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Biomedical subjects

W S Edwards

Publications and source records attributed to W S Edwards.

At least 19 recordsLinked to original sources
PubMed1996

Three-dimensional ultrasonic angiography using power-mode Doppler.

To visualize the vascular anatomy of parenchymal organs, we have developed a system for producing three-dimensional ultrasonic angiograms (3D USA) from a series of two-dimensional power-mode Doppler ultrasound (PDU) scans. PDU scans were acquired using a commercial scanner and image-registration hardware. Two-dimensional images were digitized, and specially designed software reconstructed 3D volumes and displayed volume-rendered images. The geometric accuracy of our system was assessed by scanning a flow phantom constructed from tubing. The system was tested on patients by scanning native and transplanted kidneys, and placentas. Three-dimensional images of the phantoms depicted the spatial relationships between flow within the tubing segments and contained less than 1 mm of geometric distortion. Three-dimensional images of the kidney and placenta demonstrated that spatial relationships between vasculature structures could be visualized with 3D USA. Applications of this new technique include analysis of vascular anatomy and the potential assessment of organ perfusion.

Angiography↗
PubMed1987

Thomas G. Orr Memorial Lecture. Surgical informed consent: what it is and is not.

A more systematic approach to addressing the crucial issue of informed consent is needed in medical education. Surgeons cannot afford gaps in their medical education regarding the communication process with patients. We found that many surgical residents and faculty understand the mechanics of the informed consent process quite well and could perform well under the artificial circumstances of our video interview. Whether they would do as well if a real patient was considering nonoperative therapy, or was a ne'er-do-well, or an alcoholic is not known. Two main causes of interference with the process have been identified: conflicting messages which surgeons get from within the profession, from the courts, and from within themselves and lack of time for dialogue with patients, and poor timing of the consent process. Areas that were uncovered that need further investigation include the barrier created by some surgeons' internal, often unrecognized, biases about surgery being the only satisfactory mode of treatment for some illnesses and some surgeons' belief that longevity should be the goal of all therapy, without considering that for some patients, maintenance of certain quality lifestyles is more important than a longer life. We hope that surgeons can learn to look at the informed consent process as a wonderful opportunity to communicate their personal concern for the patient as a person, not just a sick gallbladder to remove, and that this process can become the channel through which the wounded relationship of the patient and the physician can be healed.

Communication↗
PubMed1987

Recurrent carotid stenosis after autologous tissue patching.

This study was carried out to evaluate two techniques of widening the carotid bifurcation with autologous material after endarterectomy to determine whether the incidence of recurrent stenosis could be reduced. As a control, a similar series was performed without patching. Autologous saphenous vein was used as a patch in one group of patients, whereas in another, the bifurcation was widened by suturing the external carotid to the internal carotid artery, advancing the bifurcation by several centimeters, a technique we termed bifurcation advancement. All three groups were studied at least 1 year after operation by means of Doppler ultrasonography. We found no difference in either of the patched techniques compared with unpatched controls. Significant recurrent stenosis (greater than 50% diameter reduction) was found in 12.5% of reconstructions with a vein patch, 12.5% of those with bifurcation advancement, and 16.6% of those with simple closure. The overall incidence of significant recurrent stenosis was 13.8%, with symptoms occurring in 2.7%.

Aged↗
PubMed1984

Carotid arterial bifurcation advancement.

Acute postoperative thrombosis and late restenosis are well known complications of carotid endarterectomy. Vein or synthetic patches are imperfect solutions leading to occasional infections, false aneurysms and possible rupture. A new technique is described that patches the internal carotid artery with the external carotid artery after complete endarterectomy of both vessels. Twenty-five of these procedures were performed upon 22 symptomatic patients with no early or late morbidity or mortality. Theoretic advantages include wide patching of the internal carotid artery above the endarterectomy end point where narrowing is most dangerous, full endarterectomy of the external carotid artery and double tacking of the endarterectomy end points to deter circumferential intimal flaps.

Carotid Arteries↗
PubMed1983

Selective management of penetrating neck wounds.

Of 67 patients with penetrating neck wounds admitted to the hospital between 1969 and 1979, 22 (32.8%) were taken to the operating room and 14 (63.6%) were found to have major structural damage. Three patients died (4.4%), all as a direct result of their associated head injuries and none as a result of their neck wounds, regardless of management. Five patients (7.4%) had complications. The average hospital stay for patients undergoing surgery was 4.9 days; for those observed with multiple injuries, 4.6 days; and for those observed with isolated neck wounds, 2.4 days. Indications for selective exploration are presented.

Adolescent↗
PubMed1982

A remotely programmable insulin delivery system. Successful short-term implantation in man.

A remotely controlled, programmable insulin delivery system was implanted in a diabetic man and the feasibility of the technique was examined. Specific problems included (1) development of an appropriate surgical approach, (2) identification of methods to assess the integrity of the insulin delivery system following implantation, and (3) assessment of plasma glucose and free-insulin profiles obtained with the implanted system. The insulin pump was implanted submuscularly through a midline abdominal incision. The insulin reservoir was placed subcutaneously to allow percutaneous refilling. The insulin delivery catheter terminated in the peritoneal space. No postoperative wound infection occurred and rapid healing of the surgical site ensued. In vivo assessment of the system included (1) dye contrast roentgenography, (2) vasopressin stimulation, and (3) reservoir volume monitoring. Short-acting insulin was then placed in the implanted reservoir and delivered by the system for one month. Mean plasma glucose concentration declined to normal levels, as did glycosylated hemoglobin. Plasma insulin profiles were normalized with appropriate insulin peaks with each meal. We conclude that implantation of a remotely programmable insulin pump is feasible in type I diabetic man. Additional studies are necessary to define which patients will benefit from this type of insulin delivery system.

Blood Glucose↗
PubMed1982

Effectiveness of leg compression in preventing venous stasis.

To compare the ability of intermittent calf compression with that of sequential leg compression to prevent venous stasis, the clearance time of radiopaque dye, as determined by sequential phleborheograms performed on anesthetized patients, were compared. Calf compression was superior to no compression in clearing the dye from the calf alone, but did not aid clearance from the rest of the leg. Sequential leg compression was superior to intermittent calf compression in clearing dye from the calf and popliteal areas. Since intermittent leg compression has been as effective as small-dose heparin therapy in preventing postoperative deep venous thrombosis [7], the use of sequential leg compression may prove to be more effective and have less complication than heparin administration.

Humans↗
PubMed1982

Discordance in the sizing of abdominal aortic aneurysm and its significance.

Much of the confusion surrounding the repair of asymptomatic abdominal aortic aneurysms related to inaccuracies in their measurement, both preoperatively and intraoperatively. Multiple measurements of aneurysms at operation have convinced us that the largest and least variable diameter is the anteroposterior diameter measured from aortic wall anteriorly to vertebral bodies posteriorly. This AP-to-spine distance is accurately predicted by ultrasonography to within 0.3 cm. Computerized tomography does no better. plain radiography is accurate but seldom applicable. When properly estimated, aneurysm size can be accurately determined preoperatively by either ultrasonography, computerized tomography, or plain radiography, in that order of preference. Since the decision to operate on asymptomatic aneurysms is based largely on their size, accurate preoperative estimation is essential.

Aorta, Abdominal↗
PubMed1982

A-V fistula after venous reconstruction. A simplified method of producing and obliterating the shunt.

To improve patency of the low flow, low pressure crossover venous graft for unilateral iliac venous occlusions, complementary arteriovenous fistula has been effective. Two additional anastomoses are usually required to construct a complementary A-V fistula, and a sometimes difficult and potentially dangerous dissection may be required to take down the fistula. A technique has been developed for producing an A-V fistula with only one additional anastomosis. This fistula can be obliterated later by tightening a previously placed loop left in a subcutaneous position. This technique has been used successfully in two patients.

Adult↗