Perfusion index for clinical monitoring of noxious stimuli

Objective To assess the role of perfusion index in monitoring noxious stimuli during total intravenous general anesthesia.Methods Thirty-six patients undergoing gynecological celiotomy were randomly assigned to three groups according to different dosages of fentanyl used(n=12): Group Ⅰ,fentanyl 1 μg/kg;Group Ⅱ,fentanyl 3 μg/kg,and Group Ⅲ,fentanyl 5 μg/kg.Anesthesia was induced by target-controlled infusion(TCI) of propofol,different doses of fentanyl and 0.1 mg/kg vecuronium.Tracheal intubation was performed when effect compartment concentration(ECC) of propofol reached 3 μg/mL(the beginning of tracheal intubation) and skin incision was done when reached 3.9 μg/mL(the beginning of incision).The heart rate(HR),mean arterial pressure(MAP),bispectual index and perfusion index were record at the following time points: baseline,concentration of propofol(1,2 and 3 μg/mL),process of intubation(10,30,60 s) and process of skin incision(10,30,60,and 120 s).Results When there were noxious stimuli,the perfusion index decreased remarkably and immediately;HR increased significantly only after intubation and MAP increased only after incision.The perfusion indices were obviously changed in almost every patients,with the lowest values appearing at(43±7) s after intubation and(17±5) s after incision.During the intubation,perfusion index decreased by more than 20% of the baseline value in 89%(34/36) patients,and decreased by more than 30% in 31 patients.The proportion of patients with decreased HR was significantly higher than that with increased HR(n=20,P=0.002).During the incision,perfusion index decreased by more than 20%,with those in 35 patients decreased by more than 30%.The proportion of patients with decreased perfusion index significantly higher than those with increased MAP(n=13,P0.01).Conclusion Perfusion index can reflect the noxious stimuli of the intubation and the incision effectively and immediately.(Shanghai Med J,2010,33: 151-155).