Hypothermic Storage of Feline Kidneys for Transplantation: Successful Ex Vivo Storage Up to 7 Hours

Objective—To describe the effect of hypothermic storage on transplanted feline kidneys.
Study Design—Kidneys were stored in University of Wisconsin (UW) sodium gluconate (n = 3) or phosphate-buffered sucrose (n = 5) solutions before transplantation.
Animal Population—Eight cats with renal failure and seven normal cats as kidney donors.
Methods—Kidneys were perfused through the renal artery with cold (10°C) storage solution and immersed in the solution on ice until transplantation.
Results—Mean ex vivo storage time was 4.8 ± 0.36 hours (range, 3.5 to 7 hours). Seven recipient cats survived surgery. Five of the cats had decreased serum creatinine concentrations from a mean of 8.2 mg/dL (range, 4.0 to 15.8 mg/dL) preoperatively to 1.7 mg/dL (range, 1.3 to 2.2 mg/dL) within 4 days of surgery. In one cat, serum creatinine concentration dropped from 15.1 to 3.7 mg/dL in 3 days, but the cat developed a ureteral stricture that required revision. One graft did not function, and the cat died on day 19. The mean postoperative survival time of cats that were discharged from the hospital (n = 6) was 254 days (range, 49 to 717 days) at the time of this report. Long-term renal function (>60 days postoperatively; n = 5) was excellent with mean serum creatinine concentrations of 1.6 ± 0.15 mg/dL.
Conclusions—Hypothermic storage is feasible for short-term preservation of feline kidneys.
The maximal length of feasible storage remains unknown.
Clinical Relevance—Hypothermia protects against ischemia-induced nephron loss during ex vivo manipulation of the allograft and allows longer safe vascular anastomosis times. Short-term hypothermic storage also provides time to accommodate modifications in scheduling or anesthetic management of the recipient operation.     

A Comparison of Indirect Blood Pressure Monitoring Techniques in the Anesthetized Cat

Objective —To determine the accuracy of three indirect blood pressure monitoring techniques (oscillometric technique [OS], Doppler [DOP], and optical plethysmography [OP] [blood pressure determined with a pulse oximeter waveform]) when compared with direct arterial pressure measurement in cats. Study Design —Prospective study. Animal Population —Eight healthy (five female, three male), domestic short-hair cats, weighing 3.5 ± 0.8 kg Methods —Cats were anesthetized with isoflurane. The inspired concentration of isoflurane was adjusted to produce mild hypotension (80 to 100 mm Hg direct systolic), moderate hypotension (60 to 80 mm Hg direct systolic), and severe hypotension (<60 mm Hg direct systolic). Indirect pressure measurements were obtained from the thoracic limb and compared with concurrent direct measurement using regression analysis and a modification of Bland and Altman's technique. Results —All three techniques underestimated systolic pressure. OS produced the best prediction of systolic pressure with a bias ± precision of -15.9 ± 8.1 mm Hg. DOP and OP were relatively inaccurate with a bias ± precision of -25 ± 7.4 mm Hg and -25 ± 7.5 mm Hg. All three techniques correlated well with direct pressure with r values of 0.81, 0.88, and 0.88 for OS, DOP, and OP. DOP and OP provided an accurate prediction of direct mean arterial pressure with a bias ± precision of -0.8 ± 6 mm Hg and 0.6 ± 5.5 mm Hg. Correlation was good between DOP and mean arterial pressure with r = 0.89. Correlation was also good between OP and mean arterial pressure with r = 0.90. Conclusions —OS provided the most accurate prediction of direct systolic pressure. DOP and OP provided a good prediction of mean arterial pressure in the cat. Clinical Relevance —All three of these techniques are useful for detecting trends. Direct monitoring of blood pressure should be considered if accurate blood pressure measurement is required.     

Cardiovascular Effects of Enoximone and Epinephrine on Heparin Reversal With Protamine in Conscious Dogs

Objective—To compare enoximone with epinephrine as treatments for the cardiotoxic effects of protamine sulfate.
Study Design—Prospective randomized study.
Animal Population—12 healthy cross-bred dogs weighing 23 ± 4 kg.
Methods—The dogs were anesthetized with xylazine and ketamine to allow instrumentation. Femoral arterial and venous catheters were inserted for pressure monitoring and to allow drug infusion. A thermodilution catheter mounted with a fast response thermistor was inserted into the pulmonary artery via the jugular vein to measure cardiac output and right ventricular volumes. Heparin 300 units/kg followed by protamine 4.5 mg/kg were administered 45 minutes after the xylazine/ketamine. Four animals were not treated (controls), four received enoximone, and four were given epinephrine. Cardiopulmonary parameters were monitored for a period of 30 minutes.
Results—Cardiac index was 104 ± 15 mL/kg/min in the enoximone group, 72 ± 13 mL/kg/ min in the epinephrine group, and 63 ± 10 mL/kg/min in the control group ( P < .05 enoximone versus control and epinephrine). Right ventricular end systolic volume was 18 ± 3, 27 ± 4, and 29 ± 6 mL in the enoximone, epinephrine, and control groups ( P < .05 enoximone versus control and epinephrine). There were no differences in mean arterial pressure or pulmonary and systemic vascular resistance between the groups.
Conclusions and Clinical Relevance—In this study, enoximone was more effective than epinephrine at reversing the hemodynamic changes associated with protamine sulfate administration.     

Comparison of High Performance Liquid Chromatography and Immunoassay Methods for Measurement of Cyclosporine A Blood Concentrations After Feline Kidney Transplantation

Objective —To compare two methods of whole blood cyclosporine A (CsA) measurement in cats.
Study Design —Whole blood samples were analyzed for CsA concentrations with use of high performance liquid chromatography (HPLC) and monoclonal immunoassay methods.
Animals —Blood (n = 36 samples) was obtained from six cats after renal transplantation.
Methods —Results were compared by linear regression analysis using both pooled and individual patient data. Eight samples were off-scale on the immunoassay and were excluded.
Results —There was significant correlation between CsA measured using HPLC and immunoassay methods ( P < .001; r = .942; r²= .887). However, individuals varied nonrandomly from the mean pooled patient data. Correlation between the assay methods was higher for individual patients using data only from that specific individual (mean r value = .976; r²= .955). Clinical utility of the immunoassay (ie, results would prompt an appropriate CsA dosage adjustment) was good when based on individually derived conversion factors (27 of 28 [96.5%] of decision events).
Conclusion—HPLC is superior for measurement of blood CsA concentrations in cats after kidney transplantation. However, an immunoassay may provide reliable information for CsA management if a comparative database (HPLC v immunoassay) has been previously determined in a specific patient.
Clinical Relevance —Locally available monitoring of CsA by immunoassay in cats may provide significant advantages when shipping of blood samples to distant locations is required to obtain analysis by HPLC. These advantages may include cost and timeliness of results in circumstances where daily blood CsA concentrations may be desired, such as when managing an acute rejection reaction.     

Microvascular Free Tissue Transfer: Results in 57 Consecutive Cases

Objective —To evaluate the outcomes and complications in a consecutive series of animals undergoing microvascular reconstructive procedures at two veterinary institutions. Study Design—Retrospective study. Animals or Sample Population—A total of 44 client-owned dogs and one red-necked wallaby. Methods —The medical records of all animals undergoing reconstructive microsurgical procedures at the Western College of Veterinary Medicine and Michigan State University were reviewed. Microvascular flap survival and related complications were described. Statistical analysis was performed to determine the significance of relationships between operative factors and outcome. Results —A total of 57 microvascular procedures were performed on 55 animals. Reconstruction was required after trauma in 42 animals, after ablative cancer surgery in 11 animals and for correction of congenital tissue aplasia in 1 animal. Donor tissues included the superficial cervical cutaneous, medial saphenous fasciocutaneous or musculofasciocutaneous, caudal superficial epigastric cutaneous, trapezius muscle or musculocutaneous, caudal sartorius muscle, latissimus dorsi muscle or musculocutaneous, cranial abdominal myoperitoneal, carpal footpad, digital footpad, and vascularized ulnar bone flaps. A total of 53 of 57 flaps (93%) survived. There was a significant relationship between flap failure and level of assistant surgeon experience (P < .05). Latissimus dorsi flaps were significantly more likely to fail when compared with pooled data from all other flap types (P < .01). Conclusions —The success of microvascular tissue transfer in this case series compares favorably with those reported in human reconstructive microsurgery. Both the primary and assistant surgeon should be practiced in microsurgical technique. Failure of latissimus dorsi flaps was not likely caused by an inherently deficient flap design, but was more likely attributed to the location and severity of trauma at the recipient site, the difficulty in isolating suitable recipient vessels for anastomosis or the absence of a trained assistant surgeon during these procedures. Clinical Relevance —This retrospective study documents the successful application of microvascular technique in a series of clinical cases requiring tissue reconstruction.     

Limb Salvage Surgery for Osteosarcoma of the Proximal Humerus: Outcome in 17 Dogs

Objective —To describe function and identify factors that affect outcome in dogs undergoing limb salvage surgery for osteosarcoma (OS) of the proximal humerus.
Study Design —A retrospective study of dogs in which OS of the proximal humerus was treated with limb salvage surgery.
Animals —17 client-owned dogs.
Methods: Records were analyzed for functional outcome, recurrence, metastasis, and survival.
Results —Outcome was good to excellent in 12% of dogs. Recurrence, metastasis, and survival were significantly affected by completeness of surgical margins. Double plating of the distal allograft-host junction significantly reduced frequency of biomechanical failure.
Conclusions —Limb salvage surgery for OS of the proximal humerus did not result in acceptable function and was fraught with postoperative complications. Outcome was significantly affected by completeness of surgical margins.
Clinical Relevance —Limb salvage surgery for OS of the proximal humerus in dogs cannot be recommended until improvement in functional outcome and reduction in postoperative complications can be achieved. The dependence of outcome on completeness of surgical margins supports aggressive en bloc resection and marking and evaluating surgical margins.     

Biomechanical Comparison of the Trocar Tip Point and the Hollow Ground Tip Point for Smooth External Skeletal Fixation Pins

Objective —To compare the insertional characteristics of external fixator pins with hollow ground (HG), modified HG, and trocar (T) points.
Study Design —An acute, in vitro biomechanical evaluation.
Sample Population—Thirteen radii from canine cadavers.
Methods —A total of 16 T-tipped and 16 HG-tipped pins were inserted into 8 canine radii. Ten pins of each modification of the HG tip (length of the cutting edge reduced by 0.127 mm and 0.254 mm, respectively) were inserted into another five radii. All pins were inserted with low-speed power drilling and 80 N drilling load. Differences between peak tip temperature, drilling energy, and pullout force were determined for each pin type at both diaphyseal and metaphyseal locations.
Results —HG-tipped pins showed a 40% lower tip temperature in diaphyseal bone, a 25% reduction in drilling energy in diaphyseal bone, and a reduction of pullout force in both diaphyseal (65%) and metaphyseal (50%) bone compared with T-tipped pins. HG 0.254-mm pins generated higher tip temperatures and had greater pullout than HG pins in diaphyseal bone.
Conclusions —The HG tip was a more efficient design; however, the reduction in pullout force suggests that, because a better hole was drilled, radial preload is reduced. Reduction of the cutting edge by 0.254 mm increased the pullout force but also increased the temperatures.
Clinical Relevance —Thermal and microstructural damage are reduced by the HG tip, but pin-bone interface stability is also compromised. The use of a tip with 0.254 mm reduction in the cutting edge may optimize the biological and mechanical factors at the pin-bone interface.     

Repair of Complete Dorsal Fracture of the Proximal Phalanx in Two Horses

Simple complete dorsal fractures of the proximal phalanx were repaired in 2 mature pleasure horses with cortical bone screws placed in lag fashion. Healing occurred within 12 weeks and both horses returned to their previous performance level of light pleasure riding within 6 months of injury.     

Plasma Concentrations and Cardiovascular Influence of Lidocaine Infusions During Isoflurane Anesthesia in Healthy Dogs and Dogs With Subaortic Stenosis

Objective—To determine the plasma concentrations and cardiovascular changes that occur in healthy dogs and dogs with aortic stenosis that are given an infusion of lidocaine during isoflurane anesthesia. Study Design—Phase 1, controlled randomized cross-over trial; Phase 2, before and after trial Animals—Phase 1, 6 healthy dogs (4 female, 2 male) weighing 23.8 ± 7.4 kg; Phase 2, 7 dogs (4 female, 3 male) with moderate to severe subaortic stenosis (confirmed by Doppler echocardiography) weighing 31.1 ± 14.5 kg. Methods—After mask induction, intubation, and institution of positive pressure ventilation, instrumentation was performed to measure hemodynamic variables. After baseline, measurement at an end-tidal isoflurane concentration of 1.9% (phase 1) or 1.85% (phase 2), a loading dose infusion of lidocaine at 400 μg/kg/min was given. Phase 1: Maintenance doses of lidocaine were administered consecutively (40, 120, and 200 μg/kg/min) after the loading dose (given for 10, 10, and 5 minutes, respectively) in advance of each maintenance concentrations. Measurements were taken at the end of each loading dose and at 25 and 35 minutes during each maintenance level. The same animals on a different day were given dextrose 5% and acted as the control. Phase 2: Dogs were studied on a single occasion during an infusion of lidocaine at 120 μg/kg/ min given after the loading dose (10 minutes). Measurements occurred after the loading dose and at 25 and 35 minutes. A blood sample for lidocaine concentration was taken at 70 minutes. Data were compared using a one-way ANOVA for phase 1, and between phase 1 and 2. Statistical analysis for phase 2 was performed using a paired r-test with a Bonferroni correction. A P value ± .05 was considered significant. Results—Phase 1: Plasma lidocaine concentrations achieved with 40, 120, and 200 μg of lidocaine/kg/min were 2.70, 5.27, and 7.17 μg/mL, respectively. A significant increase in heart rate (HR) (all concentrations), central venous pressure (CVP), mean pulmonary areterial pressure (PAP), and a decrease in stroke index (SI) (200 μg/kg/min) were observed. An increase in systemic vascular resistance (SVR) and mean PAP, and a decrease in SI also followed the loading dose given before the 200 μg/kg/min infusion. No other significant differences from the control measurements, during dextrose 5% infusion alone, were detected. Phase 2: Plasma lidocaine concentrations achieved were 5.35, 4.23, 4.23, and 5.60 μg/mL at 10, 25, 35, and 70 minutes, respectively. They were not significantly different from concentrations found in our healthy dogs at the same infusions. A significant but small increase in CVP compared with baseline was noted after the loading dose. There were no significant differences from baseline shown in all other cardiovascular data. There were no statistically significant differences in any measurements taken during the lidocaine infusion between the dogs in phase 1 and phase 2. Dogs with aortic stenosis tended to have a lower cardiac index than healthy dogs at baseline (88 v 121 mL/kg/min) and during lidocaine infusion (81 v 111 mL/kg/min). A small, statistically significant difference in systolic PAP was present at baseline. Conclusions—There does not appear to be any detrimental cardiovascular effects related to an infusion of lidocaine at 120 μg/kg/min during isoflurane anesthesia in healthy dogs or dogs with aortic stenosis. The technique used in this study resulted in therapeutic plasma concentrations of lidocaine. Clinical Relevance—Methods shown in the study can be used in clinical cases to achieve therapeutic lidocaine levels without significant cardiovascular depression during isoflurane anesthesia.