Table 3.

Characteristics of included studies

Authors/Year	Country	Study Design	Participants	Comparison	Device	Outcomes
Rees and Willis 1988 [47]	UK	Simulation based non-randomised crossover study	8 medical doctors (7 anaesthetists and one cardiologist)	Chest compression (CC) in various angles; 0°, 27°, 32°, 49° and 90° left lateral tilt (LTT)	Calibrated force transducer fitted on the plane	- Resuscitative (compression) force as % of body weight (mean, standard deviation [SD])
Goodwin 1992 [46]	UK	Simulation based non-randomised crossover study	18 midwives	CC in supine without manual left uterine displacement (LUD) vs. CC in lateral tilt produced by human wedge (the degree of tilt not reported)	Laerdal Resusci Anne® Skill Reporting System	- Correct chest compressions (definition not described), % (mean, SD) - Correct expired air ventilations (definition not described), (mean, SD)
Lee et al. 2011 [40]	South Korea	Simulation-based crossover RCT	30 emergency medical residents and technicians	CC in supine without manual LUD vs. CC in 30° LLT surface	Laerdal Resusci Anne® Skill Reporting System (Stavanger, Norway)	- Compression rate, per minute (mean, 95% confidence interval [CI]) - Compression depth, mm (mean, 95% CI) - Correct compression depth rate, 50–60 mm, % (mean, 95% CI) - Correct recoil rate, % (mean, 95% CI) - Correct hand position rate, % (mean, 95% CI) - Highest compression angle (mean, 95% CI) - Lowest compression angle (mean, 95% CI) - Subjective difficulty of CC, 5-point Likert scale (mean, 95% CI)
Kim et al., 2013 [41]	South Korea	Simulation-based crossover RCT	32 BLS-trained medical students (inexperienced rescuers without CPR experience)	CC in supine without manual LUD vs. CC in 30° LLT surface	Laerdal Resusci Anne® Skill Reporting System (Stavanger, Norway)	- Compression rate, per minute (mean, 95% CI) - Compression depth, mm (mean, 95% CI) - Correct compression depth rate, 50–60 mm, % (mean, 95% CI) - Correct recoil rate, % (mean, 95% CI) - Correct hand position rate, % (mean, 95% CI) - Highest compression angle (mean, 95% CI) - Lowest compression angle (mean, 95% CI) - Subjective difficulty of CC, 5-point Likert scale (mean, 95% CI)
Komasawa et al. 2013 [42]	Japan	Simulation-based crossover RCT	27 male medical doctors (with CPR experience)	CC in supine without manual LUD vs. CC in 27° LLT surface (by standing on the left and right sides of the patient)	Laerdal Resuci Anne® Skill Reporting System (Stavanger, Norway)	- Compression rate, per minute (mean, SD) - Compression depth mm (mean, SD) - Correct compression depth rate (> 50 mm), % (mean, 95% CI) - Correct recoil rate, % (mean)
Ip et al. 2013 [45]	UK	Simulation-based crossover RCT	40 healthcare professionals (anaesthetists and midwives)	CC in the LLT with the soft wedge (pillow) vs. firm wedge (foam-rubber) vs. hard wedge (wooden) vs. human wedge	Laerdal Resusci Anne® Skill Reporting System (Kent, UK),	- Compression rate, per minute (mean, 95% CI) - Compression depth mm (median, interquartile range [IQR]) - Correct compression depth rate (> 50 mm), % (median, IQR) - Correct recoil rate (proportion of compressions adequately released), % (mean, 95% CI) - Subjective stability of CC, 5-point Likert scale (median, IQR)
Butcher et al. 2014 [43]	UK	Simulation-based crossover RCT	20 BLS/ALS-trained healthcare professionals (10 anaesthetists and 10 midwives)	CC in supine with manual displacement of uterus vs. CC in LLT produced by a preformed firm-rubber wedge on the floor and on a bed (angle not reported)	Laerdal Resusci Anne® Skill Reporting System (Kent, UK), with ‘pregnancy bump’	- Compression rate, per minute (mean, SD) - Compression depth mm (median, IQR) - Correct compression depth rate (> 50 mm; median, IQR) - Correct recoil rate, % (median, IQR) - Subjective stability and ease of CC, 5-point Likert scale (median, IQR)
Dohi et al., 2017 [44]	Japan	Simulation-based crossover RCT	20 BLS-certified healthcare professionals	CC in supine without manual LUD vs. 30° LLT surface	Laerdal Skill Reporting System	- Compression rate, per minute (mean, SD) - Compression depth mm (mean, SD) - Correct compression depth rate (50–60 mm), % (mean, SD) - Correct recoil rate (within 5 mm of baseline chest height), % (mean, SD) - Correct hand position rate, % (mean, SD) - Subjective ease of CC, 5-point Likert scale (mean, 95%CI)

Abbreviations: RCT Randomized Controlled Trial, CC chest compression, LUD left uterine displacement, LLT left lateral tilt, CPR cardiopulmonary resuscitation, BLS Basic life support, ALS advanced life support, SD standard deviation, CI confidence interval, IQR interquartile range