Prognostic value of the indocyanine green plasma disappearance rate in critically ill patients.

OBJECTIVE Measurement of the indocyanine green plasma disappearance rate (ICG-PDR) has been proposed as a clinical tool for the assessment of liver perfusion and function in transplant donors as well as a prognostic marker. In this study, we analyzed the prognostic value of the ICG-PDR in critically ill patients. DESIGN Retrospective analysis. SETTING Operative ICU of a university hospital. MEASUREMENTS AND RESULTS We analyzed 336 critically ill patients (120 female and 216 male; age range, 10 to 89 years; mean +/- SD age, 53 +/- 19 years) who were treated in our ICU between 1996 and 2000. All these patients were hemodynamically monitored by the transpulmonary double indicator (thermo-dye) dilution technique. Each patient received a femoral artery sheath through which a 4F flexible catheter with an integrated thermistor and fiberoptic was advanced into the abdominal aorta. The ICG-PDR was calculated using a computer system. For each measurement, 15 to 17 mL of 2% indocyanine green were injected in a central vein. Statistical analysis using the lowest value of the ICG-PDR in each individual showed that it was significantly lower in nonsurvivors (n = 168) than in survivors (n = 168) [median, 6.4%/min vs 16.5%/min; p < 0.001]. Sensitivity and specificity with respect to survival was analyzed by receiver operating characteristics. The area under the curve (AUC) as a measure of accuracy was 0.815 when using lowest the ICG-PDR in each patient. For ICU admission (data from 178 patients), AUCs were 0.680 for the APACHE (acute physiology and chronic health evaluation) II, 0.755 for the simplified acute physiology score (SAPS) II, and 0.745 for the ICG-PDR. CONCLUSION The ICG-PDR as a marker of liver perfusion and function is a good predictor of survival in critically ill patients: mortality increased with lower ICG-PDR values, and nonsurvivors had significantly lower ICG-PDR values than survivors. Sensitivity and specificity of the ICG-PDR on ICU admission with respect to survival was comparable to that of APACHE II and SAPS II scores.