Klein 2004.

Methods	Parallel‐group randomized trial, conducted in Canada. Study dates not reported.
Participants	152 people undergoing coronary artery bypass graft or valvular surgery. Exclusion: past history of hiatus hernia, heartburn, or previous gastric surgery, morbid obesity, taking antiemetic medications, H₂ receptor antagonist, or proton pump inhibitors. No details about withdrawals or loss to follow‐up.
Interventions	Acupressure wristbands on P6 acupoint on both wrists before induction of anaesthesia, removed 24 h after extubation (n = 75). Sham acupressure wristbands on P6 acupoint of both wrists before induction of anaesthesia, removed 24 h after extubation. Sham group had band without a bead placed on P6 acupoint (n = 77).
Outcomes	Nausea (0 ‐ 24 h), vomiting (0 ‐ 24 h), risk of rescue antiemetic drug, risk of adverse effects.
Notes	Rescue antiemetic was dimenhydrinate 50 mg IV for participants who reported moderate or severe nausea, or who experienced retching or vomiting. No significant adverse effects reported in either group. No details about any declarations of interest among authors. Acupressure bands were provided by Sea Band, United Kingdom.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Patients were randomized by computer‐generated random number tables to either acupressure or placebo control groups".
Allocation concealment (selection bias)	Unclear risk	Insufficient information.
Blinding of patients (performance bias) All outcomes	Low risk	Authors took adequate steps to make interventions appear similar.
Blinding of healthcare providers (performance bias) All outcomes	Low risk	"The anaesthesiologist caring for the patient was not aware of group allocation".
Blinding of outcome assessor (detection bias) All outcomes	Low risk	"All patients were assessed for nausea and vomiting by nursing staff in the intensive care unit, who were unaware of treatment allocation".
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing data reported for the 152 participants analysed.
Selective reporting (reporting bias)	Low risk	Reported all expected outcomes.
Other bias	Low risk	Baseline characteristics were comparable. "There were no differences between the 2 groups with regard to demographic data and surgical characteristics".