Changes of heart vegetative tonus after intravenous administration of three different agents for induction of general anesthesia

Abstract

Background: Aim of the study. Evaluation of heart vegetative tonus changes after intravenous administration of propofol, midasolam or tiopental for induction of general anesthesia. Material and methods: The study was performed within Institute of Emergency Medicine and was approved by the Ethic Committee of the ”Nicolae Testemițanu” SUMPh. In the study groups were involved 141 patients scheduled for elective general surgery. With TLC 5000 Holter ECG there were registered LFun (Low Frequency) – marker of sympathetic heart tonus, HFun (High Frequency) – marker of parasympathetic heart tonus and the HFun/HFun ratio – marker of sympathetic-parasympathetic heart balance. The heart vegetative tonus was registered 5 minutes in baseline and 5 minutes after intravenous administration of 2,5 mg/kg propofol with 2,0 mkg/kg fentanyl (group 1); 0,2-0,3 mkg/kg midasolam with 2,0 mkg/kg fentanyl (group 2) or 7-8 mg/kg tiopental with 2,0 mkg/kg fentanyl (group 3). Results: Group 1: LFun enhanced from 66,8(95%CI62,6-70,9) to 72,0(95%CI 67,9-76,1) (p=0,004); HFun reduced from 33,2 (95%CI29,0-37,4) to 26,4(95%CI 20,4-34,3) (p=0,007) and the LFun/HFun ratio enhanced from 2,7(95%CI2,1-3,2) to 3,9(95%CI2,9-4,8) (p=0,003). Group 2: LFun reduced from 67,7(95%CI 62,9-72,5) to 52,4(95%CI 62,9-70,0) (p=0,14); HFun enhanced from 27,4(95% CI21,4-37,0) to 47,5(95%CI 30,4-37,4) (p=0,01) and the LFun/HFun ratio reduced from 3,1(95%CI2,4-3,8) to 1,1(95%CI0,6- 1,8) (p=0,02). Group 3: LFun enhanced from 65,5(95%CI 60,8-70,1) to73,5(95%CI 68,4-78,6)(p=0,001); HFun reduced from 34,5(95%CI29,8- 39,2) to 24,5(95%CI20,3-28,7)(p=0,001) and the LFun/HFun ratio enhanced from 2,7(95%CI 2,1-3,3) to 4,4(95%CI3,5-5,2) (p<0,001). Conclusions: Administration of propofol or tiopental for induction of general anesthesia is associated with enhanced heart sympathetic vegetative tonus. Administration of midasolam for induction of general anesthesia leads to the development of heart parasympathicotonia.