Vet Tips

Techniques that facilitate Induction to Anesthesia
12/18/2008

Injectable anesthesia: Most hypnotic drugs (thiopental, propofol, etomidate) produce anesthesia by interacting with the gamma amino butyric acid subtype A (GABAA) receptor. Benzodiazepines (diazepam, midazolam) modulate this receptor facilitating the hypnotic effects of these injectable anesthethic drugs. The administration of an IV diazepam or midazolam immediately before the IV administration of propofol, for example, reduces the dose of propofol required to produce anesthesia thereby decreasing the potential for side effects (hypoventilation, apnea, hypotension).
a. Determine the animals body weight (kg)
b. Determine and administer appropriate preanesthetic medication (ex. ace/butorp.; midazolam/hydromorph.)
c. Place and secure an intravenous (cephalic vein) catheter
d. Administer 0.2 mg/kg midazolam IV
e. Administer up to 2 mg/kg propofol IV to effect (orotracheal placement of an endotracheal tube)
f. Administer additional (0.2 mg/kg, IV) midazolam if required for intubation

Example: 10 yr old, 10 kg, castrated, mixed breed dog in good health admitted for dental prophylaxis.
-Administer: 0.05 mg/kg acepromazine [0.5 mg] and 0.2 mg/kg butorphanol [2 mg] IM
-Wait 15 to 20 minutes and place an IV catheter
-Administer 0.2 mg/kg [2 mg] IV midazolam and then up to 2 mg/kg [20 mg] IV propofol to effect.
-Administer an additional 0.2 mg/kg [2 mg] IV midazolam if necessary for orotracheal intubation.

Submitted by:
William Muir DVM, PhD, ACVA, ACVECC, VCPCS
338 West 7th Avenue
Columbus, Ohio 43201