de Laat 2007.

Methods	Initially an RCT with split‐plot design, randomized to time after surgery (first tier), then body position (second tier). However, non‐randomized reference group included after interim analysis Pre‐specified method of analysis before interim analysis not described. Study reported model of bioequivalence for comparison between randomized groups and non‐randomized reference group
Participants	69 postoperative myocardial revascularization adults with PA catheter and arterial line in situ and haemodynamic values within safe ranges (safe range defined as CI > 1.5 L/min/m2 or MAP, PCWP and RAP not exceeding baseline > 15% or MABP not < 15% below baseline) Sex (M/F) 52/17, mean age from 63.4 to 68 years between groups Exclusion: no ventricular assist device Termination criteria: values that fall outside the ‘safe range’ (described above) in the lateral position. In addition, protocol indicated that participants in pain during lateral position would be turned back Setting: 14‐bed ICU, Radboud University, Nijmegen Medical Centre, The Netherlands
Interventions	Group A (n = 27) commenced lateral position 2 hours after surgery, turned to right lateral (n = 13) versus left lateral (n = 14) positions Group B (n = 28) commenced lateral position 4 hours after surgery, turned to right lateral (n = 14) versus left lateral (n = 14) positions Group C (n = 14) maintained in supine position for 6 hours commencing 2 hours after surgery (non‐randomized reference group) Group A and B period schema: baseline positionT15, lateral positionT120, supine positionT120 (T in minutes)
Outcomes	Groups A and B: CI at 30, 120, 150 and 240 minutes (equivalent to 30 and 120 minutes in lateral position, then 30 and 120 minutes in supine position) Group C: CI at 30 minutes, 2 hours, 2 hours 30 minutes, 4 hours, 4 hours 30 minutes and 6 hours
Standard management	Mechanical ventilation not described but implied within text Quotation "The 30° lateral position ... was adapted to the specific situation of sedated and ventilated patients in cooperation with a physiotherapist" IABP (n = 6), antihypertensives (n = 28), inotropes or vasopressors (n = 21), with minimal high‐dose inotropes (n = 1). Analgesics given according to prescription, with no additional analgesia required. Changes in medication or dose rate to be recorded for interpretation of changes in CI on a participant level Comment: Statement implies that medication may have been titrated during the study
Position description	30 degrees lateral rotation, 30 degrees wedge cushion, angle verification method not described 20 degrees HOB elevation for lateral position, no description for supine position. Positioning instructions given to nurses
Washout period	Not applicable for design
Notes	No sample size calculation described Length of duration in each body position for Groups A and B was mean 117 ± 8 minutes (range 104 to 158 minutes), with some participants turned later than protocol because of other ICU priorities Supine position data for Groups A and B analysed according to group allocation Comment: termination criteria possibly subjected to measurement error, as transducers measuring MABP, PCWP and RAP were levelled to phlebostatic axis for all body positions Unclear whether any percentage change was associated with difference in hydrostatic pressure Quotation: "no signs of discomfort in lateral position in both groups were observed"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Random assignment by drawing sealed envelopes for 4 positioning conditions (Groups A and B). Unclear random sequence generation method for participants randomized to groups. Nonetheless, high risk of selection bias, as not all eligible participants were randomized to groups. Non‐randomized reference group (Group C) selected from eligible population following interim analysis of data (first 15 participants). Investigators acknowledged selection bias, but reported groups were comparable, as baseline CI data and starting values for initiating the study were not significantly different between groups Comment: Group differences other than baseline CI may confound results. Unclear how eligible participants were selected for randomization procedures vs non‐randomization following interim analysis. Investigator knowledge of haemodynamic status of participants as a pre‐requisite for eligibility may have influenced unintentional or intentional group selection
Allocation concealment (selection bias)	High risk	Group C allocation not concealed. No description for other groups (except use of sealed envelopes)
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not described
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Not described Comment: objective outcome measures taken from real‐time physiological monitoring system; therefore, lack of outcome assessor blinding unlikely to bias results
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	75 participants eligible (3 refused consent, 3 excluded because of postop complications before group allocation). Trial profile figure indicates that 69 participants (A, B, C groups) completed trial. Missing data point for lateral position (n = 1) because participant turned back early at 31 minutes as the result of an adverse event (pneumothorax later identified), but not explicitly clear whether all data points for supine position were available for analysis. No group/subgroup numbers provided for results or analysis
Selective reporting (reporting bias)	High risk	High risk of selective reporting after interim analysis, with primary analysis performed according to post hoc design change and findings from subgroup analysis forming major conclusions of the study. Post hoc subgroup analysis conducted on number of participants receiving vasoactive medication at the start of the lateral position who demonstrated a decrease in CI > 15% for the lateral position (all groups, including reference group). Analysis ambiguous, as supine reference group (C) was not measured in the lateral position, and participant measurement intervals were split into 2 groups (CA and CB) to correspond with Group A and Group B time points, with frequencies analysed separately (i.e. CA vs group A, CB vs group B). Data from reference group likely to be reported more than once within the analysis (unit of analysis error)
Other bias	Unclear risk	No withdrawals based on termination criteria. Primary outcome reporting (CI) unlikely to be biased by potential measurement error of termination criteria variables (i.e. MABP, PCWP and RAP) Descriptive statistics tabulated for each group (A, B, CA, CB) for baseline haemodynamics and inotropic and vasoactive medication, with dose rate for each drug 5 minutes before turning to the lateral position. Group participants appear to be using more than 1 drug Comment: Unclear whether all participants received the same management for ventilation, titration of medication and fluid replacement. Unclear if group differences in baseline variables and standard management