Serial venous lactate measurement following gastrointestinal surgery in horses.

BACKGROUND: Prospective clinical study of blood lactate concentration in horses undergoing colic surgery is needed to determine utility in outcome prediction. OBJECTIVES: To evaluate venous lactate measurements in horses following colic surgery, including immediately after anesthetic recovery and daily throughout hospitalization, as well as to determine if lactate concentrations were significantly higher in horses that developed postoperative complications or did not survive to hospital discharge. METHODS: Horses > 1 year of age undergoing surgery for colic and recovered from general anesthesia were sampled. A portable lactate meter was used to measure venous samples collected immediately following anesthetic recovery and daily throughout hospitalization. Complications arising during hospitalization and survival to hospital discharge were recorded. RESULTS: Fifty one horses were enrolled, ranging in age from 2 to 29 years. Lactate concentration immediately following anesthetic recovery was higher in horses that developed complications during hospitalization (p = 0.046). The odds of developing complications postoperatively were doubled for horses with a venous lactate concentration > 5 mmol/L. Lactate measurements in non-survivors were significantly higher compared to survivors by 96 h postoperatively (p < 0.006). CONCLUSIONS: Higher venous lactate concentrations in the postoperative colic period were associated with an increased risk of complications and death. Results suggest horses with higher venous lactate measurements in recovery are more likely to have postoperative complications, with the odds of developing complications doubled for horses with a venous lactate > 5 mmol/L. Evaluation of venous lactate could provide information on prognosis in the postoperative period for horses with surgical colic.

Catastrophic complication following injection and extracorporeal shock wave therapy of a medial femoral condyle subchondral cystic lesion in a 14 year old Arabian mare.

This report describes fibrous cyst lining injection and extracorporeal shock wave therapy (ESWT) of a medial femoral condyle (MFC) subchondral cystic lesion (SCL) resulting in catastrophic MFC fracture in an Arabian mare. The mare was presented for evaluation of a severe hind limb lameness of approximately 4 months duration. On presentation, a non-weight bearing lameness of the left hind limb with severe effusion and soft tissue swelling of the stifle region was noted. Radiographic evaluation of the stifle revealed a large SCL of the MFC with associated osteoarthritis. Arthroscopic guided intra-lesional injection of the SCL with corticosteroids and autologous bone marrow concentrate was performed followed by ESWT of the MFC. The mare was discharged walking comfortably 48-hours post-operatively. An acute increase in lameness was noted 14 days post-operatively. Imaging revealed catastrophic fracture of the left MFC. Possible mechanisms leading to failure of the MFC secondary to the described treatment are discussed.

Effects of tourniquet number and exsanguination on amikacin concentrations in the radiocarpal and distal interphalangeal joints after low volume intravenous regional limb perfusion in horses.

OBJECTIVE: To determine the influence of a dual tourniquet technique and limb exsanguination on amikacin concentrations in the synovial fluid of the radiocarpal joint (RCJ) and distal interphalangeal joint (DIPJ) after low volume, cephalic intravenous regional limb perfusion (IVRLP). STUDY DESIGN: Randomized cross-over design. ANIMALS: Six healthy adult horses. METHODS: One gram of amikacin in 6 mL of 0.9% NaCl was infused via cephalic IVRLP in 6 standing, sedated horses using 4 techniques: proximal pneumatic tourniquet (P), proximal pneumatic tourniquet with exsanguination (PE), proximal pneumatic and distal Esmarch tourniquet (PD), and proximal pneumatic with distal Esmarch tourniquet and exsanguination (PDE). Amikacin concentrations were measured in RCJ and DIPJ synovial fluid samples, collected just before perfusion (time 0), and at 15 and 30 minutes (before tourniquet release) after perfusion. RESULTS: Synovial fluid amikacin concentrations achieved in the RCJ were higher with techniques PD and PDE than those achieved with techniques P and PE 15 and 30 minutes after perfusion (P < .0001). Synovial fluid amikacin concentrations in the DIPJ were higher with techniques P and PE than those achieved with techniques PD and PDE at 15 minutes (P = .0002) and were higher than technique PDE at 30 minutes after perfusion (P < .0001). CONCLUSION: Low volume (10 mL) cephalic IVRLP should be combined with the placement of 2 tourniquets (proximal and distal to the carpus) to achieve therapeutic amikacin concentrations in the RCJ. Exsanguination prior to low volume IVRLP does not alter synovial fluid amikacin concentrations.

Effect of Regional Intravenous Limb Perfusate Volume on Synovial Fluid Concentration of Amikacin and Local Venous Blood Pressure in the Horse.

OBJECTIVE: To determine the effect of volume of amikacin perfusate for intravenous regional limb perfusion (IVRLP) via the cephalic vein in standing, sedated horses on (1) amikacin concentrations in the synovial fluid of the radiocarpal joint (RCJ) and distal interphalangeal joint (DIPJ) and, (2) amikacin concentration in the systemic circulation, and (3) regional intravenous pressure. STUDY DESIGN: Randomized cross-over design. ANIMALS: Six adult horses. METHODS: Each horse received IVRLP using 4 perfusate volumes (10, 30, 60 & 120 ml) in random order, after a minimum of 1 week washout. After application of a pneumatic tourniquet, IVRLP with 1 g of amikacin in 0.9% NaCl was performed. Synovial fluid from the RCJ and DIPJ, and systemic and regional venous blood were sampled, and regional blood pressure was measured, immediately before perfusion (time 0), and 15 and 30 minutes after perfusion but before tourniquet release. RESULTS: No difference was observed in the mean amikacin concentration of synovial fluid for the 4 perfusate volumes (P>.09). For all volumes, mean amikacin concentration for DIPJ synovial fluid was higher than for RCJ (P<.0001). The mean amikacin concentration in DIPJ synovial fluid was therapeutic for resistant pathogens using the 10, 60, and 120 mL volumes but the mean amikacin concentration for RCJ synovial fluid was not therapeutic for resistant pathogens with any perfusate volume. All volumes resulted in an immediate increase in mean regional intravascular pressure after perfusion (P<.0001) but was not different across the 4 perfusate volumes. CONCLUSION: Cephalic IVRLP of 1 g of amikacin diluted to a volume of 10-120 mL with 0.9% NaCl will achieve amikacin concentrations therapeutic for resistant pathogens in the synovial fluid from the DIPJ. Concentrations below therapeutic levels for resistant pathogens are reached in the synovial fluid from the RCJ.