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Biomedical subjects

D L Holmberg

Publications and source records attributed to D L Holmberg.

36 records · Page 2Linked to original sources

Management of pyothorax.

Pyothorax is a serious disease process which requires both medical and surgical intervention. Late recognition, management problems, and likely recurrence make successful treatment difficult and often frustrating. Aims of therapy should be to avoid undue stress to the patient, to relieve respiratory distress by thoracocentesis, to eliminate infectious agents with antimicrobials, to remove pleural exudate, and to provide supportive care. Close monitoring of the patient is necessary to prevent iatrogenic complications such as pneumothorax, hemothorax, hypothermia, or hypoproteinemia. Exploratory thoracotomy for removal of granulomatous material and fibroelastic pleural "peels" is occasionally necessary to resolve compressive cardiopulmonary lesions.

Animals↗

Vascular ring anomalies: case report and brief review.

During early fetal life six pair of aortic arches surround the esophagus and trachea. Normal maturation and selective regression of these structures form the adult vasculature. Abnormal location or development of the aortic arches may result in pressure on adjacent organs. Vascular ring anomalies must be considered with any patient with a history of regurgitating food shortly after eating. Physical examination, test feedings, survey and contrast radiographs may give an accurate impression of the problem but a final diagnosis can only be made following surgical exploration. In the case presented, the dog had all the clinical and diagnostic signs suggestive of a vascular ring anomaly. Thoracotomy and elimination of the vascular constriction around the esophagus was both diagnostic and therapeutic for the condition. It is important that owners be made aware that surgical correction of the stenosis does not guarantee a successful conclusion to the case. If the dilation of the esophagus cranial to the stenosis is severe, accumulation of food with subsequent regurgitation may persist. A dilation of the esophagus caudal to the stenosis is present in a large percentage of cases and this also may result in an unrelenting problem. Unfortunately, the probability of these complications cannot be accurately evaluated prior to treatment.The hereditary potential for this defect must also be considered. Congenital vascular anomalies such as patent ductus arteriosus would seem to have a hereditary basis. Therefore, it is probably correct to advise against breeding affected animals. Further, the inbreeding of nonaffected animals which come from litters containing affected animals should be avoided.

Animals↗

Prophylactic use of antibiotics in surgery.

"Sound and careful surgery is the sine qua non of wound management; antimicrobials are adjunctive." The key to successful use of prophylactic antibiotics in surgery is careful selection of cases and medication. There are no final rule or formulas that will always give optimal results. Listed below are some guidelines that may assis the clinician in determining the need and form of antimicrobial use. 1. The operation must carry a significant risk of bacterial contamination. Refined-clean and clean procedures should not be given prophylactic antibiotics. 2. Bacterial cultures should be taken when possible, and the medication used for prophylaxis should be effective against the organisms expected to be encountered. 3. Narrow spectrum antibiotics should be used to conserve the body's normal flora. Broad spectrum antibiotics needed to combat resistant infections should not be used for prophylaxis. 4. The antibiotic should be present in the wound in effective concentrations at the time of the incision and be maintained only as long as the risk of new bacterial contamination exists.

Anti-Bacterial Agents↗

Proximal urethral reconstruction using a distally based ventral bladder tube flap. An experimental study.

Reconstruction of the proximal urethra using a distally based tube flap mobilized from the ventral bladder wall was performed on 12 clinically normal dogs after total prostatectomy and resection of 2 cm of membranous urethra. One dog was euthanized at 6 hours and one at 36 hours after surgery because of surgical complications. Five dogs were euthanized at 10 days, two dogs at 6 weeks and three dogs at 12 weeks. Advancement of the tube flap allowed for tension-free anastomosis to the membranous urethra. Vascular integrity was maintained in all flaps. Intermittent to continuous postoperative urinary incontinence occurred in 7 of 10 dogs. The incontinence was transient in all 6 and 12 week dogs except one in which a persistent stress incontinence developed. Mild to severe dysuria was noted in 8 of 10 dogs, but was also transient in all of the 6 and 12 week dogs, with the exception of one dog. Postoperative urethral closure pressure profilometry revealed decreased tone in the membranous urethra in all 6 and 12 week dogs. It was concluded that proximal urethral reconstruction, using a ventral bladder tube flap, is a viable technique that may permit functional urodynamic recovery in dogs with significant proximal urethral loss.

Anastomosis, Surgical↗

Anesthesia and cardiopulmonary bypass technique in calves and sheep.

The number of research institutions using calves and sheep as models for open heart surgical procedures is increasing. The Artificial Heart Laboratory of the University of Utah has developed an effective protocol for thoracic procedures in these animals. Routine barbiturate induction and maintenance with fluothane and a pressure-regulated ventilator have minimized anesthetic problems. A membrane oxygenator with blood flows of 50 to 75 ml/kg body weight/min. seems to give adequate circulatory support during heart-lung bypass. Although animals implanted with total artificial hearts do not have problems with arrhythmias, changes in pulmonary function and peripheral vascular tone can alter their cardiac performance. The judicious use of ventilatory support and specific vasoactive drugs can significantly improve the animal's intraoperative blood pressure and postoperative arterial gases. A summary of the techniques and drugs which were used successfully in 187 of 189 animals during a 2 year period are presented.

Anesthesia, Intravenous↗

Esophageal replacement in the dog by microvascular colon transfer.

An orthotopic colon graft based on the middle colic artery and vein was implanted with microvascular technique and a stapling instrument in five dogs. The grafts were successful in four dogs. A similar colon autograft was used to replace the entire thoracic esophagus in five dogs. The recipient vessels were the left carotid artery and left external jugular vein. Four of the grafts failed because of kinking and thrombosis of the arterial supply (2 dogs) or the venous outflow (2 dogs). One graft, which had a viable vascular supply, developed a severe leak at the colon-to-stomach anastomosis, and the dog was euthanatized on day 3. The recipient vascular pedicle was modified and used successfully to replace a portion of the cervical esophagus in three dogs. The grafts survived, the dogs could swallow liquids and semisolid food well, and, at necropsy after 4 weeks, the anastomotic sites were well healed. The graft sites contained essentially normal colon mucosa.

Anastomosis, Surgical↗

Ventral rhinotomy in the dog and cat.

The nasal cavities of 14 dogs and three cats were explored surgically using a ventral rhinotomy. The exposure achieved through this approach was considered to be equal to a dorsal rhinotomy. One animal died during the immediate postoperative period from perforation of a gastric ulcer. The other animals recovered well and had no significant complications. The long-term survival of the animals was consistent with previous reports for their diseases. Ventral rhinotomy is no more difficult than dorsal rhinotomy, has less patient morbidity and fewer postoperative complications, and is more cosmetically acceptable.

Animals↗

A comparison of manual and power-assisted thoracolumbar disc fenestration in dogs.

Thoracolumbar disc fenestration was performed in eight canine cadavers. A hole was cut in the anulus fibrosus with a scalpel in four dogs, and with a high speed drill and burr in four dogs. A curette was used to remove as much of the nucleus pulposus as possible. Sixty-five percent of the nucleus pulposus was removed with the power-assisted technique and 41% was removed by manual fenestration. Manual and power-assisted disc fenestration were performed on alternate intervertebral discs from T11-12 to L5-6 in four dogs. Six months after surgery, results of high-detail radiographic and histologic evaluation of the vertebral bodies and discs showed minimal difference in the sequelae of the two techniques. A retrospective medical records analysis and follow-up of 60 clinical cases treated with prophylactic, power-assisted disc fenestration failed to identify any cases with postoperative recurrence of neurologic deficits. Ten percent of the dogs had periodic back pain of unknown etiology, without other signs of intervertebral disc disease. The findings of this study indicate that power-assisted disc fenestration permits more complete evacuation of the nucleus than manual fenestration, causes no more postoperative complications, and results in a low recurrence rate of neurologic deficits.

Animals↗

Enterocystoplasty with cystectomy and subtotal intracapsular prostatectomy in the male dog.

Urinary diversion by implantation of the ureters into an isolated segment of jejunum was evaluated in eight clinically normal male dogs. Total cystectomy and subtotal intracapsular prostatectomy were performed, and the intestinal loop was sutured to the prostatic remnant. General health, renal function, acid-base balance, urinary tract infection, and urinary continence were monitored during observation periods of 4 to 30 weeks. All dogs survived the observation period and seven were in excellent general health at the time of euthanasia. Six of the 16 ureterointestinal anastomoses were complicated by complete ureteral obstruction. Absorption of urea from the intestinal loop was speculated as the reason for significant increases in serum urea nitrogen concentrations in all of the dogs. Serum creatinine concentrations generally remained within the normal range, but were significantly increased from preoperative baseline values by week 30. There was dilation of 12 renal pelves and ureters in seven dogs. Urine bacterial cultures were positive in six dogs, but histologic evidence of pyelonephritis was present in only five kidneys. Ejaculation was not affected by the procedure, but epididymitis was present in five dogs. The dogs could urinate consciously and did not dribble urine continuously; however, they urinated hourly. While the procedure was well tolerated by the dogs, the frequency of urination makes this technique unacceptable for most household pets.

Anastomosis, Surgical↗

Magnetic motor evoked potentials for assessing spinal cord integrity in dogs with intervertebral disc disease.

Magnetically elicited transcranial motor evoked potentials (MEPs) were studied in 37 dogs with type 1 intervertebral disc (IVD) disease. The waveforms were recorded from both cranial tibial muscles before and after surgery. The latencies and amplitudes obtained were compared to those of a control population (n = 14). MEPs were recordable in all dogs with mild or no neurologic deficits, but they were recordable in only 50% of ambulatory dogs that were severely ataxic. MEPs could not be elicited from nonambulatory dogs. There was a significant attenuation of the amplitudes in all clinical cases, even if the dogs demonstrated back pain alone. Significantly prolonged latencies were associated with neurologic deficits. MEPs were not good predictors of neurologic recovery. The responses obtained from the side where the disc material was found were not different from those recorded from the opposite side. MEPs were very sensitive to lesions of the spinal cord, as indicated by the significant changes in the waves in patients with mild or no neurologic deficits and in the loss of response in dogs that still demonstrated purposeful movement. Neurologic exams provided more accurate diagnoses and prognoses than did MEPs in dogs with IVD disease.

Animals↗

Renal allograft survival in outbred mongrel dogs using rabbit anti-dog thymocyte serum in combination with immunosuppressive drug therapy with or without donor bone marrow.

Therapeutic renal transplantation in dogs is currently being investigated as a treatment for endstage renal disease. This pilot study examines the effect of donor bone marrow (DBM) infusion and antithymocyte serum (ATS) in combination with immunosuppressive drug therapy in prolonging renal allograft survival in dogs. Seven normal outbred mongrel dogs received an unmatched renal allograft. All dogs received rabbit anti-dog thymocyte serum (RADTS), prednisone (Pr), cyclosporine-A (CsA) and azathioprine (Aza). In addition, three dogs (group 1 test) received DBM and four dogs (group 2 control) did not receive DBM. Serum CsA levels were measured throughout the study. Immunosuppressive therapy was gradually reduced with Pr, CsA, and Aza withdrawn at 200, 450, and 680 days, respectively. Allograft rejection was treated with prednisolone sodium succinate. One dog in group 1 and one in group 2 died as a result of infectious canine rhinotracheitis and rejection early in the study. Renal allograft torsion occurred in one group 1 dog. The remaining four dogs survived the 2 years of the study. The dogs in group 2 (three dogs) all rejected the renal allograft after total drug withdrawal, the surviving dog in group 1 did not. This study demonstrates that RADTS, Pr, CsA, and Aza in combination can prolong renal allograft survival in mongrel dogs, whereas DBM may enhance the unresponsive state.

Animals↗

Ex vivo biomechanical comparison of pin fixation techniques for canine distal femoral physeal fractures.

OBJECTIVE: To compare the biomechanical properties of five intramedullary (IM) pin fixation techniques for Salter-Harris type I fractures of the distal femur in dogs. STUDY DESIGN: Randomized, one-way factorial design composed of five treatment groups: (1) single IM pin, (2) dynamic IM crossed pins, (3) paired convergent pins, (4) crossed pins, and (5) crossed polyglycolic acid (PGA) rods. SAMPLE POPULATION: Forty pairs of cadaver canine femurs. MATERIALS: One femur of each pair was manually fractured and subsequently repaired; the contralateral intact femur served as its control. Each femur was loaded in torsion until-failure occurred and load-deformation curves were generated. RESULTS: The crossed-pin technique sustained the greatest load to failure (116.8%) followed by the paired convergent pins (104.8%), dynamic IM pins (90.6%), single IM pin (72.1%), and crossed PGA rods (71.9%). Statistically significant differences in strength at failure were detected between the crossed-pin and single IM pin and the crossed-pin and crossed PGA rod techniques. All fixation techniques underwent greater deformation (1.5 times as much) and had a lower stiffness (66% to 75%) compared with the intact controls; however, there was no significant difference between techniques. Failure in the paired convergent and crossed-pin techniques occurred by fracture of the bone; failure in the other techniques occurred by distraction at the fracture site. CONCLUSION: The rotational stability of any of the fixation techniques appears to be primarily determined by the ability to prevent distraction and maintain interdigitation of the physis. CLINICAL RELEVANCE: When choosing a particular fixation technique for repair of a distal femoral physeal fracture, consideration should be given to the technique's relative biomechanical merits.

Animals↗

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 microg/kg/min was given. Phase 1: Maintenance doses of lidocaine were administered consecutively (40, 120, and 200 microg/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 microg/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 t-test with a Bonferroni correction. A P value < or = .05 was considered significant. RESULTS: Phase 1: Plasma lidocaine concentrations achieved with 40, 120, and 200 microg of lidocaine/kg/min were 2.70, 5.27, and 7.17 microg/mL, respectively. A significant increase in heart rate (HR) (all concentrations), central venous pressure (CVP), mean pulmonary arterial pressure (PAP), and a decrease in stroke index (SI) (200 microg/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 microg/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 microg/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 microg/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.

Anesthesia, Inhalation↗

Kidney transplantation in dogs with naturally occurring end-stage renal disease.

Renal allografts were performed between unrelated donors and 15 dogs with naturally occurring end-stage renal disease. Donor selection was based on compatible dog erythrocyte antigen typing and cross-matching. An immunosuppressive protocol consisting of rabbit antidog antithymocyte serum, cyclosporin-A, azathioprine, and prednisone was used to control postoperative rejection of the donated kidney. Although seven animals died because of technical failures or rejection episodes, a median survival time of eight months has been achieved, with two dogs living for longer than five years after surgery. Long-term survivors have died from a variety of problems not related to renal allograft rejection.

Animals↗