Crush Injuries in Haiti
January 16, 2010 in Medicine
After being trapped under the rubble of her house in Port-au-Prince for 2 days, her right leg caught under a heavy piece of metal, an 11 year old girl died within 24 hours of being rescued. She had been awake and alert (though in pain) and was able to drink water while rescuers worked to save her. The only injuries mentioned were to her right leg and shoulder. There did not seem to be any severe internal organ damage and no indication of massive bleeding or overwhelming infection. So why did she die and so suddenly after being rescued?
As far back as 1910 following an earthquake in Messina and then during World War I, it had been observed that people who initially survived being tapped in rubble with only apparent minor injuries to muscles and extremities would develop a shock-like condition and dark urine before dieing. During the bombing of London in 1941, two British doctors, Eric Bywaters and Desmond Beall, observed a subset of patients who were tapped for several hours “often with compression of an extremity from fallen masonry”. The crushed extremity would gradually loose sensation and become paralyzed and following rescue would develop very tense swelling with either no skin changes or slight patchy red spots followed by blister formation. At first the patient’s blood pressure would be normal but over several hours it would fall and the patient would go into shock, the urine output would gradually decrease, and the urine would turn very dark brown. This condition would often worsen despite amputation of the damaged limb and two-thirds of these patients died within a week where death “usually occurred suddenly and was occasionally preceded by cardiac irregularities.”
On autopsy of these patients, Bywaters found that the muscle in the crushed extremity had lost most of its myoglobin, a protein similar to hemoglobin found in red blood cells. Myoglobin stores oxygen for use by muscle cells and is a pigment which gives raw meat its characteristic red color (via an iron atom attached to two oxygen molecules). Much of the missing myoglobin was found in the kidneys. With these findings, Dr. Bywaters had discovered the mechanism and syndrome of rhabdomyolysis in which severe injury to muscle tissue causes a massive release of myoglobin into the blood where it travels to the kidneys. In the kidneys the myoglobin is toxic to the cells of the proximal tubules and causes cellular dysfunction and cell death (acute tubular necrosis). This leads to acute kidney failure, shock from acidosis, and a high mortality rate without proper treatment.
Dr. Bywaters found as well that severe muscle damage in crush injuries leads to a massive amount potassium release. This salt is normally found inside cells and is released into the blood when damaged cells die and break open. The kidneys normally regulate the pH and potassium levels of the blood and after they are severely damaged by the myoglobin, the potassium levels rise and the blood becomes acidotic (a low pH) which itself leads to further potassium leakage out of cells and higher potassium levels. The lethal effect of high potassium levels in the blood is usually from an induced cardiac arrhythmia which can occur suddenly without warning leading to rapid death and is consistent with what Bywaters and Beall observed.
Rhabdomyolysis and acute kidney failure from crush injuries is survivable and the odds are greatly increased by having quick access to modern and aggressive medical treatment. This includes very aggressive IV fluid resuscitation that ideally should start even before the patient is extracted from the rubble. These patients are often dehydrated from having little to no access to water and blood loss and swelling (third-spacing) in the injured body parts can worsen already low fluid volume (hypovolemia) and increase their risk of kidney failure. In addition, IV fluid treatment is thought to help decrease the risk of kidney failure by helping to wash out the myoglobin from the proximal tubules before it has a chance to collect and become toxic. Following extraction from the rubble, these patients require very close monitoring of kidney function, urine output, potassium levels, and overall fluid status and may require hemodyalysis.
Under ideal conditions these patients would be monitored in the ICU of a hospital. But Haiti, the poorest nation in the western hemisphere, probably has fewer ICU beds and dialysis machines than most small American cities and this was before the 7.0 earthquake of 1-12-10. For now, the best that western aid workers will be able to manage is getting as much isotonic IV fluids as they can get their hands on, “guesstimating” fluid status and kidney function, and hope that potassium levels don’t get too high or kidney function gets too low.