cerebral edema, it is important to evacuate the patient so that they receive care in the hospital.
According to reports from specialized groups such as Institute of Mountain Emergency Medicine And International Society for Mountain Medicine.(8.9)
This article was originally published on Univadis, part of the Medscape professional network.
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