Effect of Hypotension and Dobutamine on Gastrointestinal Microcirculations of Healthy, Anesthetized Horses.
Abstract: Horses undergoing abdominal exploratory surgery are at risk of hypotension and hypoperfusion. Normal mean arterial pressure is used as a surrogate for adequate tissue perfusion. However, measures of systemic circulation may not be reflective of microcirculation. This study measured the mean arterial pressure, cardiac index, lactate, and four microcirculatory indices in six healthy, anesthetized adult horses undergoing elective laparotomies. The microcirculatory parameters were measured at three different sites along the gastrointestinal tract (oral mucosa, colonic serosa, and rectal mucosa) with dark-field microscopy. All macro- and microcirculatory parameters were obtained when the horses were normotensive, hypotensive, and when normotension returned following treatment with dobutamine. Hypotension was induced with increases in inhaled isoflurane. The horses successfully induced into hypotension did not demonstrate consistent, expected changes in systemic perfusion or microvascular perfusion parameters at any of the three measured gastrointestinal sites. Normotension was successfully restored with the use of dobutamine, while the systemic perfusion and microvascular perfusion parameters remained relatively unchanged. These findings suggest that the use of mean arterial pressure to make clinical decisions regarding perfusion may or may not be accurate.
Publication Date: 2024-02-19 PubMed ID: 38393113PubMed Central: PMC10891611DOI: 10.3390/vetsci11020095Google Scholar: Lookup
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- Journal Article
Summary
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This research investigates how hypotension affects the microcirculation within the gastrointestinal tract of horses, and what impact the medication dobutamine has on restoring normal blood pressure. The study finds that usual indicators of circulatory health may not accurately reflect what is happening at the microvascular level.
Objective and Methodology
- This study aimed to uncover more about the correlation between mean arterial pressure and the microcirculation within a horse’s gastrointestinal tract. The researchers hypothesized that typical indicators of systemic circulation might not accurately show what’s happening on a microvascular level.
- To carry out this research, six anesthetized adult horses, undergoing controlled diagnostic laparotomies, were observed.
- Hypotension in the test subjects was artificially induced using inhaled isoflurane, a common anesthetic vet practitioners use.
Data Recording
- The arterial pressure, cardiac index, lactate concentration, and four essential microcirculatory parameters were recorded for every horse at different stages of the experiment – the normotensive stage, the artificially-induced hypotensive stage, and during the recovery stage when the horses’ normal blood pressure was restored using the drug dobutamine.
- These measurements were taken at three different sites along each horse’s gastrointestinal tract: the oral mucosa, the colonic serosa, and the rectal mucosa. The researchers used a method called dark-field microscopy to obtain the microcirculatory data.
Findings
- Expected changes in systemic or microvascular perfusion parameters due to artificially induced hypotension did not consistently show in the horses’ results.
- Even after normotension was successfully restored with dobutamine, systemic perfusion or microvascular perfusion parameters did not significantly change.
- This suggests that using mean arterial pressure as a primary basis for diagnosing and treating perfusion-related issues may not always be the wisest choice, as it might not accurately reflect the condition of microcirculations.
Cite This Article
APA
Kieffer PJ, Williams JM, Shepard MK, Giguère S, Epstein KL.
(2024).
Effect of Hypotension and Dobutamine on Gastrointestinal Microcirculations of Healthy, Anesthetized Horses.
Vet Sci, 11(2), 95.
https://doi.org/10.3390/vetsci11020095 Publication
Researcher Affiliations
- Evidensia Specialisthästsjukhuset Helsingborg, Bergavägen 3, 254 52 Helsingborg, Sweden.
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
- MedVet Medical & Cancer Centers for Pets, Chicago, IL 60618, USA.
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
Grant Funding
- Intramural- no grant number- For The Love of The Horse / University of Georgia
Conflict of Interest Statement
The authors declare no conflict of interest.
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