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Biomedical subjects

D Samson

Publications and source records attributed to D Samson.

At least 73 records · Page 4Linked to original sources
PubMed1992

The current position of allogeneic and autologous BMT in multiple myeloma.

The projected outcome of allogeneic BMT for myeloma based on the EBMT data is as follows: for patients transplanted after first line therapy there is a 30% risk of transplant related death, a 55% chance of being alive at 5 years and a 35% chance of being alive in complete remission at 5 years. If BMT is performed later in the course of the disease, the risk of transplant related death is increased and the chance of long term relapse-free survival correspondingly reduced. Conversely, ABMT has a low mortality risk, but there is currently no evidence that ABMT using unpurged marrow can produce long term cure as no series has shown any evidence of a plateau in remission duration. The early results of maintenance interferon are encouraging but longer follow-up is needed to determine whether the proportion of patients in continuing remission at 5 years will approach that seen after allogeneic BMT. Early results of peripheral blood stem cell transplantation are also encouraging but longer follow-up is required. It remains extremely important when comparing results of ABMT with chemotherapy alone to compare similar patient groups, bearing in mind that patients who have autologous transplantation in first response are by definition responders with good performance status and without significant renal failure. In order to address this problem in a prospective manner, a randomised study has been planned by the EORTC in collaboration with the EBMT. In this study, patients with adequate renal function will be randomised at diagnosis to chemotherapy followed by either autologous BMT or continuing chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Marrow Purging↗
PubMed1992

Arteriovenous malformations of the brain: choosing embolic materials to enhance safety and ease of excision.

The authors report their experience with surgical resection of 108 previously embolized arteriovenous malformations (AVM's). Embolization was performed via only transfemoral catheterization in 70 lesions and via the surgical exposure of feeding vessels in 32. The remaining six patients were referred for resection following silicone sphere embolization elsewhere. Materials used included polyvinyl alcohol (PVA) foam, platinum microcoils, detachable silicone balloons, surgical silk, a mixture of 33% ethanol and microfibrillar collagen, and isobutyl cyanoacrylate (IBCA). It is believed that proximal arterial occlusion with balloons is an inferior choice for preresection embolization, because the technical difficulty of placement is high and the nidus of the AVM is unaffected. Vascular coagulation and section and AVM retraction are more difficult with IBCA; therefore, this is also considered an inferior choice. Among the materials studied, the combination of PVA for distal occlusion and microcoils for proximal occlusion appears to be the superior choice. Fewer complications (stroke or hemorrhage) are seen when intraarterial Amytal (amobarbital) testing is used to guide the embolization. Data regarding toxicity, oncogenicity, and vascular metabolism or recanalization associated with PVA, IBCA, and n-butyl cyanoacrylate are reviewed.

Bucrylate↗
PubMed1991

Management of hemorrhagic complications from preoperative embolization of arteriovenous malformations.

Endovascular embolization procedures have undergone dramatic evolution and improvement in recent years. Despite these advances, controversy remains regarding the optimal role of these procedures in treating cerebral arteriovenous malformations (AVM's) and whether their purpose should be as a presurgical adjunct or as primary therapy. This controversy risks fragmentation between disciplines in the broader efforts to improve management of cerebrovascular disorders. The authors report seven cases of life-threatening hemorrhages that occurred during staged invasive therapy for AVM's which illustrate the value of a unified team approach to optimize patient care. Each patient underwent at least one embolization procedure using polyvinyl alcohol particles, followed in two cases by the occlusion of proximal feeding vessels by platinum microcoils and in one case by the attempted detachment of an endovascular balloon. In three patients, catheter penetration into the subarachnoid space resulted in subarachnoid hemorrhage. One patient suffered rupture of a large feeding vessel during balloon inflation. The final three patients sustained intracranial hemorrhage 2 hours, 8 hours, and 5 days, respectively, following embolization. All but two patients underwent emergency craniotomy at the time of the complication. These cases underscore the advantages of interdisciplinary management optimizing decision-making and providing expeditious care when life-threatening complications develop.

Adult↗
PubMed1990

Transcranial Doppler ultrasound as a guide to graded therapeutic occlusion of the carotid artery.

Although gradual carotid artery occlusion is an accepted and effective treatment for some surgically inaccessible intracranial aneurysms, there are no specific guidelines to determine the optimal amount of carotid artery narrowing at each adjustment. The technique of transcranial Doppler ultrasound, however, allows continuous measurement of blood velocity in the middle cerebral artery as the carotid artery is narrowed, so that hemodynamic effects and development of collateral flow can be immediately assessed at the bedside at each adjustment of the carotid artery diameter. This case report describes the use of transcranial Doppler to guide the rate of carotid occlusion in a patient with an unclippable giant aneurysm of the carotid artery. Sudden carotid occlusion and gradual occlusion at the usual rate were not tolerated by the patient, but repeatedly tightening the clamp until the first signs of attenuation of the Doppler signal allowed an expedient occlusion without complication. Transcranial Doppler ultrasound can provide a useful dynamic guide to gradual therapeutic carotid occlusion.

Carotid Arteries↗
PubMed1990

Intracarotid hydroxyethyl methacrylate solution causing stroke in dogs.

Hydroxyethyl methacrylate (HEMA) has been advocated as a polymerizing solution with which to prevent deflation of detachable balloons in interventional neuroradiology. It is pertinent to know if unpolymerized HEMA would have untoward effects if accidentally released into the carotid artery by balloon rupture or deflation. Seven mongrel dogs underwent transfemoral catheterization of the common carotid artery and subsequent injection of HEMA solution in volumes of 1 cc in five dogs, 2 cc in one, and 4 cc in one. Angiography performed at the time of injection revealed evidence of intravascular thrombosis as well as possible spasm. Three surviving animals were sacrificed at 48 hours; the brains were fixed and examined histopathologically. One brain was normal and one was autolyzed and could not be examined. Five of the seven animals had histopathologically documented cerebral infarctions of varying size. No foreign substance was seen within the blood vessels to suggest intravascular polymerization. The animals injected with 2 or 4 cc HEMA solution did not survive 48 hours. Literature review reveals little documentation of the toxicology of intravascular HEMA. With its increasing popularity as a compound for polymerization in detachable balloons introduced into the brain, further investigations are warranted to understand the physical properties of the compound and potential risks of its use.

Animals↗
PubMed1990

Preoperative embolization of cerebral arteriovenous malformations with polyvinyl alcohol particles: experience in 51 adults.

In order to determine possible risk factors and to assess the value of platinum microcoils added to polyvinyl alcohol particles in preoperative embolization of cerebral arteriovenous malformations in adults, we reviewed our experience with this procedure. Between September 1985 and June 1989, we performed embolizations in 54 patients with cerebral arteriovenous malformations. Of these, procedures in 51 adults involved the use of polyvinyl alcohol particles, either alone (n = 29) or in combination with platinum microcoils (n = 21). A complication during catheterization precluded embolization in another patient. Beginning as flow-directed embolizations via carotid artery catheterizations (n = 12), newer catheters allowed progression to superselective intracerebral catheterizations (n = 38). Embolization has led to shorter surgical procedures, more clearly defined operative margins, and less bloody operative fields. We have not found recanalization to significantly hinder embolization results with polyvinyl alcohol when resection is undertaken within 1-4 weeks of embolization. Its relative safety and ease of manipulation at surgery argue for its use. We found no significant increase in complications based on patient age, venous drainage of the arteriovenous malformation, or the circulation embolized. Embolization results in cerebral arteriovenous malformations were improved with superselective catheterization and most improved with the combined use of polyvinyl alcohol for nidus embolization followed by occlusion of the feeding vessel with microcoils.

Adolescent↗
PubMed1989

Infusion of vincristine and doxorubicin with oral dexamethasone as first-line therapy for multiple myeloma.

32 previously untreated patients with multiple myeloma received vincristine, doxorubicin ('Adriamycin'), and dexamethasone (VAD) as first-line therapy. The overall response rate was 84%, with 28% of all patients entering complete remission. Response was rapid, with near-maximum response occurring after two courses of treatment and rapid improvement in bone-marrow function. Median response duration was 18 months and this seemed to be unaffected by initial prognostic criteria or by degree of remission achieved. The projected median survival was 44 months, with 75% of all patients and 83% of responders being alive at 2 years. Side-effects due to steroids were common, but there was only 1 treatment-related death. The high response rate and lack of toxicity offer an advantage over other forms of initial treatment, although other strategies will be necessary to prolong the duration of response.

Administration, Oral↗
PubMed1989

[Autologous transfusion by peroperative salvage in orthotopic transplantation of the liver].

As large quantities of blood are required during orthotopic liver transplantation, intraoperative autotransfusion is therefore often carried out in adult patients. This study aimed to assess the ease of use of this technique, its efficiency and possible side-effects. Intraoperative blood salvage was carried out using a Cell Saver 4R (Haemonetics) in 14 patients. The chest blood was collected, anticoagulated with heparin and sodium citrate, centrifuged and washed with Ringer lactate. During surgery, and the subsequent 5 days, the following data were recorded: red cell and platelet count, haemoglobin concentration, parameters of renal function, potassium, citrate and fibrinogen levels, parameters of renal function, blood cultures and the extubation delay. Autotransfusion was simple to use, with no side-effects during the procedure. An average of 20.5 red cell packs were required, of which 59.2 +/- 2.3% were supplied by autotransfusion. The volume of transfused blood was similar, or inferior, to other studies. The different haematological parameters, blood gases and serum potassium levels remained stable. Only 4 +/- 2.8 red cell packs were required postoperatively to maintain a stable haematocrit value. There was no increase in thrombin time, and therefore no effect due to the used heparin. Citrate levels were correlated with the amount of autotransfused blood. They were lower than in other studies because autotransfusion limited the citrate load. There was no haemolysis. Postoperative renal function remained normal. There was no change in the blood coagulation profile, except when large volumes were transfused, resulting in a dilutional coagulopathy. Extubation was always carried out during the first two postoperative days. Bacteriological studies remained negative, no bacteraemia being noted. During orthotopic liver transplantation autotransfusion is a simple, reliable technique, with few side-effects.

Adult↗
PubMed1988

Intraoperative ventricular puncture.

Modern neuroanesthetic techniques frequently provide the neurosurgeon with adequate brain relaxation for an atraumatic frontotemporal or transylvian dissection. Circumstances such as recent subarachnoid hemorrhage with brain edema and acute hydrocephalus can mandate significant frontal lobe retraction before access to cerebrospinal fluid (CSF) drainage from the basal cisterns is gained. A simple technique can give the "early" aneurysm surgeon reliable access to the frontal horn of the lateral ventricle for intraoperative drainage of CSF before brain retraction.

Cerebral Ventricles↗