Effects of continuous rate infusion of butorphanol in isoflurane-anesthetized calves

Abstract

PURPOSE:To assess the hemodynamic changes and bispectral index (BIS) following administration of a continuous rate infusion (CRI) of butorphanol in isoflurane-anesthetized calves. METHODS:Eight calves weighing 110 ± 12 kg were included in the study. Anesthesia was induced with 5% isoflurane in O 2 delivered via face mask and maintained with end-tidal concentration of 1.4%. IPPV was set to a peak inspiratory airway pressure of 15 cmH 2 O and respiratory rate of six breaths minute -1 . Forty minutes after the start of anesthetic maintenance, 0.1 mg kg -1 butorphanol was administered intravenously, followed by a CRI of 20 µg kg -1 minute -1 . Hemodynamic variables and BIS were recorded before butorphanol administration (T0), and at 10, 20, 40 and 80 minutes following the CRI. Anesthesia was discontinued after the last recording and the calves were allowed to recover. The time to sternal recumbency (SRE) and standing (ST) were evaluated. RESULTS:There were no significant differences between the moments in all hemodynamic variables and BIS. The time to SRE and ST was 9 ± 5 and 14 ± 7 minutes, respectively. CONCLUSION:The continuous rate infusion did not produce clinically relevant changes in hemodynamic or bispectral index values compared to baseline in mechanically ventilated and unstimulated calves anesthetized at 1.4% isoflurane.

Bispectral index assessment in calves subjected to the continuous infusion of propofol combined with fentanyl administration

“…Using the BIS, APREA et al (2014) clearly showed in a case report of the cardiopulmonary resuscitation of a propofol-anesthetized calf that the BIS values that were assessed had varied with cardiovascular function and that BIS was indicative of cerebral perfusion in cattle. ARAÚJO et al (2014) and reported mean BIS values of approximately 40 when conducting studies in calves using inhalation anesthesia with isoflurane combined with butorphanol infusion, and assessing BIS in isoflurane-anesthetized calves with or without CRI of lidocaine, respectively. Such values were slightly lower than those reported in this study, which is most likely related to the protocol that was used and to the difference in anesthetic plan.…”