Effects of inspired oxygen concentration on ventilation, ventilatory rhythm, and gas exchange in isoflurane-anesthetized horses.
Abstract: To compare the effects of 2 fractions of inspired oxygen, 50% and > 95%, on ventilation, ventilatory rhythm, and gas exchange in isoflurane-anesthetized horses. Methods: 8 healthy adult horses. Methods: In a crossover study design, horses were assigned to undergo each of 2 anesthetic sessions in random order, with 1 week separating the sessions. In each session, horses were sedated with xylazine hydrochloride (1.0 mg/kg, IV) and anesthesia was induced via IV administration of diazepam (0.05 mg/kg) and ketamine (2.2 mg/kg) Anesthesia was subsequently maintained with isoflurane in 50% or > 95% oxygen for 90 minutes. Measurements obtained during anesthesia included inspiratory and expiratory peak flow and duration, tidal volume, respiratory frequency, end-tidal CO(2) concentration, mixed expired partial pressures of CO(2) and O(2), PaO(2), PaCO(2), blood pH, arterial O(2) saturation, heart rate, and arterial blood pressure. Calculated values included the alveolar partial pressure of oxygen, alveolar-to-arterial oxygen tension gradient (PaO(2) - PaO(2)), rate of change of PAO(2) - PaO(2), and physiologic dead space ratio. Ventilatory rhythm, based on respiratory rate and duration of apnea, was continuously observed and recorded. Results: Use of the lower inspired oxygen fraction of 50% resulted in a lower arterial oxygen saturation and PaO(2) than did use of the higher fraction. No significant difference in PaCO(2), rate of change of PAO(2) - PaO(2), ventilatory rhythm, or other measured variables was observed between the 2 sessions. Conclusions: Use of 50% inspired oxygen did not improve the ventilatory rhythm or gas exchange and increased the risk of hypoxemia in spontaneously breathing horses during isoflurane anesthesia. Use of both inspired oxygen fractions requires adequate monitoring and the capacity for mechanical ventilation.
Publication Date: 2013-02-01 PubMed ID: 23363340DOI: 10.2460/ajvr.74.2.183Google Scholar: Lookup
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- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
Summary
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The research article investigates the impact of differing levels of inspired oxygen (50% and >95%) on the respiration and gas exchange in horses under isoflurane anesthesia. It concluded that using 50% inspired oxygen did not enhance ventilatory rhythm or gas exchange, and it actually increased the potential for low oxygen levels in the horses’ bloodstream during anesthesia.
Research Methodology
- The researchers conducted a crossover study with eight healthy adult horses.
- The horses were subjected to two anesthesia sessions each, in a random sequence, with a gap of a week between the sessions.
- Sedation was induced with xylazine hydrochloride followed by diazepam and ketamine to initiate anesthesia. Isoflurane mixed with either 50% or >95% oxygen was used to maintain the anesthesia for a 90-minute duration.
- The researchers recorded several respiratory and blood parameters, including tidal volume, respiratory frequency, blood pressure, and arterial oxygen saturation. They also monitored the rate of change of alveolar-to-arterial oxygen tension and dead space ratio.
- Ventilatory rhythm (based on respiratory rate and apnea duration) was continuously observed and documented.
Results and Analysis
- The use of the lower fraction of 50% inspired oxygen led to lower arterial oxygen saturation and PaO2 (partial pressure of oxygen).
- However, there was no significant difference in PaCO2 (partial pressure of carbon dioxide), rate of change of alveolar-to-arterial oxygen tension, ventilatory rhythm, or other monitored variables between the two sessions.
- In other words, using a lower inspired oxygen fraction of 50% neither improved the ventilatory rhythm nor gas exchange, and it enhanced the likelihood of hypoxemia (Low oxygen levels in the blood) in the anesthetized horses.
Conclusion
- Based on the analysis, it can be inferred that using 50% inspired oxygen is not beneficial in enhancing the gas exchange or ventilation of horses under isoflurane anesthesia.
- Both levels of inspired oxygen demand adequate monitoring and the ability for mechanical ventilation due to the potential risks involved.
Cite This Article
APA
Crumley MN, McMurphy RM, Hodgson DS, Kreider SE.
(2013).
Effects of inspired oxygen concentration on ventilation, ventilatory rhythm, and gas exchange in isoflurane-anesthetized horses.
Am J Vet Res, 74(2), 183-190.
https://doi.org/10.2460/ajvr.74.2.183 Publication
Researcher Affiliations
- Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA. mariana.crumley@yahoo.com
MeSH Terms
- Anesthesia / adverse effects
- Anesthesia / veterinary
- Anesthetics, Inhalation / administration & dosage
- Animals
- Cross-Over Studies
- Horses / physiology
- Isoflurane / administration & dosage
- Oxygen / administration & dosage
- Oxygen / blood
- Oxygen Consumption / drug effects
- Partial Pressure
- Pulmonary Artery / metabolism
- Pulmonary Gas Exchange / drug effects
- Respiration, Artificial / veterinary
Citations
This article has been cited 5 times.- Tucker L, Almeida D, Wendt-Hornickle E, Baldo CF, Allweiler S, Guedes AGP. Effect of 15° Reverse Trendelenburg Position on Arterial Oxygen Tension during Isoflurane Anesthesia in Horses. Animals (Basel) 2022 Feb 1;12(3).
- Savvas I, Pavlidou K, Braun C, Schauvliege S, Staffieri F, Moens Y. Evaluation of the Effect of the Inspired Oxygen Fraction on Blood Oxygenation during Inhalant Anaesthesia in Horses: A Systematic Review with Meta-Analysis. Animals (Basel) 2021 Jul 30;11(8).
- Jara CP, Carraro RS, Zanesco A, Andrade B, Moreira K, Nogueira G, Souza BL, Prado TP, Póvoa V, Velander W, Velloso LA, Araújo EP. A Smartphone App for Individual Xylazine/Ketamine Calculation Decreased Anesthesia-Related Mortality in Mice. Front Vet Sci 2021;8:651202.
- 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.
- Bukoski A, Downs J, Hodgson DS, Le-Bert CR, Thomen R, Flors L, Thombs L, Bailey J. Cardiopulmonary effects of apneustic anesthesia ventilation in anesthetized pigs: a new mode of ventilation for anesthetized veterinary species. Front Vet Sci 2024;11:1378617.
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