Crush Syndrome: Estimating Skeletal Muscle Damage by the Rule of Thirds

Crush injuries in the everyday prehospital world are a rarity. However, during earthquakes, hurricanes or tornadoes; when innocent men, women and children become victims of religious or political zealots; or when our military’s armed forces are asked to go into “harm’s way,” these injuries are more likely to be encountered.

The first apparent report of crush injury (CI) was made by a German, von Colmers, in describing injuries sustained from the 1909 Messina, Sicily earthquake.1 Additional reports of CI and crush syndrome (CS) were made by German physicians during World War I.2 Bywaters and Beall were the first to fully describe CI and CS during the blitz in London during World War II.3 From that time until the present, there is no method for estimating the amount of skeletal muscle (SM) involvement as the result of CI. Therefore, the purpose of this article is to present a method for calculating the percentage of SM injury for patients with CS, using information gathered from modern electronic scanning equipment.

Crush injury is defined as a mechanism of injury in which SM tissue is locally compressed by high-pressure forces. Crush syndrome is a systemic disorder for severe metabolic disturbances resulting from the crush of SM. For CS to occur, the SM must be exposed to the high-pressure forces for an extended period of time.4 The minimum time documented for CS to develop is four hours.5 During this continuous pressure and the resulting minimal circulation, the crushed SM tissue undergoes necrosis (tissue death). Once the pressure has been removed from the SM, toxins are released into the circulatory system. This toxic cocktail contains myoglobin (a muscle protein), phosphate and potassium (from cellular death), lactic acid (from anaerobic respiration) and uric acid (from protein breakdown).4 Therefore, the greater the SM involved, the greater the toxic release into the circulatory system. Crush syndrome will present systematically as follows: extreme hypovolemic shock, hyperkalemia, hypocalcemia, metabolic acidosis, acute myoglobinuric renal failure and compartment syndrome.6 Treatment of CS patients varies from infusion of isotonic saline solution (up to 1.5 liters/hour), crystalloid infusion to dilute myoglobin, mannitol infusion or bolus to serve as an osmotic diuretic, use of dopamine (2–10 micrograms/kg/min), hemofiltration, administration of glucose and insulin, surgical fasciotomy and hyperbaric oxygen therapy.7-9 To better ensure patient survivability and provide for a continuity of care, a method to estimate SM involvement is needed. In this situation, when prehospital personnel report on a “crush-syndrome patient with 30% SM involvement,” the severity can be realized and preparation for treatment can be initiated with patient arrival.

Skeletal Muscle Distribution

It is necessary to determine the distribution of SM in the body in order to estimate the amount of SM involved in a crush injury. Magnetic resonance imaging (MRI) scanning was utilized to determine SM distribution.10,11 The amount of SM in the lower extremities was determined using MRI scans extending from one image below L4-L5 to the foot.10 Total body appendicular SM and trunk and head SM were determined using a similar method.11

Janssen, et al.,10 reported that the percentages of SM distribution were 42.9% upper body and 54.9% lower body for man and 39.7% upper and 57.7% lower body for women. Using these figures for the lower body (below L4-L5), SM distribution is approximately 60%. Kim, et al.,11 reported that in men, 86% of total body SM is appendicular and in women, 88%–89% of total body SM is appendicular. Additionally, the remaining percentages (approximately 14% in men and 11% in women) are in the trunk, with a very small percentage in the head region.12 With this information, it is possible to develop a SM distribution map for adult patients (see Table I).

From Figure 1, an approximation of the upper extremities suggests 15% SM is contained in each arm and 30% SM in each leg. Further, these estimates can be subdivided as: upper arm from the forearm and hand, and the thigh from the lower leg and foot. Determining total area of SM, an anatomically correct muscle chart of an adult male was dissected with an X-acto knife. The resulting cutouts were weighted on an analytical (Mettler AE 260 DeltaRange) scale to the nearest 0.0001 gram. The lower extremity included all muscles from the foot up to and including the gluteus maximus muscle (m) in the posterior region. The upper extremity included all muscles from the fingertips up to and including the deltoid m., omohyoid m., supraspinatus m., infraspinatus m., teres minor m. and teres major m. From this, it was possible to develop the SM distribution map seen in Figure 1.

Summary

Since the early 1900s, CI and CS have been observed and reported. However, there has not been a method to rapidly determine the severity of CS based on the amount of SM damaged as the result of high-pressure forces exerted on the tissue. The amount of SM involved in the CI is directly proportional to the severity of the resulting CS. The severity of the CS dictates the level and complexity of care needed to best ensure patient survivability. Unlike surface burn injuries, where the “rule of nines” or the “rule of palm” are used to estimate the percentage of surface area involved, no such method has ever been presented for use in CS. In fact, there has been an attempt to use the “rule of nines” in CS patients.13 In developing a method to estimate percentage of SM involved in CS, it is hoped that retrospective studies can be performed to generate a workable model for treatment of CS patients.

References

1. Better OS. History of the crush syndrome: From the earthquake of Messina, Sicily, 1909, to Spitak, Armenia 1988. Am J Nephrol 17:392–394, 1997.
2. Michaelson M. Crush injury and crush syndrome. World J Surg 16:899–903, 1992.
3. Bywaters E, Beall D. Crush injuries with impairment of renal function. Br Med J 1:427–432, 1941.
4. Bledsoe BE, Porter RS, Cherry RA. Paramedic Care: Principles & Practice, Trauma Emergencies. Volume 4, Soft-Tissue Injuries, pp. 122–169. Ed: Greg Vis. Upper Saddle River, NJ: Prentice Hall Health, 2001.
5. Michaelson M, Taitelman U, Bshouty Z, et al. Crush syndrome: Experience from the Lebanon War 1982. Isr J Med Sci 20:305, 1984.
6. Better OS. Rescue and salvage of casualties suffering from the crush syndrome after mass disasters. Mil Med 164:366–369, 1999.
7. Nespoli A, Corso V, Mattarel D, et al. The management of shock and local injury in traumatic rhabdomyolysis. Minerva Anestes 65:256–262, 1999.
8. Oda Y, Shindoh M, Yukioka H, et al. Crush syndrome sustained in the 1995 Kobe, Japan, earthquake: Treatment and outcome. Ann Emerg Med 30: 507–512, 1997.
9. Siriwanij V, Vattanavongs V, Sitprija V. Hyperbaric oxygen therapy in crush injury. Nephron 75:484–485, 1997.
10. Janssen L, Heymsfield SB, Wang Z, Ross R. Skeletal muscle mass and distribution in 468 men and women aged 18–88 years. J Appl Physiol 89:81–88, 2000.
11. Kim J, Wang Z, Heymsfield SB, et al. Total-body skeletal muscle mass: Estimation by a new dual-energy x-ray absorptiometry method. Am J Clin Nutr 76:378–383, 2002.
12. Personal communication with D. Gallagher.
13. Chang HR, Kao CH, Lian JD, et al. Evaluation of the severity of traumatic rhabdomyolysis using technetium-99m pyrophosphate scintigraphy. Am J Nephrol 21:208–214, 2001.