The effect of changing the mode of ventilation on the arterial-to-end-tidal CO2 difference and physiological dead space in laterally and dorsally recumbent horses during halothane anesthesia.
Abstract: To evaluate the effect of changing the mode of ventilation from spontaneous to controlled on the arterial-to-end-tidal CO2 difference [P(a-ET)CO2] and physiological dead space (VD(phys)/VT) in laterally and dorsally recumbent halothane-anesthetized horses. STUDY DESIGN; Prospective, experimental, nonrandomized trial. Methods: Seven mixed breed adult horses (1 male and 6 female) weighing 320 +/- 11 kg. Methods: Horses were anesthetized in 2 positions-right lateral and dorsal recumbency-with a minimum interval of 1 month. Anesthesia was maintained with halothane in oxygen for 180 minutes. Spontaneous ventilation (SV) was used for 90 minutes followed by 90 minutes of controlled ventilation (CV). The same ventilator settings were used for both laterally and dorsally recumbent horses. Arterial blood gas analysis was performed every 30 minutes during anesthesia. End-tidal CO2 (PETCO2) was measured continuously. P(a-ET)CO2 and VD(phys)NT were calculated. Statistical analysis included analysis of variance for repeated measures over time, followed by Student-Newman-Keuls test. Comparison between groups was performed using a paired t test; P < .05 was considered significant. Results: P(a-ET)CO2 and VD(phys)/VT increased during SV, whereas CV reduced these variables. The variables did not change significantly throughout mechanical ventilation in either group. Dorsally recumbent horses showed greater P(a-ET)CO2 and VD(phys)/VT values throughout. PaCO2 was greater during CV in dorsally positioned horses. Conclusions: Changing the mode of ventilation from spontaneous to controlled was effective in reducing P(a-ET)CO2 and physiological dead space in both laterally and dorsally recumbent halothane-anesthetized horses. Dorsal recumbency resulted in greater impairment of effective ventilation. Capnometry has a limited value for accurate estimation of PaCO2 in anesthetized horses, although it may be used to evaluate pulmonary function when paired with arterial blood gas analysis.
Publication Date: 2000-03-24 PubMed ID: 10730713DOI: 10.1111/j.1532-950x.2000.00200.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research examined the impact of switching the ventilation mode from spontaneous to controlled on the arterial-to-end-tidal CO2 difference and physiological dead space in anesthetized horses. The findings suggest that the controlled ventilation reduces both variables while dorsal recumbency impairs effective ventilation more.
Study Design and Methods
- The research was a prospective, nonrandomized trial with a sample of seven adult horses.
- Each horse was anesthetized in two positions—right lateral and dorsal recumbency—with a gap of at least one month between sessions.
- Horses were kept under anaesthesia with halothane in oxygen for 180 minutes in each session.
- For the first 90 minutes, the horses underwent spontaneous ventilation (SV), followed by 90 minutes of controlled ventilation (CV).
- At regular intervals of 30 minutes, arterial blood gas analysis was performed, and the end-tidal CO2 (PETCO2) was measured continuously.
Results
- The study found higher values of arterial-to-end-tidal CO2 difference (P[a-ET]CO2) and physiological dead space (VD[phys]/VT) during spontaneous ventilation (SV).
- The use of controlled ventilation (CV) lowered these variables.
- There were no significant changes in these variables during mechanical ventilation in either group.
- Horses in dorsal recumbency had higher values of P(a-ET)CO2 and VD(phys)/VT throughout the observation period, and a greater PaCO2 during CV.
Conclusions
- Switching from spontaneous to controlled ventilation effectively reduced the P(a-ET) CO2 and physiological dead space in both dorsally and laterally recumbent horses under halothane anesthesia.
- However, the study also found that horses in dorsal recumbency had a greater impairment of effective ventilation.
- Therefore, while capnometry may not be fully accurate in estimating PaCO2 in anesthetized horses, it could be used alongside arterial blood gas analysis to evaluate pulmonary function in these animals.
Cite This Article
APA
Neto FJ, Luna SP, Massone F, Thomassian A, Vargas JL, Junior JR, D'Utra Vaz BB, Crocci AJ.
(2000).
The effect of changing the mode of ventilation on the arterial-to-end-tidal CO2 difference and physiological dead space in laterally and dorsally recumbent horses during halothane anesthesia.
Vet Surg, 29(2), 200-205.
https://doi.org/10.1111/j.1532-950x.2000.00200.x Publication
Researcher Affiliations
- Department of Veterinary Surgery and Anesthesiology, Faculty of Veterinary Medicine and Animal Science, University of São Paulo State, Botucatu, Brazil.
MeSH Terms
- Anesthetics, Inhalation
- Animals
- Female
- Halothane
- Horses / physiology
- Male
- Posture
- Prospective Studies
- Respiration, Artificial / veterinary
- Respiratory Dead Space / physiology
Citations
This article has been cited 4 times.- Niyom S, Mama KR, King M, Contino E, Ferris D, Valdes-Martinez A, Frisbie DD, McIlwraith W, Zumbrunnen J. Influence of changing lateral recumbency and mode of ventilation on the alveolar-arterial oxygen tension gradient and selected laboratory analytes in adult isoflurane anesthetized horses.. J Vet Med Sci 2018 Nov 1;80(10):1584-1589.
- Mosing M, Böhm SH, Rasis A, Hoosgood G, Auer U, Tusman G, Bettschart-Wolfensberger R, Schramel JP. Physiologic Factors Influencing the Arterial-To-End-Tidal CO(2) Difference and the Alveolar Dead Space Fraction in Spontaneously Breathing Anesthetised Horses.. Front Vet Sci 2018;5:58.
- Gonçalves Dias LG, Nunes N, Lopes PC, de Almeida RM, Neto GB, de Souza AL, de Almeida Belmonte E. The effects of 2 levels of the inspired oxygen fraction on blood gas variables in propofol-anesthetized dogs with high intracranial pressure.. Can J Vet Res 2009 Apr;73(2):111-6.
- Koenig J, McDonell W, Valverde A. Accuracy of pulse oximetry and capnography in healthy and compromised horses during spontaneous and controlled ventilation.. Can J Vet Res 2003 Jul;67(3):169-74.
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