Fig. 2.

Suggested algorithm using the ROX index to help with intubation decision. Because the index includes in a single value three relevant respiratory parameters, the overall philosophy of the index is that if its value is increasing, the patient’s respiratory status is improving. For each time-point, there are three possibilities: (1) the patient’s ROX index is below the cut-off value, we suggest considering intubation of the patient; (2) the index is between the lower and the higher cut-off value, we suggest increasing the level of NHF (increase flow to its maximum and FiO₂ to 1) and re-evaluate after 30 min; (3) finally, if the index is above the upper boundary, we suggest pursuing NHF and close monitoring of the patient. Of note, this algorithm will require a formal validation by a RCT comparing standard of care and application of the algorithm in terms of safety and efficacy (timing of intubation)