Critical care : the official journal of the Critical Care Forum
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Due to complexities in its measurement, adequacy of ventilation is seldom used to categorize disease severity and guide ventilatory strategies. Ventilatory ratio (VR) is a novel index to monitor ventilatory adequacy at the bedside. VR=(VEmeasured × PaCO₂measured)/(VEpredicted × PaCO₂ideal). VEpredicted is 100 mL.Kg-1.min-1 and PaCO₂ideal is 5 kPa. Physiological analysis shows that VR is influenced by dead space (VD/VT) and CO₂ production (VCO₂). Two studies were conducted to explore the physiological properties of VR and assess its use in clinical practice. ⋯ VR is an easy to calculate bedside index of ventilatory adequacy and appears to yield clinically useful information.