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Biomedical subjects

W H Baker

Publications and source records attributed to W H Baker.

At least 91 records · Page 5Linked to original sources
PubMed1986

Quantitative analysis of continuous-wave Doppler spectral broadening for the diagnosis of carotid disease: results of a multicenter study.

This article reports the results of a multicenter study that compares 333 frequency analysis studies with the continuous-wave Doppler method with angiography. With receiver operating characteristic curves, the study documents the accuracy of the Doppler technique for the diagnosis of extracranial carotid arterial stenosis greater than 45% diameter reduction. It confirms the accuracy of the measurement of the maximal peak Doppler frequency and, in addition, shows that quantitative analysis of the instantaneous Doppler spectrum at peak systole by the measurement of the spectral broadening index is of diagnostic value. Likelihood ratios have been calculated with the use of curve-fitting techniques and it has been demonstrated how both the peak frequency and the spectral broadening index can be used together to improve the certainty of diagnosis. It is concluded that the probability that an individual patient has significant carotid arterial disease can be determined with the measurements of peak frequency and spectral broadening index from the continuous-wave Doppler spectral waveform.

Carotid Arteries↗
PubMed1986

Acute aortic occlusion--a multifaceted catastrophe.

Eighteen patients whose mean age was 61 years were referred to us with acute aortic occlusion from 1977 to 1985. Ten patients had cardiac emboli (group I) and eight had aortoiliac occlusive disease (group II). Fourteen of these patients had paresis or paralysis. Diagnosis was prompt but the time lapse from onset of symptoms to revascularization averaged 18 hours (group I, 10.3 hours; group II, 26.1 hours). All 10 patients in group I had embolectomy alone; of the eight patients in group II, two had transfemoral thrombectomy and six had bypass procedures. The perioperative mortality rate was 40% in group I and 62.5% in group II. Complications developed in 12 patients (nine died); renal failure occurred in 11, compartment syndrome in nine, adult respiratory disease syndrome in three, acute myocardial infarction in three, disseminated intravascular coagulation in two, and paraplegia in one. No amputations were required in the nine survivors and limb function was restored in eight of these patients. Acute aortic occlusion sets in motion a chain of events that threatens life and limb. Prompt diagnosis and revascularization by the simplest operation are required to decrease morbidity and mortality.

Acute Disease↗
PubMed1985

Intracranial hematoma with subsequent brain abscess after carotid endarterectomy.

A 62-year-old man developed an infected left carotid endarterectomy with false aneurysm formation and subsequent bacteremia after staged carotid endarterectomies. He was found to have a right frontal lobe hemorrhage that developed into a staphylococcal brain abscess. We postulate there was bacterial seeding of the hematoma resulting in brain abscess formation.

Brain Abscess↗
PubMed1985

Usefulness of fibrinopeptide A generation tests in experimental and clinical studies with low molecular weight heparin fractions.

FPA generation test provides a sensitive tool to study the events leading to the production of fibrin from fibrinogen. Drug modulation of pathways resulting in thrombin generation can be readily assessed utilizing the FPA generation test. In circumstances in which conventional clotting and amidolytic methods fail to detect any antiprotease effects, the FPA generation test provides the sensitivity to study these actions. The FPA generation test demonstrates the collective action of antithrombotic agents on inhibition of activation of the pathways leading to the generation of thrombin. The generation systems are easily modified by activators to provide identification of sites, components, and modulating interaction of various heparin derivatives on the hemostatic system. The FPA generation test assesses the overall inhibitory effects of heparin and thus provides insight into the pharmacokinetics of the biologically active components of these agents. Currently, the FPA generation test may be utilized to demonstrate pharmacokinetics and pharmacodynamics but has limited quantitative capacity in this regard. The FPA generation test performed on native plasma may provide insight into the great variation in individual hemostatic parameters important to dosage determinations.

Blood Coagulation Tests↗
PubMed1985

Carotid artery thrombosis associated with lupus anticoagulant.

A young man with cerebral infarction and circulating lupus anticoagulants was found to have a partially occluding intraluminal thrombosis in the left internal carotid artery. Immediate thrombectomy and medical therapy was followed by gradual partial clinical improvement. Pathologic examination revealed an organized thrombus with diffuse hypersensitivity vasculitis of the small arteries in a skin and muscle biopsy specimen. Increased physician awareness may lead to more prompt diagnosis and treatment of this unusual clinical syndrome.

Adult↗
PubMed1984

Elastolytic and collagenolytic studies of arteries. Implications for the mechanical properties of aneurysms.

Studies were performed in vitro on cylindrical segments of 56 canine common carotid arteries, 32 human external iliac arteries, nine internal iliac arteries, and ten common iliac arteries, using purified elastase and purified collagenase. Treatment with elastase caused the canine vessels to dilate but to remain intact. Similar results were obtained with the human vessels, except that treatment with elastase caused only slight dilation. All canine and human vessels treated with collagenase ruptured. We concluded that wall integrity depends on intact collagen rather than elastin. Comparison between external iliac arteries and internal and common iliac arteries showed that the latter vessels exhibited dramatically greater dilatation and compliance changes after treatment with collagenase. This finding corresponds to the greater tendency of aneurysms to develop in internal and common iliac arteries.

Aneurysm↗
PubMed1984

Late sequelae of deep venous thrombosis. Diagnostic and therapeutic considerations.

The efficacy of heparin, sodium warfarin, and elastic stockings in preventing the late leg sequelae of deep venous thrombosis was evaluated by reexamining 15 patients with previous acute deep venous thrombosis so treated. All 5 patients with iliocommon femoral disease and only 5 of 10 patients with distal disease had evidence of postphlebitic syndrome. Venous Doppler and strain gauge plethysmography confirmed these clinical findings. The most striking and consistent laboratory abnormalities were in the patients with proximal disease. Treatment of acute deep venous thrombosis by traditional means does not prevent the clinical and laboratory late leg sequelae. In light of these findings, serious investigation of new therapeutic modalities is strongly suggested.

Clothing↗
PubMed1984

Carotid endarterectomy without a shunt: the control series.

Nine hundred forty carotid endarterectomies were performed without the use of a temporary indwelling shunt. Six patients (0.6%) died, all from stroke; 17 other patients (1.8%) had another stroke, and 21 patients (2.2%) had temporary neurologic symptoms. Complete x-ray films detailing the opposite internal carotid artery and carotid artery back pressure were available for 783 operations. Correlation of stroke to back pressure, status of the contralateral internal carotid artery, preoperative neurologic deficit, and carotid clamp time was examined. Statistical analysis demonstrated significantly increased neurologic complications only if the systolic carotid back pressure was less than or equal to 50 mm Hg or the contralateral internal carotid artery was occluded. Analysis to determine if these factors were dependently related showed that when both a contralateral carotid occlusion and a carotid back pressure of less than or equal to 50 mm Hg coexisted (82 patients), the rate of permanent deficit was 11.0% compared with 2.8% when either factor was singly present and 0.9% when neither factor was present. No statistical difference exists between the group with only a single factor and those with neither factor. When a temporary shunt is not used during carotid endarterectomy, the risk of neurologic complication is increased if both a contralateral internal carotid artery occlusion and a carotid back pressure of less than or equal to 50 mm Hg coexist. The use of a shunt in this patient population may be beneficial.

Adult↗
PubMed1984

External carotid endarterectomy.

Forty-nine external carotid revascularization procedures were performed in 36 patients. Indications included transient ischemic attacks, amaurosis fugax, and the procedure as a prelude to extracranial-to-intracranial bypass. Twenty patients had a preoperative neurologic defect. Twelve patients were classified as having bilateral and 24 as having unilateral carotid disease. Unilateral external carotid endarterectomy was performed in 29 patients, with the remaining patients undergoing procedures for additional occlusive lesions. Five patients had operation-related strokes (one death). Three of eight patients with bilateral disease and a preoperative neurologic defect had a stroke. Five additional patients had late neurologic events. Although technically easy, external carotid thromboendarterectomy should be advised with caution in patients with identifiable risk factors.

Aged↗
PubMed1984

Factors influencing morbidity of carotid endarterectomy without a shunt.

A retrospective analysis of 156 unshunted carotid endarterectomies in 124 patients indicates that at least three factors may influence the surgeon to consider using an indwelling shunt. Contralateral internal carotid artery occlusion, prolonged cross-clamp time, and possibly stump pressures less than 25 mm Hg torr were associated with increased rate of permanent neurologic deficit. Selective shunting would not be based on stump pressures less than 50 mm Hg torr, previous ipsilateral stroke, or abnormal intraoperative electroencephalogram.

Adult↗
PubMed1983

Hemodynamics of sequential grafts.

Sequential femoropopliteal-tibial grafts have been advocated as a promising treatment for use in patients with severe ischemia of the distal lower extremity. Proponents hypothesize better patency rates due to documented increases in proximal graft flow with the sequential technique. We hypothesized that the effect of the sequential graft was to create competitive collateral flow and that distal graft flow would not be increased with the addition of a sequential anastomosis. Seven adult dogs with chronic occlusions were studied with angiography and underwent sequential iliofemoral bypass grafting. Proximal and distal flows were measured with and without the sequential anastomosis open to flow. Proximal graft flows increased significantly whereas distal flows decreased significantly in all dogs with an open sequential anastomosis. The study suggests that there may be limitations to the use of sequential bypass grafts.

Angiography↗
PubMed1983

Neutrophil migration in canines: in vivo comparison of granulocyte function following 24-hour storage at 6 or 20 degrees C of leukocyte concentrates or of granulocytes purified by counterflow centrifugation--elutriation.

The use of granulocyte-rich concentrates from leukaphresis purified by counterflow centrifugation--elutriation to obtain pure granulocytes for transfusion studies in cyclophosphamide-induced neutropenic animal models is reported. Our data for granulocyte-rich leukapheresis concentrates indicate that room temperature (20 degrees C) appears to be preferred to 6 degrees C for short-term granulocyte storage. The data also indicate that although the granulocytes isolated by counterflow centrifugation--elutration may retain in vitro functions of chemotaxis, phagocytosis, and bactericidal activity, the in vivo function of migration into skin chambers for isolated granulocytes is seriously impaired after storage for 18 to 24 hr at both 6 and 20 degrees C. This loss of in vivo function of stored granulocytes occurs in isolated granulocytes obtained by both counterflow centrifugation--elutriation and dextran sedimentation, and it is not observed in the leukocyte concentrates held at 20 degrees C. The results of these studies are four-fold. First, freshly isolated granulocytes display no apparent loss of either in vivo or in vitro function. Second, granulocytes isolated by counterflow centrifugation--elutriation or dextran sedimentation and stored at 6 or 20 degrees C are severely impaired in terms of their in vivo chemotactic function but display no loss of in vitro efficacy. Third, 20 degrees C storage of granulocyte-rich leukapheresis concentrates for 18 to 24 hr is superior to 6 degrees C storage. Fourth, in vitro analysis may be limited in its ability to indicate in vivo function as a measure of success in granulocyte preservation studies.

Animals↗