Persistent lactic acidosis after chronic topical application of silver sulfadiazine in a pediatric burn patient: a review of the literature.

A 3-year old male who sustained 2(nd) and 3(rd) degree burns that covered approximately 60% TBSA presented to a large adult and pediatric verified burn center. On hospital day (HD) 26 of his stay, Candida fungemia was identified by blood culture, delaying operative management until HD 47. On HD 47, after his first operative intervention, the patient developed a persistent metabolic and lactic acidosis. On HD 66, a search for a cause of his osmol gap of 56 mOsm/kg revealed a potential source-propylene glycol. Previous studies have implicated the propylene glycol emulsifier in the silver sulfadiazine that was being applied to his skin as a rare cause of lactic acidosis in severely burned patients. Within 24 hours of stopping the silver sulfadiazine therapy, his lactic acidosis and osmol gap resolved; within 72 hours his metabolic acidosis resolved. Silver sulfadiazine is commonly used adjunct therapy in the treatment of 2(nd) and 3(rd) degree burns and generally has few adverse reactions. The absorption of propylene glycol systemically can rarely occur when applied to extensive burns, presumably due to the disruption of the skin barrier; the half-life of PG is 10 hours and can be prolonged with renal disease because ~50% of the sulfadiazine is excreted in the urine unchanged. When propylene glycol is present systemically, it is metabolized to lactic acid in the liver, which can cause a lactic acidosis. Several commonly used drugs also use propylene glycol as an emulsifier, including IV preparations of lorazepam, pentobarbital, phenobarbital, and phenytoin. In all of these clinical scenarios, including severe burn patients that are being treated with silver sulfadiazine, both lactic acid and propylene glycol levels should be measured to monitor for this rare, potentially serious co-morbidity.