Evaluation of serial venous and arterial lactate concentrations in healthy anesthetized sheep undergoing ovariectomy.

OBJECTIVE: To determine if lactate concentrations in jugular venous and auricular arterial blood differ in anesthetized sheep. STUDY DESIGN: Prospective, controlled experimental study. ANIMALS: Twelve healthy adult ewes, 4-7 years and weighing 62-77 kg. METHODS: Jugular venous blood was collected before anesthesia (PreOv ) for measurement of lactate concentration, packed cell volume and total protein. Ewes were administered a standard anesthesia protocol. Jugular venous (IntraOv ) and auricular arterial (IntraOa ) blood samples were obtained 40 minutes after induction of anesthesia, and again in recovery (PostOv and PostOa ). An additional blood sample was drawn 6 weeks post-operatively from non-fasted sheep (NF_Lact). Lactate concentrations were compared among PreOv , IntraOv and IntraOa , PostOv and PostOa , and between PreOv and NF_Lact with paired t-test and repeated measure analyses of variance (anova) with PreOv as a covariate (p ≤ 0.05). RESULTS: IntraOv lactate concentration had decreased from PreOv There were significant differences between arterial and venous IntraO and PostO lactate concentrations. There was no significant difference between IntraO and PostO, or PreOv and NF_Lact. CONCLUSIONS AND CLINICAL RELEVANCE: Lactate concentrations were significantly lower in anesthetized sheep compared to non-anesthetized sheep. Lactate concentrations in venous blood were higher than in arterial blood. Therefore, anesthetic status and sampling site should be considered when interpreting lactate concentrations, and the sampling site should be consistent for repeated measurements.