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We introduce a constant-flow ventilation (CFV) circuit for stabilizing the lungs during intravital microscopy while supporting oxygenation. In CFV, a cannula is placed in the trachea with its tip near the carina. Fresh gas enters the catheter at a steady, high flow rate. Outflow exits around the outside of the catheter at the same rate. Gas exchange occurs by diffusion. Constant-flow ventilation has previously been tested in large animals and humans.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We implement CFV in rats, with a custom\u00a0circuit and orotracheal cannula that enable smooth switching between CFV and conventional mechanical ventilation (CMV). We initiate lung injury with zero end-expiratory\u00a0pressure\/excessive tidal volume CMV. Then we ventilate with protective CMV; 5\u00a0min of CFV (100% oxygen, 1.2\u00a0L\/min\/kg flow rate and cannula tip at the carina) during which we surgically open a window in an intercostal space and image the lungs; and, again, protective CMV.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Throughout CFV, peripheral arterial oxygen saturation (93%) and heart rate (316\u00a0min\n                      <jats:sup>\u22121<\/jats:sup>\n                      ) are constant. Our CFV circuit enables sufficient lung stability, despite cardiac motion, for imaging by brightfield and longer-duration confocal microscopy. Airway pressure is stable during CMV-CFV switching.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>This technique could enable new research investigations, e.g., of in vivo microvascular\/alveolar mechanics without vacuum artifacts or cardiopulmonary coupling, and could potentially have clinical applications, e.g., protection against ventilation-induced lung injury.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1007\/s10439-026-04031-x","type":"journal-article","created":{"date-parts":[[2026,4,15]],"date-time":"2026-04-15T18:00:42Z","timestamp":1776276042000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Design and In Vivo Validation of a Constant-Flow Ventilation Circuit for Tissue Stabilization During Intravital Imaging of the Lungs"],"prefix":"10.1007","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7938-2037","authenticated-orcid":false,"given":"Alcendino C.","family":"Jardim-Neto","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5435-191X","authenticated-orcid":false,"given":"Carrie E.","family":"Perlman","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,4,15]]},"reference":[{"key":"4031_CR1","doi-asserted-by":"publisher","first-page":"R64","DOI":"10.1186\/cc5940","volume":"11","author":"LA Pavone","year":"2007","unstructured":"Pavone, L. 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