Sublingual microcirculation in isoflurane-anesthetized horses receiving dexmedetomidine and lidocaine constant rate...

To assess the sublingual microcirculation in horses anesthetized with isoflurane and undergoing constant rate infusion of dexmedetomidine (DEX) and lidocaine (LID).

16 horses undergoing arthroscopy were included in a blind, randomized study comparing 2 groups: a DEX group (DEX-LID; 1.75 μg·kg-1·h-1 with a LID bolus of 1.3 mg·kg-1 followed by a continuous infusion of 0.05 mg·kg-1·min-1) and a LID-only group (LID; at the same dose). Hemodynamic variables, including mean, systolic, and diastolic blood pressure; heart rate; capnography; blood gas analysis; blood lactate; and orthogonal polarization spectral imaging were measured. Measurements were taken before infusion and at 15, 30, and 60 minutes after infusion initiation.

No differences were observed in microcirculation variables between the groups. At 60 minutes, the total vessel density was 18.73 ± 0.97, the microvascular flow index 3.59 ± 0.39, and the De Backer score 12.4 ± 0.95 in the DEX-LID group. The total vessel density was 20.15 ± 2.23, microvascular flow index 3.62 ± 0.5, and De Backer score 13.41 ± 2.32 for the LID group. Notably, 5 of 8 horses in the LID group required ephedrine for hypotension management (mean arterial pressure < 65 mm Hg), whereas none in the DEX-LID group did.

The combination of DEX and LID during isoflurane anesthesia provided stable hemodynamic conditions during arthroscopic surgery in horses without adversely affecting sublingual microcirculation or recovery.

These findings support that the combination of DEX and LID maintains hemodynamic variables during surgery without compromising microcirculation function.