{
  "abstract": "Introduction Recent analyses have shown high concordance between alveolar volume (VA) and total lung capacity (TLC) in patients with restrictive lung conditions (Alexiou et al, 2024). Given the high burden of care for people with interstitial lung disease (ILD), we aimed to validate these findings in a cohort of patients with confirmed ILD.Research question: Can VA be used as a surrogate for TLC in patients with known ILD?Methods Retrospective analysis of 560 patients diagnosed with ILD between 2015 and 2025 at the Regional Birmingham Multidisciplinary Team (MDT) meeting was performed. Patients with both gas transfer and lung volume (helium dilution & nitrogen washout) measures were included. Sensitivity, specificity, positive and negative predictive value (PPV & NPV, respectively) of VA to predict TLC were calculated, based on a Z score cut-off threshold of above or below -1.645. Sub-analysis was performed for patients with ILD with co-existing obstruction on baseline spirometry. Tests of difference were performed between obstructive and non-obstructive groups, with statistical significance accepted when p < 0.05.Results Of 560 patients, 435 had both gas transfer and lung volume measures (77.6%). The median difference between VA and TLC was 212 mL (156 – 496 mL). VA was highly predictive of TLC in patients with confirmed ILD, with a sensitivity of 95.3%, specificity of 78.4%, PPV of 90.8% and NPV of 88.2%. In the 38 patients with ILD with co-existing airflow obstruction on spirometry, larger differences between VA and TLC were present (427 mL (185 – 862 mL), p= 0.025). Despite this, VA to predict TLC still had a sensitivity of 100%, specificity of 75.9%, PPV of 56.3% and NPV of 100% in this group.Conclusion Measurements of VA are highly concordant with measurements of TLC (using dilution methodologies) in patients with ILD, including those with co-existing airflow obstruction.Reference Alexiou, et al. The utility of gas transfer measurement to identify low total lung capacity. ERJ. 2024.",
  "authors": [
    {
      "affiliations": [
        "Birmingham Heartlands Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK"
      ],
      "name": "Robyn Gregory"
    },
    {
      "affiliations": [
        "Birmingham Heartlands Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK"
      ],
      "name": "Christopher Huntley"
    },
    {
      "affiliations": [
        "Birmingham Heartlands Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK"
      ],
      "name": "Gareth Walters"
    },
    {
      "affiliations": [
        "Birmingham Heartlands Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK"
      ],
      "name": "Samuel Wallbanks"
    }
  ],
  "title": "P14 Can alveolar volume (VA) be used as a surrogate for total lung capacity in patients with interstitial lung disease(s)?",
  "uid": "4445f4da-a13d-5928-90af-40a2c11e5162"
}