Indocyanine green elimination rate detects hepatocellular dysfunction early in septic shock and correlates with survival

Abstract

Objective 

To determine whether indocyanine green clearance is an early indicator of hepatocellular injury in septic shock and to assess its predictive value.

Design 

Observational study with prospective data collection.

Setting 

Traumatology and critical care unit in a city hospital, staffed by traumatology and intensive care clinicians.

Patients 

Twelve patients in septic shock who survived at least 2 months (group S) and nine patients who died within 2 wks (group N).

Interventions 

Routine resuscitation from septic shock (surgery, fluid loading, and administration of catecholamines and antibiotic drugs).

Measurements and Main Results  

Pulmonary artery occlusion pressure, cardiac index, oxygen delivery index, oxygen consumption index, and the indocyanine green elimination rate constant (K_ICG; or the slope of the loge [indocyanine green concentration] vs. time curve) 3–9 mins after injection were measured within 12 hrs of the onset of hypotension, then at 24 hrs, and every 24 hrs thereafter. Alanine aminotransferase and total bilirubin were measured on day 0 and day 1. Volume of fluid administered and duration of shock were the same in survivors and nonsurvivors. The oxygen consumption index was higher in survivors at 12 hrs, but no intergroup difference in pulmonary artery occlusion pressure, cardiac index, or oxygen delivery index was significant at any time point. K_ICG in nonsurvivors was lower than in survivors both initially and after 24 hrs, and it was subnormal in all patients except one survivor (p < .05). The K_ICG increased between 24 and 120 hrs in 11 survivors but progressively decreased and remained below 0.05 in seven nonsurvivors. The remaining two nonsurvivors died within 24 hrs of the initial measurement of K_ICG, which was >0.05. Alanine aminotransferase and total bilirubin were less sensitive measures of hepatic dysfunction in the first 24 hrs than the K_ICG.

Conclusions 

The K_ICG can identify reversible liver injury in septic shock, suggesting good prognosis. Either failure to increase the K_ICG within 120 hrs or an extremely low K_ICG is a poor prognostic sign.