Bone and Joint Institute

Document Type

Article

Publication Date

1-1-2017

Journal

Physiological Reports

Volume

5

Issue

2

URL with Digital Object Identifier

10.14814/phy2.13074

Abstract

© 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society. In this study, we aim to quantify the differences in lung metrics measured in free-breathing and mechanically ventilated rodents using respiratory-gated micro-computed tomography. Healthy male Sprague-Dawley rats were anesthetized with ketamine/xylazine and scanned with a retrospective respiratory gating protocol on a GE Locus Ultra micro-CT scanner. Each animal was scanned while free-breathing, then intubated and mechanically ventilated (MV) and rescanned with a standard ventilation protocol (56 bpm, 8 mL/kg and PEEP of 5 cm H2O) and again with a ventilation protocol that approximates the free-breathing parameters (88 bpm, 2.14 mL/kg and PEEP of 2.5 cm H2O). Images were reconstructed representing inspiration and end expiration with 0.15 mm voxel spacing. Image-based measurements of the lung lengths, airway diameters, lung volume, and air content were compared and used to calculate the functional residual capacity (FRC) and tidal volume. Images acquired during MV appeared darker in the airspaces and the airways appeared larger. Image-based measurements showed an increase in lung volume and air content during standard MV, for both respiratory phases, compared with matched MV and free-breathing. Comparisons of the functional metrics showed an increase in FRC for mechanically ventilated rats, but only the standard MV exhibited a significantly higher tidal volume than free-breathing or matched MV. Although standard mechanical ventilation protocols may be useful in promoting consistent respiratory patterns, the amount of air in the lungs is higher than in free-breathing animals. Matching the respiratory patterns with the free-breathing case allowed similar lung morphology and physiology measurements while reducing the variability in the measurements.

Notes

© 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

The original article is available at:

N. L. Ford et al., "A respiratory-gated micro-CT comparison of respiratory patterns in free-breathing and mechanically ventilated rats", Physiolog. Rep., vol. 5, no. 2, Jan. 2017. DOI: https://doi.org/10.14814/phy2.13074

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.