Physical Perils Grow as Heat, Oxygen Ebb, Medical Experts Say

The 118 Russians trapped in the crippled nuclear submarine beneath the surface of the Barents Sea face a host of increasing physical perils as time passes, according to medical experts.

Diminishing oxygen, accumulating carbon dioxide and extreme cold all can muddle their thinking, mar their judgment and eventually cause their bodies to simply shut down.

“If your oxygen gets very low, you just pass out, and you die,” said physiologist Leon Greenbaum, executive director of the Undersea and Hyperbaric Medical Society in Kensington, Md. “And it would be a quiet death.”

But it’s likely that as oxygen levels drop, carbon dioxide is building up from the Russian sailors exhaling in an enclosed space. That excess carbon dioxide can make breathing quite uncomfortable, said the former U.S. Navy diver and expert on submarine medicine.

Breathing becomes labored. You begin to hyperventilate. That’s followed by headaches, nausea and--in extreme cases--convulsions and loss of consciousness.

Of some comfort, said Dr. Scott Votey, an associate professor of internal medicine at UCLA, is that survivors of carbon dioxide poisoning recall little of their experiences other than the sensation of “getting confused and going to sleep.”

Cold is another creeping threat to the body and mind for the sailors, whose submarine sank Saturday in 354 feet of water above the Arctic Circle.

With ocean temperatures in the 30s, the crewmen of the Kursk “have nothing to protect themselves against the cold outside, and eventually it transmits to the [submarine] interior. The heat from their bodies keeps them warmed a little bit and . . . warms the spaces a little bit,” Greenbaum said.

But after days, the cold also takes its toll.

When the body first senses cold, it revs up the metabolic rate through shivering, which burns more energy, Votey explained. Healthy people can shiver for several hours. Eventually, though, they run out of energy to shiver.

Once shivering ceases, the body starts to cool, the heart slows and the brain works less effectively. As the body’s metabolic processes progressively slow, death nears.

U.S. submarine crews typically have access to insulated clothing that can keep them warm for days. But if the Russian sailors lack power and such clothing, Votey said, “they’re likely cold and out of it by now.”

Pressure inside the submarine also is a critical element to survival, especially as a rescue is being attempted.

Greenbaum explained that the submarine normally would be maintained at sea-level pressure.

Under those conditions, there is no problem breathing air, which is made up mostly of nitrogen.

If the crew members can be evacuated into a rescue vessel that is pressurized to the same levels, there will be no need to worry about a condition called “the bends.” During rapid undersea ascents to surface level, the change in atmospheric pressures causes nitrogen to build up in the body tissues and form bubbles in the bloodstream. The bends can cause problems as simple as muscle pain and disorientation and as serious as brain damage.

The risk of suffering the bends is greater if crew members are forced to escape using some other method, such as swimming to the surface in pressurized suits or riding in some models of a diving bell.

The bends can be treated in a decompression chamber that essentially increases pressure on the body to shrink the gas bubbles and then gradually restores pressure to normal levels so that the excess nitrogen can be “washed out” of the tissues and eventually exhaled.

Greenbaum warned that anyone attempting to make a free ascent from the submarine to the surface also could have a problem with the air in the lungs expanding too quickly.

“The real problem . . . is a rupture of the lungs, unless you’re well trained to exhale all the way,” Greenbaum said.

Navy medical officials in Washington and San Diego declined to comment on the plight of the submariners.

“Nobody in the U.S. Navy is authorized to talk about the Russian sub,” said Doug Sayers, a spokesman for the Naval Medical Center in San Diego.