Pearls & oy-sters: status epilepticus from hyperammonemia after lung transplant.

CASE REPORT A 64-year-old woman with familial pulmonary fibrosis underwent bilateral lung transplantation under general anesthesia with midazolam, propofol, and fentanyl. Her post-transplant immunosuppression regimen consisted of prednisone, azathioprine, and tacrolimus. She was initially alert and following commands but on postoperative day 3 became increasingly somnolent, necessitating reintubation. Sodium, renal and liver function tests, and CSF analysis (including opening pressure) were normal. Noncontrast CT scan of the head was unrevealing with no early evidence of cerebral edema. EEG showed diffuse delta with frequent 1to 2-Hz triphasic waves. Her somnolence was attributed to her tacrolimus level (66.8 ng/mL) and the medication was held with normalization of the level by postoperative day 4. On postoperative day 5, she had persistent arrhythmic twitching of her left arm that within a minute generalized to a full-blown convulsive status epilepticus. Multiple doses of Ativan, totaling 10 mg, and 20 mg/kg PE of fosphenytoin were administered, with cessation of seizures. An ammonia level was obtained and was unreadable at greater than 1,200 g/dL. AST was 36 U/L. Lactulose, rifaximin, and continuous venous-venous hemofiltration (CVVH) were initiated to normalize the ammonia level and continuous EEG monitoring was initiated. An intraparenchymal intracranial pressure (ICP) monitor was placed but the initial intracranial pressure was 4 mm Hg. Two hours after initial cessation of seizures, she had recurrent left arm twitching, which quickly generalized and was refractory to additional 4 mg/kg PE of fosphenytoin, maximal infusion rates of midazolam and propofol, and ultimately was controlled with pentobarbital infusion at a rate of 5 mg/kg/h, at which point the background changed from a pattern of generalized spike and waves to a completely suppressed background in the 1to 2-Hz range without reactivity. Clinical seizures became under control within 1 hour after onset. Full resolution of electrographic status epilepticus took 6 hours longer. At that time, propofol and midazolam were stopped. Lactulose, rifaximin, and CVVH were continued and arterial ammonia declined gradually. After arterial ammonia had normalized, pentobarbital was slowly weaned. Her ICP remained below 10 mm Hg with the exception of 2 isolated spikes to 19 mm Hg lasting several minutes each on postoperative days 8 and 9. A repeat CT scan of the head on postoperative day 11 showed lack of gray–white matter differentiation and absence of sulci (figure). When the pentobarbital was no longer detectable in her blood, the patient was declared brain dead.