Sites 2014.

Methods	2‐group RCT comparing peppermint spirit aromatherapy to controlled breathing
Participants	42 adult surgical patients (16 aromatherapy/26 controlled breathing) "18 years and older, male or female, of any ethnic background, ASA status I or II, able to breathe through their nose, capable of verbalizing occurrences of nausea and/or vomiting, scheduled for laparoscopic, ENT, orthopedic, or urological day surgery procedures undergoing general anaesthesia with intubation. Exclusion criteria included nausea and/or vomiting within 24 hours of admission, history of alcoholism, allergy to menthol or peppermint, weekend or emergent surgeries, department of correction clients, pregnant women, patients taking disulfiram (Antabuse) or metronidazole (Flagyl), and minors." Setting: PACU or day surgery unit, rural hospital, USA
Interventions	"Upon initial complaint of PONV, either in PACU or Day Surgery, all subjects were instructed to inhale deeply through their nose to the count of 3, hold their breath to the count of 3, and exhale to the count of 3. A single treatment was composed of 3 repetitions of this deep breathing. PONV symptoms were reassessed 5 minutes after initial complaint, and if symptoms persisted a second treatment was administered. At 10 minutes following initial complaint, symptoms were reassessed." Participants randomized to aromatherapy also received peppermint spirit vapour from a vial held under their nose during controlled breathing, participants in the controlled breathing group received a similar vial without peppermint spirit. "A 13‐dram vial containing a cotton braid impregnated with 500 microlitres of pharmacy‐grade peppermint spirits (Humco, Peppermint Spirits USP: ethyl alcohol 82%, NF Grade peppermint leaf extract, peppermint oil, purified water) was placed under the nostrils at midseptum of subjects randomised to the AR group during the controlled breathing treatments. A sham vial without peppermint was used with CB subjects while they were receiving treatments."
Outcomes	Nausea severity as measured by descriptive ordinal scale (0 = no nausea, 10 = worst possible nausea) at initial complaint, 5 min and 10 min. "Treatment effectiveness was equated with a DOS score of 0 postintervention. Efficacy was a measure of no postintervention antiemetic rescue desired by subjects regardless of their DOS score."
Notes	Unequal group sizes, likely due to study design. Addtional information requested. No information on funding sources
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"A computer generated random number table was used to determine subject assignment" Comment: likely done
Allocation concealment (selection bias)	Unclear risk	Probably not done: no documentation of allocation concealment in an otherwise well‐documented study
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: a sham aromatherapy vial without peppermint was used in the controlled breathing group, however due to the odour of the peppermint, the group allocation would have been immediately apparent to both the nurse (who delivered the treatment and assessed the outcomes) and the participant.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: a sham aromatherapy vial without peppermint was used in the controlled breathing group, however due to the odour of the peppermint, the group allocation would have been immediately apparent to both the nurse (who delivered the treatment and assessed the outcomes).
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: does not appear to have been an issue once participants had entered into the study phase. Outcome data reported for all participants who received the treatment.
Selective reporting (reporting bias)	High risk	"The study evaluated a single episode of PONV whether it occurred in PACU or Day Surgery." Comment: participants who experienced multiple episodes of PONV did not have those recorded.
Other bias	Low risk	Comment: no other sources of bias apparent