Table 3.

Summary of the evidence for conscious prone positioning prior to the COVID-19 pandemic

AuthorsnIntervention (respiratory device)SettingOutcomeKey resultsStrengthsLimitations
Scaravilli et al, 20153315Prone episodes, 1–3 per patient with duration 2–4 hours (longest 8 hours)
Oxygen facemasks, CPAP and HFNC)
ICU (ARDS)Change in PaO2/FiO2 from supine to prone position, then return to supinePaO2/FiO2 (kPa) 11.9±3.7 to 16.5±7.1* (returning to 12.1±5.6)*Measured response to re-supination after 6–8 hoursRespiratory device the same over prone episode in only 18/43
Ding et al, 20203420Protocolised trials of HFNC or CPAP/BiPAP +/− prone positioningICU (ARDS)Intubation rate
Change in PaO2/FiO2 from supine to prone position
55% intubated (expected 75%)
PaO2/FiO2 (kPa) 12.7±2.9 to 17.3±4.7 kPa (those who avoided intubation)
Meaningful primary outcome
Suggests benefit in moderate ARDS or varying aetiology
Complex protocol with combination of interventions unachievable on wards
Results for success and failure groups reported separately
Valter et al, 2003354Single episode of prone positioning, duration 50 minutes to 5 hours
(CPAP/BiPAP used pre-prone positioning in n=3)
ICU (ARF)Change in PaO2/FiO2 from supine to prone positionPaO2/FiO2 (kPa) 11.9 to 24.7 (mean values)Small case series
Bellone and Basile, 2018363Repeated episodes of prone positioning for 6 hrs/day (HFNC during prone positioning)Emergency ward (ARF)Change in PaO2/FiO2 from supine to prone positionPaO2/FiO2 (kPa) 15.7 to 36.7 (1 day of intervention) to 40.4 (9 days of interventionSuggests improvement with sustained use of prone positioningSmall case series
  • ARF = acute respiratory failure; BiPAP = bilevel positive airway pressure; CPAP = continuous positive airway pressure; ED = emergency department; HFNC = high flow nasal cannula; ICU = intensive care unit. *p<0.05 from preceding intervention. p=0.016, HFNC to HFNC + prone.