• 1. Verschakelen JA, van Fraeyenhoven L, Laureys G, et al. Differences in CT density between dependent and nondependent portions of the lung: influence of lung volume. AJR Am J Roentgenol 1993;161:713717.

    • Search Google Scholar
    • Export Citation
  • 2. Ahlberg N, Hoppe F, Kelter U, et al. A computed tomographic study of volume and x-ray attenuation of the lungs of Beagles in various body positions. Vet Radiol 1985;22:4347.

    • Search Google Scholar
    • Export Citation
  • 3. Duggan M, Kavanagh BO. Pulmonary atelectasis: a pathogenic perioperative entity. Anesthesiology 2005;102:838854.

  • 4. Magnusson L, Spahn DR. New concepts of atelectasis during general anesthesia. Br J Anaesth 2003;91:6172.

  • 5. Brismar B, Hedenstierna G, Lundquist H, et al. Pulmonary densities during anesthesia with muscular relaxation: a proposal of atelectasis. Anesthesiology 1985;62:422428.

    • Search Google Scholar
    • Export Citation
  • 6. Woo SW, Berlin D, Hedley-White J. Surfactant function and anesthestic agents. J Appl Physiol 1969;26:571577.

  • 7. Trzil JE, Reinero CR. Update on feline asthma. Vet Clin North Am Small Anim Pract 2014;44:91105.

  • 8. Henao-Guerrero N, Ricco C, Jones JC, et al. Comparison of four ventilator protocols for computed tomography of the thorax in healthy cats. Am J Vet Res 2012;73:646653.

    • Search Google Scholar
    • Export Citation
  • 9. Lundquist H, Hedenstierna G, Strandberg A, et al. CT-assessment of dependent lung densities in man during general anaesthesia. Acta Radiol 1995;36:626632.

    • Search Google Scholar
    • Export Citation
  • 10. Joyce CJ, Baker AB. What is the role of absorption atelectasis in the genesis of perioperative pulmonary collapse? Anaesth Intensive Care 1995;23:691696.

    • Search Google Scholar
    • Export Citation
  • 11. Staffieri F, De Monte V, De Marzo C, et al. Alveolar recruiting maneuver in dogs under general anesthesia: effects on alveolar ventilation, gas exchange, and respiratory mechanics. Vet Res Commun 2010;34:S131S134.

    • Search Google Scholar
    • Export Citation
  • 12. Staffieri F, Franchini D, Carella GL, et al. Computed tomographic analysis of the effects of two inspired oxygen concentrations on pulmonary aeration in anesthetized and mechanically ventilated dogs. Am J Vet Res 2007;68:925931.

    • Search Google Scholar
    • Export Citation
  • 13. Giglio RF, Winter MD, Reese DJ, et al. Radiographic characterization of presumed plate-like atelectasis in 75 non-anesthetized dogs and 15 cats. Vet Radiol Ultrasound 2013;54:326331.

    • Search Google Scholar
    • Export Citation
  • 14. le Roux C, Cassel N, Fosgate GT, et al. Computed tomographic findings of pulmonary atelectasis in healthy anaesthetized Beagles. Am J Vet Res 2016;77:10821092.

    • Search Google Scholar
    • Export Citation
  • 15. Staffieri F, De Monte V, De Marzo C, et al. Effects of two fractions of inspired oxygen on lung aeration and gas exchange in cats under inhalant anaesthesia. Vet Anaesth Analg 2010;37:483490.

    • Search Google Scholar
    • Export Citation
  • 16. Lamb CR, Jones ID. Associations between respiratory signs and abnormalities reported in thoracic CT scans of cats. J Small Anim Pract 2016;57:561567.

    • Search Google Scholar
    • Export Citation
  • 17. Thrall DE. Principles of radiographic interpretation of the thorax. In: Textbook of veterinary diagnostic radiology. 6th ed. St Louis: Saunders Elsevier, 2013;474488.

    • Search Google Scholar
    • Export Citation
  • 18. Morandi F, Mattoon JS, Lakritz J, et al. Correlation of helical and incremental high-resolution thin-section computed tomographic imaging with histomorphometric quantitative evaluation of lungs in dogs. Am J Vet Res 2003;64:935944.

    • Search Google Scholar
    • Export Citation
  • 19. Franquet T, Stern EJ, Gimenez A, et al. Lateral decubitus CT: a useful adjunct to standard inspiratory-expiratory CT for the detection of air trapping. AJR Am J Roentgenol 2000;174:528530.

    • Search Google Scholar
    • Export Citation
  • 20. Choi SJ, Choi BK, Kim HJ, et al. Lateral decubitus HRCT: a simple technique to replace expiratory CT in children with air trapping. Pediatr Radiol 2002;32:179182.

    • Search Google Scholar
    • Export Citation
  • 21. Lucaya J, Garcia-Pena P, Herrera L, et al. Expiratory chest CT in children. AJR Am J Roentgenol 2000;174:235241.

  • 22. Morandi F, Mattoon JS, Kakritz J, et al. Correlation of helical and incremental high-resolution thin-section computed tomographic and histomorphometric quantitative evaluation of an acute inflammatory response of lungs in dogs. Am J Vet Res 2004;65:11141123.

    • Search Google Scholar
    • Export Citation
  • 23. Oliveira CR, Mitchell MA, O'Brien RT. Thoracic computed tomography in feline patients without use of chemical restraint. Vet Radiol Ultrasound 2011;52:368376.

    • Search Google Scholar
    • Export Citation
  • 24. Lee SK, Park S, Cheon B, et al. Effect of position and time held in that position on ground-glass opacity in computed tomographic images of dogs. Am J Vet Res 2017;78:279288.

    • Search Google Scholar
    • Export Citation
  • 25. Kim T, Chang D, Chang J, et al. Assessment of computed tomographic lung density in Beagle and Shih Tzu dogs. J Vet Clin 2010:273–283.

  • 26. Rozanski EA, Bedenice D, Lofgren J, et al. The effect of body position, sedation, and thoracic bandaging on functional residual capacity in healthy deep-chested dogs. Can J Vet Res 2010;74:3439.

    • Search Google Scholar
    • Export Citation
  • 27. Gattinoni L, Caironi P, Pelosi P, et al. What has computed tomography taught us about the acute respiratory distress syndrome? Am J Respir Crit Care Med 2001;164:17011711.

    • Search Google Scholar
    • Export Citation
  • 28. Vieira SR, Puybasset L, Richecoeur J, et al. A lung computed tomographic assessment of positive end-expiratory pressure-induced lung overdistension. Am J Respir Crit Care Med 1998;158:15711577.

    • Search Google Scholar
    • Export Citation
  • 29. Mets OM, de Jong PA, van Ginneken B, et al. Quantitative computed tomography in COPD: possibilities and limitations. Lung 2012;190:133145.

    • Search Google Scholar
    • Export Citation
  • 30. Yamashiro T, Matsuoka S, Bartholmai B, et al. Collapsibility of lung volume by paired inspiratory and expiratory CT scans: correlations with lung function and mean lung density. Acad Radiol 2010;17:489495.

    • Search Google Scholar
    • Export Citation
  • 31. Arakawa A, Yamashita Y, Nakayama T, et al. Assessment of lung volumes in pulmonary emphysema using multidetector helical CT: comparison with pulmonary function tests. Comput Med Imaging Graph 2001;25:399404.

    • Search Google Scholar
    • Export Citation
  • 32. Xie X, de Jong PA, Oudkerk M, et al. Morphological measurements in computed tomography correlate with airflow obstruction in chronic obstructive pulmonary disease: systematic review and meta-analysis. Eur Radiol 2012;22:20852093.

    • Search Google Scholar
    • Export Citation
  • 33. Akira M, Toyokawa K, Inoue Y, et al. Quantitative CT in chronic obstructive pulmonary disease: inspiratory and expiratory assessment. AJR Am J Roentgenol 2009;192:267272.

    • Search Google Scholar
    • Export Citation
  • 34. Lee YK, Oh YM, Lee JH, et al. Quantitative assessment of emphysema, air trapping, and airway thickening on computed tomography. Lung 2008;186:157165.

    • Search Google Scholar
    • Export Citation
  • 35. Matsuoka S, Kurihara Y, Yagihashi K, et al. Quantitative assessment of peripheral airway obstruction on paired expiratory/inspiratory thin-section computed tomography in chronic obstructive pulmonary disease with emphysema. J Comput Assist Tomogr 2007;31:384389.

    • Search Google Scholar
    • Export Citation
  • 36. Kauczor HU, Hast J, Heussel CP, et al. CT attenuation of paired HRCT scans obtained at full inspiratory/expiratory position: comparison with pulmonary function tests. Eur Radiol 2002;12:27572763.

    • Search Google Scholar
    • Export Citation
  • 37. Newman KB, Lynch DA, Newman LS, et al. Quantitative computed tomography detects air trapping due to asthma. Chest 1994;106:105109.

  • 38. Adamama-Moraitou KK, Patsikas MN, Koutinas AF. Feline lower airway disease: a retrospective study of 22 naturally occurring cases from Greece. J Feline Med Surg 2004;6:227233.

    • Search Google Scholar
    • Export Citation
  • 39. Gadbois J, d'Anjou MA, Dunn M, et al. Radiographic abnormalities in cats with feline bronchial disease and intra- and inter-observer variability in radiographic interpretation: 40 cases (1999–2006). J Am Vet Med Assoc 2009;234:367375.

    • Search Google Scholar
    • Export Citation

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Effect of body position and time on quantitative computed tomographic measurements of lung volume and attenuation in healthy anesthetized cats

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  • 1 Unit of Diagnostic Imaging, Faculty of Science, School of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia.
  • | 2 Unit of Diagnostic Imaging, Faculty of Science, School of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia.
  • | 3 School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia.
  • | 4 Unit of Anaesthesia, Faculty of Science, School of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia.
  • | 5 Unit of Diagnostic Imaging, Faculty of Science, School of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia.

Abstract

OBJECTIVE To quantify the effect of time and recumbency on CT measurements of lung volume and attenuation in healthy cats under general anesthesia.

ANIMALS 8 healthy research cats.

PROCEDURES Anesthetized cats were positioned in sternal recumbency for 20 minutes and then in left, right, and left lateral recumbency (40 minutes/position). Expiratory helical CT scan of the thorax was performed at 0 and 20 minutes in sternal recumbency and at 0, 5, 10, 20, 30, and 40 minutes in each lateral recumbent position. For each lung, CT measurements of lung volume and attenuation and the extent of lung areas that were hyperaerated (−1,000 to −901 Hounsfield units [HU]), normoaerated (−900 to −501 HU), poorly aerated (−500 to −101 HU), or nonaerated (−100 to +100 HU [indicative of atelectasis]) were determined with a semiautomatic threshold-based technique. A restricted maximum likelihood analysis was performed.

RESULTS In lateral recumbency, the dependent lung had significantly greater attenuation and a lower volume than the nondependent lung. Within the dependent lung, there was a significantly higher percentage of poorly aerated lung tissue, compared with that in the nondependent lung. These changes were detected immediately after positioning the cats in lateral recumbency and remained static with no further significant time-related change.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that once anesthetized healthy cats were positioned in lateral recumbency, the dependent lung lobes underwent a rapid reduction in lung volume and increase in lung attenuation that did not progress over time, predominantly attributable to an increase in poorly aerated lung tissue.

Abstract

OBJECTIVE To quantify the effect of time and recumbency on CT measurements of lung volume and attenuation in healthy cats under general anesthesia.

ANIMALS 8 healthy research cats.

PROCEDURES Anesthetized cats were positioned in sternal recumbency for 20 minutes and then in left, right, and left lateral recumbency (40 minutes/position). Expiratory helical CT scan of the thorax was performed at 0 and 20 minutes in sternal recumbency and at 0, 5, 10, 20, 30, and 40 minutes in each lateral recumbent position. For each lung, CT measurements of lung volume and attenuation and the extent of lung areas that were hyperaerated (−1,000 to −901 Hounsfield units [HU]), normoaerated (−900 to −501 HU), poorly aerated (−500 to −101 HU), or nonaerated (−100 to +100 HU [indicative of atelectasis]) were determined with a semiautomatic threshold-based technique. A restricted maximum likelihood analysis was performed.

RESULTS In lateral recumbency, the dependent lung had significantly greater attenuation and a lower volume than the nondependent lung. Within the dependent lung, there was a significantly higher percentage of poorly aerated lung tissue, compared with that in the nondependent lung. These changes were detected immediately after positioning the cats in lateral recumbency and remained static with no further significant time-related change.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that once anesthetized healthy cats were positioned in lateral recumbency, the dependent lung lobes underwent a rapid reduction in lung volume and increase in lung attenuation that did not progress over time, predominantly attributable to an increase in poorly aerated lung tissue.

Contributor Notes

Address correspondence to Dr. Makara (mariano.makara@sydney.edu.au).