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

Abstract

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

Methods: 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.

Results: 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.

Conclusions: 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.

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