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The missing Titan submersible has five passengers that are running low on oxygen. The Joint Rescue Coordination Centre Halifax tweeted on Tuesday that the Royal Canadian Navy joined the search for the submersible, bringing a six-person mobile hyperbaric recompression chamber, used to treat decompression sickness (DCS).
DCS, aka the bends, is caused by a rapid decrease in air or water pressure. The submersible should maintain atmospheric pressure in the cabin, "so they could come right back to the surface and not have any decompression sickness at all," said Richard Moon, medical director of the Center for Hyperbaric Medicine & Environmental Physiology at the Duke University Medical Center.
But the chamber could be used if the vessel experiences a pressure change when it is brought to the surface, Canada's Department of National Defence told Insider in an email.
DCS is most often associated with scuba and deep-sea diving, but astronauts can get the bends as well.
The deeper you sink into the ocean, the greater the pressure will be from all the water above. If a diver rises to the surface too quickly after a deep dive, the sudden pressure change can cause gas bubbles, often nitrogen, to release into the bloodstream. Moon compares it to the bubbles that form when you open a carbonated beverage.
The nitrogen bubbles can damage blood vessels and impede blood flow, with often painful and sometimes serious results similar to a blood clot, Nilufer Norsworthy, a hyperbaric medicine specialist with University of Washington Medical Center – Northwest, said.
"To decrease the damage we need to get the bubbles as small as possible as early as possible," she said. Symptoms of DCS include joint pain, headache, fatigue, and weakness in the limbs, according to Harvard Medical School.
Hyperbaric oxygen therapy is an effective treatment for DCS. A hyperbaric oxygen chamber delivers 100% oxygen to occupants in a pressurized environment.
"Usually the compression is to almost 3 atmospheres absolute or an equivalent of 60 feet," said Moon. "So it's like going back on a 60-foot dive but breathing 100 percent oxygen."
Over the course of several hours, nitrogen transitions from gas to liquid form so it can clear from the bloodstream without blocking or damaging blood vessels. The treatment length depends on factors like the depth and duration of the dive and can range from two to six or seven hours.
Possible side effects of the treatment include middle-ear damage, collapsed lungs, low blood sugar, and sinus issues, according to Johns Hopkins Medicine.
The pressure change is greater than in an airplane, and novice divers can have difficulty equalizing the pressure in the middle ear, which can lead to pain and bleeding, Moon said.
If rescuers find the submersible, a remotely operated vehicle (ROV) will be needed to slowly haul it to the surface, according to the BBC.
This ascent can't be slow enough, Norsworthy said. If the pressure in the chamber changes from the deep sea to the surface, it could lead to ruptured capillaries in the lungs and other organ damage as the body returns to atmospheric pressure.
