Effects of a prolonged infusion of fentanyl, with or without atropine, on the minimum alveolar concentration of isoflurane in dogs

In this study, fentanyl reduced the ISOMAC by approximately 50%. The ISOMAC remained stable throughout the 300 minute CRI of fentanyl, suggesting no cumulative effect of the opioid. Atropine did not influence ISOMAC in dogs.