Sonographic evaluation of the normal response of subclavian veins to respiratory maneuvers.

Sonography of the subclavian veins is a new noninvasive, simple technique to evaluate the subclavian veins. The physiologic changes of the subclavian veins consistently respond in a predictable manner to simple respiratory maneuvers. The subclavian veins of 11 normal patients (22 veins) whose ages ranged from 18 to 60 years were studied. The most significant change in subclavian vein anteroposterior diameter during respiratory maneuvers (Valsalva/expiration/inspiration) occurred with inspiration (P less than .005), particularly during a sniff, with a mean decrease in diameter of 61%. This baseline evaluation establishes normal sonographic criteria of the subclavian veins. We suggest that real-time ultrasound using a high resolution transducer offers a rapid, reproducible, objective method of evaluating the subclavian vein directly.

Comparison of staples vs suturing for securing central venous catheters.

OBJECTIVE: To determine whether skin staples can be used to secure central venous catheters as effectively as does suturing. METHODS: A prospective, randomized trial of techniques to secure a central venous catheter was performed in a medical school human anatomy laboratory using human cadavers. Central lines were secured to the upper left thorax using either standard suture material (000 silk) or skin staples (5.7 mm x 3.8 mm). Once secured, an upward force was applied to the hub of the catheter perpendicular to the skin. The amount of force needed to break the catheter hub free of the skin was measured in kg. A total of 10 measurements were made for each of 3 methods for securing the catheters (2 sutures, 2 staples, 4 staples). In addition, the site of catheter breakage was recorded. RESULTS: Those catheter hubs secured by 2 sutures required a mean force of 3.1 +/- 0.5 kg to cause breakage, and the break always occurred at the suture. Those hubs secured by 2 staples gave way at 3.0 +/- 0.3 kg (p = NS), while those secured with 4 staples gave way at 4.5 +/- 1.4 kg (p < 0.05). Although 1 hub did break, in all other stapled cases, the break occurred at the staple. CONCLUSIONS: Based on this cadaver model, use of staples appears to be as effective as suturing for securing central venous catheters. Further studies of safety and time for placement are needed.

Lymphatic clearance of radioactive sulfur colloid.

Lymphatic clearance of radioactive sulfur colloid is measured in the hind limb of five mongrel dogs. A solid state Si(Li) detector is placed onto the skin to continuously record activity over the site of subcutaneous injection. Decrease in activity follows an exponential decay which is modeled as a dual decay occurring from both the radioactive decay of the tracer and the lymph clearance of the tagged sulfur colloid. The calculated decay constants for lymph clearance flow per tissue volume result in a mean value of 0.233 +/- 0.077 ml/hr/ml which is consistent with results of other investigators. Adjacent lymph nodes are monitored with a scintillation detector to show that the colloid is absorbed by the lymph vessels. The carotid artery and liver are similarly monitored to show that there is little or no capillary absorption of the tagged colloid.

Clinical pulmonary perfusion imaging in the dog.

Scintigraphic pulmonary perfusion imaging in the dog has been described for the clinically normal animal. The usefulness of this technique in the patient with pulmonary dysfunction was assessed by review of 76 consecutive clinical cases completed in a 6-month period. This review indicated that 3 basic patterns of perfusion defects are commonly seen in the dog. These were associated with (1) diffuse parenchymal metastatic disease, (2) mediastinal metastatic disease, and (3) heartworm disease. The technique has proved reliable as an aid in the staging of neoplastic disease and of some potential value in heartworm disease and is now performed on a routine basis at this institution for purposes of clinical diagnosis.

Evaluation of radioiodinated human serum albumin in the dog for assessment of hemodynamic function.

Radioiodinated human and dog serum albumins, each labeled with a different radioisotope of iodine (125I and 131I, respectively), were injected intravenously into dogs. Plasma volumes and plasma clearance half times were used for the comparative evaluation of the 2 radiopharmaceuticals. After repeated injections in a 6-week period, differences in these values could not be demonstrated. Plasma volumes obtained with both radioiodinated serum albumins compared favourably with the previously reported values in dogs.

Acute canine ehrlichiosis: platelet survival and factor 3 assay.

Ten dogs experimentally inoculated with Ehrlichia canis were thrombocytopenic 14 days after inoculation. Circulating platelet concentrations had declined rapidly by postinoculation day 10, but remained at or slightly below the 14-day concentration during the remainder of the 42-day experimental period. The percentage of circulating megathrombocytes also increased to 8.7 times preinoculation concentrations indicating the existence of accelerated thrombocytopoiesis. The release of platelet factor 3 (PF-3) from normal canine platelets was delayed after incubation of the platelets in globulin fractions from infected dogs. Inhibition of PF-3 release was attributed to the effect of an unidentified substance present only in the dialyzed globulin fraction of infected canine serums. The presence of antiplatelet antibody in these dogs was not evident. Survival of 51Cr-labeled platelets was decreased in infected dogs, but was most abbreviated in infected dogs that were thrombocytopenic when injected with labeled platelets. Thus, accelerated nonantibody-mediated destruction of platelets contributes markedly to the development of thrombocytopenia in dogs with acute ehrlichiosis.

Evaluation of renal function in cats, using quantitative urinalysis.

Two consecutive 24-hour quantitative urinalyses were performed on each of 12 healthy adult cats to evaluate the technique and obtain reference values for measurements of urinary excretion of several substances. Endogenous creatinine clearance (2.31 +/- 0.47 ml/min/kg) and urinary protein excretion (17.43 +/- 9.05 mg/kg/day) were determined. Additionally, clearances and ratios to creatinine clearances were calculated for phosphate, sodium, potassium, and chloride. The endogenous creatinine clearance value was compared with another estimate of glomerular filtration rate that was based on 99mTc(Sn) diethylene-triaminepentaacetic acid clearance (2.52 +/- 0.58 ml/min/kg). Evaluation of feline renal function, using 24-hour quantitative urinalysis techniques, has potential for clinical application, but has several important limitations as well.

Lymphoscintigraphy in healthy dogs and dogs with experimentally created thoracic duct abnormalities.

Lymphoscintigraphic evaluation of the thoracic duct (TD) was performed in 10 healthy and 12 dogs with experimentally created TD abnormalities (6 dogs with TD lacerations and 6 dogs with cranial vena ligations). Complete imaging took 4 hours and caused no adverse effects or complications. Lymphoscintigraphy of healthy dogs failed to image the TD; however, background activity in the abdomen and thorax, and radioactivity in the kidneys, bladder, liver, and heart were noticed. Lacerations and transections of the TD were experimentally created in 6 dogs to ascertain whether TD rupture could be detected with lymphoscintigraphy. Lymphoscintigraphy was performed within 48 hours of creating the TD defect. There was no significant difference in the scintigraphic pattern of healthy dogs and those with experimentally created TD defects. Ligation of the cranial vena cava was performed in 6 dogs; 3 dogs developed chylothorax. In those 3 dogs, diffuse radioactivity was imaged in the thorax and was compatible with thoracic lymphangiectasia. In one of these dogs, linear activity consistent with the TD and localized regions of radioactivity cranial to the heart (compatible with the mediastinal lymph nodes) were noticed. Lymphoscintigraphic findings in these dogs correlated with lymphangiographic findings.

Tracheal mucociliary transport rate in awake dogs.

To measure tracheal mucociliary transport rate (TMTR) in awake dogs, restrained in dorsal recumbency, 99mtechnetium-labeled macroaggregated albumin was administered by tracheal injection, and the cephalic movement of boluses containing the radiopharmaceutical was detected by a gamma camera positioned lateral to the dog's head and neck. The distance traveled by each bolus was measured, relative to external markers placed a known distance apart. Tracheal mucociliary transport rates were calculated by dividing the measured distance of radiopharmaceutical movement by elapsed time. The technique was efficient and well tolerated. Mean (+/- SD) TMTR was 35.3 +/- 15.9 mm/min. Significant (P = 0.029) difference in TMTR was found between males and females, but significant difference attributable to age of the dog was not detected. This method of measuring TMTR in awake dogs has potential for evaluation of clinical animal patients with suspected tracheal mucociliary abnormalities.

Comparison of four methods of estimating glomerular filtration rate in cats.

Four methods of evaluating renal function were performed in 6 cats anesthetized with halothane in oxygen. Glomerular filtration rate (GFR) was measured simultaneously in each cat by exogenous creatinine clearance (ECC), bolus inulin clearance, and 99mTc(Sn)-diethylene-triaminepentaacetic acid (DTPA) clearance determined by 2 different methods. In the first DTPA clearance method (DTPA-1), we measured radioactivity in serial blood specimens to construct plasma disappearance curves for calculation of GFR. In the second DTPA clearance method (DTPA-2), we used serial external head counts of radioactivity and a single blood specimen to construct plasma disappearance curves for calculation of GFR. Bolus inulin clearance was calculated from plasma disappearance curves using a 1-compartment open pharmacokinetic model (IN-1) and a 2-compartment open pharmacokinetic model (IN-2). Glomerular filtration rates were measured over 3 hours, for creatinine and DTPA methods, and over 4 hours for the inulin methods. The GFR obtained with the reference method (ECC) was 2.56 +/- 0.61 ml/min/kg of body weight (mean +/- SD). Values for GFR determined by ECC and DTPA-1 were significantly correlated (r = 0.852; P less than or equal to 0.05). Correlation between ECC and DTPA 2 was not as good (r = 0.783; P less than or equal to 0.10), but the 2 DTPA methods significantly correlated with one another (r = 0.897; P less than or equal to 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of beta-tricalcium phosphate in surgically created subchondral bone defects in male horses.

beta-Tricalcium phosphate (TCP) was evaluated as a synthetic bone grafting material in horses. Sixteen horses were randomly assigned to 4 groups of 4 horses. In each horse, an 11-mm by 10-mm circular defect with a smooth margin was created surgically in the weight-bearing surface of both third metacarpal bones (McIII) and the left third metatarsal bone. The defect in the left McIII was filled with TCP, the defect in the right McIII was filled with a mixture of 50% autogenous cancellous bone (ACB) and 50% TCP, and the defect in the left third metatarsal bone was not filled to serve as a control. Nuclear imaging and radiographic evaluation of surgical sites were performed at postsurgical week (PSW) 4 and 13 in group-I horses and at PSW 26, 39, and 52 in groups-II, -III, and -IV horses, respectively. Horses in groups I, II, III, and IV were euthanatized at PSW 13, 26, 39, and 52, respectively, and specimens were harvested for histologic evaluation. Results were compared among treatment methods, as well as among time intervals. The greatest activity at defect sites was seen in group-I horses at PSW 4. Activity counts in limbs of group-I horses at PSW 13 and counts in limbs of group-II horses at PSW 26 were not significantly (P less than or equal to 0.05) different. Activity counts in groups-III and -IV horses at PSW 39 and 52, respectively, were less than those in groups I and II. However, there was no significant difference in activity counts between limbs implanted with TCP or ACB:TCP.(ABSTRACT TRUNCATED AT 250 WORDS)

Control of radiation in animal facilities.

Use of radioactive materials in animals for research and clinical studies is on the increase. These studies may be undertaken with little or no disruption of normal facility operations if a few facts are considered. The primary factor of consideration is the radiopharmaceutical--its pharmacologic behavior and physical characteristics. The preferred radionuclide is one with the shortest half-life compatible with the variables to be measured. The fact that an animal is a source of radiation as well as a potential source of contamination must be kept in mind. Improper use of radiopharmaceuticals is inexcusable.

Use of hepatobiliary scintigraphy in the diagnosis of extrahepatic biliary obstruction in dogs and cats: 25 cases (1982-1989).

Twenty-five animals (21 dogs and 4 cats) in which hepatobiliary scintigraphy (HBS) was performed between 1982 and 1989 were included in a retrospective study to determine the utility of HBS for diagnosis of extrahepatic biliary obstruction. Final diagnoses, which were based on liver biopsy results and surgical findings in all animals, were hepatocellular disease alone (n = 17), hepatocellular disease and extrahepatic biliary obstruction (n = 7), and normal liver (n = 1). Hepatobiliary scintigraphy was performed by use of 99mTc-diisopropyl iminodiacetic acid in all cases. All 7 cases of extrahepatic biliary obstruction were confirmed at surgery. In animals with biliary obstruction, HBS failed to demonstrate radiolabel within either the gallbladder or intestine at any time. Using nonvisualization of the intestine by 180 minutes as the scintigraphic criterion for diagnosis of biliary obstruction, sensitivity was 83% and specificity was 94% in this series. Hepatobiliary scintigraphy was concluded to be an accurate indicator of extrahepatic biliary obstruction in this group of animals. High serum bilirubin concentration at the time HBS was performed did not appear to reduce the diagnostic usefulness of the scintigraphic findings.

Multicentric osseous lymphoma with spinal extradural involvement in a dog.

Multicentric osseous lymphoma involving the ribs and multiple vertebrae was observed in a 7-year-old Siberian Husky. Extradural spinal cord compression was treated by surgical decompressive hemilaminectomy of L1-2 without noticeable improvement of signs neurologic dysfunction. However, palliation of signs of pain was noticed after irradiation in conjunction with chemotherapy and surgical decompression.