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Biomedical subjects

R S Lord

Publications and source records attributed to R S Lord.

At least 19 recordsLinked to original sources
PubMed1992

Unilateral carotid stenosis and impaired cerebral hemispheric vascular reserve.

Single photon emission computed tomography (SPECT) scanning with 99TcHMPAO (Ceretec) was used to demonstrate regional cerebral blood flow (rCBF) in sixteen patients with hemodynamically significant unilateral carotid stenosis. All patients were demonstrated by cerebral computed tomography to be without cerebral infarction. When dysautoregulation was induced by intravenous acetazolamide, eight patients demonstrated a perfusion defect ipsilateral to carotid stenosis. Repeat SPECT scanning with dysautoregulation following carotid endarterectomy showed improved or normal cerebral perfusion in seven of these patients. The results suggest that a hemodynamic mechanism for cerebral ischemic events, including transient ischemic attacks (TIA) may be more common than previously suspected. Carotid disobliteration usually improves ipsilateral cerebrovascular reserve in patients with a preoperative perfusion defect.

Acetazolamide↗
PubMed1991

Complementary value of traditional bedside teaching and structured clinical teaching in introductory surgical studies.

A prospective randomized trial was conducted to see if student performance in a combined multiple choice and objective structured clinical examination was better following a period of structured clinical teaching compared with traditional bedside teaching. Student groups were crossed over in a second phase of the experiment to allow the two teaching techniques to be compared sequentially in the same group. There was no significant difference between the two teaching techniques as measured by performance in a criterion-referenced examination. The results of the study led to modification of the curriculum for third-year introductory surgical studies to incorporate both teaching strategies, which are regarded as complementary in value.

Australia↗
PubMed1991

Use of technetium-HMPAO to demonstrate changes in cerebral blood flow reserve following carotid endarterectomy.

Cerebral perfusion through stenosed internal carotid arteries is usually maintained by autoregulation. However, flow reserve may be reduced, suggesting hemodynamically significant stenosis, and such reduction should be improved by carotid endarterectomy. This concept was studied in 20 subjects with unilateral internal carotid artery stenosis (major stenosis greater than or equal to 70%, minor stenosis less than or equal to 50%). Thirteen had experienced recent transient ischemic attacks and seven had no definite focal symptoms. Subjects underwent Tc-HMPAO cerebral SPECT during acetazolamide dysautoregulation before and after internal carotid endarterectomy. Nine (45%) had perfusion defects that improved after surgery, suggesting surgery had improved cerebral flow reserve. Seven had defects that did not improve after surgery. Four had worsened or new defects after surgery, suggesting perioperative infarcts. The relatively large proportion of patients with improved cerebral blood flow reserve after surgery suggests that this technique may have a significant role to play in assessing which patients might benefit from carotid endarterectomy.

Aged↗
PubMed1990

Transient monocular blindness.

Transient monocular blindness (TMB) or amaurosis fugax is diagnosed when visual disturbance or loss (blindness, dimming, fogging, blurring) affects one eye for seconds or minutes. TMB may occur alone or in combination with transient hemispheric ischaemia (TIA). The cause of TMB is usually an atheromatous plaque at the carotid bifurcation in the neck liberating emboli or causing a temporary reduction in carotid and retinal blood flow. In most patients no embolus or ischaemic change is visible in the fundus. TMB should be investigated and treated in the same way as neurologic TIAs with emphasis on rapid detection of extracranial arterial disease, cardiac abnormalities and haematological disorders.

Blindness↗
PubMed1990

Initial experience of intra-operative red cell salvage.

The use of red cell saving machines is described in 16 cases of aortic reconstruction. There were 3 deaths in the series, all unrelated to use of the technique. Salvaged autologous blood accounted for 45% of red cell requirements. Biochemical and haematologic parameters were monitored before, during and after operation. When large volumes of blood are salvaged, the system becomes cost effective and the risks of homologous transfusion are reduced.

Blood Specimen Collection↗
PubMed1989

Failure of clinical tests to predict cerebral ischemia before neck manipulation.

A case report is presented of a patient with vertebral artery occlusion, demonstrated by digital subtraction angiography, in whom clinical tests designed to test for potential vertebrobasilar insufficiency were negative. The clinical tests used to examine our patient included the vertebrobasilar artery functional maneuver, the Smith and Estridge, Maigne's, Hautand's and Underberge's tests. This case report highlights the limited diagnostic value of these tests.

Adult↗
PubMed1989

Comparison of saphenous vein patch, polytetrafluoroethylene patch, and direct arteriotomy closure after carotid endarterectomy. Part I. Perioperative results.

To evaluate the perioperative outcomes and the immediate increases in size after patch closure, 140 carotid endarterectomies were randomized into one of three groups: direct no-patch closure, saphenous vein patch closure, and polytetrafluoroethylene patch closure. Seven patients (4.4%) experienced signs of cerebral ischemia in the immediate postoperative period. In three cases this was transient and reversible. In the other four reexploration was undertaken and carotid thrombosis was corrected by thrombectomy. The condition of one of these patients deteriorated to a permanent stroke, whereas the other patients made a complete recovery. Neurologic complications were more frequent in the no-patch group, but the differences between the groups were not significant. The incidence of perioperative internal carotid stenosis, aneurysmal dilatation, and other morphologic abnormalities was assessed in 131 intravenous digital subtraction angiograms taken before the patient was discharged from the hospital. Eight (17.0%) of the endarterectomies in the no-patch group were narrowed by 30% to 50% diameter stenosis, whereas none of the patched arteries had more than 30% stenosis. In contrast, dilatation of the common or internal carotid artery to more than twice the measured diameter was absent in non-patched arteries but was present in seven (17.0%) saphenous patch closures and four (9.23%) polytetrafluoroethylene patch closures. We conclude that patch closure after carotid endarterectomy is less likely to cause stenosis in the perioperative period. Poly-tetrafluoroethylene patches resist dilatation better than do saphenous vein patches and are less likely to become aneurysmal.

Aged↗
PubMed1988

Prospective randomized trial of polytetrafluoroethylene and Dacron aortic prosthesis. I. Perioperative results.

Over a two year period 80 patients were entered into a prospective randomized trial comparing polytetrafluoroethylene (PTFE) and Dacron infrarenal aortic reconstructions. Fifty-four patients were treated for aneurysm (30 single tubed grafts; 24 bifurcation grafts), and 26 patients were treated for occlusive disease (26 bifurcation grafts). The groups were matched for age, sex and preoperative risk factors. Five patients died after operation (6.3%) including two from hemorrhage, but there were no significant differences in mortality and morbidity between the PTFE and Dacron groups. The volume of blood lost at operation (1930 +/- 1340 ml, all patients); the volume of blood transfused (2.98 +/- 2.43 units); the volume of crystalloids infused (3050 +/- 1390 ml); the intraoperative heparin dosage (67.9 +/- 20.5 mg); the clamp time (71.6 +/- 34.5 min); and the total operating time (228.1 +/- 78.3 min) also showed no significant differences between PTFE and Dacron. The ankle systolic pressure index rose more for PTFE (0.96 +/- 0.24) than for Dacron (0.82 +/- 0.20; P less than 0.002) at the time of discharge. This partially reflects a difference in the index between the groups before operation (PTFE 0.79 +/- 0.30; Dacron 0.72 +/- 0.32), but it may also indicate that PTFE is less thrombogenic than Dacron.

Aged↗
PubMed1987

Duodenal obstruction following abdominal aortic reconstruction.

Four patients developed duodenal obstruction after 161 abdominal aortic reconstructions, an incidence (2.5%) rivaling that of graft infection and arterioenteric fistula. The diagnosis is easily confirmed by gastrointestinal contrast studies. Duodenal obstruction is usually caused by perigraft collagenous adhesions and is probably less likely to occur if the mobilized duodenum is not replaced directly over the aorta during resuture of the retroperitoneum. Undetected duodenal obstruction leads to rapid dehydration and electrolyte and caloric depletion.

Aged↗
PubMed1987

Carotid endarterectomy, siphon stenosis, collateral hemispheric pressure, and perioperative cerebral infarction.

To determine whether moderate stenosis (50% to 80%) of the intracranial segment of the internal carotid artery increases the risk of cerebral infarction after carotid endarterectomy, the arteriograms, ocular pneumoplethysmograms, internal carotid back pressure, and clinical outcome after 169 operations were reviewed. Siphon stenoses less than 50% were not included because of their doubtful anatomic and hemodynamic significance. No patients with stenosis greater than 80% underwent operation. Moderate siphon stenosis affected 37 vessels, 24 (14.2%) ipsilateral and 13 (7.6%) contralateral to the side of operation. Eight patients had bilateral siphon stenosis. Three patients had stroke after operation; none of these cases had siphon stenosis. Moderate siphon stenosis did not increase the risk of perioperative cerebral infarction. Stroke only occurred in those patients in whom there was arteriographic or functional evidence that the affected hemisphere was isolated from effective collateral vessels.

Adult↗
PubMed1986

Rationale for simultaneous carotid endarterectomy and aortocoronary bypass.

Seventy-eight patients were treated for coexistent carotid and coronary stenosis by simultaneous reconstructions. Five patients died (6.4%), one from a stroke contralateral to the carotid reconstruction. Four others suffered a perioperative stroke (total stroke incidence 6.4%). Three myocardial infarctions occurred (3.8%) including one fatal infarct. Analysis of the most recent 36 combined reconstructions indicates that the extramorbidity in this group increased the stroke or death rate for all carotid endarterectomies carried out in the same period by only 1%. Alternatively if these patients had been operated upon by aortocoronary grafting alone the mortality would have increased by 0.1% assuming no neurologic complications. Since these 36 patients had severe carotid stenosis and would have been refused carotid endarterectomy as an isolated procedure the results seem better than would have been achieved by staged operations.

Adult↗
PubMed1986

The validity of internal carotid back pressure measurements during carotid endarterectomy for unilateral carotid stenosis.

Peri-operative neurological deficits in 212 patients undergoing carotid endarterectomy for unilateral carotid stenosis were examined to determine whether the internal carotid back pressure (ICBP) correctly predicted the need for a protective shunt during temporary carotid occlusion. Three strokes occurred in 149 patients who were not shunted. In one of these the ICBP indicated the need for a shunt, but shunting was not possible for technical reasons and a stroke due to hypoperfusion occurred. In another patient a stroke occurred as a result of embolism. There was only one patient where the ICBP possibly incorrectly predicted that a shunt would not be necessary. Four strokes due to various causes occurred in the 63 shunted patients. Shunting was not withheld from these patients in order to prove that ICBP would correctly predict their vulnerability to hypoperfusion since to have done so would be unethical. The results indicate that in patients with unilateral carotid stenosis the ICBP is an accurate indicator of which patients can undergo carotid endarterectomy without the need for shunting.

Aged↗
PubMed1985

Combined carotid coronary reconstructions--synchronous or sequential?

Analysis of 16 synchronous with 26 sequential combined carotid coronary reconstructions showed no statistical advantage of either approach. Sequential operations are more convenient but increase the total operating time by an hour or so. Synchronous operations can be carried out without carotid shunting despite hypotension provided hypothermia is established. In other circumstances the internal carotid back pressure is used to indicate the need for carotid shunting. In the 42 patients there were three strokes (7%) including one fatal stroke (2%) and two myocardial infarctions, both fatal (5%).

Cardiopulmonary Bypass↗
PubMed1979

A comparison of proximal with distal arterial reconstruction in the treatment of advanced lower limb ischaemia.

Elective arterial surgery for lower limb ischaemia due to chronic occlusive disease has been performed in 212 patients over a five-year period. Of this group, 93 patients were treated for limb-threatening ischaemia. The remainder were treated for intermittent claudication. The clinical and haemodynamic responses to surgery are analysed in this series of 93 patients. The results of proximal reconstruction, in terms of a living patient with patent graft and functional limb, were significantly better (75%) at one year than in patients undergoing distal segment reconstruction (45%). Successful aortoiliac surgery was associated with a mean increase in the ankle systolic pressure index of 0.36, comparied with 0.46 in the distal reconstruction group.

Aged↗