Profound Decrease of Liver Maximum Function Capacity Test of Isoflurane Sedated Patients: A Report of Three Cases

Abstract Background: Recently, inhaled sedation and liver function capacity measurement using 13C-methacetin breath test (LiMAx) have become an integral part of intensive care. The aim of this report is to present the results of LiMAx-testing during isoflurane sedation, which were unexpectedly low. The findings are discussed in view of the available literature.Case presentation: We present a series of three patients in a university hospital surgical intensive care unit who had received inhaled isoflurane sedation by the Anaesthetic Conserving Device after trauma, sepsis or pulmonary hemorrhage. When isoflurane was administered, LiMAx values decreased profoundly (1 to 71 µg/kg/h), indicating significant liver damage. Before and after isoflurane administration, more plausible LiMAx values between 151 and 496 µg/kg/h were obtained, indicating only minor impairment of normal liver function. Neither the progression of the associated laboratory parameters (alanine aminotransferase, aspartate aminotransferase, international normalized ration, creatinine, bilirubin, lactate) nor the clinical condition (absence of ascites, hepatic coagulation disorders or icterus) were suggestive of temporary liver damage of this severity.Conclusion: Measurement of enzymatic liver function capacity is practicable in intensive care patients and may help to determine liver function in different conditions. Unexpectedly low LiMAx values in isoflurane sedated patients may be caused by reduced cytochrome P450(CYP)1A2 enzyme activity due to a severe disease pattern, or by interaction of isoflurane with CYP1A2 or with the breath test itself. We propose that, until the breath test on enzymatic liver function has been validated in the critical care setting, LiMAx-test results should be interpreted with caution in patients sedated with isoflurane.