Robert Fitridge

Microvascular Basal Lamina Antigens Disappear During Cerebral Ischemia and Reperfusion

BACKGROUND AND PURPOSE Changes in vascular permeability are well-known and important consequences of cerebral ischemia. The development of edema and of petechial hemorrhage is connected to altered vascular integrity. A major part in microvascular integrity is played by the basal lamina. METHODS The fates of the basal lamina components laminin, fibronectin, and type IV collagen during middle cerebral artery occlusion (2 hours, n = 3) and occlusion (3 hours) with reperfusion (1 hour, n = 3; 4 hours, n = 3; and 24 hours, n = 4) were evaluated in the nonhuman primate. Specific monoclonal antibodies against these components were used. The number and size distribution of the microvessels in each specimen were determined by video-imaging microscopy, and the relative fluorescence intensity of laminin was semiquantified by laser confocal microscopy. Basal lamina antigen presentations were compared by double-stain immunofluorescence histochemistry. RESULTS The number of microvascular structures defined by the presence of each basal lamina antigen decreased significantly up to 24 hours of reperfusion (P < .0001). The ratio of laminin-containing vessels between the ischemic and nonischemic territories decreased significantly from control (0.98 +/- 0.04) to 2 hours of ischemia (0.83 +/- 0.09) and 1 hour (0.79 +/- 0.08), 4 hours (0.77 +/- 0.06), and 24 hours of reperfusion (0.55 +/- 0.07). The ratio of fibronectin (cellular) and of collagen (IV)-containing vessels decreased from 0.98 +/- 0.04 to 0.75 +/- 0.1 and from 1.02 +/- 0.03 to 0.57 +/- 0.1, respectively. Mean laminin fluorescence intensity decreased from 76.1 +/- 6.0 U (controls) to 52.0 +/- 14.6 U (24 hours of reperfusion; P < .001). CONCLUSIONS The significant parallel losses of three basal lamina components, both in number and intensity, contribute to loss of microvascular integrity. These phenomena may be important for understanding cell extravasation and the hemorrhagic consequences of acute stroke.

A Systematic Review of Strategies to Improve Prophylaxis for Venous Thromboembolism in Hospitals

Objective:To assess the effectiveness of different strategies for increasing the uptake of prophylaxis for venous thromboembolism (VTE) in hospitalized patients through a systematic review of the literature. Methods:Literature databases and the Internet were searched from 1996 to May 2003. Studies of strategies to improve VTE prophylaxis practice were included. Studies where no policy or guideline was implemented or where the focus of the study was not VTE prevention were excluded. Results:Thirty studies were included. The quality of the available evidence was average with the majority of studies being uncontrolled before and after design and thus limited by the historical nature of much of the available data. Adherence to guidelines and the provision of adequate prophylaxis were poor in studies which relied on passive dissemination of guidelines. In general, the use of multiple strategies was more effective than a single strategy used in isolation. The most effective strategies incorporated a system for reminding clinicians to assess patients for VTE risk, either electronic decision-support systems or paper-based reminders, and used audit and feedback to facilitate the iterative refinement of the intervention. There were no studies adequately powered to demonstrate a reduction in rates of VTE. Insufficient evidence was available to make useful comparisons of strategies in terms of costs and resource utilization. Conclusions:Passive dissemination of guidelines is unlikely to improve VTE prophylaxis practice. A number of active strategies used together, which incorporate some method for reminding clinicians to assess patients for DVT risk and assisting the selection of appropriate prophylaxis, are likely to result in the achievement of optimal outcomes.

Systematic review of endovenous laser treatment for varicose veins

The safety and effectiveness of endovenous laser treatment (EVLT) for varicose veins are not yet fully evaluated.

Integrin αIIbβ3 Inhibitor Preserves Microvascular Patency in Experimental Acute Focal Cerebral Ischemia

Background and Purpose—Platelets become activated and accumulate in brain microvessels of the ischemic microvascular bed after experimental focal cerebral ischemia. The binding of glycoprotein IIb/IIIa (integrin αIIbβ3) on platelets to fibrinogen is the terminal step in platelet adhesion and aggregation. This study tests the hypothesis that inhibition of platelet-fibrin(ogen) interactions may prevent microvascular occlusion after experimental middle cerebral artery occlusion (MCA:O). Methods—TP9201 is a novel Arg-Gly-Asp (RGD)-containing integrin αIIbβ3 inhibitor. Microvascular patency after 3-hour MCA:O and 1-hour reperfusion within the ischemic and nonischemic basal ganglia was compared in adolescent male baboons who received high-dose TP9201 (group A: IC80 in heparin, n=4), low-dose TP9201 (group B: IC30 in heparin, n=4), or no treatment (group C: n=4) before MCA:O. Results—After MCA:O, microvascular patency decreased significantly in group C. However, in the ischemic zones of groups A and B compared w...

A Model to Predict Outcomes for Endovascular Aneurysm Repair Using Preoperative Variables

PURPOSE Models have been developed to predict the likely outcomes of endovascular aneurysm repair (EVAR) for patients, based on a longitudinal Australian audit. METHODOLOGY Mid-term progress of 961 Australian patients who underwent EVAR has been collected and used to develop predictive models for 17 outcomes. Stepwise forward logistic regressions determined the significant preoperative patient variables to be included in each outcome model. An interactive program was subsequently developed to allow surgeons to review the predicted success rates for patients about to undergo the procedure. Each model was assessed using a global goodness of fit test and was internally validated using bootstrapping. RESULTS Eight pre-operative variables were included in the interactive model for 17 outcomes. The eight variables used were aneurysm size, age, ASA, gender, creatinine, aortic neck angle, infrarenal neck diameter and infrarenal neck length. The outcomes predicted included perioperative mortality, perioperative morbidity, mid-term survival and reintervention rates. All outcome models achieved reasonable goodness of fit, with the exception of the model for conversion to open repair (p=0.04). With respect to validation, survival, aneurysm related deaths, migrations, ruptures and conversions to open repair performed best in terms of predictive discrimination. Models for survival, migrations and conversions to open repairs performed best in terms of bias corrected R-squared index. The models with the smallest calibration error were 3 and 5 year survival, early deaths and mid-term type I endoleaks. CONCLUSIONS An interactive model is available, which can assist vascular surgeons to evaluate the expected outcomes for a particular patient undergoing EVAR. The validated model is useful for counselling and pre-operative decision making.

Carotid bifurcation CT angiography: assessment of interactive volume rendering.

PURPOSE The purpose of this study was to compare the accuracy of CT angiography (CTA) for the assessment of carotid bifurcation stenosis, using interactive volume rendering (VR), maximum intensity projection (MIP), and 2D transverse CT technique (t-CT). METHOD Nineteen consecutive patients were prospectively studied with CTA and selective digital subtraction angiography (DSA). There were 13 men and 6 women from 51 to 84 years old (mean 70 years). Results of DSA were compared with those of interactive VR, MIP, and conventional t-CT results, using North American Symptomatic Carotid Endarterectomy Trial criteria for stenosis grading. RESULTS There were a total of 38 carotid bifurcations studied, with 9 mild, 10 moderate, and 15 severe stenoses and 4 occlusions. Overall agreement with DSA for VR was achieved in 76%. Eighty percent of the severe stenoses were correctly predicted by VR. The overall agreement between t-CT and DSA was 89%. MIP images, when analyzed independently, showed an overall agreement with angiography of only 71%. VR was not significantly different from MIP (p = 0.60). The difference between VR and t-CT had borderline significance (p = 0.09). MIP had significantly poorer agreement with angiography than t-CT (p = 0.02). CONCLUSION CTA has a high degree of accuracy for the assessment of carotid artery disease compared with catheter angiography. Interactive VR increases the accuracy of diagnosing carotid stenosis and decreases the number of unsatisfactory studies as compared with MIP. Further advances in computation speeds and improvements in software may dramatically alter the future use of VR for the communication of results to clinicians; however, careful analysis of transverse sections is essential to accurate CT interpretation.

Upper extremity arterial injuries: Experience at the Royal Adelaide Hospital, 1969 to 1991

PURPOSE A review of upper extremity arterial injuries managed at the Royal Adelaide Hospital between 1969 and 1991 was undertaken because the optimal management of complex upper extremity trauma, particularly in proximal injuries, remains unclear. METHODS Patients were identified from the computer registry of patients treated by the vascular unit at the Royal Adelaide Hospital. They were studied in three groups: (1) subclavian and axillary artery, (2) brachial artery, and (3) radial and ulnar artery injuries. The mechanism of injury, associated injuries, treatment and outcome were reviewed. RESULTS There were 114 patients with upper extremity arterial injuries: 28 with subclavian and axillary, 62 with brachial, and 24 with radial and ulnar artery injuries. Good upper limb function was obtained in 32% of subclavian and axillary artery injuries, 79% of brachial artery injuries, and all radial and ulnar artery injuries. Amputation was performed in 14% of the proximal injuries and 8% of the brachial artery injuries. Three deaths occurred in this study group. CONCLUSION Blunt proximal injuries were usually associated with neurologic, soft tissue, and bony damage, which was responsible for the poor functional outcome. Critical limb ischemia or severe hemorrhage rarely occurred. Complete brachial plexus lesions resulted in uniformly poor outcomes. More distal injuries were associated with fewer nerve and soft tissue injuries, resulting in a more satisfactory outcome.

Cognitive performance in patients after carotid endarterectomy

OBJECTIVE Research investigating the benefits of carotid endarterectomy (CEA) on cognitive functioning remains inconclusive. This study sought to determine what patient characteristics affect cognitive functioning and whether changes in cognitive functioning occur following surgery after controlling for these characteristics. METHODS In a prospective longitudinal study, 39 patients scheduled for CEA surgery underwent neuropsychological testing in the week prior to their surgery. Two patients had a stroke following surgery, leaving 37 patients who were tested again at 7 days and 3 months following surgery. The surgery was performed under a locoregional anesthetic. RESULTS Patient characteristics associated with cognitive functioning were age, education, and IQ. In addition, differences in cognitive performance on a number of tests were related to presenting symptoms. Stroke patients (n = 6) differed significantly from symptom-free patients (n = 18) and patients with symptoms (n = 13) on measures of verbal fluency, visual search and mental flexibility, and verbal learning. When differences in patient characteristics were controlled for, no significant changes in cognitive functioning were found that could be attributed to the effects of surgery. CONCLUSIONS No changes in cognitive functioning were associated with CEA. Differences in cognitive functioning, however, were associated with patient characteristics, including differences in presenting symptoms.

The Incidence of Hyperhomocysteinaemia in Vascular Patients

INTRODUCTION Hyperhomocysteinaemia has recently been identified as an important risk factor for atherosclerotic vascular disease. Screening for hyperhomocysteinaemia has been recommended, however, the incidence of hyperhomocysteinaemia in vascular patients is not known. AIMS To determine the incidence of hyperhomocysteinaemia in vascular patients, to determine the relation of hyperhomocysteinaemia with folate, vitamin B12 levels and lipid profiles in vascular patients. To examine if there is a relationship between the degree of vascular injury and homocysteine concentration. METHODS New vascular patients at The Queen Elizabeth Hospital were recruited and divided into peripheral, and aneurysmal presentations. Patients demographics were recorded, blood samples were taken for fasting lipid profile, and homocysteine concentration. Samples were also taken for vitamin B12, plasma and red cell folate levels. Sixty age and sex matched controls were included for comparison. RESULTS One hundred and twenty-six patients have been recruited, (95 men and 31 women) with a median age of 68 years (61-74 years). The incidence of elevated homocysteine, and cholesterol levels was 33, 47 and 24%. The levels of vitamin B12 and folate were normal in all patients. Homocysteine was elevated in 27% of claudicants, 50% of patients with rest pain and 53% of patients with an aortic aneurysm. CONCLUSION There is a high rate of hyperhomocysteinaemia in vascular patients with a higher incidence in patients with rest pain. There was also a high incidence of elevated homocysteine levels in patients with an abdominal aortic aneurysm. The rate of growth of these aneurysms is currently under review. Low folate or B12 concentrations is not the cause of raised homocysteine levels.

Applications of modern sensors and wireless technology in effective wound management

The management of chronic wounds has emerged as a major health care challenge during the 21st century consuming, significant portions of health care budgets. Chronic wounds such as diabetic foot ulcers, leg ulcers, and pressure sores have a significant negative impact on the quality of life of affected individuals. Covering wounds with suitable dressings facilitates the healing process and is common practice in wound management plans. However, standard dressings do not provide insights into the status of the wound underneath. Parameters such as moisture, pressure, temperature and pH inside the dressings are indicative of the healing rate, infection, and wound healing phase. But owing to the lack of information available from within the dressings, these are often changed to inspect the wound, disturbing the normal healing process of wounds in addition to causing pain to the patient. Sensors embedded in the dressing would provide clinicians and nurses with important information that would aid in wound care decision making, improve patient comfort, and reduce the frequency of dressing changes. The potential benefits of this enabling technology would be seen in terms of a reduction in hospitalization time and health care cost. Modern sensing technology along with wireless radio frequency communication technology is poised to make significant advances in wound management. This review discusses issues related to the design and implementation of sensor technology and telemetry systems both incorporated in wound dressings to devise an automated wound monitoring technology, and also surveys the literature available on current sensor and wireless telemetry systems.