Comparison of Transdermal Fentanyl and Intramuscularly Administered Buprenorphine for Postoperative Pain in Pregnant Sheep
Abstract
Designing perioperative analgesic regimen for ruminants is problematic as pain
assessment is difficult and pregnancy adds additional considerations. The aim of this
study was to assess the nociceptive properties of intramuscularly administered
buprenorphine and transdermally administered fentanyl utilizing a composite pain score
system. To better confirm that the observed abnormal behavior was related to pain, the
current study attempted to characterize the nociceptive properties of the analgesic agents
at a given plasma drug concentration, which has not previously been done. Additionally,
the study characterized transplacental movement of analgesic agents via fetal plasma
drug concentrations.
In this study, we compared intramuscularly administered buprenorphine at a dose of
0.01 mg/kg every 8 hours for 48 hours starting at induction for surgery (n=6) to
transdermal fentanyl patches (n=6) applied in the dorsal thorax region 24 hours before
surgery at a dose of 2μg/kg/hr for postoperative pain. Ewe blood samples were collected
and signs of pain and sedation were measured 24 hours before surgery (time -24),
induction to surgery (time 0), and 2, 4, 6, 8, 12, 24, 36, 48 hours after. Using an
indwelling fetal arterial catheter that was placed during the surgery, fetal blood pressure
was recorded and blood samples were collected. Drug concentrations were measured in
maternal and fetal plasma and amniotic fluid. The buprenorphine treated ewes exhibited
more pain consistent behaviors than those treated with fentanyl, and their postoperative
pain scores were significantly higher than the preoperative value. There were also
significant differences in cardiovascular variables from the anesthesia records between
the two groups. Overall, transdermal administration of fentanyl provided adequate
analgesia with little adverse effects, making it a candidate for optimal postoperative pain
management in sheep.
Citation
Padgett, Ashley Loren (2018). Comparison of Transdermal Fentanyl and Intramuscularly Administered Buprenorphine for Postoperative Pain in Pregnant Sheep. Master's thesis, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /174041.