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Biomedical subjects

J D Beard

Publications and source records attributed to J D Beard.

At least 55 records · Page 3Linked to original sources
PubMed1997

The effect of placing an aortic Wallstent across the renal artery origins in an animal model.

OBJECTIVES: To assess the effect on renal blood flow and renal function of placing a Wallstent (Schneider (Europe) AG) across the renal artery origins in an animal model. DESIGN: Laboratory animal study. MATERIALS AND METHODS: Six Large White pigs had Wallstents placed across the origins of one or both renal arteries. Preoperative jugular venous blood samples were submitted for blood count and urea and electrolyte estimation. The pigs were recovered for 6 weeks. At sacrifice the renal arteries and their origins were examined by aortography and direct pressure measurements were recorded from the renal arteries and both the stented and unstented portions of the aorta. Renal venous blood samples were submitted for blood count, urea and electrolyte and renin estimation while renal arterial blood samples were submitted to examination for red blood cell fragmentation. The aorta with contained stent, renal arteries and kidneys were submitted for histological examination. RESULTS: At sacrifice no renal arteries had occluded and the stent-covered origins appeared normal with no evidence of stenosis. This was confirmed histologically. There was no statistically significant difference between the arterial pressures measured in the stented and unstented portions of aorta and the renal arteries whether or not their origins had been covered by the stent. There was no statistically significant difference between the urea and electrolyte and renin levels of renal venous blood samples irrespective of whether or not the relevant kidney had a stent across its renal artery origin. Renal arterial blood samples showed no evidence of red blood cell fragmentation and histological examination of the kidneys showed no evidence of infarction or micro-emboli. Examination of the specimens by light and scanning electron microscopy demonstrated partial endothelialisation of the stents but the renal artery origins remained widely patent despite being crossed by at least one wire in all cases. CONCLUSIONS: It may be necessary to place stents across renal artery origins during endovascular repair of abdominal aortic aneurysms. It would appear that covering renal artery origins with a Wallstent has no effect on renal perfusion pressure or function in this short-term animal model.

Animals↗
PubMed1997

A prospective study of the effect of limb-threatening ischaemia and its surgical treatment on the quality of life.

OBJECTIVE: To assess the quality of life after treatment for limb-threatening ischaemia. DESIGN: An open, prospective, observational study in a Vascular Unit of a University Hospital. MATERIALS: One hundred and fifty consecutive patients presenting with actual or threatened tissue loss of the leg. METHODS: A single, experienced observer assessed the patients for pain, mobility, anxiety, depression, self-care and lifestyle at presentation, 6 and 12 months later. RESULTS: Six different treatment outcomes were recognised: successful angioplasty, successful thrombolysis/thrombectomy, successful surgical bypass, amputation after failed revascularisation, primary unilateral amputation and primary bilateral amputation. Pain was significantly improved in all groups (p < 0.05) except for patients after failed revascularization (p = 0.08). Mobility improved in patients who underwent angioplasty (p = 0.05) or a successful surgical bypass (p = 0.001). Anxiety and depression both improved significantly only after surgical reconstruction (p < 0.02). Self-care ability improved significantly after angioplasty (p < 0.05), surgical reconstruction (p < 0.005) and unilateral primary amputation (p < 0.05), but was unaltered in the other groups. Lifestyle significantly deteriorated following thrombolysis/thrombectomy and failed surgical reconstruction (p < 0.05), but was maintained in all other groups. CONCLUSIONS: The treatment of limb-threatening ischaemia should aim to maintain pre-morbid lifestyle, an aim which is best achieved by limb-salvage. The patient's own expectations and needs have a major bearing on the choice of therapy.

Activities of Daily Living↗
PubMed1997

Middle cerebral artery blood velocity, embolisation, and neurological outcome during carotid endarterectomy: a prospective comparison of the Javid and the Pruitt-Inahara shunts.

OBJECTIVES: To investigate the in vivo haemodynamic performance and neurological outcome of two types of carotid shunt. DESIGN: Randomised single surgeon study of consecutive symptomatic patients. SETTING: 163 consecutive patients undergoing carotid endarterectomy for symptomatic carotid disease were randomised to the Javid or Pruitt shunt. CHIEF OUTCOME MEASURES: Middle cerebral artery velocity (MCAV), preoperatively, during clamping, during shunting and post-restoration of flow, embolic episodes, neurological outcome. MAIN RESULTS: The MCAV preoperatively, at carotid clamping, and postoperatively was the same for both groups (p > 0.15). During shunting the MCAV was significantly lower in the Pruitt group, p < 0.005, 59% of the Javid and 34% of the Pruitt shunts maintained MCAV at preoperative levels p < 0.005, chi 2 = 8.92. The Javid shunt produced significantly more emboli (73% of cases) at declamping than the Pruitt (41%), p < 0.0002, chi 2 = 14.7. Four Javid patients and one Pruitt had disabling thromboembolic strokes; overall thromboembolic stroke rate 3.7%. The difference in stroke rates was not statistically significant (p = 0.14). CONCLUSIONS: The Pruitt shunt was unable to maintain preoperative MCAV in 66% of cases, the Javid shunt had a higher incidence of emboli on declamping. These factors may lead to an increased risk of stroke; however, the numbers required for statistical confirmation would be large.

Adult↗
PubMed1996

Actions of acute ethanol intoxication on cardiopulmonary function after an endotoxin challenge.

BACKGROUND: This study examined whether acute ethanol (EtOH) intoxication could alter the systemic inflammatory response evoked by endotoxin (lipopolysaccharide, LPS). METHODS: Anesthetized (fentanyl) and mechanically ventilated mongrel pigs were administered 20% EtOH (3 gm/kg) or its vehicle (VEH) by means of gastric lavage. After 60 minutes of equilibration, blood levels were 110 to 130 mg/dl, and LPS (1 microgram/kg per 30 minutes) was infused intravenously to mimic the type of sepsis that might be encountered after a penetrating abdominal injury. RESULTS: LPS caused initial pulmonary vasoconstriction followed by cardiovascular collapse in 7 of 14 pigs with EtOH versus 0 of 14 pigs with VEH (p = 0.0058); survival time averaged 2.4 +/- 0.5 hours for EtOH versus 4.5 +/- 0.3 hours for VEH (p = 0.002). At 3 to 5 hours after LPS infusion the survivors were acidotic (base excess, -5.1 +/- 1.5 versus 0.4 +/- 1.1 mEq/L; p = 0.007) and vasodilated (systemic vascular resistance, 54% +/- 9% versus 111% +/- 9% baseline; p = 0.005). Systemic arterial pressure and cardiac filling pressures were maintained with fluid resuscitation, but more was required for EtOH versus VEH (80 +/- 11 versus 42 +/- 5 ml/kg/hr; p = 0.0034). A diffuse capillary leak was detected with gamma scintigraphy and regional uptake of technetium 99m albumin. With EtOH versus VEH microvascular permeability was higher in abdomen (p = 0.01) and liver (p = 0.06) but not in lung (p = 0.29). These changes were probably mediated in part by leukosequestration: neutrophil counts were initially reduced more than 80% in both groups, but they then rebounded with VEH (p < 0.05) but not EtOH. The early versus late deaths within the EtOH group were distinguished by higher baseline levels of cortisol (1.4 +/- 0.3 versus 0.9 +/- 0.2 micrograms/dl; p = 0.075) and by a 50% decrease evoked by EtOH (p = 0.0042) versus no change in the late death subgroup. After LPS infusion cortisol peaked sooner and then recovered with VEH (p < 0.05), whereas the peak occurred later and there was no decay with EtOH. In addition, at 60 and 90 minutes after LPS infusion tumor necrosis factor was 119 +/- 27 and 240 +/- 40 pg/ml with VEH versus 62 +/- 15 and 95 +/- 23 pg/ml with EtOH (p = 0.041 and p = 0.0030). CONCLUSIONS: By means of a leukocyte-mediated mechanism in the splanchnic circulation, acute EtOH impaired host defense, which exacerbated LPS-evoked systemic inflammatory response. In context with our earlier experimental study and two large clinical trials, it appears that acute EtOH can have opposite effects on the vulnerability to posttrauma sepsis, depending on the timing of the septic insult and on the immune status at the time of septic challenge.

Animals↗
PubMed1996

A new animal model for abdominal aortic aneurysms:initial results using a multiple-wire stent.

OBJECTIVES: The effect of a plain 48-wire self-expanding flexible stent (Wallstent-Schneider (Europe) AG) on abdominal aortic aneurysms has been studied in a new animal model. METHODS: Aneurysms were created by interposing fusiform segments of glutaraldehyde-tanned bovine internal jugular vein into the infrarenal aortas of 12 Large White pigs. The first six pigs were assessed after 6 weeks by ultrasonography and arteriography; they were then sacrificed for pathological examination. Endovascular placement of the stents, 2 weeks after aneurysm creation, was performed under arteriographic control in the next six pigs. These pigs were assessed by ultrasonography and arteriography 6 weeks after stenting; they were then sacrificed for pathological examination. RESULTS: At 6 weeks the aneurysms in the first group were pulsatile with partial endothelialisation and no mural thrombus. Placement of the stent in the second group was accomplished easily. Stenting resulted in an immediate reduction in wall pulsatility of all aneurysms and thrombosis of the excluded aneurysm sac occurred in three cases. In the other three cases the pulse pressure in the sac was reduced. In all cases there was a significant reduction in maximum aneurysm diameter when measured 6 weeks after stenting. CONCLUSIONS: A pulsatile, non-thrombogenic aortic aneurysm model approaching human dimensions has been successfully developed for the study of endoprostheses prior to their clinical use. Endovascular placement of a plain, multiple-wire Wallstent was associated with reductions in aneurysm pulsatility, pulse pressure within the sac and maximum aneurysm diameter over the study period. Stenting was associated with thrombosis of the excluded aneurysm sac in 50% of cases.

Animals↗
PubMed1996

The costs of managing lower limb-threatening ischaemia.

One hundred and fifty consecutive patients presenting with limb-threatening ischaemia were studied prospectively to determine treatment and rehabilitation costs in the first year. Limb salvage was attempted in 104 (69%) patients but failed in 13%. Mortality at 1 year was 27%. The cost of treatment, inpatient stay, occupational therapy, physiotherapy, convalescence, disablement services, home adaptations, home care, district nursing, transportation and outpatient visits were determined for each patient. The patients were classified according to their presentation and initial treatment into five groups (number of patients) whose median management costs (interquartile range) for 12 months were: Gp 1 (23 - Revascularisation for acute ischaemia = 3970 pounds (2984-5511) Gp 2 (29) - Angioplasty for critical ischaemia = 6611 pounds (3630-10,200) Gp 3 (52) - Reconstruction for critical ischaemia = 6766 pounds (4337-9677) Gp 4 (34) - Primary amputation = 10,162 pounds (7894-13,026) Gp 5 (12) - Primary bilateral amputations = 13,848 pounds (11,440-18,056) At 1 year, there was no significant difference in the cost of managing a patient with a critically ischaemic limb by angioplasty or surgical reconstruction. The cost of revascularisation for acute ischaemia was comparatively low because these patients required minimal rehabilitation. The median cost of managing a patient following amputation was almost twice that of successful limb salvage justifying an aggressive revascularisation policy. However, justification of such a policy on economic grounds requires salvage failure episode to be minimised as they increase costs considerably.

Absenteeism↗
PubMed1996

European carotid angioplasty trial.

The Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS) is an international multicenter randomized trial, the primary aims of which are: (1) to determine the risks and benefits of carotid and vertebral artery transluminal angioplasty; and (2) to compare these with surgical treatment (carotid endarterectomy) or best medical treatment. Through the end of October 1995, 193 patients have been randomized (90 at our center). In this article, the rationale for the trial, its design and protocol, and the experience of our institution within the trial will be discussed.

Angioplasty, Balloon↗
PubMed1996

Thrombo-embolectomy and thrombolytic therapy in acute lower limb ischaemia. A five year experience.

Between 1988 and 1993, 82 patients with a median age (iq range) of 81 (73-87) years underwent thrombo-embolectomy (TE) and thrombolysis for acute lower limb ischaemia at the Royal Hallamshire Hospital, Sheffield. 28 patients (Group 1) underwent TE prior to the introduction of thrombolysis in 1991. TE with intraoperative thrombolysis (IT) as an adjunct was performed in 34 patients (Group 2) and 20 patients (Group 3) were treated using percutaneous thrombolysis (PT) in the first instance. 41 of these patients were in AF at presentation. Although 24 were on digoxin, only 4 were on warfarin. Group 3 patients were younger (p < 0.05; ANOVA) with a longer duration of ischaemia (p < 0.05; ANOVA) and had less limbs suffering a sensorimotor deficit (p = 0.007; chi 2) compared with Groups 1 and 2 which were similar in these respects. Overall mortality was 17%. Successful revascularisation was achieved in 18 (64%), 28 (82%) and 15 (75%) patients in Groups 1, 2 and 3 respectively. 14 of the 15 patients successfully treated initially by PT required further intervention in order to maintain revascularisation. Revascularisation failure was associated with the presence of a sensorimotor deficit but not associated with patient age or duration of ischaemia.

Acute Disease↗
PubMed1995

Surgery for limb threatening ischaemia: a reappraisal of the costs and benefits.

OBJECTIVES: To study the quality of life of patients following surgery for critical limb is ischaemia. DESIGN: Part retrospective, part prospective open study. SETTING: Vascular unit of a University Hospital. MATERIALS: Seventy-nine consecutive patients, medium age 75 years (range 44 to 94), who presented with leg threatening ischaemia and who underwent successful revascularisation or a major amputation were studied. CHIEF OUTCOME MEASURES: Six separate quality of life measures were recorded at 6 months: pain, mobility, anxiety, depression, activities of daily living (Barthel) and lifestyle (Frenchay). MAIN RESULTS: The mortality of this group of patients after six months was 24%. Forty-seven patients were available for quality of life assessment six months after initial intervention. Overall, amputation was more costly than successful revascularisation and limb salvage. Limb salvage resulted in greater mobility (p < 0.001) and better performance in self-care (p < 0.001) and lifestyle (p = 0.006), but produced more anxiety and depression (p = 0.04) than major amputation. A subgroup of patients who had major amputation after a failed limb salvage operation consumed a disproportionate amount of resources and, although their mobility was typical of amputees, their self-care and lifestyle scores were similar to those who had successful limb salvage. OBSTRUCTIONS: Limb salvage is attempted in up to 22% of patients for whom primary amputation may provide more expeditious rehabilitation with minimal impairment of their lifestyle performance.

Activities of Daily Living↗