Biomedical subjects

R G Turnbull

Publications and source records attributed to R G Turnbull.

8 recordsLinked to original sources

PubMed2002

Patency of superficial femoral vein employed as a crossover femoral artery bypass conduit.

This study assesses the patency of superficial femoral vein used as a crossover femoral artery bypass conduit in patients presenting either with localized groin sepsis, generalized sepsis or in patients with occluded or heavily diseased superficial femoral artery outflow. Twenty patients were followed prospectively with femoral crossover grafts constructed of superficial femoral vein. Twelve patients presented with sepsis and 8 with chronic ischemia from iliac artery occlusion and severely diseased superficial femoral artery outflow. Graft patency was assessed with regular duplex ultrasound examination. There was one perioperative death. Six patients died during the follow-up period. Mean follow-up time was 24.3 months. No graft occluded or required revision. There was no limb loss, graft infection, or graft hemorrhage. Superficial femoral vein offers an effective femoral crossover bypass graft in patients with either localized/generalized sepsis or disadvantaged outflow tracts.

Adult↗

PubMed2001

Predicting death from ruptured abdominal aortic aneurysms.

BACKGROUND: We have previously reported preoperative and immediate postoperative formulae to estimate mortality in patients with ruptured abdominal aortic aneurysms (rAAA). In this study, we prospectively compared these formulae in patients with rAAA with their actual outcomes. METHODS: Information was collected on 134 patients from two centers over a 3-year period. Preoperative mortality risk was estimated using coefficients for age, level of consciousness, and cardiac arrest. Mortality risk in the immediate postoperative state was based on the presence of coagulopathy, ischemic colitis, prolonged requirement for inotropes, time from arrival at hospital to surgery, patient age, perioperative myocardial infarction, renal failure, and pre-operative hemoglobin level. RESULTS: The average age was 73 years (range 30 to 92 y) and 20 of 134 (15%) patients were women. Sixty-three patients (47%) survived. For patients with a calculated preoperative mortality risk of >90%, the sensitivity, specificity, and positive and negative predictive values were 25%, 98%, 95%, and 54%, respectively. For a mortality risk >80%, these values were 37%, 94%, 87%, and 57%, respectively. For patients with an estimated immediate postoperative mortality risk > or = 90%, the sensitivity, specificity, and positive and negative predictive values were 17%, 87%, 60%, and 49%, respectively. For a predicted mortality > or = 80%, these values were 22%, 84%, 60%, and 50%, respectively. CONCLUSIONS: Our formula for predicting mortality for preoperative rAAA patients may be useful for patients with an estimated mortality risk >/=90%, based on the high positive predictive value. The formula for immediate postoperative rAAA patients was not useful in predicting death.

Aged↗

PubMed2000

Effect of endothelial and adventitial injury on somatostatin receptor expression.

BACKGROUND: The somatostatin analog, angiopeptin, inhibits intimal hyperplasia formation; although the specific somatostatin receptor (SSTR) subtypes transducing this effect are unknown. The purpose of this study was to determine the expression of SSTR subtypes in rat iliac arteries after balloon catheter endothelial injury and perivascular dissection. METHODS: Male rats received balloon endothelial injury to their left common and external iliac arteries with or without circumferential arterial dissection. The right arteries served as controls. At 1 and 2 months after intimal injury, animals were killed and their iliac arteries harvested and studied for SSTR expression by using immunocytochemical and molecular techniques. Quantitative polymerase chain reaction was used to determine the level of SSTR expression. RESULTS: Normal rat iliac arteries expressed only SSTR2 and 3. After balloon endothelial injury, there was significant upregulation of SSTR2 messenger RNA at 1 and 2 months after injury as compared with controls (1 month, 1.8 +/- 0.3 vs 0.4 +/- 0.1 zmol, P < .001; 2 months, 2.7 +/- 0.5 vs 1.1 +/- 0.2 zmol, P < .001). The addition of adventitial dissection to endothelial injury also showed a significant increase in SSTR2 expression (1 month, 2.4 +/- 0.4 vs 0.8 +/- 0.2, P < .05; 2 months, 1.3 +/- 0.3 vs 0.7 +/- 0.3, P < .05), but not significantly greater than that seen after balloon endothelial injury alone. Immunocyto-chemical studies also demonstrated an increase in SSTR2 immunoreactivity on the luminal surface of the endothelial cells in the balloon catheter-injured arteries. CONCLUSIONS: These findings show that SSTR2 is the primary SSTR that is upregulated after injury and likely mediates the effects of somatostatin analogs on intimal hyperplasia.

Animals↗

PubMed2000

Assessment of patient waiting times for vascular surgery.

OBJECTIVES: To assess patient waiting times for vascular surgery and to determine if complications of the disease develop while the patients are awaiting surgery. DESIGN: Prospective cohort study. SETTING: A university-affiliated tertiary care institution. PATIENTS: All 554 patients who underwent scheduled vascular surgical procedures between April 1995 and October 1996. OUTCOME MEASURES: A literature review carried out to develop guidelines for acceptable waiting times for surgery associated with various vascular disorders based on their natural history (benchmark target); actual waiting times, defined as the interval from the date each patient was booked for surgery to the date of admission to hospital for the procedure; the proportion of patients admitted within the benchmark targets; and whether prolonged waiting time placed patients at risk for complications of their disease. RESULTS: Of the 554 patients, 382 (69%) were admitted within the benchmark waiting times. Of 84 patients having an abdominal aortic aneurysm, the aneurysm ruptured during the waiting period in 6, and 4 of them died, for a complication rate of 7% and a death rate of 5%. Two of the 6 aneurysms ruptured after the patient had waited longer than the target time. Three of 100 patients with symptomatic carotid artery stenosis awaiting admission for carotid endarterectomy suffered ischemic stroke, for a 3% complication rate; all had waited longer than the target period. One patient suffered occlusion of a femoropopliteal bypass graft while awaiting revision of a stenosed bypass graft. CONCLUSIONS: This study suggests that although most patients are admitted for operation within the benchmark time, one-third are admitted late and may suffer serious complications of their disease while awaiting admission for the procedure.

Aortic Aneurysm, Abdominal↗

PubMed1998

Successful innominate thromboembolectomy of a paradoxic embolus.

A 54 year-old man had symptoms of acute right hemispheric cerebral ischemia. He was initially considered for participation in a trial of early thrombolysis in stroke, but an innominate artery embolus was found with no apparent arterial source. The embolus was removed by means of a combined brachial and carotid bifurcation approach to protect the cerebral vasculature from embolic fragmentation during extraction. Further investigation revealed deep venous thrombosis, evidence of pulmonary emboli, and a patent foramen ovale, supporting a diagnosis of paradoxic embolus. Additional treatment included anticoagulation and placement of an inferior vena caval filter. The unusual condition of paradoxic embolus is reviewed, and the management of this patient is discussed.

Brachiocephalic Trunk↗

PubMed1995

Hemodynamic changes and gut barrier function in sequential hemorrhagic and endotoxic shock.

Multisystem organ failure (MSOF) is the major cause of late death following trauma. The gut is hypothesized to be the source of an ongoing systemic inflammatory response that drives MSOF. It has also been suggested that while a single physiologic insult might not reliably cause MSOF, the addition of a delayed second stress will. This is known as the "two-hit" theory. The purpose of this study was to investigate the two-hit theory by observing the hemodynamic and bacteriologic response to a second stress in a subacute pig model of hemorrhagic and endotoxic shock. Swine (n = 18, 30-40 kg) were fed an antibiotic-free diet for 14 days. During instrumentation and experimentation on days 1 and 3, all animals were anesthetized (ketamine, isofluorane). On day 1, all animals had placement of central venous and arterial catheters, a portal venous catheter, and superior mesenteric artery flow probe. Group E (n = 6) underwent instrumentation on day 1, then infusion of endotoxin (25 mcg/kg E. coli lipopolysaccharide) on day 3. Group HE (n = 7) underwent instrumentation then hemorrhagic shock (mean arterial pressure = 40 mm Hg for 4 hours) on day 1, then infusion of endotoxin on day 3. Group H (n = 5) were instrumented and hemorrhaged on day 1, and underwent anesthesia only on Day 3. Between periods of anesthesia the animals were allowed food and water ad lib and systemic blood was sampled for culture every 12 hours. On day 5, the animals were euthanized prior to organ sampling for bacterial culture. One animal from group HE died during endotoxic shock on day 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Multiple spontaneous intestinal perforations from atheroembolism after thrombolytic therapy: a case report.

Atheroembolism after thrombolytic therapy, although rare, is unpredictable and carries a poor prognosis. Early diagnosis is difficult because of the many forms of presentation. A 76-year-old man with no history of atheromatous disease, who had received streptokinase as treatment for myocardial infarction, had lower gastrointestinal bleeding, progressive renal failure and peripheral ischemia. At laparotomy performed when the peritoneal dialysate was found to contain enteric contents, numerous ischemic small-bowel infarcts were seen, many of which had perforated. The entire intestine was involved, and despite efforts to repair the perforations, the patient had a downhill course and died 44 days after admission to hospital. In patients with disseminated atheroembolism after thrombolytic therapy, supportive care is the only treatment currently available. As thrombolytic therapy becomes more common in the treatment of myocardial infarction, greater effort will be needed to provide better treatment for patients with disseminated atheroembolism as a result of thrombolytic therapy.

Aged↗

PubMedDate not supplied

Benzoporphyrin derivative monacid ring A (Verteporfin) alone has no inhibitory effect on intimal hyperplasia: in vitro and in vivo results.

Benzoporphyrin derivative monoacid ring A (Verteporfin, BPD-MA), a photosensitizing drug, has been suggested as having inhibitory effects on smooth muscle cell (SMC) proliferation in rabbit aortic intimal injuries. The effect of BPD-MA on vascular SMCs in the absence of light stimulation in vitro and in vivo was studied using models of intimal hyperplasia. Human SMCs were incubated with BPD-MA for 4 h in darkness. A small (20%) but significant decrease in viability (n =42,p < .05) was noted for BPD-MA concentrations above 15 microg/mL. This was an all-or-none phenomenon with no further decrease in viability at higher concentrations. Treatment with BPD-MA was also carried out in vivo using a balloon injury model of intimal hyperplasia in rabbit aortas. Thirty-three rabbits were randomized into five groups and given intravenous BPD-MA (2 mg/kg) according to the following schedule: Group 1 (n = 8), BPD-MA 25 min prior to injury; Group 2 (n = 8), BPD-MA 25 min prior to injury plus a second dose 4 weeks later; Group 3 (n = 4), BPD-MA immediately postinjury; Group 4 (n = 7), BPD-MA immediately postinjury plus a second dose 4 weeks later; or Group 5 (n = 6), no drug (control group). No statistically significant difference was seen in the amount of intimal hyperplasia that developed in the five groups.

Angioplasty, Balloon↗