Abstract
One of the challenges that emerged during the coronavirus disease 2019 (COVID-19) pandemic and is still relevant today is the need to identify patients with acute respiratory failure (ARF) who could benefit from conventional oxygen therapy (COT) - oxygen supplementation with nasal cannulas, Venturi masks, and non-rebreather masks - without recurring to advanced respiratory therapy, such as high-flow nasal cannula (HFNC), continuous positive airway pressure (CPAP), non-invasive ventilation (NIV), or invasive mechanical ventilation. The aim of the study was to develop a clinical tool able to predict the failure of COT in COVID-19 patients presenting to the emergency department (ED) with ARF. This was a retrospective monocentric cohort study carried out in the ED of the University Hospital of Bologna Sant’Orsola-Malpighi Polyclinic, Italy. The cohort comprised 101 COVID-19 patients with ARF from the first pandemic wave who received COT. This cohort was used to develop a scale that considers serum lactate concentration, partial arterial oxygen pressure/inspired oxygen fraction (PaO2/FiO2) ratio, and body temperature to predict COT failure, referred to as the Lactate, Oxygenation, and Temperature (LOT) score. The highest possible score was 17 points. The LOT score was associated with COT failure (area under the receiver operating curve or AUROC = 0.79, 95% CI 0.69 - 0.89, p < 0.001); the cut-off value of > 5 points had optimal predictive power and showed significantly higher 30-day mortality (log-rank χ2 = 28,828, p < 0.0001). The LOT score was able to effectively predict COT failure in COVID-19 patients with ARF. Patients with LOT score > 5 had a very high risk of therapy failure, and more advanced respiratory therapies must be considered in these patients.
Highlights
In December 2019, a cluster of patients with severe pneumonia of unknown origin was identified in Wuhan, China [1]
We aimed to evaluate the efficacy of conventional oxygen therapy (COT) in nonsevere COVID-19 patients presenting to the emergency department (ED) with acute respiratory failure (ARF) by developing a clinical scoring system for the prediction of its failure
COVID-19 patients presenting to the ED with ARF during the months of March and April 2020, the first COVID-19 pandemic wave in Italy, who received COT (NCs, Venturi masks (VMs), non-rebreather masks (NRBs)), were enrolled in the study, excluding patients who did not have ARF at presentation or severe patients who started any form of advanced respiratory therapy (HFNC, continuous positive airway pressure (CPAP), non-invasive ventilation (NIV), or invasive mechanical ventilation (IMV)) at admission; patients not admitted to the hospital were excluded from the study
Summary
In December 2019, a cluster of patients with severe pneumonia of unknown origin was identified in Wuhan, China [1]. COVID-19 patients with ARF, but whose clinical condition is not critical at the moment of admission to the ED, present the clinician with a challenge: to correctly and precisely estimate the risk of disease and ARF progression and to choose the optimal treatment, the ideal oxygen or respiratory therapy. This task is often further complicated by the availability of resources, such as hospital beds, ventilators, and healthcare professionals, which may change from one local reality to another and from one moment to another
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