Arnberger 2007.

Methods	Parallel‐group randomized trial, conducted in Switzerland and Austria. Study dates not reported.
Participants	220 women undergoing elective gynaecological and abdominal laparoscopic surgery of more than 1 hour duration. Exclusion: pregnant and breast‐feeding women, and women with eating disorders, obesity (BMI > 35kg/m²), severe renal or liver impairment, central nervous system injury, vertebrobasilar artery insufficiency, vestibular disease, cytostatic therapy, and preoperative vomiting or antiemetic therapy. No participant withdrew from study.
Interventions	P6 group: during anaesthesia, neuromuscular blockade was monitored by a conventional nerve stimulator at a frequency of 1 Hz over the median nerve (first electrode 1 cm proximal to P6 acupoint and second electrode placed 2 cm distal to the P6 acupoint) on the dominant hand (n = 110). Sham group: during anaesthesia, neuromuscular blockade was monitored by a conventional nerve stimulator at a frequency of 1 Hz over the ulnar nerve (first electrode 1 cm proximal to the point at which the proximal flexion crease of the wrist crosses the radial side of the tendon to the flexor carpi ulnaris muscle at the volar side of the wrist and second electrode placed 3 cm proximal to the distal electrode) on the dominant hand (n = 110).
Outcomes	Nausea (0 ‐ 24 h), vomiting (0 ‐ 24 h), risk of rescue antiemetic drug (0 ‐ 24 h), risk of adverse effects.
Notes	Rescue antiemetic was ondansetron 4 mg IV if 2 or more episodes of vomiting or persistent nausea; with repetition after 2 hours. No local irritation, redness, contact dermatitis or muscle ache (side effects) were recorded. Nausea (0 ‐6 h), vomiting (0 ‐ 6 h), and incidence of rescue antiemetic (0 ‐ 6 h) also reported. Support was provided solely from institutional sources. Authors declared no conflict of interests.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"After induction of anaesthesia, patients were assigned to one of two groups using a set of computer‐generated random numbers".
Allocation concealment (selection bias)	Low risk	"The assignments were kept in sealed, sequentially numbered envelopes until used, and the envelope numbers with the assignment were recorded".
Blinding of patients (performance bias) All outcomes	Low risk	"Patients and PONV evaluators were not informed of the group assignments".
Blinding of healthcare providers (performance bias) All outcomes	High risk	"The attending anaesthesiologist could not be blinded to the group assignment, but he or she was not involved with the PONV assessment".
Blinding of outcome assessor (detection bias) All outcomes	Low risk	"Patients and PONV evaluators were not informed of the group assignments".
Incomplete outcome data (attrition bias) All outcomes	Low risk	"Two hundred twenty patients were recruited for this study without any dropout over the observation period".
Selective reporting (reporting bias)	Low risk	All expected outcomes reported.
Other bias	Low risk	Baseline characteristics were comparable. "Demographic and morphometric characteristics and factors likely to influence PONV were similar in the two groups".