Berger 2017.

Methods	Design: parallel (2 arms) Country: Austria Multisite: no International: no Treatment duration: not stated Follow‐up: 48 hours Rate of ascent (m/h): unclear Final altitude reached: 3450 m AMS scale: Lake Louise Consensus Symptoms score (LLS) + AMS‐C Score
Participants	40 participants enrolled (healthy lowlanders, non‐smoking). None of the participants had an altitude exposure > 2000 m within 30 days before the study, and none of them took any regular medication Exclusion criteria: participants with a history of migraine Participants randomized to RIPC protocol (n = 20, 50%) Sham protocol (n = 20, 50%) 2 participants were excluded after 25 and 48 hours due to severe AMS Main characteristics of participants Age (mean, SD): RIPC group = 35 years (10), sham group = 32 years (11) Number of men/women: RIPC group = male 8, female 12; sham group = male 7, female 13 Body mass index (mean, SD): RIPC group = 22.3 ± 2.2; sham group = 22.7 ± 2.2
Interventions	RIPC group (intervention): 4 cycles of lower limb ischaemia, induced by inflation of 2 thigh cuffs to 200 mmHg. Cuffs were left inflated for 5 minutes, followed by 5 minutes of deflation. Sham group (control): 4 cycles of sham ischaemia, induced by inflation of 2 thigh cuffs to 20 mmHg. Cuffs were left inflated for 5 minutes, followed by 5 minutes of deflation. Both protocols were performed al low altitude (750 m) and were completed approximately 30 minutes before ascent.
Outcomes	Outcomes were not pre‐defined as primary or secondary Proportion of participants considered as AMS‐positive Assessment of systolic pulmonary artery pressure and haemodynamics Blood gas analysis Plasma levels of total oxidant and antioxidant capacity Plasma levels of ascorbic acid
Notes	Trial registration: not stated Sponsor: not stated Role of sponsor: not stated A priori sample size estimation: yes Conducted: not stated Declared conflicts of interest: yes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information to score this item as low or high risk of bias Quote: "subjects were randomly assigned to undergo either RIPC or sham preconditioning (...)" Page 5
Allocation concealment (selection bias)	Unclear risk	Insufficient information to score this item as low or high risk of bias
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "subjects were informed that the aim of the study was to explore differences between preconditioning by ischaemia of the arterial plus venous versus the venous vasculature alone. The investigator who performed the preconditioning procedure was excluded from the assessment of other study data" Page 6
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information to score this item as low or high risk of bias
Incomplete outcome data (attrition bias) All outcomes	Low risk	2 patients (RIPC group) were excluded from analysis after 25 hours of follow‐up. However, these exclusions did not affect the estimation of AMS cases and severity (measured at 24 hours)
Selective reporting (reporting bias)	High risk	Patient‐important outcomes, such as adverse events, were not reported
Other bias	Low risk	No additional biases were identified