By David Brown
Washington Post Staff Writer
Saturday, May 17, 2008
For people pinned in the wreckage after catastrophes such as this week's earthquake in China, a successful rescue often marks the beginning, not the end, of the danger.
Crushed and damaged muscle tissue can flood the bloodstream with toxic substances capable of killing within a few hours. If a person avoids that problem, kidney failure caused by the toxins is often fatal in a few weeks.
"Crush syndrome," the collective name for these problems, is second only to trauma from falling debris as the cause of death in earthquakes, but many of those deaths can be prevented if the right treatment is give in time. For the last decade, the international medical community has been trying to make that happen.
On Thursday, a team of kidney specialists from the International Society of Nephrology, headquartered in Brussels, flew to China to offer expertise, and possibly also equipment and manpower, to rescuers there. It is the eighth natural disaster to which the Renal Disaster Relief Task Force has responded.
The physiological effects of having parts of the body pinned under pressure for long periods of time were first described in detail by Eric G.L. Bywaters, a physician caring for victims of the London Blitz in World War II. He established a treatment -- lots of intravenous fluids often fortified with sodium bicarbonate, or baking soda -- that is still the mainstay.
The need to be prepared for these problems was apparent after an earthquake in Armenia in 1988. That disaster killed 25,000 people and left 600 of the injured with acute renal failure, a severe decline in kidney function that was fatal to many.
"The international society realized after that we had to have something set up in advance," Raymond Vanholder, a Belgian physician who leads the task force of kidney specialists, said this week.
While the numbers vary from disaster to disaster -- in part depending on how quickly victims are rescued -- it appears that up to 10 percent of people who make it to the hospital end up with acute renal failure from crush injuries. About half will need dialysis -- the filtering of waste products from the blood with a machine -- to survive. Vanholder said a Chinese kidney specialist in Chengdu told him by e-mail on Thursday that only 14 people were on that treatment.
"I expect at least several hundred needing dialysis," he said. "If that is not right, it is because the rescue and the transport has been difficult."
The release of the damaging substances is the result of mechanical stretching of crushed muscles and the death of tissue because of insufficient blood.
"Cell contents are dangerous. That is why they have membranes around them," said Marvin L. Birnbaum, a critical-care physician at the University of Wisconsin School of Medicine and president of the World Association for Disaster and Emergency Medicine. "When that stuff gets released into the circulation, it's not just kidneys it can damage."
The damage, however, often begins only when a survivor is extricated. Until then, the debris functions as a tourniquet, effectively isolating the pinned body part (the legs more than half the time) from the circulation.
"When they are under the rubble they are relatively safe. When the pressure is taken away and the blood goes into the muscle, that is when the trouble starts," Vanholder said.
The most immediate threat is potassium, the ion that is in high concentration inside muscle cells and is essential to their ability to contract. Too much potassium in the bloodstream can cause the heart to beat erratically and ultimately stop; it is an ingredient in the lethal intravenous cocktail used to execute prisoners.
The other major toxin is myoglobin, a protein that binds oxygen in muscles so they can work at peak efficiency. Once released into the blood, it is filtered by the kidney, where it accumulates, blocks microscopic tubules and damages the organ, sometimes permanently.
Giving a victim intravenous fluid dilutes these substances and helps flush them from the body. Various other steps can help protect the heart from the toxic effects of potassium. If the injury is severe enough, dialysis is necessary.
With dialysis, the kidneys often heal and return to normal function, although on average a person needs at least two weeks of the therapy, which can lead to other life-threatening complications, such as infection and bleeding.
Even with ideal care, about 15 percent to 20 percent of people with kidney damage from crush syndrome die, according to data collected by Turkish physicians who have done extensive research on treating earthquake victims.
Crush syndrome is less common in infants and the elderly, presumably because they have less muscle than young adults.
"The feeling is adult males are more prone to develop the syndrome because they have a bigger mass of muscle. They are the ones we really want to treat early," said Itamar Ashkenazi, an Israeli surgeon who has written about the field care of rubble-trapped disaster victims.
The Renal Disaster Relief Task Force goes out with a team from Médecins Sans Frontières (also known as Doctors Without Borders), which provides the logistics. It keeps 20 dialysis machines in the organization's Brussels warehouse. Frequently, however, the task force doesn't bring in machinery but helps organize treatment with equipment already in the country.
The biggest response so far was for the 1999 earthquake in Marmara, Turkey. It consisted of about 50 people in a half-dozen teams that included physicians, nurses and dialysis technicians. The team that went to China on Thursday had two Belgians and two Chinese from Hong Kong.