A 35-year-old, otherwise healthy patient with acidosis, hyperkalemia, and hypocalcaemia

After a high-speed motor vehicle collision（碰撞） resulting in multiple injuries, a 35-year-old, otherwise healthy patient is admitted to the ICU after operative fixation（固定） of a right femur（股骨） and a left tibial（胫骨） fracture. Postoperative laboratory results are significant for acidosis, hyperkalemia（高钾血症）, and hypocalcaemia（低钙血症）. Because the patient’s urine is a dark brown, a creatine kinase（磷酸肌酸激酶） level is ordered, with a result of 18,000 U/L.

Which of the following is correct with regard to treatment of rhabdomyolysis（横纹肌溶解）?

A. Administration of bicarbonate（碳酸盐） and mannitol（甘露醇） will reduce the incidence of renal failure.

B. Administration of Ringer lactated solution（乳酸林格液）, 200 mL/hr, is recommended over the administration of normal saline.

C. Administration of loop diuretics（利尿剂） is beneficial and generally recommended in patients with oliguria（少尿） following traumatic rhabdomyolysis in the absence of preexisting（既往存在） renal failure.

D. Administration of normal saline, 200-1,000 mL/hr, is recommended in the absence of contraindications（禁忌） for administration of significant volume load.

解析：

Posttraumatic rhabdomyolysis is common and associated with significant morbidity（发病率） and mortality（死亡率）. In earthquake（地震） survivors, it is the second most important cause of mortality. Nontraumatic causes of rhabdomyolysis include extreme exertion（过度劳累）, grand mal seizures（癫痫）, delirium（谵妄）, drugs, toxins, infections, and endocrine disorders. Prolonged anesthetics（麻醉剂） can be associated with rhabdomyolysis, especially in young muscular patients. A common feature of both traumatic and nontraumatic rhabdomyolysis is massive necrosis（坏死） resulting in limb（肢） weakness, myalgia（肌痛）, and gross pigmenturia.

The pathophysiologic process involves sarcolemmic（肌纤维膜） injury as well as depletion（耗尽） of ATP within the myocyte（肌细胞）. This leads to a detrimental（有害的） increase in intracellular calcium. Tight（严格的） calcium regulation is necessary in order to ensure proper（本身的） contractile function （收缩功能）(low concentrations at rest and increasing concentrations during a state of activation facilitate proper actin myosin- binding（肌动蛋白肌球蛋白结合） and contraction). Channels and pumps that regulate this calcium concentration are ATP dependent and, once ATP depletion occurs, are no longer able to maintain calcium homeostasis（钙稳态）. The muscle persistently（持续） contracts, and calcium-dependent proteases（蛋白酶） and phospholipases（磷脂酶） are activated, eventually leading to destruction（毁灭） of the myocyte. Kidney injury commonly results as a consequence（结果） of renal vasoconstriction（血管收缩）, direct and ischemic tubule injury, and tubular obstruction.

After identification and treatment of the cause of rhabdomyolysis, the important steps to prevent acute kidney injury include aggressive（积极的） volume administration with the goal of maintaining and enhancing renal perfusion to minimize cast formation（铸型） and/or to flush out casts that have already formed. Another goal is enhancement（增强） of urinary potassium excretion（尿钾排泄）, since death from hyperkalemia is a major complication of traumatic rhabdomyolysis. Although the optimal type of fluid and rate of repletion is unclear, potassium-containing fluids should be avoided, especially in the initial phase, and administration of normal saline at 1-2 L/hr is generally recommended initially（最初的）.

Despite the theoretical（理论上的） benefits of bicarbonate（碳酸盐） administration (prevention of nephrotoxic（肾毒性） effects of myoglobinuria（肌红蛋白尿） such as heme protein precipitation with Tamm-Horsfall protein, decrease of release of free iron from myoglobin and prevention of formation of uric acid crystals（尿酸结晶）), the administration of bicarbonate plus mannitol over normal saline alone has not been shown to prevent renal failure, reduce the need for dialysis（透析） or prevent death in trauma patients. There was, however, a trend towards better outcome in patients with CK values over 30,000 U/L.

The use of loop diuretics remains controversial（有争议的）. No study has shown a clear benefit to patients with rhabdomyolysis. The use of loop diuretics therefore is recommended in the same manner as that for acute kidney injury that is due to other causes.

References:

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3. Warren JD, Blumbergs PC, Thompson PD. Rhabdomyolysis: a review. Muscle Nerve. 2002 Mar;25(3):332-347.
4. Brown CV, Rhee P, Chan L, Evans K, Demetriades D, Velmahos GC. Preventing renal failure in patients with rhabdomyolysis: do bicarbonate and mannitol make a difference? J Trauma. 2004.