Hyperammonemia After Lung Transplantation: A Rare and Fatal Complication

SESSION TITLE: Transplantation SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 31, 2017 at 01:30 PM - 02:30 PM INTRODUCTION: Hyperammonemia clinically presents with altered mental status and is associated with a high rate of morbidity and mortality. In adults, it is most commonly a consequence of secondary hepatic dysfunction but it may also represent the late diagnosis of a primary inborn error of metabolism. In rare instances, however, hyperammonemia may develop as a complication following organ transplantation, including lung transplantation. The clinical course and underlying pathophysiology of hyperammonemia after lung transplantation is poorly understood. CASE PRESENTATION: A 63 year old woman with a history of COPD underwent a single left lung transplant. Immediately prior to transplant she required 1L of oxygen support at night, had no clinical evidence of infection and was cognitively intact. She was extubated on postoperative day (POD) 2, however, on POD 3 she became increasingly somnolent. On POD 6 her mental status continued to deteriorate and the patient was re-intubated. At time of intubation, a serum ammonia level was 133 umol/dL and rapidly increased to 197 umol/dL within a day. Upon discovery of the elevated ammonia levels, calcineurin inhibitors were held, bowel decontamination was initiated, and a bronchoscopy with bronchoalveolar lavage (BAL) was performed. Subsequently doxycycline was empirically started to treat possible infection with urea-splitting organisms, ammonia scavengers were started, and continuous renal replacement therapy (CRRT) was initiated. BAL samples detected Ureaplasma on PCR and culture and Mycoplasma hominus on culture. Ammonia levels began to trend down and ammonia scavengers and CRRT were discontinued. By POD 18 repeat BAL cultures for Mycoplasma and Ureaplasma were negative and ammonia level returned to normal. Mental status was normalizing by POD 20. Hospitalization progressed without recurrence of hyperammonemia but the patient had other complications and succumbed to her illness on hospital day 40. DISCUSSION: An acute elevation of ammonia levels is a rare complication after lung transplantation that remains poorly understood. Etiologies for this include an unmasking of urea cycle disorders, effects of immunosuppressive medications, or infections with urea-splitting organisms such as Mycoplasma or Ureaplasma. Current treatment practices target each of these potential etiologies. CONCLUSIONS: The development of hyperammonemia after lung transplantation is an often fatal complication of the transplant process. A multi-modal treatment approach is required to achieve survival in this critically ill patient population. Prompt discontinuation of calcineurin inhibitors, enhanced ammonia elimination, and evaluation for and treatment of urea-splitting organisms should be considered in all post lung transplant patients presenting with hyperammonemia. Reference #1: Chen, C., et al., Hyperammonemia Syndrome After Lung Transplantation: A Single Center Experience. Transplantation, 2016. 100(3): p. 678-84. DISCLOSURE: The following authors have nothing to disclose: Benjamin Henkle, William Amundson, Patrick Arndt No Product/Research Disclosure Information