Arterial blood gas tensions during recovery in horses anesthetized with apneustic anesthesia ventilation compared with conventional mechanical ventilation.
Abstract: To compare PaO2 and PaCO2 in horses recovering from general anesthesia maintained with either apneustic anesthesia ventilation (AAV) or conventional mechanical ventilation (CMV). Methods: Randomized, crossover design. Methods: A total of 10 healthy adult horses from a university-owned herd. Methods: Dorsally recumbent horses were anesthetized with isoflurane in oxygen [inspired oxygen fraction = 0.3 initially, with subsequent titration to maintain PaO2 ≥ 85 mmHg (11.3 kPa)] and ventilated with AAV or CMV according to predefined criteria [10 mL kg-1 tidal volume, PaCO2 40-45 mmHg (5.3-6.0 kPa) during CMV and < 60 mmHg (8.0 kPa) during AAV]. Horses were weaned from ventilation using a predefined protocol and transferred to a stall for unassisted recovery. Arterial blood samples were collected and analyzed at predefined time points. Tracheal oxygen insufflation at 15 L minute-1 was provided if PaO2 < 60 mmHg (8.0 kPa) on any analysis. Time to oxygen insufflation, first movement, sternal recumbency and standing were recorded. Data were analyzed using repeated measures anova, paired t tests and Fisher's exact test with significance defined as p < 0.05. Results: Data from 10 horses were analyzed. Between modes, PaO2 was significantly higher immediately after weaning from ventilation and lower at sternal recumbency for AAV than for CMV. No PaCO2 differences were noted between ventilation modes. All horses ventilated with CMV required supplemental oxygen, whereas three horses ventilated with AAV did not. Time to first movement was shorter with AAV. Time to oxygen insufflation was not different between ventilation modes. Conclusions: Although horses ventilated with AAV entered the recovery period with higher PaO2, this advantage was not sustained during recovery. Whereas fewer horses required supplemental oxygen after AAV, the use of AAV does not preclude the need for routine supplemental oxygen administration in horses recovering from general anesthesia.
Copyright © 2023 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.
Publication Date: 2023-01-28 PubMed ID: 36781322DOI: 10.1016/j.vaa.2023.01.004Google Scholar: Lookup
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- Journal Article
Summary
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The research compared the effects of two types of ventilation, apneustic anesthesia ventilation (AAV) and conventional mechanical ventilation (CMV), on the arterial blood gas tensions in horses recovering from general anesthesia. The study concluded that while horses ventilated with AAV entered recovery with higher arterial oxygen pressure (PaO), this advantage was not maintained during recovery.
Study Design
- The study was a randomized, cross-over design involving 10 healthy adult horses from a university-owned herd.
- The horses, in a dorsally recumbent position (lying on their back), were anesthetized with isoflurane in oxygen, with the oxygen fraction initially set at 0.3. The oxygen fraction was subsequently adjusted to maintain PaO at or above 85 mmHg.
- The horses were ventilated with either AAV or CMV. Parameters for each mode for maintaining the pressure of carbon dioxide in the arteries (PaCO) were defined: 40-45 mmHg during CMV and less than 60 mmHg during AAV.
- A protocol was followed to gradually discontinue ventilation, and the horses were then moved to a stall for recovery without assistance. Blood samples were collected from the horses at predetermined time points throughout the experiment for analysis.
Results
- Data from all 10 horses were analyzed, and it was observed that the PaO in horses immediately after discontinuation of ventilation was significantly higher for those ventilated via AAV than CMV.
- However, when horses were in the sternally recumbent position (lying on their stomach), the PaO was significantly lower for those ventilated via AAV compared to CMV.
- There were no noticeable differences in PaCO between the two ventilation modes.
- All horses ventilated with CMV required additional oxygen, whereas three horses ventilated with AAV did not.
- Time taken for the horse’s first movement after recovery was shorter with AAV ventilation.
- There were no significant differences in time to oxygen insufflation between the two ventilation modes.
Conclusion
- The results suggested that although horses ventilated with AAV entered recovery with higher PaO levels, this advantage was not sustained during the recovery period.
- Also, fewer horses required supplemental oxygen after AAV ventilation. However, the usage of AAV did not eliminate the need for routine supplemental oxygen administration in horses recovering from general anesthesia.
Cite This Article
APA
Fisher K, Dodam J, Bailey J, Thombs L, Hodgson D, Bukoski A.
(2023).
Arterial blood gas tensions during recovery in horses anesthetized with apneustic anesthesia ventilation compared with conventional mechanical ventilation.
Vet Anaesth Analg, 50(3), 238-244.
https://doi.org/10.1016/j.vaa.2023.01.004 Publication
Researcher Affiliations
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA.
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA.
- Innovative Veterinary Medicine, Ponte Vedra, FL, USA.
- Department of Statistics, College of Arts and Science, University of Missouri, Columbia, MO, USA.
- Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA. Electronic address: bukoskia@missouri.edu.
MeSH Terms
- Horses
- Animals
- Respiration, Artificial / veterinary
- Respiration, Artificial / methods
- Prospective Studies
- Anesthesia, General / veterinary
- Oxygen
- Cytomegalovirus Infections / veterinary
- Horse Diseases
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