Pleural liquid pressure measured with rib capsules in anesthetized ponies.
Abstract: Pleural liquid pressure was measured at end expiration in 11 spontaneously breathing anesthetized ponies in the prone and supine positions. A liquid-filled capsule was implanted into a rib to measure pleural liquid pressure with minimal distortion of the pleural space (Wiener-Kronish et al., J. Appl. Physiol. 59: 597-602, 1985). Capsule position relative to lung height was measured from thoracic radiographs taken in each position. In each body position, pleural liquid pressure was most negative in the superior lung regions and least negative in the inferior lung regions. In the supine position, the magnitude of the vertical gradient in pleural liquid pressure was 0.67 cmH2O/cm ht and was not significantly different from 1 cmH2O/cm ht. In the inferior lung regions (less than 50% lung ht), pleural liquid pressure averaged -1.3 cmH2O, indicating a low transpulmonary pressure over the region of the chest where most of the lung mass is located. When animals were in the prone position, the magnitude of the vertical gradient in pleural liquid pressure was 0.14 cmH2O/cm ht and was not statistically different from 0 cmH2O/cm ht. In each body position, mean transpulmonary pressure, measured postmortem, was similar to the estimated magnitude of pleural liquid pressure at 50% lung ht. This suggests that pleural liquid pressure is closely related to pleural surface pressure. These results are consistent with the poor ventilation distribution and reduced lung volumes measured in anesthetized horses in the supine position compared with values measured in horses in the prone position.
Publication Date: 1988-01-01 PubMed ID: 3356626DOI: 10.1152/jappl.1988.64.1.102Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study, conducted on anesthetized ponies, investigated the pleural liquid pressure at the end of exhalation in different body positions and found specific trends based on the ponies’ spatial orientation, providing insights into how the position affects lung function.
Methods
- The researchers measured pleural liquid pressure in 11 anesthetized ponies in prone and supine positions.
- A liquid-filled capsule was implanted into a rib to measure the pressure with minimal distortion of the pleural space. This method was based on a protocol established by Wiener-Kronish et al.
- The position of the capsule relative to the lung height was tracked through thoracic radiographs taken in each position.
Results
- The study found that pleural liquid pressure becomes more negative in the upper regions of the lungs and least negative in the lower regions, regardless of the pony’s body position.
- When the ponies were lying on their backs (supine position), the vertical gradient in pleural liquid pressure was slightly less than 1 cmH2O/cm height.
- The pleural liquid pressure in the lower lung regions showed a low transpulmonary pressure over the region of the chest where most of the lung mass is located.
- When the ponies were lying on their bellies (prone position), the vertical gradient in pleural liquid pressure was not significantly different from 0 cmH2O/cm height.
- After the ponies had died, the mean transpulmonary pressure measured was similar to the estimated pleural liquid pressure at 50% lung height. This suggests that pleural liquid pressure is closely related to pleural surface pressure.
Conclusions
- The results align with previous findings of poor ventilation distribution and reduced lung volumes in anesthetized horses lying on their backs compared to those lying on their bellies. This suggests that the body position of an animal could affect measurement and understanding of their respiratory physiology.
Cite This Article
APA
Olson LE, Lai-Fook SJ.
(1988).
Pleural liquid pressure measured with rib capsules in anesthetized ponies.
J Appl Physiol (1985), 64(1), 102-107.
https://doi.org/10.1152/jappl.1988.64.1.102 Publication
Researcher Affiliations
- Department of Veterinary Physiology and Pharmacology, Ohio State University, Columbus 43210-1092.
MeSH Terms
- Animals
- Female
- Functional Residual Capacity
- Horses / physiology
- Male
- Pleura / physiology
- Posture
- Pressure
- Residual Volume
- Respiration
Citations
This article has been cited 5 times.- Karrasch NM, Hubbell JA, Aarnes TK, Bednarski RM, Lerche P. Comparison of cardiorespiratory variables in dorsally recumbent horses anesthetized with guaifenesin-ketamine-xylazine spontaneously breathing 50% or maximal oxygen concentrations. Can Vet J 2015 Apr;56(4):387-92.
- Hubbell JA, Aarnes TK, Bednarski RM, Lerche P, Muir WW. Effect of 50% and maximal inspired oxygen concentrations on respiratory variables in isoflurane-anesthetized horses. BMC Vet Res 2011 Jun 3;7:23.
- Mentzelopoulos SD, Roussos C, Zakynthinos SG. Static pressure volume curves and body posture in acute respiratory failure. Intensive Care Med 2005 Dec;31(12):1683-92.
- Rohdin M, Petersson J, Mure M, Glenny RW, Lindahl SG, Linnarsson D. Protective effect of prone posture against hypergravity-induced arterial hypoxaemia in humans. J Physiol 2003 Apr 15;548(Pt 2):585-91.
- Perlman CE, Knudsen L, Smith BJ. The fix is not yet in: recommendation for fixation of lungs within physiological/pathophysiological volume range in preclinical pulmonary structure-function studies. Am J Physiol Lung Cell Mol Physiol 2024 Aug 1;327(2):L218-L231.
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