Effect of remifentanil infusion on haemodynamics and stress response to pre-bypass phase of paediatric cardiac surgery

ABSTRACT

Fifty-two infants and children under 5 years old were randomized to receive one of four remifentanil infusion rates [0.25, 1.0, 2.5, or 5.0 mug.kg-1 min-1]. Blood samples were obtained at induction, pre-surgery, 5 min after opening the chest and immediately pre-bypass. Whole blood glucose was measured at all time points, while cortisol and neuropeptide Y [NPY] were measured in the first and last samples. Heart rate and arterial pressure were also recorded. There was a significant increase in whole blood glucose 5 min after opening the chest and pre-bypass in patients receiving remifentanil 0.25 mug.kg-1 min-1, but not in those receiving higher doses. Increased remifentanil dosage was associated with reduced plasma cortisol during surgery. Baseline NPY showed considerable variation and there was no association between pre-bypass NPY and remifentanil dose. There was a significantly higher heart rate at the pre-bypass stage of surgery in the remifentanil 0.25 mug.kg-1 min-1 group compared with higher doses. Four out of five neonates with complex cardiac conditions showed severe bradycardia associated with remifentanil. From these data, it was concluded that in infants and children under 5 years, remifentanil infusions of 1 mug.kg-1 min-1 and greater can suppress the glucose increase and tachycardia associated with the pre-bypass phase of cardiac surgery; while 0.25 mug.kg-1 min-1 did not. Remifentanil should be used with caution in neonates with complex congenital heart disease