International Journal of COPD (Jul 2022)

Respiratory Impedance is Associated with Ventilation and Diffusing Capacity in Patients with Idiopathic Pulmonary Fibrosis Combined with Emphysema

  • Yamamoto Y,
  • Hirata H,
  • Shiroyama T,
  • Kuge T,
  • Matsumoto K,
  • Yoneda M,
  • Yamamoto M,
  • Naito Y,
  • Suga Y,
  • Fukushima K,
  • Miyake K,
  • Koyama S,
  • Iwahori K,
  • Nagatomo I,
  • Takeda Y,
  • Kumanogoh A

Journal volume & issue
Vol. Volume 17
pp. 1495 – 1506

Abstract

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Yuji Yamamoto,1 Haruhiko Hirata,1 Takayuki Shiroyama,1 Tomoki Kuge,1 Kinnosuke Matsumoto,1 Midori Yoneda,1 Makoto Yamamoto,1 Yujiro Naito,1 Yasuhiko Suga,1 Kiyoharu Fukushima,1 Kotaro Miyake,1 Shohei Koyama,1 Kota Iwahori,1 Izumi Nagatomo,1 Yoshito Takeda,1 Atsushi Kumanogoh1– 4 1Department of Respiratory Medicine and Clinical Immunology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan; 2Department of Immunopathology, WPI, Immunology Frontier Research Center (iFReC), Osaka University, Suita, Osaka, Japan; 3Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita, Osaka, Japan; 4Center for Infectious Diseases for Education and Research (CiDER), Osaka University, Suita, Osaka, JapanCorrespondence: Yuji Yamamoto, Department of Respiratory Medicine and Clinical Immunology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka, 565-0871, Japan, Tel +81 6-36879-3833, Fax +81 6-6879-3839, Email [email protected]: Pulmonary fibrosis and emphysema result in relatively maintained ventilation and reduced diffusing capacity. This pulmonary functional impairment complicates the evaluation of pulmonary function in patients with combined pulmonary fibrosis and emphysema (CPFE). Therefore, a single and easy-to-use pulmonary function index to evaluate patients with CPFE warrants further studies. Respiratory impedance can easily be provided by oscillometry and might be a candidate index to evaluate pulmonary function in patients with CPFE. As a preliminary study to assess the utility of respiratory impedance, we investigated the associations of physiological indices, including respiratory impedance, in patients with idiopathic pulmonary fibrosis (IPF) with and without emphysema.Patients and Methods: This retrospective study evaluated patients with IPF who did and did not satisfy the diagnostic criteria of CPFE. All patients underwent oscillometry, spirometry, and diffusing capacity for carbon monoxide (DLCO). Correlations of the obtained physiological indices were analyzed.Results: In total, 47 patients were included (18 and 29 patients with CPFE and IPF, respectively). Respiratory reactance (Xrs) at 5 Hz (X5) in the inspiratory phase was associated with forced vital capacity (FVC) % predicted in patients with CPFE (rS=0.576, P=0.012) and IPF (rS=0.539, P=0.003). Inspiratory X5 positively correlated with DLCO % predicted only in patients CPFE (rS=0.637, P=0.004).Conclusion: Emphysema might associate Xrs with ventilation and diffusing capacity in patients with IPF and emphysema. Given the multiple correlations of Xrs with FVC and DLCO, this study warrants further studies to verify the utility of oscillometry in a large-scale study for patients with CPFE.Keywords: chronic obstructive pulmonary disease, forced oscillation technique, gas exchange, idiopathic pulmonary fibrosis, ventilation

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