Serum Ammonia Screening and Donor Mollicutes Detection for Hyperammonemia Syndrome Post-Lung Transplantation: A Prospective Observational Study.

Abstract

Hyperammonemia syndrome (HS) is a rare but potentially fatal complication of lung transplantation (LT). Optimal screening methods are unknown. Here we investigated serum ammonia screening (SAS) for HS and compared it with polymerase chain reaction (PCR) for Mollicutes (Urease-producing bacteria). All LT recipients from July 2019 to February 2020 and October 2021 to November 2022 with available donor bronchial wash samples from the LT biobank were included. Mollicutes PCR was performed using 2 commercially available kits. Daily ammonia serum levels were measured for the first 14 days. Recipients were prospectively followed for HS for 30 days post-LT. HS was defined by new neurological symptoms and the presence of elevated serum ammonia (>1 × >70 µmol/L). Of 241 LT recipients, 5 (2%) developed HS within the first month post-LT. Median time to HS was 8 (interquartile range, 5-10) days. All HS was diagnosed within the first 14 days post-LT, while daily SAS was in place. Ammonia was confirmed elevated (>1 × >70 µmol/L) in 4% (9/241) during follow-up; however, outside of HS, 4 were found to be related to liver disease. Donor and recipient Mollicutes PCR was positive in 8% (19/241) and 1% (1/72), respectively, at transplant. Donor Mollicutes PCR, in contrast to recipient Mollicutes PCR, was associated with HS but only in 2 of the 5 HS cases. No HS patient died within 90 days post-LT. HS was a rare complication in our LT cohort. Daily post-LT SAS might add to early HS diagnosis and treatment and is potentially associated with improved outcome. Donor screening with Mollicutes PCR has limited predictive value for HS post-LT.