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19-09-2011 | Article

Crushing severity determines fluid volume needed for kidney protection

Abstract

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MedWire News: The volume of fluid needed to prevent acute kidney injury (AKI) in patients who sustain rhabdomyolysis during a disaster such as an earthquake varies with the extent of their muscle injuries, shows research.

"Unfortunately, most of the existing protocols regarding fluid therapy do not meet the demands of the real situation of a disaster's aftermath," say Safari Saeed (Tehran University of Medical Sciences, Iran) and team in the American Journal of Emergency Medicine.

"In fact, the present protocols of crush syndrome are more appropriate to the limited number of victims after the destruction of a building block or complex rather than the extensive threats of the deadliest earthquakes."

The researchers analyzed data on 638 patients who were hospitalized with rhabdomyolysis (creatine phosphokinase [CPK] ≥10,000 IU/l) caused by crushing during the Bam earthquake, which struck the Kerman province of Iran in 2003. AKI was defined as more than one serum creatinine value of at least 1.6 mg/dl, and this occurred in 21% of patients, 82% of whom needed dialysis.

In univariate analysis, rates of AKI rose in line with CPK level, time spent under rubble, and delay in receiving fluid therapy, but fell in line with the amount of intravenous fluid given per day during the first 5 days after injury.

The most striking reduction in AKI rates occurred with administration of between 1 and 3 L of fluid per day, with rates falling from about 40% to 20%. For 3 to 9 L of fluid, AKI rates only fell from 20% to 15%.

However, on multivariate analysis, receiving fluid volumes of 3 L or less did not affect patients' risk for kidney injury, whereas receipt of more than 6 L/day was associated with a 92% reduction in the risk for AKI and a 96% reduction in the need for dialysis.

Having a CPK level of at least 15,000 IU/L raised patients' risk for AKI 23.7-fold and their risk for needing dialysis 18.0-fold. Spending more than 5 hours under rubble raised their risk for AKI and needing dialysis 15.5- and 14.1-fold, respectively.

Delay to fluid administration did not affect patients' risk for kidney injury in the multivariate analysis.

These findings demonstrate "the need for justification of fluid therapy in earthquake-crushed victims based on trauma severity," say Saeed et al.

They recommend at least 6 L/day of prophylactic fluid for patients with severe rhabdomyolysis (CPK ≥15,000 IU/l), but say that smaller volumes, of 3-6 L/day, would be effective for less traumatized patients.

But the team also notes that at least 10% of patients developed kidney complications despite receiving large quantities of fluid, implying a role for other factors in acute kidney injury.

By Eleanor McDermid