Effect of body position on respiratory system volumes in anesthetized red-tailed hawks (Buteo jamaicensis) as measured via computed tomography.
OBJECTIVE
To determine the effects of body position on lung and air-sac volumes in anesthetized and spontaneously breathing red-tailed hawks (Buteo jamaicensis).


METHODS
6 adult red-tailed hawks (sex unknown).


METHODS
A crossover study design was used for quantitative estimation of lung and air-sac volumes in anesthetized hawks in 3 body positions: dorsal, right lateral, and sternal recumbency. Lung volume, lung density, and air-sac volume were calculated from helical computed tomographic (CT) images by use of software designed for volumetric analysis of CT data. Effects of body position were compared by use of repeated-measures ANOVA and a paired Student t test.


RESULTS
Results for all pairs of body positions were significantly different from each other. Mean +/- SD lung density was lowest when hawks were in sternal recumbency (-677 +/- 28 CT units), followed by right lateral (-647 +/- 23 CT units) and dorsal (-630 +/- 19 CT units) recumbency. Mean lung volume was largest in sternal recumbency (28.6 +/- 1.5 mL), followed by right lateral (27.6 +/- 1.7 mL) and dorsal (27.0 +/- 1.5 mL) recumbency. Mean partial air-sac volume was largest in sternal recumbency (27.0 +/- 19.3 mL), followed by right lateral (21.9 +/- 16.1 mL) and dorsal (19.3 +/- 16.9 mL) recumbency.


CONCLUSIONS
In anesthetized red-tailed hawks, positioning in sternal recumbency resulted in the greatest lung and air-sac volumes and lowest lung density, compared with positioning in right lateral and dorsal recumbency. Additional studies are necessary to determine the physiologic effects of body position on the avian respiratory system.
Malka
Shachar
S
William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Hawkins
Michelle G
MG
Jones
James H
JH
Pascoe
Peter J
PJ
Kass
Philip H
PH
Wisner
Erik R
ER
D000400:Air Sacs / Q000000981:diagnostic imaging / Q000502:physiology; D000758:Anesthesia; D000778:Anesthetics, Dissociative / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D018592:Cross-Over Studies; D046428:Hawks / Q000502:physiology*; D008176:Lung Volume Measurements / Q000662:veterinary; D011187:Posture; D015656:Respiratory Mechanics / Q000502:physiology*; D014057:Tomography, X-Ray Computed
D000778:Anesthetics, Dissociative; D018686:Anesthetics, Intravenous