Surviving When All Collapses Around You : Disasters: What kept two women going during the long days they were trapped in the rubble of a Seoul department store? Experts say certain physical and psychological responses are key to survival.

Pulled from the ruins of the Sampoong department store in Seoul, South Korea, on Saturday--16 days after its collapse on June 29--Park Sung Hyon, a 19-year-old sales clerk, defied medical odds, surviving long after most experts would have predicted.

Four days earlier, another 19-year-old clerk, Yoo Ji-hwan, had been pulled out. Through her exhaustion, she exhibited a sense of humor, reportedly joking and flirting with her rescuers as they pulled her from the site, where the death toll is now more than 400.

Such stories amaze and inspire the rest of us--and evoke questions about just what are the human limits, both physical and psychological.

While these limits vary considerably based on physical and mental health, here is a rundown, provided by experts, of what a healthy person of average weight and fitness level might expect during a long ordeal in a collapsed building and how the likelihood of survival increases.

Day 1

On a physical level, the primary concern should be oxygen, says Dr. Dario McDonald, an emergency medicine specialist at Santa Monica Hospital Medical Center. “Without any oxygen, brain death is imminent within five to 10 minutes.”

The trapped person should work to establish a source of fresh air, trying to pry open a door or a window. One saving grace: An inactive body consumes less oxygen.

Water is the next concern. “Generally the body cannot go without water longer than 72 hours,” McDonald says. Looking around for a source of water--from pipes or condensation on windows--should be the next priority.

But McDonald and other medical experts concede that there is a lot of variability on how long the body can go without drinking. “These numbers quoted are averages,” says Dr. Stephen Docherty, also an emergency medicine specialist at Santa Monica Hospital Medical Center. “Some people could go much longer.”

Indeed, Docherty says, medical experts will probably rethink calculations about how long the body can go without water in the wake of the long-term South Korean survivors. Then again, the survivors who say they did not drink any water may be confused or may be remembering incorrectly, Docherty adds.

Within 24 hours, the digestive tract is probably empty of food if the person has no food supply, Docherty says. When this happens, the liver begins producing glucose, dumping it into the blood stream for the body to use, a process called gluconeogenesis.

On a psychological level, the immediate reaction to catastrophe is often, “It’s a dream, it can’t be happening to me,” says Dr. Calvin Frederick, a UCLA professor of medical psychology and former director of emergency mental health services and disaster assistance for the National Institute of Mental Health.

After this initial shock phase, it’s then common to try to interact with the environment, to yell for help. In a group, trapped people may try to create an escape plan.

Day 2

By now, the body may shift into lipolysis, the burning of stores of fat, although the processes of gluconeogenesis and lipolysis often overlap, McDonald says. Burning of fat stores can continue for many weeks but is highly variable depending on a person’s size and other factors.

“Psychic numbing” can begin, during which people try to depersonalize the situation. Discouragement and depression may set in. People begin to feel a loss of power, Frederick says.

Days 3-6

Without any water, death is probable at the 72-hour mark, McDonald says. The body needs water on a more regular basis than food because water is vital to maintain metabolic status. Adequate water helps keep in balance levels of sodium and other electrolytes, substances that help regulate body processes. Water also helps regulate body temperature and ease digestion.

How much water is needed to sustain life depends on body size and activity. A person who was well-hydrated at the beginning of the ordeal has an advantage.

Maintaining some body movement is wise, McDonald says, because lying too long in one place could result in breakdown of muscle tissue.

Staying in a cool area, if possible, can help to maintain body fluids. but beyond that, McDonald says, there’s not a lot you can do to reduce fluid loss. Even in cooler areas, perspiration occurs. Fat burning continues.

Hunger pains may decline after a few days, McDonald says.

People are likely to drift in and out of depression. Keeping the mind occupied becomes extremely important. Experts say how a captive does that is less important than the act of doing it. During the Beirut hostage crisis, for instance, Frederick remembers that hostage David Jacobsen did pushups to stay strong, reasoning he would be ready for escape opportunities. Some people may become irrational. By now, a sense of time is often lost. This contributes to the trauma, Frederick says, and should be dealt with later in treatment.

A lack of light will make eyes sensitive upon rescue, but McDonald says the condition usually passes quickly and leaves no lasting damage. Eye shades are generally used. The eyes readjust, he says, much like they do after a person leaves a dark movie theater.

But, Frederick says, the lack of light could compound the fear while waiting to be rescued.

Days 7-9

If no food has been found, the body will continue to burn fat stores.

The time required to deplete the fat stores varies, with medical literature predicting it occurs in about 60 days in non-obese people, McDonald says. But one obese person was reported to have survived a 310-day fast.

Once fat stores are depleted, the body will start feeding on muscle tissue, with additional weight loss resulting.

If too much muscle tissue is lost, the survivor can take on the gaunt look common in concentration camp survivors.

Day 10 and Beyond

“Many people may feel like giving up hope at this point, but they don’t,” Frederick says. Some switch to what experts call survival mode. “One way is to shut down all external stimuli and focus on the moment,” Frederick says. “They might listen to their heartbeat and breathing to cling [to hope] and reassure themselves they are alive.”

After the Rescue

Replenishing fluids is vital, McDonald says. Often intravenous fluids are given to restore a normal balance of fluids and electrolytes. Then, the survivors are treated like any other trauma victim.

While happy to be rescued, survivors can sometimes hardly believe it, Frederick says. But they don’t always exhibit the expected reaction. “They don’t always burst out crying [even though] the people around them do.”

Mental health treatment should be given on the survivor’s timetable. “[Some] experts want survivors to spill their guts right away,” Frederick complains. His advice: “Let people be.” Rushing them “can be an additional trauma,” he says.