Frequency of Electrical Acupoint Stimulation on Hypotension During Induction

Hypotension is defined as a Mean arterial pressure (MAP) reduction of more than 20% from baseline or a MAP less than 65 mm Hg for at least 1 minute.

The baseline MAP is measured during the 5 minutes before start of intervention

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.

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.

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

assessed from the electrocardiography,High-frequency HRV (HF-HRV) at 0.15-0.4 Hz and low-frequency HRV (LF-HRV) at 0.04-0.15 Hz