THE CRUSH SYNDROME : A MEDICAL PAPER BY CHARLES A.O’MALLEY FRCSI

The crush syndrome - as opposed to simple crush injury is a medical situation which occurs when a patient has had a limb crushed and trapped for over an hour, with the circulation of blood to the limb severely restricted. When the patient is rescued and the limb released, all appears well for a period of hours, until the kidneys fail and no urine is produced for some days. The patient is then likely to die as a result; Effective treatment greatly increases the chance of life and limb being saved.

While the crush syndrome is well covered in medical textbooks and particularly in war surgery manuals for doctors, it has not been covered in detail in many first aid manuals and Emergency Medical Technicians' manuals. I believe that everyone involved in rescue and first aid in disaster and war should know about this syndrome.

The cause of crush syndrome is the accumulation of toxic products in the trapped limb, which are then loaded into the general circulation when the blood supply to the limb is restored. These toxins include potassium from broken red blood cells, myoglobin which is a large working protein from muscle, lactic and uric acids, and phosphates. When these pass through the kidney, they are filtered into the kidney tubules which then close up resulting in kidney failure with no urine output. At the same time, the patient is likely to have circulatory shock, which in medical terms means a state of poor circulation of blood due to shortage of blood and fluids. This in turn increases the risk of kidney failure.

The ideal treatment at the scene for a patient who has had a major limb crushed and trapped for over an hour is for the patient to be assessed by the site doctor, and then treated with an intravenous drip before release so that large quantities of warmed fluids are given, making the kidneys put out a large volume of alkaline urine (more than 100ml per hour) before the limb is released. This means that when the toxins from the limb are dumped into the circulation, they will be washed through the kidney tubules and the chances of kidney failure are reduced.

If the patient's limb is unsalvageable a decision which should betaken by an experienced surgeon - then it is possible to amputate the trapped limb at the scene without removing the crushing weight. This makes casualty extraction easier, and reduces the risk of kidney failure, but it must be certain that the limb could never have been saved. Finally, in this ideal situation, if the patient's kidneys do fail, renal dialysis is used until they recover.

So much for ideal treatment in the ideal situation. In a major war or earthquake, especially, when this occurs in a country whose infrastructure is overstretched or undeveloped, large numbers of such casualties may occur at once and overwhelm the facilities and resources available. This is the sort of situation which volunteer medical teams may find themselves in at short notice. In such circumstances, there may be too few doctors on the team for each crushed patient to even be assessed by a doctor. In this case, extra lives may be saved by preliminary training of the paramedical staff in the recognition of the possible problem, and treatment by inserting intravenous lines and following an established protocol of intravenous therapy. This approach will require pre-planning and training, as the skills involved in putting in intravenous lines are difficult to acquire and maintain.

"I believe that everyone involved in rescue and first aid in disaster and war should know about the crush syndrome."

What if there are not enough drips and intravenous fluids? During the Second World War this syndrome became widely recognised because of extensive civilian air raid casualties. (It had been described in the Messina Earthquake in 1909, and in German literature in 1914-18, but was not widely known then.) In his book Surgery of Modern Warfare, (1944), Hamilton Bailey described the use of a high intake of fluids by mouth and the use of a tourniquet which was released gradually. Sodium citrate and sodium bicarbonate were added to the oral fluids to make the urine alkaline. Hamilton Bailey advocated the gradual release of the tourniquet over several hours, which had to be supervised by the surgeon - a luxury unlikely to pertain in our scenario above. Intravenous fluids were available in his time, but not as freely as now. He must have had some improvement in outcome with this treatment, but the use of oral fluids in injured patients causes a major problem if they are going to need surgery for their wounds under general anaesthesia. I could only advocate this old regime in dire straits.

The crush syndrome is a life and limb threatening problem of disaster and war. I advocate that all personnel going in to provide help in these situations should know about it, in order to improve recognition, communication and treatment.