Effects of dobutamine on hepatic metabolism in paediatric patients evaluated by LiMON^®

Introduction

Multiple organ dysfunction syndrome (MODS) is a major therapeutic challenge for intensive care physicians treating critically ill patients. The mortality rate in MODS still exceeds 50% despite recent improvements in supportive treatment in the intensive care unit. Abnormal perfusion of the liver can persist after resuscitation in critically ill children, leading to hepatic dysfunction. Since systemic haemodynamic measurements provide a poor estimate of splancnic blood flow, specific tools are required to assess the adequacy of tissue perfusion and oxygenation in critically ill children. These tools have allowed detection of splancnic hypoperfusion even in the absence of altered systemic hemodynamics.

Aim

To evaluate the effects of dobutamine on hepatosplacnic perfusion and hepatocytic clearance in critically ill children.

Patients and methods

After resuscitation involving volume expansion with NaCl 0.9%, 14 haemodynamically stable patients (median age: 9 years, median weight 28 kg, height 140 cm) were given an infusion of 6 μg/kg/min dobutamine for 1 hour. Hepatocytic clearance was assessed with plasma disappearance rate of indocyanine green (PDR dye) elimination at basal time (B0) and after 1 hour (B1). All measurements of PDR dye were made before dobutamine infusion and 1 hour after dobutamine infusion. Analgo-sedation was standard with remifentanyl (0.25 μg/kg/min)–midazolam (0.03 mg/kg/hour) and all patients were in mechanical ventilation with standard settings: pressure controlled with peak inspiratory pressure < 20 cmH₂O, mean airway pressure 10 cmH₂O, PEEP 5 cmH₂O.

Results

In all patients at baseline the PDR dye was: median 28.8% (range: 37–23.09%); PDR dye changed significantly after dobutamine infusion: 35.9% (range: 28.1–49.8%), with an increase in PDR dye of 22.14%. Haemodynamic values showed: baseline PVC median value 5 (range 2–14), mean blood pressure (MBP) 70 mmHg (range 47–84), HR 110 beats/min (range 78–150); after dobutamine infusion PVC median value 6 (range 4–15), MBP 84 mmHg (range 65–96), HR 121 beats/min (range 93–145).

Discussion

We have used the indocyanine green (ICG) elimination technique to assess hepatic perfusion. This approach relies on the assumption that hepatic elimination of ICG is flow-dependent. Variations in the plasma ICG disappearance rate therefore directly reflect variations in hepatic blood flow. In summary, our preliminary data show that dobutamine increases hepatocytic clearance in critically ill children.