{
  "abstract": "Introduction COVID-19 has challenged traditional models of respiratory failure, and several studies have suggested that gas exchange impairment in COVID-19 pneumonia may involve mechanisms beyond anatomical shunt. This has renewed interest in non-invasive physiological tools to explore gas exchange abnormalities, including the evaluation of shunt, dead space and ventilation/perfusion mismatch.Material and methods This prospective cross-sectional study was conducted between October 2020 and January 2021 at Papa Giovanni XXIII Hospital (Bergamo, Italy), enrolling adults with acute respiratory failure due to COVID-19 or other pneumonias. Pulmonary shunt fraction was estimated non-invasively via the BEACON system using peripheral oxigen saturation (SpO₂)/fraction of inspired oxygen responses during incremental oxygen steps. Chest CT scans were quantitatively analysed for pathological patterns. The primary outcome was the comparison of BEACON-estimated shunt fraction between COVID-19 and non-COVID-19 groups; the secondary outcome included correlations with CT findings.Results A total of 51 patients were enrolled, including 36 with COVID-19 and 15 with non-COVID-19 pneumonia. COVID-19 patients showed significantly higher pulmonary shunt fractions (18.2% vs 12.5%, p=0.022). In non-COVID-19 cases, shunt fraction correlated positively with the extent of CT consolidations (ρ=0.567, p=0.035) and negatively with ground-glass opacities (ρ =–0.565, p=0.035). No significant correlations between shunt and CT findings were observed in COVID-19 patients.Conclusions Our findings demonstrate increased estimated shunt in COVID-19 pneumonia despite comparable radiological severity to non-COVID-19 pneumonias, reinforcing the concept of distinct gas exchange pathophysiology across different pneumonia aetiologies.",
  "authors": [
    {
      "affiliations": [
        "Respiratory Unit, Medicine Department, ASST Papa Giovanni XXIII, Bergamo, Italy"
      ],
      "name": "Federico Raimondi"
    },
    {
      "affiliations": [
        "Respiratory Unit, Medicine Department, ASST Papa Giovanni XXIII, Bergamo, Italy"
      ],
      "name": "Luca Novelli"
    },
    {
      "affiliations": [
        "Respiratory Unit, Medicine Department, ASST Papa Giovanni XXIII, Bergamo, Italy"
      ],
      "name": "Luca Malandrino"
    },
    {
      "affiliations": [
        "Don Gnocchi Foundation, Milan, Lombardy, Italy"
      ],
      "name": "Simone Pappacena"
    },
    {
      "affiliations": [
        "Department of Neurorehabilitation Sciences, Casa di Cura Igea, Milan, Lombardy, Italy"
      ],
      "name": "Giuseppe F Sferrazza Papa"
    },
    {
      "affiliations": [
        "Department of Neurorehabilitation Sciences, IRCCS Istituto Auxologico Italiano, Milan, Italy",
        "Department of Biomedical Sciences for Health, University of Milan, Milan, Italy"
      ],
      "name": "Antonio Caronni"
    },
    {
      "affiliations": [
        "Department of Neurorehabilitation Sciences, IRCCS Istituto Auxologico Italiano, Milan, Italy",
        "Department of Biomedical Sciences for Health, University of Milan, Milan, Italy"
      ],
      "name": "Laura Perucca"
    },
    {
      "affiliations": [
        "General Intensive Care Unit, ASST Papa Giovanni XXIII, Bergamo, Italy"
      ],
      "name": "Gianmariano Marchesi"
    },
    {
      "affiliations": [
        "Scienze Radiologiche Unit, Department of Medicine and Surgery, University Hospital of Parma, Parma, Italy"
      ],
      "name": "Gianluca Milanese"
    },
    {
      "affiliations": [
        "Radiology Unit, Department of Oncology, University of Turin, San Luigi Gonzaga Hospital, Orbassano, Italy"
      ],
      "name": "Maurizio Balbi"
    },
    {
      "affiliations": [
        "Respiratory Unit, Medicine Department, ASST Papa Giovanni XXIII, Bergamo, Italy",
        "Department of Health Sciences, University of Milan, Milan, Italy"
      ],
      "name": "Fabiano Di Marco"
    }
  ],
  "title": "Shunt estimation in pneumonia of different aetiologies: a non-invasive physiological assessment",
  "uid": "a7760e7e-22b1-5187-8b3b-4cea023a40cf"
}