Frequency of Electrical Acupoint Stimulation on Hypotension During Induction

The area under the curve representing the change in mean arterial pressure during the induction period relative to the baseline.

The area under the curve (AUC) below baseline mean arterial pressure (MAP) is calculated as: ∑ (((Si - Sbaseline)+(Si-1 - Sbaseline))/2 × ΔX) where Sbaseline is the baseline MAP, Si is the MAP at the i-th minute (i = 1…15), and ΔX is the time interval between two measurements.

Time frame: from start of induction to 15 minutes after induction

The dosage of vasoactive drugs

Any MAP drop by more than 20% from baseline or a MAP less than 65 mm Hg for at least 1 minute within the first 15 minutes after general anesthesia induction triggered the administration of norepinephrine boluses (5 μg). If hypotension persisted after 2 boluses, a norepinephrine infusion (0.02-0.3 μg/kg/min) was initiated and continued until the MAP became stable and reached 65 mm Hg or higher. If hypotension reoccurred, 2 boluses of norepinephrine were repeated.

Time frame: from start of induction to 15 minutes after induction

lowest MAP

Time frame: from start of induction to 15 minutes after induction

standard deviation of R-R intervals (SDRR)

assessed from the electrocardiography, key index of heart rate variability (HRV)

Time frame: from start of induction to 15 minutes after induction

ratio of low-frequency HRV/high-frequency HRV (LF/HF ratio)