AAST consensus statement on critical care-related aspects of rhabdomyolysis patients

In what patient population should rhabdomyolysis be suspected?

Trauma patients

Recommendation

Rhabdomyolysis should be suspected in patients with a large burden of traumatic injury involving muscular tissue, especially patients with crush injuries involving the extremities or mangled extremities. Patients with vascular injuries or muscle ischemia with subsequent reperfusion are also at higher risk for rhabdomyolysis.

Metabolic etiologies

Recommendation

Rhabdomyolysis should be suspected in any patient with a medical condition causing increased metabolic demands on myocytes in excess of the available supply of ATP. This may result from extreme exertional demands on skeletal muscle from exercise, exogenous agents such as drugs or toxins, genetic defects or myopathies affecting the muscle cell, and infections. 

What clinical findings are expected with rhabdomyolysis?

Recommendation

Rhabdomyolysis presentation may vary from asymptomatic to commonly implicated clinical features, including acute muscle weakness, pain/tenderness, and swelling (dolor, tumor) of the affected extremity or body region. Darkened (tea-colored) urine may be an additional common finding. A low threshold of clinical suspicion in the proper laboratory and historical context is warranted to initiate appropriate therapy. 

What laboratory findings aid in the diagnosis of rhabdomyolysis?

Recommendation

The most commonly implicated variables include elevated serum concentrations of CK (>5× the upper limit of normal or >1000 IU/L), myoglobin, lactate dehydrogenase (LDH), potassium, creatinine, and aspartate aminotransferase (AST). Elevated urine myoglobin provides additional evidence. A low threshold of suspicion in the proper clinical context is warranted to initiate appropriate therapy. A strategy for disease monitoring with serial CK measurement should be additionally undertaken. Interval CK values should be followed until a peak concentration is identified (typically at 24–72 hours), discontinued once the CK is reliably downtrending. 

What is the optimal crystalloid type, rate of administration, and urine output goals to prevent AKI in rhabdomyolysis?

Recommendation

Either lactated Ringer's solution or saline (0.9% or 0.45%) is an acceptable fluid for resuscitation in rhabdomyolysis. A starting rate of 400 mL/hour can be initiated, with goal-directed therapy of urine output of 1 mL/kg/hour to 3 mL/kg/hour, and up to 300 cc/hour. 

Are diuretics and/or bicarbonate administration beneficial?

Recommendation

Clinical studies evaluating the efficacy of sodium bicarbonate and/or diuretic use (mannitol, loop diuretics) for prevention of rhabdomyolysis-induced AKI are limited by a lack of appropriate control groups, standardized definitions, retrospective design, and low statistical power. Given these significant limitations, the use of sodium bicarbonate or diuretics for prevention of AKI in rhabdomyolysis is not recommended.

What electrolyte abnormalities should be expected and what are the optimal methods for management?

Recommendation

Hyperkalemia, hyperphosphatemia, and hypocalcemia are electrolyte abnormalities most commonly encountered when treating rhabdomyolysis. Correcting biochemical equilibrium and electrolytes during rhabdomyolysis should proceed meticulously to avoid complications from treatment. Hyperkalemia is the electrolyte abnormality that requires timely correction to reduce risk of cardiac arrhythmia.

What is the role of RRT in rhabdomyolysis?

Recommendation

There is no role for RRT (either continuous (CRRT) or intermittent) in rhabdomyolysis to prevent AKI. The utilization of RRT in patients with rhabdomyolysis should be based on traditional indications for AKI and the degree of renal impairment.

In patients with rhabdomyolysis who develop AKI and need RRT, either CRRT or intermittent RRT should be used based on the degree of renal impairment and the clinical status of the patient. There are no recommendations regarding RRT modalities (filtration vs. diffusion), filter type (low vs. high cut-off membranes), or high-flow versus low-flow dialysis. 

What complications should be suspected by clinicians treating rhabdomyolysis?

Recommendation

Clinicians should monitor for a variety of complications, ranging from an asymptomatic elevation of muscle protein to an accumulation of electrolyte imbalances, edema, and toxic cellular components. Morbidity can present early or late, including hyperkalemia, hepatic dysfunction, cardiac dysfunction, AKI, acute renal failure (ARF), disseminated intravascular coagulation (DIC), and compartment syndrome. AKI is the most common systemic complication of rhabdomyolysis and is responsible for most of the morbidity and mortality associated with rhabdomyolysis.

Can prediction scoring be used in rhabdomyolysis?

Recommendation

The risk of AKI, RRT, and/or in-hospital mortality in patients with rhabdomyolysis can be estimated using admission demographic, clinical, and laboratory variables. Risk prediction scores may not directly influence treatment; however, they may be useful in estimating prognosis and setting expectations.

As no single laboratory value is sufficient to predict the course of rhabdomyolysis, a combined index of metrics, the McMahon Score, may be calculated at admission for prognostication.³ A score greater than or equal to 6 is predictive of a need for high-volume fluid resuscitation, RRT, and death.

"Rhabdomyolysis is a relatively uncommon but important condition seen in critically ill and injured patients. Surgical critical care providers should be familiar with the less frequently encountered metabolic etiologies of rhabdomyolysis, in addition to the well-known traumatic causes," wrote the authors.

"The diagnosis is made with a combination of clinical and laboratory findings and should lead to prompt intervention to halt any processes causing muscle damage and to prevent or treat known complications of the disease."

"Although traditional therapies such as urine alkalinization and diuresis are often employed in an effort to prevent rhabdomyolysis-associated AKI, evidence-based treatments with outcome benefits are lacking," the authors concluded. "There is a critical need for quality research."

Reference:

Kodadek L, Carmichael II SP, Seshadri A, et alRhabdomyolysis: an American Association for the Surgery of Trauma Critical Care Committee Clinical Consensus DocumentTrauma Surgery & Acute Care Open 2022;7:e000836. doi: 10.1136/tsaco-2021-000836