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Biomedical subjects

R N Baird

Publications and source records attributed to R N Baird.

At least 109 records · Page 6Linked to original sources
PubMed1991

Intra-arterial streptokinase infusion in acute lower limb ischaemia.

Between 1986 and 1988, 38 patients (29 men and nine women), median age 65 years (range 38-85 years), underwent local intra-arterial streptokinase therapy for acute lower limb ischaemia. Three patient groups were identified: 15 with acute on chronic ischaemia (group 1), 12 postangioplasty (group 2) and 11 postfemorodistal bypass (group 3). Distal arteriographic run-off was a significant discriminant between success and failure in group 1 (n = 15, chi 2 = 11.5, P = 0.001) and in the overall group (n = 38, chi 2 = 17.2, P less than 0.001). In group 2, four patients with good run-off had an unsuccessful outcome; this was due in all cases to technical problems (haemorrhage in two and intimal dissection in two). In group 3, two patients with good run-off had unsuccessful streptokinase infusions. In both cases the graft failed in the early postoperative period (less than 30 days). By contrast, the four patients whose grafts occluded after 30 days had successful streptokinase infusions and long-term graft patency was achieved by further surgery and balloon dilatation. In all groups, no patient with a poor run-off had a successful outcome following streptokinase administration. The role of local intra-arterial streptokinase therapy in the critically ischaemic limb remains controversial, but these results suggest that an adequate run-off is an important factor in the selection of patients for treatment.

Acute Disease↗
PubMed1991

Effect of weight on claudication distance.

Conservative measures to improve claudication distance include advice on smoking, exercise, diet and weight reduction. Although the effects of smoking, exercise and diet are established, the effect of weight is less clear. The aim of this study was to investigate the effect of carrying extra weight on the maximum walking distance in stable claudicants. Twenty stable claudicants were exercised on a treadmill (3.5 km/h, 0 degrees slope) carrying 0, 2.5, 5, 7.5 and 10 kg weights in randomized sequence. Maximum claudication distance and ankle: brachial pressure indices were recorded. Patients were categorized into mild or severe claudicants depending on their ability to walk 200 m. A response index (RI) was calculated as the reduction in claudication distance per kilogram load; RI = [CD0-CD10]/10 m/kg, where CD0 and CD10 represent claudication distance with 0 and 10 kg weights, respectively. Claudication distance was significantly reduced in subjects carrying 5 kg or more (P less than 0.01). A linear relationship was demonstrated between the mean claudication distance and the load carried (r = 0.98, P less than 0.01) with a mean response index of 10.2 m/kg. The mean(s.e.m.) RI in mild claudicants (25.9(9.5) m/kg) was greater than the value observed in the severe claudicants (3.3(0.8) m/kg; P less than 0.01, Mann-Whitney U test). This study demonstrates that weight adversely affects claudication distance and suggests that weight reduction may deserve greater emphasis in the management of some patients with intermittent claudication.

Adult↗
PubMed1991

Failure of peripheral arterial balloon angioplasty: does platelet deposition play a role?

The pathophysiological response to peripheral percutaneous transluminal balloon angioplasty in 20 patients was investigated using 111-Indium labelled platelets. Platelet deposition was quantified by measuring the degree of radioactivity uptake at angioplasty and control sites using a computer linked system and expressing the uptake as a ratio of angioplasty/control. Following platelet labelling, scans were performed before angioplasty and at 1, 24 and 48 h after angioplasty. To assess patency of the angioplasty, ankle brachial Doppler pressure indices were performed and supported by repeat angiograms if doubt of patency existed. All patients were followed-up at 1 week, 1 month and 6 months to correlate the degree of early platelet uptake with failure. The mean +/- sem platelet radioactivity ratio at the angioplasty site increased from 1.1 +/- 0.1 prior to the procedure to a peak of 2.1 +/- 0.3 at 1 h (p less than 0.01), 1.6 +/- 0.2 at 24 h (p less than 0.05), and 1.7 +/- 0.3 at 48 h (p less than 0.05). Angioplasties that failed within 6 months tended to have a higher maximum early platelet uptake (3.1 +/- 0.6) compared to successful angioplasties (1.9 +/- 0.3) but the difference was not significant in the numbers studied. This study provides a suitable model to assess the role of platelet accumulation in angioplasty failure and the influence of various antiplatelet regimes.

Adult↗
PubMed1991

The value of duplex scanning with venous occlusion in the preoperative prediction of femoro-distal vein bypass graft diameter.

The diameter of the long saphenous vein has been shown to affect the outcome of femoro-distal bypass. Many surgeons regard a vein with a diameter of less than 3 mm as being unsuitable. The long saphenous vein was studied in 35 patients undergoing femoro-distal bypass. Diameter measurements of the vein were performed using an ATL duplex scanner at the groin, mid-thigh and knee. Measurements were performed preoperatively both at rest and with a venous occlusion cuff to dilate the vein, and subsequently at 7 days and 2 months after implantation. The mean diameter of the vein at the mid-thigh was 4.1 mm non-dilated, 5.1 mm with occlusion, 5.0 mm 7 days postoperatively and 5.2 mm at 2 months (ANOVA, p less than 0.05). The mean diameter of the vein at the knee was 3.9 mm non-dilated, 4.8 mm with occlusion, 4.8 mm at 7 days and 4.9 mm at 2 months after operation (ANOVA, p less than 0.025). In all five patients whose preoperative resting vein diameter at the knee or mid-thigh was less than 3 mm, preoperative dilatation occurred, such that the diameter became greater than 3 mm. These results suggest that by using a technique of venous occlusion at the time of pre-operative vein mapping, the functional diameter of the vein can be predicted and vein utilisation may be increased.

Aged↗
PubMed1991

Impedance analysis to identify the at risk femorodistal graft.

Computer-assisted impedance analysis is a newly developed technique to identify femoropopliteal and distal vein graft stenoses before failure. Pulsatile flow is measured from the proximal and distal graft by use of an 8Mhz Doppler velocimeter. A pulse volume recorder measures pulsatile pressure within the thigh and calf. Fourier transfer analysis is performed on paired Doppler pulse volume recorder waveforms and an impedance score derived for the thigh and calf, respectively. In a retrospective review of 50 nonreversed femoropopliteal/distal grafts performed for limb salvage, postoperative biplanar intraarterial digital subtraction arteriography was compared with impedance analysis. Arteriography showed graft or runoff stenoses in 22 grafts (at risk) and 28 normal grafts (controls). Impedance scores were significantly higher in the at risk group (0.58 + [0.43 to 0.72]*), when compared with the controls (0.34 + [0.30 to 0.38], p less than 0.001*). A thigh or calf impedance score of greater than 0.45 was able to detect 20 of 22 stenoses, including 6 lesions in grafts with normal resting and postexercise ankle pressures. This score was then applied prospectively and compared with serial biplanar digital subtraction arteriography in a further 56 femoropopliteal/distal bypasses for limb salvage. Thirty-three of 34 lesions were successfully predicted and impedance scores were significantly higher in the at risk limbs (0.56 + [0.44 to 0.68]*) when compared with the controls (0.38 + [0.35 to 0.41], p less than 0.001*). In this series impedance analysis proved more sensitive than resting or stressed ankle pressures and, unlike Duplex scanning, was able to detect runoff as well as graft stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

A haemodynamic evaluation of the femoro-femoral cross-over bypass.

The femoro-femoral cross-over bypass has become a popular choice for the management of unilateral iliac artery disease, being used in preference to aorto-femoral or extraperitoneal ilio-femoral bypasses. It is a relatively minor procedure and associated with a small incidence of side effects, the main one being the risk of development of a steal of blood from the donor limb by the bypass. Although this problem has been widely discussed, haemodynamic studies have been limited by the use of indirect measurements of blood flow, such as ankle systolic pressures or by the use of electromagnetic flowmetry at the time of surgery. No study employing volumetric blood flow measurements to identify and quantify blood steal in the postoperative patient has been reported to date. With aims of studying the haemodynamic effects of a femoro-femoral cross-over bypass on the circulation in both the recipient and donor limbs, and of identifying preoperatively, problems likely to lead to haemodynamic problems or to graft failure, the present study of 31 patients undergoing femoro-femoral bypass was undertaken. The patients, 18 of whom had rest pain and 13 intermittent claudication, were studied preoperatively using arteriography and a non-invasive assessment. At 3 months from the operation, all received a clinical assessment and a further non-invasive assessment, including a measurement of blood volume flow. Flow measurements were made in the bypass at rest and during a reactive hyperaemia test. In addition, flow measurements were made in the donor limb below the bypass origin at rest and during hyperaemic testing of the recipient limb in order to assess any steal effect the bypass might cause to the donor limb circulation. All 31 patients were improved by surgery, but five developed donor limb claudication which was attributed to steal in three cases. Resting blood flow in the bypasses, 161 (65-282)ml/min [median (range)], rose by 116% (5-428%) to 300 (82-1114)ml/min after hyperaemic testing. Simultaneously, bypass hyperaemia caused a fall in donor limb blood flow of 32% (0-74%). Of the preoperative non-invasive tests, only donor femoral artery pulse rise time was related to the later development of objective evidence of steal. Successful Gruntzig dilatation of four major stenoses resulted in a satisfactory outcome.

Adult↗
PubMed1990

Fate of patients undergoing transluminal angioplasty for lower-limb ischemia.

A prospective study of 370 patients who underwent 500 percutaneous transluminal angioplasties (PTAs) for lower-limb ischemia over a 7-year period was performed. A 97% follow-up rate was achieved. The first PTA was successful in 188 patients (51%). Of the failures, 31% were failed attempts at dilation and 73% occurred within 1 month of intervention. Of the patients with failed PTA, 39% underwent bypass surgery and 24% underwent amputation. The 30-day mortality rate was 3%, with 1% of the deaths attributed to PTA. The survival rate at 5 years for the successes was double that for the failures (P less than .0005). The best results were in femoropopliteal stenoses with two or three patent calf vessels (cumulative patency rate, 78% at 3 years) and the worst in femoropopliteal occlusions with one or no patent calf vessels (cumulative patency rate, 25% at 3 years). Log rank tests on the life-table data were used to show factors favoring a good outcome. It is concluded that PTA is the treatment of first choice in suitable patients and, although the failure of intervention in critical ischemia has a significant risk, it is a valuable addition to the therapeutic options in patients with little chance of surgical treatment.

Adult↗
PubMed1990

Randomized trial of laser-assisted passage through occluded femoro-popliteal arteries.

A randomized trial was carried out in patients with occlusions of the femoro-popliteal artery to compare the passage of metal-tipped optical fibres with guide wires and catheters through the occlusions, prior to balloon angioplasty. The study was in a provincial English teaching hospital providing a vascular service for the area. Fifty patients were entered; 25 into the "laser" group and 25 into the "control" group. End points were (a) the success in passage through the occlusion and (b) the outcome 1 month after passage. Comparison of the groups showed no appreciable difference between the two methods with regard to age, sex, symptoms, incidence of diabetes, or previous myocardial infarctions. Successful passage through the occlusion followed by dilatation was achieved in 18 (72%) patients in the laser group and 20 (80%) in the control group. After 1 month, 13 (52%) arteries in the laser group were patent compared to 13 (57%) in the control group. Confidence limits for the difference in success of passage are -15% to +31%, and -24% to +33% for patency after 1 month. Since these limits include zero, it is unlikely that a longer trial would alter the difference between the two methods. The results suggest that the laser system currently in use is no better than conventional methods.

Adult↗
PubMed1989

Operative assessment of femorodistal bypass grafts using a new Doppler flowmeter.

Operative measurements using a newly developed Doppler flowmeter were made on 47 in situ femorodistal bypass grafts performed for critical ischaemia. Graft blood flow, peripheral resistance and impedance were measured before and after the injection of 15 mg papaverine down the graft. The proportion of retrograde blood flow at the distal anastomosis was also measured. The success of a graft at 1 month was defined by patency on duplex ultrasound scanning, a rise in the Doppler ankle pressures and an improvement in the clinical state of the limb. By these criteria the 1-month primary success rate was 35 out of 47 (74 per cent). Graft blood flow was of little value in predicting graft outcome but, combined with segmental pressures, accurately located six of eight technical problems which were successfully corrected. After papaverine, the peripheral resistance of all the successful grafts fell below one peripheral resistance unit (PRU). No single measurement was able to completely distinguish between success and failure, although discriminant analysis of all measurements was able to predict success with a sensitivity of 100 per cent and specificity of 97 per cent. A simpler combination of a peripheral resistance after papaverine less than 1 PRU and a retrograde blood flow less than 33 per cent predicted success, with a sensitivity of 97 per cent and specificity 83 per cent. These criteria have been validated on a further 26 grafts, achieving a sensitivity of 88 per cent and a specificity of 75 per cent. Simple operative measurements, using a newly developed Doppler flowmeter, enable the detection of technical problems and the accurate prediction of the early outcome of femorodistal grafting.

Adult↗
PubMed1989

Anastomotic aneurysms of the femoral artery: aetiology and treatment.

The aetiology and treatment of 35 femoral false anastomotic aneurysms in 29 patients presenting over the 4-year period 1984-88 were reviewed retrospectively. The mean interval between primary anastomosis and false aneurysm repair was 6 years (range from 2 weeks to 16 years). Twenty-two (63 per cent) false aneurysms had occurred after previous aortobifemoral bypass grafting for occlusive aortoiliac disease. Seven (20 per cent) presented as acute surgical emergencies. Review of the records of the initial operations revealed that superficial wound infections with positive bacteriological cultures had been present in eight cases (23 per cent) and a further two (6 per cent) had lymph fistulae. Thirty-two false aneurysms were repaired, by simple reanastomosis in 14 cases, interposition grafting in 17 cases and in one case by complete revision to an aortobifemoral bypass graft. The risk of a further operative repair was less (P less than 0.05) following interposition grafting, than after simple revision. False aneurysm repairs, when compared with primary reconstructions done during the same period, were associated with more superficial wound infections (37 versus 10 per cent) and more explorations for haemorrhage within 30 days (19 versus 7 per cent).

Anastomosis, Surgical↗
PubMed1989

Abdominal aortic aneurysm repair in the over eighties.

Between January 1980 and September 1988, 34 octogenarians underwent aortic aneurysm repair. There were 26 men and eight women with a median age of 83 years (range 80-88 years). Twenty underwent 'emergency' repair after presenting with pain and/or collapse: 11 with a retroperitoneal rupture, three with an intraperitoneal rupture and six with an expanding aneurysm. The mortality rate for this group was 35 per cent. During the same period 14 patients had an elective repair and there were no deaths within 30 days. The mean hospital stay for the elective group was 14.2 days compared with 17.0 days for survivors in the emergency group. There was no significant difference in terms of risk factors between those who developed postoperative complications and those who did not. These mortality rates compare favourably with our overall mortality results for elective (4.6 per cent) and emergency (31 per cent) surgery. Those patients over 80 years of age with infrarenal abdominal aortic aneurysms should not be refused surgery on the basis of age alone; each patient should be judged individually.

Aged↗
PubMed1989

The non-reversed vein femoro-distal bypass graft: a modification of the standard in situ technique.

The results of 85 in situ vein femoro-distal bypass grafts using a modified technique where the vein was completely mobilised but left "non-reversed" have been reviewed with particular regard to risk factors and complications. The distal anastomosis was to the infrageniculate popliteal artery in 55% and to the tibioperoneal trunk or a single calf vessel in the rest. Arteriographic run-off was by a single vessel in 42%. The primary failure rate at 1 month was 20% and the secondary failure rate 9%; the majority of early failures being due to missed technical errors despite the use of a pulse volume recorder. The cumulative secondary patency rate at 1 and 2 years was 77% and 72%; limb salvage 85% and 77%; and patient survival 89% and 83% respectively. The only significant risk factors were the level of the distal anastomosis and the run-off (P = 0.002 and 0.03 respectively). Complete mobilisation of the vein allows a tension free proximal anastomosis to the common femoral artery and avoids the risk of arteriovenous fistulae. A high vein utilisation rate of 93% was achieved by using a small 2.5 mm Hall valvulotome. Although there was a trend towards lower patency rates in veins with a minimum diameter less than 4 mm the results are still superior to PTFE. Compared to reversed vein the in situ technique has a better utilisation rate and the long-term patency rates are at least as good if not better. Improved methods of haemodynamic assessment during reconstruction to reduce technical errors may be the key to better early patency rates.

Adult↗
PubMed1987

Asymptomatic carotid murmur: ultrasonic factors influencing outcome.

Sixty consecutive patients with an asymptomatic mid-cervical murmur on auscultation were identified amongst 1000 patients who underwent duplex scanning of the extracranial carotid arteries during 1981-83. They were classified according to the scan results into 12 high risk subjects with greater than 75 per cent stenosis of an internal carotid artery, 37 low risk subjects with a less than 75 per cent stenosis and 6 with no detectable stenosis. The mean duration of follow-up was 3 years (minimum 2 years) or until stroke or death. One was lost to follow-up and four were excluded having undergone carotid endarterectomy during the study. Six of twelve subjects with greater than 75 per cent stenosis suffered a stroke (five fatal and one non-fatal). There were no premonitory signs except in one patient with non-focal cerebral ischaemia for 2 months before an hemispheric stroke. There was one fatal stroke in the less than 75 per cent stenosis group and none in the control group. In all, 17 (28 per cent) patients died (myocardial infarction, 8; stroke, 6; malignant disease, 3). These results confirm that asymptomatic carotid murmurs are associated with increased mortality with most having non-severe carotid disease on duplex scanning and few strokes during follow-up. There is an important minority with tight carotid stenosis who carry a worrying risk of stroke if left untreated.

Adolescent↗
PubMed1987

Prospective assessment of carotid endarterectomy by clinical and ultrasonic methods.

Sixty-three carotid endarterectomies in 60 patients were followed by clinical and duplex scanning at 2 weeks postoperatively and at 3-monthly intervals for 3 years (mean 18 months). Four patients died (two of stroke, two of myocardial infarction) and four survivors had recurrent ipsilateral symptoms. Two had an immediate mild hemiparesis which recovered completely within 36 h; in both, the endarterectomized arteries were patent on scanning. The other two experienced amaurosis fugax for 2-3 weeks at 2 and 24 weeks; scanning showed that the sites of both endarterectomies had become occluded. Ultrasound assessment at 2 weeks showed that 43 of 61 (70.5 per cent) endarterectomized arteries were widely patent. There were three occlusions, one stenosis of greater than 75 per cent, three stenoses of greater than 50 per cent and eleven stenoses of less than 50 per cent. At 6 months a total of five vessels were occluded, with greater than 75 per cent stenosis in three and greater than 50 per cent stenosis in eight. At latest follow-up, six of eight arteries with greater than 50 per cent stenosis shown earlier had scans which had reverted to normal. Tacking down of the distal intima was associated with higher incidence of restenosis and occlusion (P less than 0.01). Women were more predisposed to restenosis by neointimal hyperplasia (P less than 0.05). All restenosis occurred within the first 6 months postoperatively (26.2 per cent) and fell to 16.4 per cent at the end of the study.

Arterial Occlusive Diseases↗
PubMed1987

The place of percutaneous transluminal angioplasty in the treatment of patients having angiography for ischaemic disease of the lower limb.

A prospective survey was made during 1 year of all 226 patients having angiography for lower limb ischaemia, to assess the accuracy of selection for angiography and the current treatment of the disease. Sixty-two percent of the patients presented with intermittent claudication and were found to have a fall in ankle systolic blood pressure on exercise. Thirty-one percent had rest pain or ischaemic skin changes. All patients had abnormal angiograms, with aorto-iliac disease present in 42%, combined with distal disease in 22%. There was a normal aorto-iliac segment in 58% of patients who had more distal disease. Calf-vessels only were affected in 15%. Treatment was by surgery only in 49%, and balloon dilatation only in 19%. A further 2% had dilatation as a complement to surgery, and 6% had surgery when dilatation failed or had complications. Dilatation was attempted unsuccessfully in 6%. No treatment was offered to 20% of patients. It is concluded that selection of patients for angiography using clinical and vascular laboratory assessment avoids unnecessary examinations and that approximately one-third of these selected patients are candidates for angioplasty, which is the preferred first option for treatment in all suitable patients.

Adult↗