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Biomedical subjects

M R Tyrrell

Publications and source records attributed to M R Tyrrell.

At least 19 recordsLinked to original sources
PubMed1997

Results and cost analysis of distal [crural/pedal] arterial revascularisation for limb salvage in diabetic and non-diabetic patients.

In order to compare the outcome and costs of femorodistal grafting in diabetic and nondiabetic patients presenting with critical limb ischaemia we analysed a consecutive series of 109 femorodistal bypasses, 38 (35%) performed on people with diabetes and 71 (65%) on non-diabetic patients. The same aggressive revascularization policy was used in both groups with the decision to operate based on the presence of a calf or foot vessel on preoperative intra-arterial digital subtraction angiography (IADSA). Data were collected prospectively and the median follow-up was 15.4 months (range 0 to 42 months). There were no significant differences in 30-day (5.3% vs 4.2%) and in-hospital mortality (13.2% vs 14.1%) between the two groups. Life table curves at 3 years in diabetic and non-diabetic patients showed 48% vs 60% survival, 76% vs 72% knee salvage, 45% vs 56% limb salvage, and 38% vs 47% secondary patency. Although there was a trend for diabetic patients to perform less well, there was no statistically significant difference in these outcome measures. In cost comparison the only significant difference was found in the total hospital cost, which was Pounds 9181 in diabetic, compared to Pounds 6350 in nondiabetic patients (p = 0.026, Mann-Whitney). However, this cost was significantly less than that of primary amputation in either group (Pounds 15500 and Pounds 12040, respectively). Femorodistal reconstruction in both diabetic and non-diabetic patients, whenever feasible, is a cheaper option than primary amputation, even though vascular surgery may be more expensive in people with diabetes.

Amputation, Surgical↗
PubMed1997

Outcome and cost analysis after femorocrural and femoropedal grafting for critical limb ischaemia.

BACKGROUND: The past decade has seen an increase in the use of distal arterial bypass grafts for treating critical lower limb ischaemia. However, this surgical policy is associated with variable results. The aims of this study were to identify factors that affect outcome and to calculate the cost of such surgical interventions. METHODS: A prospective analysis of femorocrural and femoropedal bypass grafts and primary amputations was performed between June 1991 and January 1995. A consecutive series of 109 limbs with critical lower limb ischaemia underwent a bypass graft to a single crural or pedal vessel shown on either preoperative intra-arterial digital subtraction angiography or at surgical exploration. Complete data were available for all patients during follow-up which ranged from 0 to 42 (median 12) months. The factors assessed were age, sex, diabetes, pedal arch, graft material, outflow vessel, number of calf vessels, number of vessels crossing the ankle, inflow state, previous revascularization procedures and foot gangrene and tissue necrosis. Chief outcome measures were survival, knee and limb salvage, patency rates and hospital cost. The Kaplan-Meier method was used to construct life tables and the log rank test for comparison of factors. Cost was measured according to National Health Service criteria, and comparisons were made by the Mann-Whitney U test. RESULTS: At 36 months primary patency was 27 per cent, primary assisted patency 31 per cent and secondary patency 45 per cent; limb salvage was 54 per cent, knee salvage 73 per cent and survival 58 per cent. Significant factors in predicting outcome were graft material (P = 0.004), inflow state (P = 0.0001), number of calf vessels (P = 0.039), number of vessels crossing the ankle (P < 0.0001) and the condition of pedal vessels (P < 0.0001). Cost analysis showed that the median price for a successful bypass was 4320 pounds, that of a failed bypass leading to amputation 17,066 pounds and that of primary amputation in patients with non-reconstructable distal disease 12,730 pounds. CONCLUSION: The patency rate of femorotibial and peroneal bypass depends on the inflow state, the availability of a venous conduit, the number of calf vessels, the presence of straight flow to the foot and the presence of patent pedal vessels. These factors can help in the selection of patients for femorodistal reconstruction and may explain the wide variation in published results. The low cost of revascularization compared with amputation justifies attempted reconstruction. However, repeated attempts to reconstruct patients with severe distal disease who may benefit more from primary amputation will significantly increase the cost.

Aged↗
PubMed1996

A 4-year prospective audit of the cause of death after infrarenal aortic aneurysm surgery.

This study was a 4-year prospective audit of abdominal aortic aneurysm surgery including 222 aneurysm repairs: 106 elective, 76 urgent and 40 emergency. Twenty-five patients died: four who underwent elective surgery, seven urgent and 14 emergency. The two major causes of death, multiple organ failure and colonic ischaemia, were responsible for 11 of the 25 deaths. The three deaths from myocardial infarction all occurred in patients with a leaking aneurysm. Blood loss was significantly higher in patients with multiple organ failure and in those with colonic ischaemia. Methods to identify patients at high risk of massive blood loss and colonic ischaemia may be a way to reduce mortality.

Animals↗
PubMed1996

Non-invasive assessment of arterial disease: a comparison of Quickscan with intra-arterial digital subtraction angiography.

The ability of Quickscan to identify haemodynamically significant lesions in the arteries of the lower limb was studied. Quickscan was prospectively compared with intra-arterial digital subtraction angiography (IADSA) of the iliac, femoral and popliteal arteries. In 155 patients, 631 arterial segments were evaluated. A Quickscan frequency ratio of 1:3 or greater had a sensitivity of 93 per cent and a specificity of 85 per cent in detecting a stenosis of more than 50 per cent diameter reduction (67 per cent area reduction) in the iliac artery, as shown on IADSA. The sensitivity and specificity in the femoral artery were 85 and 96 per cent respectively, and in the popliteal artery 82 and 98 per cent respectively. In the detection of occlusion, Quickscan had a sensitivity and specificity of 84 and 98 per cent respectively in the iliac artery, 94 and 97 per cent respectively in the femoral artery, and 94 and 85 per cent respectively in the popliteal artery. Quickscan is an inexpensive, quick and non-invasive method of screening for peripheral vascular disease in the lower limb.

Adult↗
PubMed1996

Mid-aortic syndrome presenting in childhood.

Mid-aortic syndrome (MAS) is an uncommon condition characterized by segmental narrowing of the proximal abdominal aorta and ostial stenosis of its major branches. It is usually diagnosed in young adults, but may present in childhood as a challenging problem. Over the past 20 years 13 patients with MAS have presented to this institution. All had hypertension, four had associated neurofibromatosis, three persistent eosinophilia and three had Williams syndrome. In all cases arteriography showed a smooth segmental narrowing of the abdominal aorta with concomitant stenosis at the origins of the renal arteries. Six children were successfully treated with antihypertensive medication alone. Percutaneous transluminal angioplasty was attempted in two cases with poor result. Surgery was indicated in seven children with refractory hypertension and progressive renal impairment. Techniques used to revascularize the kidneys included thoracoabdominal to infrarenal aortic bypass with renal artery reimplantation, splenorenal bypass, gastroduodenal to renal bypass, aortorenal bypass and autotransplantation.

Adolescent↗
PubMed1995

Incidence and management of laser-associated oesophageal perforation.

The incidence of oesophageal perforation in 350 patients referred for laser treatment to palliate malignant dysphagia is reported. Perforation occurred in 6 per cent of patients or 2 per cent of treatment episodes. Perforation was usually due to oesophageal dilatation undertaken before laser treatment (23 of 25 perforations). Immediate recognition and the institution of an aggressive non-operative management protocol resulted in survival in 20 of 23 patients.

Deglutition Disorders↗
PubMed1993

Critical leg ischaemia: an appraisal of clinical definitions. Joint Vascular Research Group.

The reliable prediction of imminent limb death remains a clinical problem. The International Vascular Symposium and European working parties each produced similar definitions of 'critical ischaemia', but this is the first attempt to address the issue with prospectively collected data. Complete 3-year follow-up data were available for 213 patients. In addition to the above two definitions, a simplified modification has been evaluated, after review of the data 1 year into this study. All three definitions were able to identify patients likely to require amputation in the absence of successful reconstruction. The sensitivity, specificity and positive predictive values with which they were able to do so was, however, poor. None of the definitions was able to predict which diabetic patients would require amputation. Diabetics were more likely to undergo amputation than non-diabetics. There was, however, no significant difference in the initial ankle artery pressures between the diabetic and non-diabetic patient subgroups. None of the definitions reliably predicted which grafts would occlude, in which event the 3-year mortality rate was approximately 35 per cent. Critical ischaemia by any of these definitions is associated with a high mortality rate. Arterial reconstruction is associated with a reduction in both mortality and amputation rates These data do not support the hypothesis that critical ischaemia is associated with a greater graft occlusion rate than lesser degrees of severe ischaemia.

Amputation, Surgical↗
PubMed1993

Targeting of microdiscs in white cells to tibial abscesses in rabbits.

The ability to deliver drugs to specific foci of infection is a sought-after goal. One solution is to use microparticles as drug carriers. This approach is limited by detection of microparticles by the reticuloendothelial system (RES). In order to reduce RES uptake of such particles, we investigated the possibility of "hiding" microparticles within white cells prior to targeting them to experimental tibial abscesses. We used radioactive silicone microdiscs, supplied by the Royal Signals & Radar Establishment. Twelve rabbits with abscesses in the right tibia were used: six control animals received radioactive opsonised microdiscs intravenously, and six animals received the same dose of microdiscs following incubation of the microdiscs with white cells. Each animal's liver, spleen, lungs, and both tibiae were removed, weighed, and homogenised. Radioactivity counts were obtained from each tissue, and the ratio of counts per gram of tissue for the right/left tibiae was calculated for the two groups of animals. The ratio of counts in the control group was 1.66 (+/- 0.57 SD), and the mean ratio of counts from the rabbits who had microdisc incubated with white cells was 3.32 (+/- 0.52 SD). This difference was statistically significant at p = 0.02 (Mann-Whitney U test).

Abscess↗
PubMed1992

Colour flow imaging in the detection of femoro-distal graft and native artery stenosis: improved criteria.

Vein graft or native artery stenosis after femoro-distal revascularisation is a common cause of graft occlusion. The early detection and treatment of such stenoses offers the potential for better graft patency than salvage procedures undertaken for graft thrombosis. In the past, two criteria using duplex scanning have been used to detect grafts at risk: (a) a localised increase in the peak velocity (V2) by 100% or more in comparison to the peak velocity (V1) 2 cm upstream (i.e. V2/V1 ratio greater than 2.0), and (b) a decrease in average peak velocity to less than 45 cm s-1. Seventy-four consecutive patients with femoro-distal vein grafts have been studied with intravenous digital subtraction angiography to detect stenosis (greater than 50% diameter) and colour flow imaging using both duplex scanning criteria (a) and (b) at 1.5, 3, 6, 9 and 12 months after operation. The results show that the V2:V1 ratio greater than criterion had a sensitivity of 100% and a specificity of 83%. Stenoses in the native distal arteries were not detected. Low average peak velocity less than 45 cm s-1 had a sensitivity of 61% and a specificity of 98%. By combining both criteria the sensitivity for detecting stenoses in both the vein graft and native distal artery, became 100% and the specificity 98%.

Angiography, Digital Subtraction↗
PubMed1990

Evaluation of fine catheter aspiration cytology of the peritoneum as an adjunct to decision making in the acute abdomen.

Fine catheter aspiration cytology of the peritoneal cavity was performed successfully in 61 patients admitted with acute abdominal pain. Aspirates were examined microscopically and the percentage of neutrophils in the specimen counted. In patients in whom the clinical need for operation was certain (n = 25) all patients required surgery and the peritoneal neutrophil count was greater than 50 per cent. In patients in whom the clinical need for operation was uncertain (n = 36) 19 patients required operation: the peritoneal neutrophil count was greater than 50 per cent in 18 and in one patient with ectopic pregnancy fresh blood was aspirated. Of the 17 patients not requiring operation the peritoneal neutrophil count was less than 10 per cent in 15 and greater than 50 per cent in two patients (both had acute pelvic inflammatory disease). This study confirms peritoneal cytology as a useful adjunct to decision making in those patients with acute abdominal pain in whom the decision to operate is in doubt.

Abdomen, Acute↗