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Biomedical subjects

D C Berridge

Publications and source records attributed to D C Berridge.

72 records · Page 4Linked to original sources

Fibrinolytic profiles in local low-dose thrombolysis with streptokinase and recombinant tissue plasminogen activator.

Fibrinolytic parameters have been monitored in 44 patients undergoing local low-dose intra-arterial thrombolysis for acute peripheral arterial ischaemia. Streptokinase (Sk), at a dose of 5,000 units/hr with 250 units/hr heparin, was used in 23 patients and recombinant tissue plasminogen activator (r-tPA) at a dose of 0.5 mg/hr was used in 21 patients. Successful lysis was seen in 18 (86%) patients following r-tPA and in 15 (65%) patients following streptokinase. There were 4 minor haematomas in each group usually at the catheter entry site. Both agents produced a systemic effect, which was still seen 12 hours post-infusion. However, that produced by r-tPA was delayed and significantly reduced compared to that produced by Sk. These results confirm the relative fibrin specificity of r-tPA. When used as a continuous low-dose intra-arterial infusion, r-tPA offers a significantly lower, potentially safer, systemic effect than conventional therapy with streptokinase.

Fibrin Fibrinogen Degradation Products↗

111In-labelled leucocyte imaging in vascular graft infection.

Twelve patients with a clinical diagnosis of possible vascular graft infection have been studied over the last 3 years. All patients had their leucocytes labelled with indium-111 and gamma-camera imaging after 24 and 48 h. Subsequent management was according to established surgical techniques. Eight patients proved to have vascular graft infection and indium uptake was seen along the length of the graft in six. Two patients with open wound infections and synthetic grafts had localized uptake only on leucocyte scanning. Four patients, all of whom had negative scans were not thought to have infected grafts after further investigation using digital subtraction angiography and computed tomography scanning. These patients have been followed up for a median period of 19 months (range 5-25 months) and have remained symptom free. Initial experience with 111In-labelled leucocyte scanning has been encouraging, both in diagnosis and in planning the management of patients with graft infections.

Bacterial Infections↗

Acute lower limb arterial ischaemia: a role for continuous oxygen inhalation.

Simultaneous readings of transcutaneous partial pressure of oxygen (Ptc,O2) were obtained from the left anterior chest wall, from 10 cm distal to the medial aspect of the knee joint, and from the first dorsal webspace in 16 patients with acute peripheral arterial ischaemia of the leg. Oxygen was administered at concentrations of 24, 40, 60 and 100 per cent. Mean (s.d.) initial chest Ptc,O2 (53(17)mmHg) was significantly higher than that of the medial lower limb site (37(17)mmHg). After inhalation of 24 per cent oxygen, a statistically significant (P less than 0.025) increase in chest Ptc,O2 was achieved (63(20)mmHg), but the increase in Ptc,O2 (43(19)mmHg) at the medial lower limb site was not statistically significant. Inhalation of 40 per cent oxygen resulted in significant increases at both sites (chest: 83(23)mmHg, P less than 0.01; limb: 53(26)mmHg, P less than 0.05). Ptc,O2 in the limb at this concentration of inhaled oxygen was equal to the initial chest level. Increasing the oxygen concentration to 60 per cent and then to 100 per cent produced further significant (P less than 0.001) increases in Ptc,O2 at both sites. The use of continuous oxygen inhalation during acute ischaemia may improve tissue nutrition before, during and after definitive treatment.

Acute Disease↗

Differential effects of low-dose tissue plasminogen activator and streptokinase on platelet aggregation.

Despite increasing success with low-dose intra-arterial thrombolysis, early rethrombosis still occurs. Platelet aggregation is thought to play a major part in this process. We have therefore investigated the effects of recombinant tissue plasminogen activator (rt-PA) and streptokinase on platelet function at doses currently used for peripheral arterial thrombolysis. Platelet-rich plasma was stirred at 37 degrees C, with either streptokinase (100, 300 or 1000 units ml-1) or rt-PA (10 (T10), 30 (T30) and 100 (T100) mg l-1), with immediate addition of an agonist for platelet aggregation (thrombin, collagen, adenosine diphosphate (ADP) or adrenaline) at a predetermined threshold dose. Significant inhibition of collagen-induced and adrenaline-induced platelet aggregation was produced with rt-PA at all doses used (P less than 0.05). With adrenaline as the agonist, T100 produced disaggregation to a mean (s.d.) level of 26 per cent. Thrombin-stimulated platelet aggregation was significantly reduced by T100 (P less than 0.001) and T30 (P less than 0.01) only, disaggregation being dose-dependent and complete with T100. Using ADP as the agonist, T100 produced a significant reduction in maximum platelet aggregation (P less than 0.01), and disaggregation was achieved to a mean (s.d.) level of 48(13) per cent. Streptokinase did not produce any significant changes in any parameter of aggregation.

Adenosine Diphosphate↗

Local low dose intra-arterial thrombolytic therapy: the risk of stroke or major haemorrhage.

The use of local low dose thrombolysis is gradually increasing. Most experience is with streptokinase, although newer agents such as recombinant tissue plasminogen activator (rTPA) may offer more effective lysis with reduced complications. We have reviewed the experience documented in 19 prospective series published between 1974 and 1988 in an attempt to define the incidence of stroke, major haemorrhage and minor haemorrhage. The overall risk of stroke was 1.0 per cent of patients (14 cases). Major haemorrhage occurred in 5.1 per cent of patients (71 cases) and minor haemorrhage occurred in 14.8 per cent (92 out of 620 cases). There was little difference between the two thrombolytic agents, although the experience with lower doses of rTPA suggests it may offer a reduced risk of haemorrhagic complications. It is essential that all studies concerning thrombolysis should give their exclusion and inclusion criteria in full to allow an accurate appraisal of haemorrhagic complications, with the hope of improved patient selection and reduced morbidity in the future.

Cerebrovascular Disorders↗

A bacteriological survey of amputation wound sepsis.

A retrospective survey of 100 lower limb amputations performed for ischaemia were analysed to assess the influence of preoperative bacterial isolates and the use of prophylactic antibiotics on wound sepsis. Forty-eight per cent had previously undergone a vascular procedure to attempt limb salvage and 17% were diabetics. Benzylpenicillin was given preoperatively and continued for 5 days; diabetics received metronidazole in addition. A total of 51 isolates were obtained from 30 patients preoperatively; Staphylococcus aureus and Enterobacteriaceae each accounted for over 25%. Postoperatively, 74 isolates (20 multiple) were obtained with an overall sepsis rate of 40%. Those patients with a positive preoperative culture were significantly more likely to develop wound sepsis. There was no significant difference in wound sepsis rates for diabetics. In view of the range of organisms causing postoperative infection, we recommend prophylaxis with a broad spectrum antibiotic for amputations.

Aged↗

Screening for clinically unsuspected abdominal aortic aneurysms in patients with peripheral vascular disease.

In patients with abdominal aortic aneurysms, most fatalities occur from rupture before the patient can be brought to hospital. Even when seen in hospital the mortality is still approximately 50% in contrast to elective repair which has a substantially reduced mortality of less than 5%. In order to reduce the number of patients dying from rupture, they must be diagnosed early to allow elective intervention, hence there has been considerable renewed interest in screening for abdominal aortic aneurysms. We have studied a consecutive series of 104 patients with either claudication or ischaemic rest pain in the lower limbs to determine the incidence of aortic aneurysms in this type of patient.

Aged↗

Do preoperative chlorhexidine baths reduce the risk of infection after vascular reconstruction?

Pathogenic organisms are frequently present on the skin of vascular patients and are a risk factor for postoperative infection. A randomised trial of preoperative antiseptic baths was performed in 64 high risk vascular patients to determine whether two chlorhexidine baths could reduce the incidence of postoperative sepsis. Although pathogenic organisms were isolated preoperatively in 35% of patients, the wound infection rate after chlorhexidine baths (26%) was greater, though not significantly, than after baths with non-medicated soap (11%). An alternative theory that infection arises via lymphatics in the limb was not confirmed when organisms could not be isolated from groin lymph nodes in a group of 35 patients. The case for preoperative antiseptic regimes in vascular surgery remains unproven.

Adult↗

Intra-arterial thrombolysis using recombinant tissue plasminogen activator (r-TPA): the optimal agent, at the optimal dose?

Thirteen patients received 15 separate courses of intra-arterial (IA) r-TPA for acute and subacute peripheral arterial thromboses. Two patients received second courses: one following rethrombosis 2 weeks after the angioplasty of a residual stenosis, the other following rethrombosis 4 months after the initially successful thrombolysis. There were 10 men and 3 women with a mean age of 75.3 yrs (+/- 12.2). The median duration of ischaemia was 18 days (range 1-60), with five patients having severe ischaemia. All patients received IA r-TPA at a dose of 0.5 mg/h for a mean period of 26.2 hrs (+/- 12.6). Angiographic evidence of lysis was seen in all patients, however, this was insufficient to reperfuse the distal limb in two patients due to absence of run-off. Early rethrombosis occurred in both of these patients (less than 24 hrs, 11 days). There were no major complications, and minor groin haematomata occurred in four patients (three of whom underwent angioplasty). A further two patients rethrombosed despite angioplasty. One was successfully retreated and remains patent 5 months later, the other underwent surgical reconstruction. A partial systemic effect was confirmed by a reduction of plasminogen and fibrinogen to 66% of initial levels, and a reduction of alpha - 2-antiplasmin to 40% of initial levels. Haemoglobin was reduced by a mean 1.28 g/dl (+/- 0.82), however no transfusions were required, and no hypotensive periods occurred. Mean ankle/brachial systolic index (ABSI) was increased by 0.43 (+/- 0.24) overall.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Second primary tumour following retinoblastoma.

Reported is a child who at the age of 18 months had presented with a left retinoblastoma. The lesion had involved the optic nerve (Stage IV), and was successfully treated by enucleation and radiotherapy. The radiation field did not include the mandible or the submandibular triangle. He was followed up until he left the area aged 11 years. He represented aged 12 years with a progressive swelling of the left submandibular gland. Histology of the surgically excised submandibular gland revealed a mucoepidermoid carcinoma of the submandibular gland. This case highlights the need for continual surveillance in survivors of retinoblastoma, as second primary tumours occur both within and outside of previous radiation fields. The clinical association between retinoblastoma and mucoepidermoid carcinoma of the submandibular gland has not been previously reported.

Carcinoma↗

A comparison between visual and quantitative analysis in a prospective evaluation of labelled 111In leucocyte imaging in vascular infection.

In a continuing evaluation of 111In-oxine labelled leucocyte imaging in vascular surgery, we have studied 16 patients with a clinical diagnosis of possible vascular graft infection. We have evaluated both visual and semi-quantitative analysis of the images obtained and have interpreted these in the light of the subsequent clinical outcome. Full length or multifocal uptake was seen in six patients, all of whom eventually required graft excision with two limbs surviving, and one death. These patients had a significantly higher uptake ratio (median = 3.26) than those with either localized (median = 1.12; p = 0.0027) or negative images (median = 0.72; p = 0.0003). Of four patients showing localized uptake only, one required amputation for continuing sepsis. Six patients had negative images, and had normal DSA and CT scans. Uptake ratios could not distinguish between those with localized images and those with negative images. Computer generated vertical profiles aided separation of patients with presumed localized and negative images. Semi-quantitative analysis has proved to be a reliable method which should allow a more direct comparison of the efficacy of various investigative techniques and of the results of therapy, independent of intra-observer subjective bias.

Aged↗

A 10-year review of false aneurysms in Nottingham.

Over a 10-year period, twenty-nine patients who developed false aneurysms were reviewed retrospectively. The diagnosis was delayed for as long as 7 months in the eight patients who developed aneurysms following trauma. However, all these patients had an excellent outcome after surgery. The results were also good in patients with non-infected false aneurysms after vascular reconstruction, with 17 of the 19 patients having the affected limb saved by remedial surgery. The main principle of remedial surgery was to perform the simplest surgical procedure possible. The results in infected false aneurysms were poor and management should be considered along the lines laid down for graft infection. The incidence of false aneurysms may be reduced by the use of suitable non-absorbable sutures, prevention of tension at an anastomosis and prevention of infection. However, degeneration of the arterial wall is thought to be a major cause of false aneurysms and is, of course, beyond control. Recent technical advances such as digital subtraction angiography, labelled leucocyte scanning and computed tomography have all contributed to improvements in the management of false aneurysms.

Adolescent↗

Leiomyosarcoma of the rectum. Report of two cases illustrating an unusual presentation and the need for repeated biopsy.

Two cases of leiomyosarcoma of the rectum are reported in which the diagnosis required repeated biopsy in order to differentiate the lesions from their benign counterparts and other tumors. One patient presented with an ischiorectal abscess. The author is unaware of any similar presentation reported previously. Close follow-up is essential in order to detect local recurrence. There is no evidence of any significant advantage in the use of chemotherapy or deep x-ray therapy, and they were therefore not used in either case.

Biopsy↗