Validity of the ROX index in predicting invasive mechanical ventilation requirement in pneumonia

Abstract

BackgroundThe ROX index (Respiratory rate-OXygenation) has been described as a prediction tool to identify the need for invasive mechanical ventilation (IMV) in community-acquired pneumonia (CAP) with acute hypoxaemic respiratory failure treated with high-flow nasal cannula in order to avoid delay of a necessary intubation. However, its use in predicting the need for ventilatory support in hospitalised patients with CAP has not been validated.MethodsThis is a retrospective cohort study including subjects with CAP treated in the general ward, emergency service or intensive care unit of a third-level centre in Cundinamarca, Colombia, between January 2001 and February 2020. The ROX index was estimated as the ratio of oxygen saturation/fraction of inspired oxygen to respiratory rate.ResultsA total of 895 patients were included, of whom 93 (10%) required IMV. The ROX index proved to be a good predictor, presenting an area under the curve of receiver operating characteristics (AUROC) of 0.733 (95% CI 0.671 to 0.795, p<0.001) when determined by pulse oximetry and an AUROC of 0.779 (95% CI 0.699 to 0.859, p<0.001) when estimated by arterial blood gas (ABG) parameters, with an intraclass correlation of 0.894. The estimated cut-off point was 14.8; a score less than 14.8 indicates high risk of requiring IMV.ConclusionThe ROX index is a good predictor of IMV in hospitalised patients with CAP. It presents good performance when calculated through pulse oximetry and can replace the one calculated by ABG.

Performance of oxygenation indices and risk scores to predict invasive mechanical ventilation and mortality in COVID-19

“…The altitude above sea level where the care center was located can be considered a limiting factor, since exceeding 2.500 meters above sea level can alter oxygenation values, as described in previous studies. (13,40) However, there are large numbers of the world's population residing at altitudes to which these ndings could be applied. The lack of a uniform take in the evaluation of arterial gasses during the evolution of patients with SARS-CoV2 can cause confusion throughout the follow-up, however, each of the analyzes at different periods of time carried out in the study consistently show differences in the OIs evaluated.…”

“…The other hand, ROX index ('Respiratory rate-OXygenation') is the ratio between peripheral blood oxygen saturation (SpO2) to fraction of inspired oxygen (FiO2) and respiratory rate, which has shown promising performance in successful prognosis of invasive and non-invasive oxygen therapy. (11)(12)(13) OIs are useful markers for the prediction of complications and mortality in patients with lung involvement, including subjects with COVID-19. (4, 9, 10) Currently, information on the performance and discriminatory capacity of OIs in patients requiring invasive ventilatory support and mortality are limited, generating signi cant variability in clinical practice.…”