PLEURAL FLUID MOVEMENT

Its effect on the appearance of ventrodorsal and dorsoventral radiographic projections

Authors

  • Timothy F. Groves DVM,

    1. Department of Veterinary Radiology, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32610, where Dr. Groves was a senior student and Dr. Ticer was Chairman and Professor.
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    • Dr. Groves’ present address is West Los Angeles Veterinary Medical Group,1559 S. Sepulveda Blvd., Los Angeles, California 90025.

  • James W. Ticer DVM, PhD

    1. Department of Veterinary Radiology, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32610, where Dr. Groves was a senior student and Dr. Ticer was Chairman and Professor.
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    • Dr. Ticer's present address is 2585 Soquel Dr., Santa Cruz, California 95065. Reprint requests should be directed to Dr. Ticer.


  • This work was performed as part of an investigation by the senior author in partial satisfaction of the curriculum requirements at the College of Veterinary Medicine.

Abstract

The present study was an attempt to illustrate the differences between ventrodorsal (VD) and dorsoventral (DV) radiographs that result from the movement of free pleural fluid. A volume of 25 ml/kg of normal saline was introduced into the pleural space of a normal dog, and radiographs of the thorax were produced in ventral and dorsal recumbency using a vertical (overhead) x-ray beam and a laterally directed horizontal x-ray beam. On the DV projection (ventral recumbency) the heart, cranial mediastinum, cranial lung lobes, and the ventral aspect of the diaphragm were submersed in fluid, which resulted in the loss of radiographically detectable borders. On the VD projection (dorsal recumbency) radiographic visualization of these structures was improved due to movement of the free pleural fluid away from them, toward the dependent caudodorsal aspect of the thorax. Radiographs of three dogs with spontaneous pleural effusion are presented to illustrate the differences in radiographic appearance of the thorax with pleural effusion when radiographed in DV and VD projections. The movement of fluid to the dorsocaudal thoracic cavity in dorsal recumbency caused lesions that were obscured on the DV projection to be revealed on the VD projection. the authors therefore recommend the use of the VD projection of the thorax in patients with pleural fluid when clinical status permits.

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