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Purpose <p>Intravital lung microscopy requires lung stabilization, which has been accomplished by vacuum fixation or imaging during ventilatory plateau phases. 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.</p> Methods <p>We implement CFV in rats, with a custom&#xa0;circuit and orotracheal cannula that enable smooth switching between CFV and conventional mechanical ventilation (CMV). We initiate lung injury with zero end-expiratory&#xa0;pressure/excessive tidal volume CMV. Then we ventilate with protective CMV; 5&#xa0;min of CFV (100% oxygen, 1.2&#xa0;L/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.</p> Results <p>Throughout CFV, peripheral arterial oxygen saturation (93%) and heart rate (316&#xa0;min<sup>−1</sup>) 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.</p> Conclusion <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.</p>

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Design and In Vivo Validation of a Constant-Flow Ventilation Circuit for Tissue Stabilization During Intravital Imaging of the Lungs

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年4月15日

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  • Alcendino C. Jardim-Neto,
  • Carrie E. Perlman

摘要

Purpose

Intravital lung microscopy requires lung stabilization, which has been accomplished by vacuum fixation or imaging during ventilatory plateau phases. 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.

Methods

We implement CFV in rats, with a custom circuit and orotracheal cannula that enable smooth switching between CFV and conventional mechanical ventilation (CMV). We initiate lung injury with zero end-expiratory pressure/excessive tidal volume CMV. Then we ventilate with protective CMV; 5 min of CFV (100% oxygen, 1.2 L/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.

Results

Throughout CFV, peripheral arterial oxygen saturation (93%) and heart rate (316 min−1) 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.

Conclusion

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.