Multipoint transcutaneous electrical stimulation reduces median effective plasma concentration of propofol: A randomised clinical trial

BACKGROUND AND AIMS: Previous work shows that transcutaneous electrical stimulation (TES) has analgesic and sedative effects. However, it is unclear whether TES can affect the sedative effect of propofol or not. This study was designed to assess the effect of TES on median effective plasma concentration (Cp50) of propofol and haemodynamic changes before and after tracheal intubation. METHODS: 48 patients belonging to ASA I or II posted for thyroidectomy were randomly allocated into control and TES groups. Up-and-down method was used to determine Cp50 of propofol. The average concentration of propofol in each crossover was calculated and the average concentration of those six values was defined as Cp50 of propofol. RESULTS: Cp50 of propofol was 3.70 ± 0.28 μg/mL and 3.08 ± 0.31 μg/mL in control and TES groups, respectively (P < 0.05). There were no significant differences in MAP (90.3 ± 12.4 mmHg vs. 97.0 ± 10.8 mmHg, 94.2 ± 18.7 mmHg vs. 98.3 ± 16.6 mmHg and 84.9 ± 14.1 mmHg vs. 91.6 ± 16.2 mmHg) and HR (78.2 ± 11.3 b/min vs. 75.6 ± 9.5 b/min, 90.9 ± 15.4 b/min vs. 90.4 ± 14.9 b/min and 86.7 ± 13.7 b/min vs. 84.0 ± 15.9 b/min) at T0, T1 and T2 between two groups. In TES group, HR changes at T1 and T2 were significantly higher than those at T0. CONCLUSION: TES can make an assistant effect on sedation and decrease Cp50 of propofol. But the haemodynamic fluctuations in TES group, especially the HR changes, seem to be more obvious than those in control group.