Kim 2011.

Methods	Parallel‐group randomized trial, conducted in Korea. Study dates not reported.
Participants	264 adult women, with ASA physical status I to II, undergoing laparoscopic hysterectomy. Exclusion criteria were women receiving antiemetics within 24 h of surgery, obesity, neuromuscular, hepatic, or renal diseases, or a history of allergic reactions to the medications used during anaesthesia.
Interventions	Group 1 (group control): 2 surface electrodes placed over ulnar nerve on dominant upper extremity before induction of anaesthesia and removed after anaesthesia in the operating room. Applied 1 Hz single twitch stimulation during anaesthesia maintenance (n = 54). Group 2 (group ST): 2 surface electrodes stimulated the median nerve at P6 acupoint on dominant upper extremity before induction of anaesthesia and removed after anaesthesia in the operating room. Applied 1 Hz single twitch stimulation during anaesthesia maintenance (n = 52). Group 3 (group TOF): 2 surface electrodes stimulated the median nerve at P6 acupoint on dominant upper extremity before induction of anaesthesia and removed after anaesthesia in the operating room. Applied TOF stimulation every 15 seconds during anaesthesia maintenance (n = 53). Group 4 (group DBS): 2 surface electrodes stimulated the median nerve at P6 acupoint on dominant upper extremity before induction of anaesthesia and removed after anaesthesia in the operating room. Applied double‐burst stimulation every 20 seconds during anaesthesia maintenance (n = 53). Group 5 (group tetanus): 2 surface electrodes stimulated the median nerve at P6 acupoint on dominant upper extremity before induction of anaesthesia and removed after anaesthesia in the operating room. Applied tetanus stimulation at 50 Hz for 5 seconds every 10 min during anaesthesia maintenance (n = 52).
Outcomes	Nausea (0 ‐ 6 h), Vomiting (0 ‐ 6 h), rescue antiemetic (ondansetron 4 mg IV), side effects.
Notes	Group 1 considered as sham. Groups 2 ‐ 5 combined as 1 acustimulation group. "No side‐effects were reported from the electrical stimulation." Participants in the acustimulation group were more likely to be highly satisfied with PONV management (VAS 7 ‐ 10) at 24 h than sham group (91% versus 75%, P = 0.003). Authors declare no conflicts of interest. No details about funding support for study.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient details given.
Allocation concealment (selection bias)	Unclear risk	Insufficient details given.
Blinding of patients (performance bias) All outcomes	Low risk	"The patients, as well as the anesthesiologist and the nursing staff, were unaware of the patient grouping."
Blinding of healthcare providers (performance bias) All outcomes	Low risk	"The patients, as well as the anesthesiologist and the nursing staff, were unaware of the patient grouping."
Blinding of outcome assessor (detection bias) All outcomes	Low risk	Independent outcome assessor "was unaware of the patient randomization and of the neuromuscular monitoring mode."
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropouts for 264 participants recruited into study.
Selective reporting (reporting bias)	Low risk	All expected outcomes reported.
Other bias	Low risk	"Baseline characteristics of study participants were similar, as were intraoperative variables."