Relationship between intra-abdominal pressure and indocyanine green plasma disappearance rate: hepatic perfusion may be impaired in critically ill patients with intra-abdominal hypertension

Background: Monitoring hepatic blood flow and function might be crucial in treating critically ill patients. Intra-abdominal hypertension is associated with decreased abdominal blood flow, organ dysfunction, and increased mortality. The plasma disappearance rate (PDR) of indocyanine green (ICG) is considered to be a compound marker for hepatosplanchnic perfusion and hepatocellular membrane transport and correlates well with survival in critically ill patients. However, correlation between PDRICG and intra-abdominal pressure (IAP) remains poorly understood. The aim of this retrospective study was to investigate the correlation between PDRICG and classic liver laboratory parameters, IAP and abdominal perfusion pressure (APP). The secondary goal was to evaluate IAP, APP, and PDRICG as prognostic factors for mortality. Methods: A total of 182 paired IAP and PDRICG measurements were performed in 40 critically ill patients. The mean values per patient were used for comparison. The IAP was measured using either a balloon-tipped stomach catheter connected to an IAP monitor (Spiegelberg, Hamburg, Germany, or CiMON, Pulsion Medical Systems, Munich, Germany) or a bladder FoleyManometer (Holtech Medical, Charlottenlund, Denmark). PDRICG was measured at the bedside using the LiMON device (Pulsion Medical Systems, Munich, Germany). Primary endpoint was hospital mortality. Results: There was no significant correlation between PDRICG and classic liver laboratory parameters, but PDRICG did correlate significantly with APP (R = 0.62) and was inversely correlated with IAP (R = -0.52). Changes in PDRICG were associated with significant concomitant changes in APP (R = 0.73) and opposite changes in IAP (R = 0.61). The IAP was significantly higher (14.6 +/- 4.6 vs. 11.1 +/- 5.3 mmHg, p = 0.03), and PDRICG (10 +/- 8.3 vs. 15.9 +/- 5.2%, p = 0.02) and APP (43.6 +/- 9 vs. 57.9 +/- 12.2 mmHg, p < 0.0001) were significantly lower in non-survivors. Conclusions: PDRICG is positively correlated to APP and inversely correlated to IAP. Changes in APP are associated with significant concomitant changes in PDRICG, while changes in IAP are associated with opposite changes in PDRICG, suggesting that an increase in IAP may compromise hepatosplanchnic perfusion. Both PDRICG and IAP are correlated with outcome. Measurement of PDRICG may be a useful additional clinical tool to assess the negative effects of increased IAP on liver perfusion and function.