Table 1.

The study schedule for enrollment, treatments, outcome measurements, and data collection.

Study period
Timepoint	Enrollment	Allocation	Post-allocation
Pre-2	0	Pre-1 (t0)	Pod-0 (t1-t2)	Pod-1 (t3)	Pod-2 (t4)	Pod-3 (t5)	Pod-5 (t6)	Pod-30 (t7)
Enrollment
Inclusion criteria	☑
Exclusion criteria	☑
Informed consent	☑
Randomization
Allocation			☑
Interventions
Active-taVNS group				☑	☑	☑
Sham taVNS group				☑	☑	☑
Outcome measurement
ALT			☑			☑		☑
AST			☑			☑		☑
TBA			☑			☑		☑
DBIL			☑			☑		☑
TBIL			☑			☑		☑
BUN			☑			☑		☑
Cr			☑			☑		☑
IL-6			☑			☑
TNF-α			☑			☑
FRAIL			☑
NRS					☑	☑		☑	☑
CAM			☑		☑	☑		☑	☑
SAS			☑		☑	☑		☑	☑
I-FEED					☑	☑	☑	☑
FSS			☑		☑	☑		☑	☑
QoR-15			☑		☑	☑		☑	☑
Adverse events			☑	☑	☑	☑	☑	☑	☑

According to SPIRIT 2013 statement: defining standard protocol items for clinical trials. Pre, preoperative day; Pod, postoperative day; ALT, Alanine aminotransferase; AST, Aspartate aminotransferase; TBA, Total bile acids; TBIL, Total bilirubin; DBIL, Indirect bilirubin; BUN, Blood Urea nitrogen; Cr, Creatinine; IL-6, Interleukin-6; TNF-α, tumor necrosis factor-α; FRAIL, Fatigue, Resistance, Ambulation, Illness and Loss of Weight Index; NRS, Numerical Rating Scale; CAM, The Confusion Assessment Method; SAS, Simpson-Angus Scale; IEED, Intake, feeling nauseated, emesis, exam and duration of symptoms; FSS, Fatigue Severity Scale; QoR-15, Quality of Recovery-15.