@article {Settfetalneonatal-2022-323900, author = {Arun Sett and Kelly R Kenna and Rebecca J Sutton and Elizabeth J Perkins and Magdy Sourial and Jack D Chapman and Susan M Donath and Arun Sasi and Sheryle R Rogerson and Brett J Manley and Peter G Davis and Prue M Pereira-Fantini and David G Tingay}, title = {Lung ultrasound of the dependent lung detects real-time changes in lung volume in the preterm lamb}, elocation-id = {fetalneonatal-2022-323900}, year = {2022}, doi = {10.1136/archdischild-2022-323900}, publisher = {BMJ Publishing Group}, abstract = {Background Effective lung protective ventilation requires reliable, real-time estimation of lung volume at the bedside. Neonatal clinicians lack a readily available imaging tool for this purpose.Objective To determine the ability of lung ultrasound (LUS) of the dependent region to detect real-time changes in lung volume, identify opening and closing pressures of the lung, and detect pulmonary hysteresis.Methods LUS was performed on preterm lambs (n=20) during in vivo mapping of the pressure-volume relationship of the respiratory system using the super-syringe method. Electrical impedance tomography was used to derive regional lung volumes. Images were blindly graded using an expanded scoring system. The scores were compared with total and regional lung volumes, and differences in LUS scores between pressure increments were calculated.Results Changes in LUS scores correlated moderately with changes in total lung volume (r=0.56, 95\% CI 0.47-0.64, p\<0.0001) and fairly with right whole (r=0.41, CI 0.30-0.51, p\<0.0001), ventral (r=0.39, CI 0.28-0.49, p\<0.0001), central (r=0.41, CI 0.31-0.52, p\<0.0001) and dorsal (r=0.38, CI 0.27-0.49, p\<0.0001) regional lung volumes. The pressure-volume relationship of the lung exhibited hysteresis in all lambs. LUS was able to detect hysteresis in 17 (85\%) lambs. The greatest changes in LUS scores occurred at the opening and closing pressures.Conclusion LUS was able to detect large changes in total and regional lung volume in real time and correctly identified opening and closing pressures but lacked the precision to detect small changes in lung volume. Further work is needed to improve precision prior to translation to clinical practice.Data are available upon reasonable request. NA.}, issn = {1359-2998}, URL = {https://fn.bmj.com/content/early/2022/06/23/archdischild-2022-323900}, eprint = {https://fn.bmj.com/content/early/2022/06/23/archdischild-2022-323900.full.pdf}, journal = {Archives of Disease in Childhood - Fetal and Neonatal Edition} }