Peri-operative plasma disappearance rate of indocyanine green after coronary artery bypass surgery

Splanchnic ischaemia and hepatic dysfunction are severe complications after coronary artery bypass grafting (CABG) and lead to increased morbidity and mortality. Non-invasive determination of the indocyanine green (ICG) plasma disappearance rate (PDR) offers an opportunity for the early diagnosis of hepato-splanchnic hypoperfusion. The aim of this study was to establish the postoperative time course of the ICG PDR in elective uncomplicated CABG surgery. After ethical approval and written informed consent, the data of 40 patients were analysed during this prospective study. Measurements of the ICG PDR and cardiac index (CI) in 40 patients undergoing elective CABG surgery were performed immediately after induction of anaesthesia, on admission to the ICU, six hours after admission to the ICU, and on the first postoperative day. Prior to surgery, baseline ICG PDR was 17.7 %/min (13.6-20.4) and baseline CI was 2.2 l/min/m(2) (1.9-2.4). All measurements after surgery showed a significantly higher PDR and cardiac index compared to the baseline measurements. The only patient with prolonged ICU treatment failed to show this increase in ICG PDR, although the CI did increase after surgery. We established normal values of ICG PDR after uncomplicated CABG surgery. The elevated ICG PDR observed in our patients was assumed to be an effect of an increased hepato-splanchnic blood flow due to an increase in the CI. Patients at risk of hepato-splanchnic hypoperfusion, displaying a missed increase or even a decrease in their ICG PDR after surgery might be at risk of hepatic hypoperfusion and in these selected patients the ICG PDR could serve as a tool to guide therapy or to select patients who might benefit from more invasive devices to monitor hepatosplanchnic perfusion and function.