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Biomedical subjects

D Samson

Publications and source records attributed to D Samson.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1988

A combined frontotemporal and lateral infratemporal fossa approach to the skull base.

A variety of neoplasms involve both the infratemporal fossa and the base of the middle cranial fossa, in medial proximity to the cavernous sinus and orbital apex. To provide simultaneous access to both the intracranial and extracranial aspects of these tumors, a temporal or frontotemporal craniotomy may be combined with a lateral exposure of the infratemporal fossa. The approach, which is readily achieved by a neurosurgeon and an otolaryngologist acting as a team, involves a unilateral frontotemporal incision extended inferiorly onto the neck, a lateral facial flap reflected anteriorly, and transection of the zygoma followed by its reflection inferolaterally with the temporalis muscle. This exposure provides excellent visualization of both the intradural and extradural aspects of the anterior portion of the cavernous sinus, allowing for an aggressive resection of neoplasms involving this region. Experience with this procedure is reported here in the management of nine patients: three with nasopharyngeal angiofibromas, three with low-grade malignancies of the upper aerodigestive tract, and three with sphenoid ridge meningiomas.

Adenocarcinoma↗
PubMed1988

Improvement in regional cerebral blood flow and cerebral vasoreactivity after extracranial-intracranial arterial bypass.

Regional cerebral blood flow was measured with xenon-133 inhalation single photon emission computed tomography in a patient who developed a neurological deficit after carotid ligation. Hemispheric hypoperfusion was noted in resting studies and impaired vasoreactivity was suggested by lack of symmetrical flow augmentation after acetazolamide administration. Because of progressive neurological deterioration, an extracranial-intracranial bypass was performed. After prompt neurological improvement, repeat cerebral blood flow measurements at 1 and 9 weeks postoperatively confirmed improvement in resting flow and vasoreactivity. It is possible that decreased cerebrovascular reserve implied by measurements of vasoreactivity can identify patients who will benefit from surgical revascularization.

Aged↗
PubMed1987

Antithrombin III Northwick Park: demonstration of an inactive high MW complex with increased affinity for heparin.

It has been shown previously that antithrombin III Northwick Park has reduced ability to inactivate thrombin and is characterized by an additional anodal component on crossed immunoelectrophoresis (Howarth et al, 1985). We have applied plasma from an affected family member to heparin-Sepharose and eluted the antithrombin III with a salt gradient. Evidence is presented that a variant component has slightly higher affinity for heparin than normal antithrombin III. Furthermore, this variant component is present in plasma as an approximately 120,000 MW inactive antithrombin III complex that can be reduced with dithiothreitol to MW approximately 60,000, indicating disulphide bridging. Using ion-exchange chromatography, the inactive complex has been isolated and shown to migrate in the same position as the anodal peak on crossed immunoelectrophoresis.

Antithrombin III↗
PubMed1987

Whole blood clotting tests: an evaluation of five methods.

Five different methods of measuring the clotting time of fresh whole blood have been compared. The Biobridge was the best instrument, and was able to measure both anticoagulation and hypercoagulation accurately and reproducibly.

Blood Coagulation Tests↗
PubMed1987

Enlargement and rupture of distal basilar artery aneurysm after iatrogenic carotid occlusion.

A case of angiographic enlargement and fatal rupture of a previously asymptomatic distal basilar aneurysm in a 12-year-old girl is reported. She had been treated by carotid sacrifice for a giant intracavernous carotid aneurysm. After superficial temporal-middle cerebral artery bypass, this patient underwent a trapping procedure and decompression of her symptomatic giant aneurysm. Despite postoperative patency of her bypass graft, the involved middle cerebral circulation was irrigated substantially by retrograde flow through her posterior communicating artery. An incidental distal basilar aneurysm involving the origin of her superior cerebellar arteries, posterior cerebral arteries, and multiple perforators was treated by a wrapping procedure. Eleven days after carotid ligation, she suffered a fatal subarachnoid hemorrhage from her basilar aneurysm. This catastrophe was undoubtedly produced by our failure to consider the additional hemodynamic stress placed upon the distal basilar artery by carotid sacrifice and may have been preventable by a more aggressive attack on this previously asymptomatic lesion.

Basilar Artery↗
PubMed1987

Surgical approaches to trigonal arteriovenous malformations.

Only about 5% of intracranial arteriovenous malformations (AVM's) are located predominantly within the ventricular system. Between July, 1981, and February, 1986, 15 patients were treated at the authors' institution for AVM's within the ventricular trigone. The mean age of this patient population was 24 years, and two-thirds were female. Intracranial hemorrhage was by far the most frequent presenting symptom and intraventricular hemorrhage occurred in 11 cases, with multiple episodes being documented in five. Arterial supply of the malformations was quite uniform, with the lateral posterior choroidal or posterior temporal branch of the posterior cerebral artery (PCA) being the most frequent source. Venous drainage was similarly stereotypic, with predominant outflow into the galenic system in all but one patient. An interhemispheric surgical approach was used in eight patients, a middle or inferior temporal gyrus incision was performed in six, and a subtemporal route was chosen in a single patient. Operative results suggest that these lesions can be removed with reasonable safety. An interhemispheric approach is recommended if the nidus projects medially from the trigone and is observed medial to the P2-P3 junction of the PCA on angiography. A middle temporal gyrus approach is suggested if the nidus is lateral to the P2-P3 junction, even when the lesion is located in the dominant hemisphere. A subtemporal approach should be reserved for inferiorly projecting AVM's with cortical representation on the fusiform or parahippocampal gyrus in the nondominant hemisphere.

Adolescent↗
PubMed1986

Arteriovenous malformations of the posterior fossa: clinical presentation, diagnostic evaluation and surgical treatment.

Infratentorial arteriovenous malformations represent only some 5-7% of malformations in major series. Since 1977 thirty-two patients with intracranial, intradural malformations of the brain stem or cerebellum have been evaluated by the Division of Neurological Surgery of The University of Texas Health Science Center at Dallas. Thirty of these patients have undergone surgical treatment. Twenty-three patients presented with intracranial hemorrhage which was recurrent in eleven cases. Nine patients were evaluated due to progressive brain stem or cerebellar deficits. A history of progressive deficits was unusual in the group that presented with hemorrhage and a prior or subsequent hemorrhage was rare in the patients initially evaluated due to progressive deficits. Seventeen of these malformations were located in the vermis, seven within the cerebellar hemisphere, two in the tonsil, two in the cerebellar-pontine angle, and four within the brain stem. Operative intervention was directed at primary resection in fifteen cases, staged resection in seven cases, embolization and resection in five cases, and evacuation of hematoma in three patients. Operative mortality in this surgical series was 7% with significant morbidity in 13%. Application of modern microsurgical techniques to the removal of arteriovenous malformations of the posterior fossa may result in improvement over the natural history of the disease process, especially in those patients who present with hemorrhage.

Cerebral Angiography↗
PubMed1986

Intracranial arteriovenous malformations associated with aneurysms.

The presence of intracranial aneurysm in association with arteriovenous malformation has been well documented. Aneurysms have been described in typical proximal sites along the feeding system to the arteriovenous malformation, in abnormal distal locations along feeding vessels, and in sites remote and apparently hemodynamically unrelated to the arteriovenous malformation. Little attention has been focused on the most appropriate medical and surgical care of patients harboring these lesions. Since 1977, 22 patients with this combination of lesions have been evaluated at our institution. Nine patients (41%) presented after intracranial hemorrhage. The remaining 13 patients were investigated because of seizures in 5 patients (23%), headaches in 4 patients (18%), and progressive ischemia in 4 patients (18%). Among the patients suffering intracranial hemorrhage, 78% had bled from an aneurysm, with 22% having hemorrhaged from their arteriovenous malformation. All 7 of the patients who suffered aneurysmal hemorrhage bled from atypical distal aneurysms on major feeding vessels. Our experience and that of others has led us to believe that the safest approach to patients with this combination of lesions is to treat the aneurysm before microsurgical resection of the associated arteriovenous malformation. Hemodynamic changes associated with the abrupt elimination of an arteriovenous malformation may place associated aneurysms at immediate risk.

Adolescent↗
PubMed1986

Potential roles for early revascularization in patients with acute cerebral ischemia.

The risk of carotid endarterectomy in acute cerebral ischemic situations is well documented. By using the superficial temporal or occipital artery, it is possible to provide relatively low flow revascularization conduits, potentially avoiding the risk of postoperative hemorrhage. Eighteen patients at The University of Texas Health Science Center at Dallas, Texas, have been treated recently with extracranial to intracranial bypass in the setting of acute neurological deficit, stroke in evolution, or recent completed infarction. Angiographic causes of these deficits included cervical carotid occlusion in 5 patients, carotid siphon disease in 2 patients, middle cerebral stenosis or occlusion in 3 patients, and delayed cerebral ischemia following subarachnoid hemorrhage in 8 patients. Neurological improvement was demonstrated within 24 hours following revascularization in 15 cases (83%); 3 patients were unchanged following bypass, and no patient's condition was worsened. The only case of postoperative intracerebral hemorrhage occurred 1 week following a long saphenous vein graft from the subclavian to the middle cerebral artery. After an average follow-up of 19 months, 7 patients are neurologically normal, 8 patients have mild to moderate deficits, and 3 patients have died. Low flow revascularization procedures appear to be safe in the setting of acute cerebral ischemia and may in selected patients boost regional cerebral blood flow from levels of symptomatic ischemia into a range compatible with normal neuronal function.

Acute Disease↗
PubMed1986

Intraoperative aneurysmal rupture: incidence, outcome, and suggestions for surgical management.

Intraoperative rupture of an intracranial arterial aneurysm can dramatically interrupt a deliberate microsurgical procedure and jeopardize the patient's chances for a favorable outcome. Intraoperative rupture occurred in 58 of 307 (19%) consecutive aneurysm procedures done at The University of Texas Health Science Center. Rupture occurred during three specific periods: early or predissection in 7%, dissection in 48%, and clip application in 45%. Outcome after rupture during the predissection interval was poor, with only 1 of 4 patients surviving. Aneurysmal rupture during dissection could be attributed to blunt dissection techniques in 75% of the cases and to sharp subarachnoid dissection in 25%. The outcome was favorable in only 50% of the patients sustaining blunt dissection errors, whereas all patients sustaining intraoperative rupture during sharp dissection recovered well. Rupture during clip application was attributed to incomplete dissection in 65%, poor clip application in 31%, and a mechanical clip failure in 1 case. Eighty-eight per cent of the patients who underwent uneventful operative procedures had favorable outcomes, whereas only 62% of the patients suffering intraoperative rupture recovered well. The use of sharp microsurgical techniques with a systematic contingency plan for dealing with sudden hemorrhage and the judicious use of temporary clips should minimize the adverse effect of intraoperative rupture on overall management morbidity and mortality.

Dissection↗
PubMed1986

Use of extracranial-intracranial bypass in the management of symptomatic vasospasm.

Delayed ischemic deficits from vasospasm after subarachnoid hemorrhage remain a major source of death and disability to patients surviving subarachnoid hemorrhage. Ideal treatment for this condition would prevent or reverse spasm in major subarachnoid vessels. This goal remains elusive. Considerable success has been obtained with augmentation of flow in ischemic regions by induced hypertension and hypervolemia. Some patients are not good candidates for this therapy because of underlying cardiovascular disease or the presence of unsecured aneurysms. A total of 11 patients have recently undergone extracranial-intracranial bypass for the treatment of symptomatic vasospasm. Bypass was performed in 4 patients due to failure of medical management and in 7 patients due to our reluctance to induce hypertension in the setting of unsecured aneurysms. Eight of the 11 patients responded neurologically to the bypass procedure within 24 hours. In 6 cases, neurological deficits either improved or resolved. After operation, all 8 patients maintained their preoperative neurological status with lower mean arterial blood pressures than before bypass. Noncomatose patients with focal middle cerebral ischemic deficits and secured aneurysms in whom medical management has failed or in whom these measures are contraindicated may indeed benefit from extracranial-intracranial bypass. Patients with unsecured aneurysms remote from an ischemic middle cerebral territory should probably be revascularized if cautious hypertension fails to improve their conditions.

Adult↗
PubMed1986

Arteriovenous malformations of the posterior fossa. Clinical presentation, diagnostic evaluation, and surgical treatment.

Infratentorial arteriovenous malformations (AVM's) represent only 5% to 7% of all AVM's in major series. Since 1977, 32 patients with intracranial intradural malformations of the brain stem or cerebellum have been evaluated at the University of Texas Health Science Center, 30 of whom underwent surgical treatment. Twenty-three patients presented with intracranial hemorrhage, which was recurrent in 11 cases, and nine patients were evaluated for progressive brain-stem or cerebellar deficits. A history of progressive deficits was unusual in the group that presented with hemorrhage, and a prior or subsequent hemorrhage was rare in the patients initially evaluated for progressive deficits. Seventeen of these AVM's were located in the vermis, seven within the cerebellar hemisphere, two in the tonsil, two in the cerebellopontine angle, and four within the brain stem. Operative intervention was directed at primary resection in 15 cases, staged resection in seven, embolization and resection in five, and evacuation of hematoma in three. Operative mortality in this surgical series was 7%, with significant morbidity in 13%. Use of modern microsurgical techniques in removal of posterior fossa AVM's may offer results better than the natural history of the disease process, especially in patients who present with hemorrhage.

Adult↗