biostudies-literatureUnknownMaj R<h4>Background</h4>Ventilatory ratio (VR) has been proposed as an alternative approach to estimate physiological dead space. However, the absolute value of VR, at constant dead space, might be affected by venous admixture and CO₂ volume expired per minute (VCO₂).<h4>Methods</h4>This was a retrospective, observational study of mechanically ventilated patients with acute respiratory distress syndrome (ARDS) in the UK and Italy. Venous admixture was either directly measured or estimated using the surrogate measure Pa_O₂/FiO₂ ratio. VCO₂ was estimated through the resting energy expenditure derived from the Harris-Benedict formula.<h4>Results</h4>A total of 641 mechanically ventilated patients with mild (n=65), moderate (n=363), oBritish journal of anaesthesiaS0007-0912(22)00624-9https://www.ebi.ac.uk/biostudies/studies/S-EPMC9718027biostudies-literatureVentilatory ratio, dead space, and venous admixture in acute respiratory distress syndrome.PMC9718027Brusatori SCamporota LMaj RMarini JJD'Albo RGattarello SGattinoni LZinnato CMeissner KRomitti FBusana MPalermo PVelati MMoerer OQuintel MChiumello DWieditz JSanderson BHerrmann PfalseVentilatory ratio, dead space, and venous admixture in acute respiratory distress syndrome.<h4>Background</h4>Ventilatory ratio (VR) has been proposed as an alternative approach to estimate physiological dead space. However, the absolute value of VR, at constant dead space, might be affected by venous admixture and CO₂ volume expired per minute (VCO₂).<h4>Methods</h4>This was a retrospective, observational study of mechanically ventilated patients with acute respiratory distress syndrome (ARDS) in the UK and Italy. Venous admixture was either directly measured or estimated using the surrogate measure Pa_O₂/FiO₂ ratio. VCO₂ was estimated through the resting energy expenditure derived from the Harris-Benedict formula.<h4>Results</h4>A total of 641 mechanically ventilated patients with mild (n=65), moderate (n=363), o2022-01-01T00:00:00Z2022 Dec2025-05-31T23:46:50.365Z2025-02-18T22:52:20.019ZS-EPMC97180273647074710.1016/j.bja.2022.10.035