Effects of airway obstruction on transmural pulmonary artery pressure in exercising horses.
Abstract: To determine whether laryngeal hemiplegia would increase transmural pulmonary artery pressure (TPAP). Methods: 6 horses. Methods: Horses were studied under 5 conditions: control conditions, after induction of left laryngeal hemiplegia, during obstruction of the left nostril, after placement of an instrumented tracheostomy, and after placement of an open tracheostomy. Horses were evaluated after being given saline solution and after being given furosemide. Methods: Horses were exercised on a high speed treadmill, using a maximum speed of 13 m/s. During each exercise, airway pressures, airflow, esophageal and pulmonary artery pressures, and blood gas partial pressures were measured. Results: When adjusted for horse, speed, and obstruction condition, mean TPAP (pulmonary artery pressure-esophageal pressure) and minimum TPAP were significantly lower after administration of furosemide than after administration of saline solution. In horses given saline solution, respiratory obstruction that increased intrapleural pressure significantly increased mean TPAP, and respiratory obstruction that decreased intrapleural pressure significantly decreased minimum TPAP. Conclusions: Changes in intrapleural pressure appear to play an important role in pulmonary artery pressure and TPAP. Conclusions: Because induction of laryngeal hemiplegia did not increase TPAP, laryngeal hemiplegia is unlikely to contribute to development of exercise-induced pulmonary hemorrhage.
Publication Date: 1997-08-01 PubMed ID: 9256978
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigates the impact of airway obstructions on the pressures in a horse’s pulmonary artery during exercise. The study found that changes in the surrounding pressure in the chest cavity are crucial in managing these internal pressures, and challenges the notion that a condition known as laryngeal hemiplegia contributes to exercise-induced lung bleeding in horses.
Research Methods
- The study involved six horses which were tested under five conditions: normal control conditions, after inducing left laryngeal hemiplegia (a condition where a horse’s larynx doesn’t open and close properly, leading to breathing difficulty), during blockage of the left nostril, after instrumented and open tracheostomy (surgical openings in the windpipe).
- Additionally, the horses were assessed after two types of injections: a solution of saline, and Furosemide (a diuretic medication).
- The horses were then exercised on a high-speed treadmill at speeds up to 13 meters per second. During this, researchers measured a range of indicators, including airway pressures, airflow, the pressures in the esophagus and pulmonary artery (the blood vessel that carries blood away from the heart to the lungs), and the partial pressures of gases in the blood.
Research Findings
- The results revealed that after controlling for the individual horse, speed, and obstruction condition, the mean and minimum transmural pulmonary artery pressures (TPAP, the difference of pressure between the pulmonary artery and esophagus) were significantly lower after getting Furosemide than after the saline solution.
- In horses given saline, a respiratory obstruction that increased the pressure inside the chest cavity significantly raised the mean TPAP. When the chest cavity pressure decreased, the minimum TPAP fell significantly.
- This suggests that changes to the pressure within the chest cavity (intrapleural pressure) play a key role in managing pulmonary artery pressure, and thus TPAP.
Conclusions
- Given that inducing laryngeal hemiplegia did not increase TPAP, the research argues against the current belief that this condition may contribute to the development of exercise-induced pulmonary hemorrhage (bleeding in the lungs) in horses.
- This has implications for the understanding and treatment of respiratory conditions in horses, particularly those related to exercise.
Cite This Article
APA
Jackson JA, Ducharme NG, Hackett RP, Rehder RS, Ainsworth DM, Shannon KJ, Erickson BK, Erb HN, Jansson N, Soderholm LV, Thorson LM.
(1997).
Effects of airway obstruction on transmural pulmonary artery pressure in exercising horses.
Am J Vet Res, 58(8), 897-903.
Publication
Researcher Affiliations
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
MeSH Terms
- Airway Obstruction / physiopathology
- Airway Obstruction / veterinary
- Animals
- Blood Pressure
- Esophagus / physiology
- Esophagus / physiopathology
- Female
- Heart Rate
- Hemiplegia / physiopathology
- Hemiplegia / veterinary
- Horse Diseases
- Horses / physiology
- Laryngeal Diseases / physiopathology
- Laryngeal Diseases / veterinary
- Male
- Orchiectomy
- Physical Conditioning, Animal / physiology
- Pulmonary Artery / physiology
- Pulmonary Artery / physiopathology
- Running / physiology
- Tracheostomy
Citations
This article has been cited 3 times.- Mellor DJ, Beausoleil NJ. Equine Welfare during Exercise: An Evaluation of Breathing, Breathlessness and Bridles. Animals (Basel) 2017 May 26;7(6).
- Hackett RP, Ducharme NG, Gleed RD, Mitchell L, Soderholm LV, Erickson BK, Erb HN. Do Thoroughbred and Standardbred horses have similar increases in pulmonary vascular pressures during exertion?. Can J Vet Res 2003 Oct;67(4):291-6.
- Bayly WM, Leguillette R, Sides RH, Massie S, Guigand C, Jones KB, Warlick LM, Thueson EL, Troudt TA, Slocombe RF, Jones JH. Equine exercise-induced pulmonary hemorrhage: the role of high left-heart pressures secondary to exercise-induced hypervolemia, and high inspiratory pressures. J Appl Physiol (1985) 2024 Nov 1;137(5):1359-1373.
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