Both glucose insulin potassium (GIK) and tri-iodothyronine (T3) may improve cardiovascular performance following cardiac surgery. The effects of combined treatment are unknown.
After obtaining local research ethics committee approval, we performed a randomised double-blind placebo-controlled trial on patients undergoing first time elective/urgent isolated CABG. Between January 2000 and September 2004, 440 patients were recruited and randomised to either placebo (5 percent dextrose) (n=160), GIK (40 percent dextrose, K+ 100 millimoles per litre, Insulin 70 units per litre) (75 millilitres per kilogram per hour) (n=157), T3 (0.8 micrograms per kilogram followed by 0.113 micrograms per kilogram per hour) (n=63) or GIK+T3 (n=60). GIK/placebo therapy was administered from time of entering theatre until 6 hours after removal of aortic cross clamp (AXC) and T3/placebo was administered for a 6-hour period from removal of AXC. Serial haemodynamic measurements were performed at baseline and up to 12 hours following removal of AXC.
Repeated measures ANOVA demonstrated a statistically significant increase in cardiac index (CI) in both the GIK and GIK/ T3 group in the first 6 hours compared with placebo (p<0.001 for both) and T3 therapy (p=0.009 and 0.029 respectively). No significant difference was observed between the two GIK treatment groups. T3 therapy led to an increase in CI versus placebo between 6 and 12 hours after AXC removal (p=0.01)) but combination therapy did not lead to any further increase in CI. Oxygen delivery but not consumption was increased in all GIK groups (p less than or equal to 0.005).
Treatment with GIK, T3 and GIK/T3 improves cardiovascular performance in patients undergoing CABG surgery. Combination therapy does not provide any additional haemodynamic effect.