Measurement of indocyanine green plasma disappearance rate by two different dosages

While using a transcutaneous system for assessment of liver function by indocyanine green plasma disappearance rate (ICG-PDR) in critically ill patients, we compared the agreement between ICG-PDR obtained by the recommended standard ICG dosage (0.5 mg/kg) and a reduced dosage (0.25 mg/kg).

Clinical study.

Intensive care unit of a university hospital.

Critically ill patients ( n=16, 5 female, 11 male) who underwent liver function monitoring by ICG-PDR for clinical indication.

We analyzed 31 pairs of ICG-PDR measurements by applying the recommended dosage (0.5 mg/kg, ICG-PDR(0.5)) and a reduced dosage (0.25 mg/kg, ICG-PDR(0.25)). For each comparative measurement either first 0.5 mg/kg or 0.25 mg/kg of ICG was injected in a random fashion and followed by the corresponding dosage 60 min later. All patients were sedated and mechanically ventilated via a tracheal tube. Each patient was monitored by an ICG finger clip which was connected to a liver function monitoring system (LiMon, Pulsion Medical Systems, Germany). ICG-PDR(0.25) was 2.7-25.0 %/min and ICG-PDR(0.5) 4.5-24.5 %/min, respectively. Linear regression analysis revealed ICG-PDR(0.25)=1.13.ICG-PDR(0.5)-0.66 %/min (r=0.95, p<0.0001) with a mean bias 1.0 %/min (standard deviation 2.5 %/min). The 15 min residual rates were also highly correlated ( r=0.92, p<0.0001) with a mean bias of 0.3%.

A reduced dosage of ICG (0.25 mg/kg) is sufficiently accurate for transcutaneous measurement of ICG-PDR in critically ill patients.