Anesthetic induction with guaifenesin and propofol in adult horses.

The research article explores the use of guaifenesin and propofol in anesthetic induction on adult horses. It investigates whether guaifenesin can prevent adverse events during induction caused by propofol, and if the combination has brief cardiovascular effects.

Research Methods

• This study involved eight healthy adult horses. The process started with the administration of guaifenesin intravenously for three minutes, which was then followed by an injection of a bolus of propofol. The propofol dose was increased if any purposeful move was detected from the horses.
• Anesthesia was then measured for two hours with either isoflurane or sevoflurane at 1.2 times the minimum alveolar concentration, combined with controlled normocapnic ventilation.
• Maintaining normotension was achieved via a dobutamine infusion. The plasma concentrations of both guaifenesin and propofol were measured every 30 minutes.

Research Findings

• The mean guaifenesin and propofol doses that induced anesthesia in half of the horses were 73 mg/kg and 2.2 mg/kg, respectively. Importantly, no adverse anesthetic induction events were observed during the procedure.
• By the 70th minute, there was no substantial increase in the dobutamine infusion rate necessary for maintaining normotension for those horses anesthetized with either isoflurane or sevoflurane.
• The mean plasma guaifenesin concentrations measured at 30, 60, 90, and 120 minutes after the anesthetic induction were 122 μM, 101 μM, 93 μM, and 80 μM respectively. All plasma propofol concentrations were found to be below the limit of quantitation.

Conclusions

• Guaifenesin successfully prevented any adverse anesthetic induction events caused by propofol. Thus, an induction combination of guaifenesin (90 mg/kg) followed by propofol (3 mg/kg) should be adequate for immobilizing over 99% of calm healthy adult horses.
• The study also found that the process of anesthetic drug washout was rapid, and there was no change in inotrope requirements following anesthesia for 70 minutes.