The rescue efforts continue in Mexico City this week after two earthquakes and their aftershocks killed more than 300 people across the country and damaged 4,000 buildings in the capital city alone. Frantic searches for survivors at the Enrique Rebsamen School, which collapsed during the 7.1-magnitude Mexico City quake on Tuesday, resulted in an astonishing eleven souls being plucked from the rubble and sent to nearby hospitals. Most of them survived because of the determined efforts of the rescue team, whose immediate medical attention prevented what can be fatal effects of having a crushed limb. Such circumstances often call for a very simple yet effective medical intervention: the tourniquet.
The probability of surviving a building collapse depends on multiple variables, of course—the most important being where the rubble has fallen on the body and what is being crushed. If a slab of cement is on the chest and breathing stops, death will ensue quickly as the brain can survive without oxygen for no longer than minutes. If vital parts of the body are crushed—such as the head, neck, or abdomen—death is imminent. If an arm or leg is crushed, survival is possible, but after just one hour, a severely crushed limb becomes so toxic that it can kill in the same manner as lethal injection. That's where the tourniquet comes in.
Both the physical crushing and subsequent lack of blood flow begin a cascade known as the crush syndrome. Diffuse muscle damage on the cellular level leads to a release of muscle-cell contents into surrounding tissue: Calcium, for instance, is normally stored inside muscle cells, and when released, it activates protein-cleaving enzymes that cause further cell damage. Massive amounts of muscle proteins begin to leak from the affected limb, clogging and overwhelming the kidney's ability to filter blood. Potassium, an ion that the electrical system of the heart is exquisitely sensitive to, also floods the bloodstream. Eventually, damaged kidneys are not able to filter the massive amounts of potassium, and left untreated will cause ventricular fibrillation and cardiac arrest. (This is the same mechanism used during lethal injection, except the prisoner is deliberately administered an overwhelming amount of potassium.)
When a person is rescued and their crushed limb is freed, the return of blood flow to the limb actually hastens the toxic process. This paradoxical reperfusion syndrome not only increases the inflammatory and immune response, but more importantly it abruptly circulates the toxins and potassium-filled blood to the rest of the body. Placing a tourniquet prior to the limb's release will stop this abrupt return of potassium, and theoretically stop a self-induced lethal injection, as suggested by multiple case reports.
Those rescued in Mexico almost certainly received IVs with liters of fluid and cardiac-stabilizing medications to prevent the effects of a flood of potassium, as this is without question the standard of care. If the kidneys suffer enough damage, the patient may need temporary dialysis to filter the blood. After the immediate life-threatening metabolic emergencies are stabilized, orthopedic and vascular treatment follows next. Depending on the extent of injuries, which is entirely specific to each patient, total or partial limb amputation is a possibility.
It's proven difficult to study the effect of tourniquets in crush injuries, as any well-done study needs to be randomized, and randomizing victims to potentially life-saving interventions outside of hospital confines is difficult. But if advanced medical care is absent, regardless of the extent of direct tissue and bone damage, the simple act of placing a tourniquet—anything that can be tied around a limb tightly above the site of injury—could be the difference between life and death.
Darragh O'Carroll, MD, is an emergency physician in Hawaii.
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