COVID-19 Pneumonia and ROX index: Time to set a new threshold for patients admitted outside the ICU
María Laura Vega,
Roberto Dongilli,
Gustavo Olaizola,
Nicolás Colaianni,
Mauro Castro Sayat,
Lara Pisani,
Micaela Romagnoli,
Greta Spoladore,
Irene Prediletto,
Guillermo Montiel,
Stefano Nava
Affiliations
María Laura Vega
Non-Invasive Respiratory Support Unit, Hospital Juan A. Fernández, Ciudad Autónoma de Buenos Aires. Argentina; IRCCS Azienda Ospedaliera-Universitaria, Division of Respiratory and Critical Care SantOrsola Hospital, Bologna Italia
Roberto Dongilli
Division of Respiratory Diseases with intermediate respiratory intensive care units, Central Hospital of Bolzano, Bolzano, Italy
Gustavo Olaizola
Unidad Asistencial Cesar Milstein. Ciudad Autónoma de Buenos Aires. Argentina
Nicolás Colaianni
Non-Invasive Respiratory Support Unit, Hospital Juan A. Fernández, Ciudad Autónoma de Buenos Aires. Argentina; Intensive Care Unit, Clínica Zabala, Ciudad Autónoma de Buenos Aires. Argentina
Mauro Castro Sayat
Non-Invasive Respiratory Support Unit, Hospital Juan A. Fernández, Ciudad Autónoma de Buenos Aires. Argentina; Intensive Care Unit, Clínica Zabala, Ciudad Autónoma de Buenos Aires. Argentina
Lara Pisani
IRCCS Azienda Ospedaliera-Universitaria, Division of Respiratory and Critical Care SantOrsol Hospital, Bologna Italia. Alma Mater Studiorum University of Bologna Department of Clinical, Integrated and Experimental Medicine (DIMES), Bologna, Italy
Micaela Romagnoli
Pulmonology Unit, Santa Maria di Ca’ Foncello Hospital, Treviso, Italy
Greta Spoladore
Division of Infectious Diseases, Central Hospital of Bolzano, Bolzano, Italy
Irene Prediletto
IRCCS Azienda Ospedaliera-Universitaria, Division of Respiratory and Critical Care SantOrsol Hospital, Bologna Italia. Alma Mater Studiorum University of Bologna Department of Clinical, Integrated and Experimental Medicine (DIMES), Bologna, Italy
Guillermo Montiel
Non-Invasive Respiratory Support Unit, Hospital Juan A. Fernández, Ciudad Autónoma de Buenos Aires. Argentina
Stefano Nava
IRCCS Azienda Ospedaliera-Universitaria, Division of Respiratory and Critical Care SantOrsol Hospital, Bologna Italia. Alma Mater Studiorum University of Bologna Department of Clinical, Integrated and Experimental Medicine (DIMES), Bologna, Italy; Corresponding author at: University of Bologna Alma Mater, Chair of Respiratory Medicine, Director Post-doctoral School in Respiratory Medicine, University Hospital of Bologna, S.Orsola-Malpighi, Director, Respiratory Diseases and Respiratory Intensive Care Unit, Via Massarenti 9, 401138 Bologna, Italy.
High flow nasal cannula (HFNC) is used to treat acute hypoxemic respiratory failure (AHRF) even outside the ICU and the ROX index (pulse oximetry/fraction of inspired oxygen/respiratory rate) may predict HFNC failure. Objective: The purpose of this investigation was therefore to verify whether the ROX index is an accurate predictor of HFNC failure for COVID-19 patients treated outside the intensive care unit (ICU) and to evaluate the validity of the previously suggested threshold. Design: Multicenter study. Retrospective observational analysis of prospectively collected data. Setting: 3 centres specialized in non-invasive respiratory support (Buenos Aires, Argentina; Bolzano and Treviso, Italy). Patients treated outside the ICU were analysed Measurements: The variables to calculate the ROX index were collected during the first day of therapy at 2, 6, 12 and 24 hours and then recorded every 24 hours. HFNC failure was defined as escalation of respiratory support to invasive mechanical ventilation (IMV) or death. Main results: A total of 35 (29%) patients failed HFNC and required intubation. ROC analysis identified the 12-hour ROX index as the best predictor of intubation with an AUC of 0.7916[CI 95% 0.6905-0.8927] and the best threshold to be 5.99[Specificity 96% Sensitivity 62%]. In the survival analysis, a ROX value <5.99 was associated with an increased risk of failure (p = 0008 log – rank test). The threshold of 4,9 identified by Roca as the best predictor in non-COVID patients, was not able to discriminate between success and failure (p = 0.4 log-rank test) in our patients. Conclusions: ROX index may be useful in guiding the clinicians in their decision to intubate patients, especially in patients with moderate ARF, treated therefore outside the ICU. Indeed, it also demonstrates a different threshold value than reported for non-COVID patients, possibly related to the different mechanisms of hypoxia.
