Dynamic determination of functional liver capacity with the LiMAx test in post‐cardiac arrest patients undergoing targeted temperature management—A prospective trial

Background Transiently increased transaminases is a common finding after cardiac arrest but little is known about the functional liver capacity (LiMAx) during the post‐cardiac arrest syndrome and treatment in the intensive care unit (ICU). The aim of this trial was to evaluate liver function capacity in post‐cardiac arrest survivors undergoing targeted temperature management (TTM) in ICU. Methods Thirty‐two post‐cardiac arrest survivors were prospectively included with all patients undergoing TTM at 33°C for 24 hours. Blood samples were collected, and LiMAx testing was performed at days 1, 2, 5, and 10 post‐cardiac arrest. LiMAx is a non‐invasive, in vivo, dynamic breath test determining cytochrome P450 1A2 (CYP1A2) capacity using intravenous (IV) 13 C‐methacetin, thus reflecting maximum liver function capacity. Static liver parameters were determined and compared to LiMAx values. Results A typical pattern of transiently, mildly increased transaminases was demonstrated without fulfilling the criteria for hypoxic hepatitis (HH). CYP1A2 activity was reduced with slow normalization over 10 days (lowest median 48 hours after cardiac arrest: 228.5 (25‐75 percentile 105.2‐301.7 μg/kg/h, P  < .05). Parameters reflecting the liver synthetic function were not impaired, as assessed by, in standard laboratory testing. Conclusion Liver functional capacity is impaired in patients after cardiac arrest undergoing TTM at 33°C. More data are needed to determine if liver functional capacity may add relevant information, especially in the context of pharmacotherapy, to individualize post‐cardiac arrest care.