Treatment of Burn patients with underlying renal insufficiency

The treatment of severely burned patients is well documented and studied. Due to the loss of the overlying dermis/epidermis the degree of fluid loss in burn patients is considerable. The standard treatment paradigm mandates aggressive fluid administration. For the initial 24 hours following the injury, the amount of fluid required can be determined by following the "Parkland Formula".

Fluid requirement in first 24hrs = 4 x %TBSA Burned x Weight (kg)

Half of this fluid volume is to be infused over the first 8 hrs following the burn, while the remainder is infused over the remaining 16hrs. The Percent of Total Body Surface Area (%TBSA) is calculated using the rules of nine and does NOT include first degree burns. This approach is straight forward and easily applied to most burn patients, however in patients with underlying renal insufficiency who are unable to tolerate aggressive fluid administration this approach creates a true conundrum for the emergency physician.

This blog was posted after reviewing two articles which looked at "the incidence and mortality of burn patients with acute renal failure" and "burn patients who presented with acute renal failure requiring dialytic support and were treated by continuous renal replacement therapy". These articles were published in the Journal of Burn Care & Research and the Burn Journal, respectively. They are referenced at the end of this bog.

The first study evaluated 238 Burn ICU patients. 39.1% of these patients were found to have Acute Renal Failure (ARF) with (serum creatine levels >1.4 mg/dl). One in three of these required renal replacement therapy (2.3%). The overall mortality for the ICU burn patient with creatine levels >1.4 mg/dl was (44.1%) whereas patients without ARF was only (6.9%). This study also looked at the mortality of rhabdomyolysis in burn patients and found that burn patients with ARF and subsequent rhabdomyolysis had a very high mortality rate/poor survival. The study also found that early ARF held a worse prognosis then late ARF. Regardless, all of the surviving patients in this study who developed ARF had full recovery of renal function and did not require life long renal replacement therapy. Upon first evaluation of this study, its easy to extrapolate that patients with ARF will have higher mortality rates than non-ARF patients. However, the non-surviving patients in this study had higher percentages of TBSA burns, where older and had higher rate of inhalation burns.

The second study examined 970 burn patients, 16 (1.6%) of which developed acute renal failure and subsequently required renal replacement therapy. Although the cause and rate of the ARF was multifactorial, the initial approach of aggressive fluid administration was unchanged. The study determined that continuous renal replacement therapy was the modality of choice in burn patients suffering from ARF. The study looked at four different types of continuous renal replacement therapy: continuous arteriovenous haemofiltration and haemodiafiltration (CAVH and CAVHDF) and continuous venovenous haemofiltration and haemodiafiltration (CVVH and CVVHDF). The was no notable statistical difference in the four different forms of renal replacement therapy. Compared to other ICU patients with ARF the burn patient required longer duration of renal replacement therapy (24.2 ± 9.4 vs. 5.3 ± 0.8 days). Not surprisingly the burn patients also required a higher degree of fluid administration (8.2 ± 0.7 vs. 3.3 ± 0.2 l/day) compared to the non-burned ICU patients. The major complication that was noted in the burn patients was a higher degree of bleeding complications (56% vs. 15%). This is likely due to the thermal regulation complications that burn patients typically incur compared to their non-burned ICU counterparts. In this study, the overall mortality between the two groups was the same at (82%). The study concluded that when aggressive initial fluid resuscitation is applied following burn injury, that ARF rates are low, delayed and multifactorial. Once a burn patient develops ARF continuous renal replacement therapies appear to be the modality of choice.

Regardless of the findings in these studies, it is still prudent to be judicious in the initial fluid administration of any burn patient. This can be accomplished by strictly following the Parkland Formula. The emergency physician however must be mindful of the amount of fluid any patient who is volume sensitive is receiving and not hesitate in preparing patients for possible renal replacement therapy in the form of dialysis catheter placement or early involvement of proper consulting services.

References:

1) Mustonen, Kukka-Maaria MD; Vuola, Jyrki MD, PhD. Journal of Burn Care & Research: January/February 2008 - Volume 29 - Issue 1 - pp 227-237. "Renal Failure in Intensive Care Burn Patients (ARF in Burn Patients)"

2) M. Leblanca, b, Y. Thibeaulta, b, S. Quérin, a, b. Burn Journal: March 1997, Volume 23, Issue 2, Pages 160-165"Continuous haemofiltration and haemodiafiltration for acute renal failure in severely burned patients".

Thanks to Dr. John Hall for this post.