Effect of two anaesthetic regimens on airway nitric oxide production in horses.
Abstract: There is evidence that halothane inhibits nitric oxide synthase in vitro, but the effect of intravenous anaesthetic agents is less clear. This study was undertaken to compare the rate of exhaled nitric oxide production (VNO) in spontaneously breathing horses anaesthetized with halothane or an intravenous regimen. Seven adult horses were studied twice in random order. After premedication with romifidine 100 microg kg(-1), anaesthesia was induced with ketamine 2.2 mg kg(-1) and maintained with halothane in oxygen (HA) or by an intravenous infusion of ketamine, guaiphenesin and romifidine (IV). Inhaled and exhaled nitric oxide (NO) concentrations, respiratory minute ventilation (VE), pulmonary artery pressure (PPA), fractional inspired oxygen concentration (FIO2), end-tidal carbon dioxide concentration (E'CO2), cardiac output (Q) and partial pressures of oxygen and carbon dioxide in arterial blood (PaO2, PaCO2) were measured. Exhaled nitric oxide production rate was significantly lower (40 min, P<0.01; 60 min, P<0.02) during HA [40 min, 1.4 (SD 1.4) pmol l(-1) kg(-1) min(-1); 60 min, 0.7 (0.7) pmol l(-1) kg(-1) min(-1)] than during IV [40 min, 9.3 (9.9) pmol l(-1) kg(-1) min(-1); 60 min, 12.5 (13.3) pmol l(-1) kg(-1) min(-1)). Mean pulmonary artery pressure was significantly higher (40 min, P<0.01; 60 min, P<0.001) during HA [40 min, 5.9 (1.1) kPa; 60 min, 5.9 (0.9) kPa] compared with IV (40 min, 4.4 (0.4) kPa; 60 min, 4.4 (0.5) kPa]. NO is reduced in the exhalate of horses anaesthetized with halothane compared with an intravenous regimen. It is suggested that increased mean pulmonary artery pressure during halothane anaesthesia may be linked to the differences in NO production.
Publication Date: 2001-09-29 PubMed ID: 11575389DOI: 10.1093/bja/86.1.127Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research evaluated the impact of two different anaesthetic procedures on the nitric oxide output in horses. The study determined that horses anesthetized with halothane had lesser nitric oxide in their breath, while the horses given intravenous anesthesia produced more nitric oxide and had lower pulmonary artery pressure.
Study Design and Methodology
- The research was designed to assess the effect of two different anaesthetic regimes – halothane and intravenous. Halothane was chosen as it’s been shown to inhibit nitric oxide synthase in test tubes, while the effect of intravenous anaesthetic agents wasn’t as clear. The focus was to compare the nitric oxide production in spontaneously breathing horses under these anesthetic regimes.
- Seven adult horses participated in the study, each one being studied twice in a randomized sequence.
- The anaesthesia process consisted of premedication with romifidine followed by induction with ketamine. Maintenance was done either with halothane in oxygen or via an intravenous infusion of ketamine, guaiphenesin, and romifidine.
- During the experiment, key physiological parameters were measured, such as nitric oxide concentrations, respiratory minute ventilation, cardiac output, and pulmonary artery pressure.
Key Findings
- The research found significant differences in nitric oxide output. The rate of exhaled nitric oxide was substantially lower during halothane anesthesia compared to the intravenous method.
- Additionally, mean pulmonary artery pressure was observed to be statistically higher under halothane, as compared to the intravenous regimen.
Conclusions
- Based on these findings, the researchers concluded that nitric oxide production is less when horses are anaesthetized using halothane compared to an intravenous regimen.
- They also suggested that the observed increased mean pulmonary artery pressure during halothane anesthesia could be related to the differences in nitric oxide production.
Cite This Article
APA
Marlin DJ, Young LE, McMurphy R, Walsh K, Dixon P.
(2001).
Effect of two anaesthetic regimens on airway nitric oxide production in horses.
Br J Anaesth, 86(1), 127-130.
https://doi.org/10.1093/bja/86.1.127 Publication
Researcher Affiliations
- Centre for Equine Studies, Animal Health Trust, Newmarket, Suffolk, UK.
MeSH Terms
- Anesthetics, Inhalation / pharmacology
- Anesthetics, Intravenous / pharmacology
- Animals
- Female
- Halothane / pharmacology
- Horses / metabolism
- Male
- Nitric Oxide / biosynthesis
- Pulmonary Wedge Pressure / drug effects
Citations
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