Risk factors for non-invasive/invasive ventilatory support in patients with COVID-19 pneumonia: A retrospective study within a multidisciplinary approach

Objectives: To investigate risk factors for non-invasive/invasive ventilatory support (NI/I-VS) in patients with coronavirus disease 2019 (COVID-19).

Methods: All consecutive patients admitted to the Infectious Diseases Unit and Intensive Care Unit (ICU) of Santa Maria Annunziata Hospital (Florence, Italy), from February 25 to April 25, 2020, with a confirmed COVID-19 diagnosis were enrolled in this retrospective cohort study. NI/I-VS was defined as the need for continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BPAP) (non-invasive ventilation) or mechanical ventilation, not including low-flow systems of oxygen therapy such as the Venturi mask or nasal cannula.

Results: Ninety-seven patients were enrolled; 61.9% (60/97) were male and the median patient age was 64 years. The in-hospital mortality was 9.3%. Thirty-five of the 97 patients (36%) required ICU admission and 94.8% (92/97) were prescribed oxygen therapy: 10.8% (10/92) by nasal cannula, 44.5% (41/92) by Venturi mask, 31.5% (29/92) by CPAP, 2.2% (2/92) by BPAP, and 10.8% (10/92) by mechanical ventilation following intubation. On univariate analysis, patients with a body mass index >30, type II diabetes mellitus, and those presenting with dyspnoea, asthenia, SOFA score ≥2 points, PaO₂/FiO₂ <300, temperature >38 °C, increased levels of lactate dehydrogenase (LDH), alanine aminotransferase, and C-reactive protein, and a d-dimer >1000 ng/mL at admission more frequently underwent NI/I-VS. Multivariate logistic regression analysis confirmed temperature >38 °C (odds ratio (OR) 21.2, 95% confidential interval (95% CI) 3.5-124.5, p = 0.001), LDH >250 U/l (OR 15.2, 95% CI 1.8-128.8, p = 0.012), and d-dimer >1000 ng/mL (OR 4.5, 95% CI 1.2-17.3, p = 0.027) as significantly associated with the requirement for NI/I-VS. A non-significant trend (p = 0.051) was described for PaO₂/FiO₂ <300.

Conclusions: Temperature >38 °C, LDH > 250 U/l, and d-dimer >1000 ng/mL were found to be independent risk factors for NI/I-VS in COVID-19 patients. In order to quickly identify patients likely at risk of developing a critical illness, inflammatory markers should be assessed upon hospital admission.