Pharyngeal pressure (PP) over the course of a gradual increase in flow. The flow is indexed to patient weight (R = 0.77, p < 0.001). A flow >2 L/kg/min is associated with mean pharyngeal pressure >4 cm H2O (sensitivity 67%, specificity 96%, positive predictive value 75%, negative predictive value 94.5%). Adapted from Milési et al. .