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Biomedical subjects

A E Giddings

Publications and source records attributed to A E Giddings.

At least 19 recordsLinked to original sources

Critical ischaemia of the upper limb.

Fifty-seven patients who presented to the Royal Surrey County Hospital, Guildford, with critical upper limb ischaemia between 1980 and 1989 were studied. Only 13 patients had emboli, while 23 presented with arteritis, seven involving large vessels and 16 with small vessel disease. Other causes included nine patients with trauma, six with atherosclerosis (of whom five were women), and four with vascular complications of thoracic outlet obstruction. Single examples of ischaemia due to radiation fibrosis and disseminated intravascular coagulation were also seen. Critical ischaemia of the upper limb remains an uncommon yet challenging problem. The review demonstrates that total limb arteriography should be performed in all patients, except the minority who present with direct arterial trauma or classical emboli.

Adult

Towards an appropriate training for vascular surgeons.

The increasing demand for fully trained vascular surgeons in the UK has highlighted the need for urgent review of that training. Such a review must examine the number of trainees required and the number and role of teaching centres. Vascular surgical training should only take place where an integrated approach, including experience in interventional radiology and intensive care, is available. The relationship of vascular to general surgery must now be defined with training needs in mind if we are to provide an appropriate service within the next decade.

Curriculum

Pulsed Doppler angiography in lower limb arterial ischemia.

A 30-channel pulsed Doppler vessel imaging system (MAVIS, GEC Medical, Middlesex, England), was used to obtain images and maximal Doppler velocity time waveforms in the diagnosis of stenosis of the origin of the profunda femoris artery (PFA) and in the detection of structural changes within Dacron arterial grafts. In PFA scans of 33 limbs in 22 patients (mean age, 52 years), PFA stenosis of more than 50% at operation was invariably associated with a damping factor of the maximal Doppler velocity-time waveform of greater than 1.5 (eight limbs). In 12 limbs with a normal PFA at operation, the damping factor was always less than 1.4, and in 13 limbs of normal patients without arterial disease, the damping factor was always less than 1.34. In studies of 10 mm arterial grafts, the internal diameter of 14 iliopopliteal grafts scanned just above the popliteal anastomosis was strikingly reduced as compared with the femoral anastomosis of 14 aortoiliofemoral grafts and seven axillobifemoral grafts. These preliminary results suggest that MAVIS studies can be used noninvasively to detect PFA stenosis and to identify luminal narrowing of iliopopliteal grafts.

Angiography

Changes in plasma lactate, phosphate and uric acid during postoperative carbohydrate infusion.

Eighteen patients undergoing elective abdominal surgery had pre- and postoperative carbohydrate infusion tests with glucose, fructose or sorbitol. All three substrates produced significant hyperlactataemia postoperatively, the elevations of plasma lactate with fructose and sorbitol infusion being significantly greater than with glucose. Plasma uric acid was unchanged but there were moderate falls in plasma phosphate postoperatively. Intravenous nutritional regimens containing fructose and sorbitol may potentiate the development of harmful metabolic acidoses in 'at risk' patients and should always be used cautiously. Glucose is the carbohydrate calorie source of choice.

Abdomen

Non-clostridial gas gangrene in the diabetic lower limb.

Three cases of non-clostridial gas gangrene in diabetic lower limbs are reported. This rare condition occurs only in diabetes with peripheral neuropathy and is invariably fatal unless treated surgically. The clinical picture is deceptive with a slow, but insidiously progressive course, and the late appearance of skin necrosis. Antibacterial therapy is ineffective in preventing death. A serious delay may be fostered by inconclusive bacteriological investigations. Urgent radical amputation is required to save the patient's life.

Adult

The analysis of decay curves.

1. The limitations inherent in the conventional treatment of glucose decay curves as first-order rate systems are described. 2. The conventionally derived K value is a rate constant and should not be confused with a rate. 3. First-order systems are described by this rate constant and the initial concentration of substance studied. They cannot be described by either factor alone. 4. Two parallel curves cannot both result from first-order systems. 5. If K is conventionally calculated for two parallel curves, then the value obtained for the upper curve must be smaller than the value for the lower.

Blood Glucose

Changes in the proportions of plasma insulin, proinsulin and a higher-molecular-weight insulin during pre- and post-operative glucose-infusion tests.

1. Glucose-infusion tests were performed on patients admitted for elective upper abdominal surgery 1 day before and 1 day after operation. In addition to insulin and proinsulin, a third immunoreactive insulin species of mol. wt. 20 000--30 000 was detected in plasma from two patients. The heterogeneity of plasma immunoreactive insulin (IRI) and the need to consider the effects of all forms, including proinsulin and the high-molecular-weight species, is emphasized. 2. During preoperative glucose infusions there was an increase in the percentage of the total plasma IRI present as high-molecular-weight forms (i.e. proinsulin plus the species of mol. wt. 20 000--30 000) from 3.9% to 10.8%. On the first postoperative morning all patients showed an increase in the amounts of the heavier IRI types, which accounted for 13.9% of the total plasma IRI. 3. The changes in insulin and proinsulin are consistent with the release from the pancreas of an insulin/proinsulin mixture of constant proportions, and the longer circulating half-life of proinsulin. 4. Increases in the amounts of high-molecular-weight IRI species after surgery may have a partial role in the development of insulin resistance but are probably not a major determinant of the insulin-resistant state.

Adult

Nitrogen-sparing effect of different feeding regimes in patients after operation.

In patients recovering from surgery, water, electrolytes, protein and calories all produce significant nitrogen sparing whether given by i.v. or intraduodenal routes. The nitrogen-sparing effect of protein and calories is greater when given to these patients via the gastrointestinal tract, and nitrogen equilibrium is approached when nutrients are supplied in amounts that satisfy theoretical requirements. I.v. regimes do not achieve nitrogen equilibrium, even when amino acids and calories are supplied in amounts that exceed theoretical requirements.

Adult

Plasma insulin and surgery. I. Early changes due to operation in the insulin response to glucose.

The effects of elective abdominal operation on the disposal of a sustained intravenous glucose load and on the biphasic response of plasma insulin have been examined. During operation, low plasma insulin concentrations were observed despite the high plasma glucose values achieved. On the morning after operation, both phases of the insulin response to glucose were increased. This increase was seen even when subjects were compared at the same plasma glucose value. The response to tolbutamide was also greatly exaggerated. Pre- and postoperative glucose curves were approximately parallel, suggesting that glucose uptake was similar in both situations despite the presence of the postoperative hyperglycemia and hyperinsulinemia. This is at variance with previous reports based on conventional bolus dose intravenous tests which have suggested reduced postoperative glucose utilization. A new interpretation of the data is proposed.

Abdomen

Plasma insulin and surgery. II. Later changes and the effect of intravenous carbohydrates.

Long-term hyperinsulinemia and improved glucose tolerance were produced postoperatively by intravenous feeding with glucose or sorbitol. Raised immuno-reactive insulin (IRI) values persisted eight hours after carbohydrate infusions although the basal plasma glucose concentrations had returned to control values. Plasma glucose curves were normal at this time but were associated with an increased IRI response. These findings suggest that insulin secretion is modified by glucose not only in the short term but also by a separate effect acting over many hours. The combination of starvation and low dose glucose infusion to simulate the hyperglycemia of operation also produced high IRI values but these were associated with a rapid fall in the plasma glucose curve. Starvation alone reduced basal values of plasma glucose and IRI, and the IRI response to glucose infusion was also reduced, despite the plasma glucose curve being at a higher level. It is suggested that the high values of IRI reported in the postoperative period are mediated by a long-term effect of the small but sustained rise in basal plasma glucose. This specific role of glucose in the long-term potentiation of insulin secretion make it the carbohydrate of choice for the intravenous feeding in postoperative patients.

Abdomen