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Biomedical subjects

W Stanford

Publications and source records attributed to W Stanford.

At least 109 records · Page 6Linked to original sources
PubMed1988

The diagnosis of bronchiectasis.

Antibiotics and childhood immunizations have made bronchiectasis a relatively rare disease. The diagnostic imaging modality of choice is computerized tomography using 4-mm sections and 5-mm intervals. Bronchography is only indicated in cases where surgical resection is contemplated. Utilizing these imaging modalities, the pulmonary internist should have little difficulty in diagnosing bronchiectasis and initiating appropriate treatment.

Bronchiectasis↗
PubMed1987

Quantitative determination of aortic regurgitant volumes in dogs by ultrafast computed tomography.

Current imaging modalities can provide only a qualitative or semiquantitative measure of the severity of aortic regurgitation. Ultrafast computed tomography (CT) has the capability of rapid imaging (17 frames/sec) coupled with high spatial resolution (1.5 mm2). Eight millimeter thick images can be acquired to interrogate simultaneously the right and left ventricles. End-diastolic and end-systolic tomograms can be reconstructed serially from apex to base by Simpson's rule to provide end-diastolic and end-systolic volumes from which the right and left ventricular stroke volumes can be derived. To determine whether the difference between left and right ventricular stroke volume measured with ultrafast CT could be used to estimate the volume of experimentally induced aortic regurgitation, we studied six dogs in which proximal aortic electromagnetic flow probes had been implanted. Varying degrees of aortic regurgitation were induced by manipulation of a basket catheter through the aortic valve. During suspended respiration in the control state in the absence of aortic regurgitation, right and left ventricular stroke volumes measured with ultrafast CT were nearly identical (mean difference 1.0 +/- 1.2 ml [mean +/- SE]). In the presence of varying degrees of aortic regurgitation, regurgitant volume derived by ultrafast CT as the difference between right and left ventricular stroke volumes correlated closely to the regurgitant volume measured by the electromagnetic flow probe (r = .99, slope = .92, y intercept = 0.98 ml, SEE = 1.02 ml, n = 16). Regurgitant fraction also correlated closely to the regurgitant fraction measured by the electromagnetic flow probe (r = .94, slope = .98, y intercept = 0.66%, SEE = 4.73%, n = 16).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1987

Superior vena cava obstruction: a venographic classification.

Analysis of venacavograms in 27 patients with superior vena caval obstruction revealed the following four patterns of venous collateral return: type I, partial obstruction (up to 90% stenosis) of the superior vena cava with patency of the azygos vein; type II, near-complete to complete obstruction (90-100%) of the superior vena cava with patency and antegrade flow through the azygos vein and into the right atrium; type III, near-complete to complete obstruction (90-100%) of the superior vena cava with reversal of azygos blood flow; type IV, complete obstruction of the superior vena cava and one or more of the major caval tributaries, including the azygos system. These patterns correlate well with the patients' clinical courses and can be used to identify patients who are at risk of developing cerebral and airway compromise and therefore would benefit from superior vena cava bypass surgery.

Adult↗
PubMed1987

Quantification of coronary artery bypass flow reserve in dogs using cine-computed tomography.

Routine coronary angiographic assessment of bypass graft patency does not allow quantification of bypass graft flow reserve. This study was designed to evaluate the use of cine-computed tomography (cine-CT) to determine relative bypass graft flow velocities and flow reserve. Saphenous vein grafts from the left innominate to the midleft circumflex coronary artery were placed in 5 dogs. The proximal portion of the left circumflex was then ligated. A 20-mHz Doppler probe to assess graft flow velocity, a cuff-type vascular occluder to provide variable graft occlusion, and an infusion line for selective drug administration were placed at the midgraft position. Electrocardiographically triggered scans were performed at levels of the aortic root and cardiac base following bolus inferior vena cava contrast administration. Continuous recordings of Doppler velocity and aortic pressure and intermittent measurements of cardiac output were obtained throughout the studies. Selective increases and decreases in coronary artery bypass graft flow velocity from control were performed using combinations of intragraft adenosine and/or variable graft occlusion. Simultaneous contrast clearance curves were generated from a region of interest in the ascending aorta and in the coronary artery bypass graft. Subsequent determinations of a parameter, delta PT (the time difference between peak opacification in the aorta and the bypass graft), were found to highly correlate with individual values of relative coronary bypass graft flow velocity (r = 0.74-0.97, n = 54). This study suggests that cine-computed tomography can be used to noninvasively quantify relative bypass graft flow velocities in individual dogs and eventually in patients.

Animals↗
PubMed1986

The role of venography and surgery in the management of patients with superior vena cava obstruction.

Venacavography proved to be an excellent guide for the design of patient management programs. Type 1 patients with incomplete obstruction of the superior vena cava (SVC) are best managed by irradiation and chemotherapy regimens and usually do not require operation to bypass the SVC. Types II and IV patients are treated by operation when symptoms of airway obstruction or cerebral venous hypertension are present. Type III patients should be considered for SVC bypass as an initial therapeutic intervention. This group is more likely to have cerebral or airway symptoms and would benefit most from the bypass operation. In terms of operative considerations, type III patients are ideal for operation because the left brachiocephalic vein is usually available for bypass. Type IV patients may also be considered, but operation is more difficult and may require venous thrombectomy or extension of the bypass graft above the thoracic inlet to obtain head and neck decompression.

Adult↗
PubMed1986

Precision of measurements of right and left ventricular volume by cine computed tomography.

Precise determination of left and right ventricular stroke volumes is limited with conventional imaging techniques. We determined whether right and left ventricular stroke volumes could be precisely measured with cine computed tomography (CT). Cine CT enables simultaneous imaging of the right and left ventricles at an 8 mm slice thickness with a maximal scanning rate of 17 frames/sec (50 msec acquisition intervals). In eight dogs, true right ventricular and left ventricular stroke volumes were determined by dividing thermodilution cardiac output by heart rate and/or with the use of an aortic electromagnetic flow probe implanted over a long term. After at least 5 sec of suspended respiration, cine CT images were acquired during central venous injection of a nonionic contrast agent. Multiple perturbations in stroke volume were induced in each dog by the administration of dobutamine, sodium pentobarbital, or sodium nitroprusside or by coronary artery occlusion. Right and left ventricular stroke volumes were obtained by Simpson's reconstruction of end-diastolic and end-systolic short-axis tomograms from apex to base. The cine CT left ventricular stroke volume (range 11 to 45 ml) correlated highly with the true left ventricular stroke volume (r = .99, slope = 1.01, y intercept = -0.2 ml, SEE = 1.5 ml, n = 25). The cine CT right ventricular stroke volume (range 11 to 34 ml) also correlated highly with the true right ventricular stroke volume (r = .98, slope = 0.9, y intercept = 2.2 ml, SEE = 1.7 ml, n = 15). In 12 studies, the mean difference between nearly simultaneous right and left ventricular stroke volumes by cine CT was 1.1 ml (range 0.1 to 3.2 ml). Calculation of right and left ventricular stroke volumes from data from cine CT were highly reproducible. Intraobserver variability in measurements of right ventricular stroke volume (r = 1.0, slope = 0.99, y intercept = 0.19 ml) and left ventricular stroke volume (r = 1.0, slope = 1.02, y intercept = -0.21 ml) was minimal. Interobserver variability in measurements of right ventricular stroke volume (r = .98, slope = 0.90, y intercept = 1.66 ml) and left ventricular stroke volume (r = .99, slope = 0.97, y intercept = -0.02 ml) was likewise minimal. Thus, precise and highly reproducible measurements of right and left ventricular stroke volumes can be obtained with cine CT.

Animals↗
PubMed1983

Esophagotracheal fistula from a pharyngoesophageal diverticulum.

Pharyngo-esophageal (Zenker's) diverticula are rarely associated with tracheal fistulas; however, the diagnosis should be suspected in the diverticulum patient who presents with spasms of coughing while eating since, if found, it changes the surgical management. The roentgenographic findings, diagnostic modalities, and surgical management of such a patient are herein presented.

Aged↗
PubMed1981

Munchausen syndrome with pulmonary manifestations.

Three patients with Munchausen's syndrome were seen with symptoms suggesting serious pulmonary disease. One patient, a student respiratory therapist, simulated respiratory failure which resulted in a tracheostomy and prolonged ventilator support. The second, a licensed practical nurse, feigned a lupus erythematosis syndrome, with alarming, simulated hemoptysis produced by slashing the posterior tongue with a razor blade. The third patient, a nurse, underwent exhaustive testing at three hospitals for profuse "hemoptysis" until she admitted she obtained the blood from her arm by venesection.

Adult↗
PubMed1980

Influence of staging in superior sulcus (Pancoast) tumors of the lung.

Fifty-three patients with superior sulcus (Pancoast) tumors of the lung followed for up to 12 years by the Armed Forces Central Medical Registry were divided into three groups. In Group 1, preoperative stagin as determined by bone, brain, and liver scans or combinations thereof and the presence of local nodal extension as determined by mediastinoscopy or scalene fat pad biopsy were negative. These 16 patients received preoperative irradiation followed by en bloc resection of the lung and of the involved chest wall in most of them. Five-year survival as determined by the actuarial method was 49.7%. The 12 patients in Group 2 either had localized nodal involvement or were not diagnosed preoperatively. Survival in this group was 13.1%. Group 3 patients were considered inoperable and were given palliative irradiation. There were 25 patients in this group, and survival was 5.5% at 4 years. It would appear that preoperative irradiation and en bloc resection give improved survival in those patients judged free from metastatic disease preoperatively.

Actuarial Analysis↗
PubMed1980

Growth hormone cell antibodies and partial growth hormone deficiency in a girl with Turner's syndrome.

Growth hormone (GH) cell auto-antibodies have been demonstrated in the serum of a girl with an iso-chromosome variant of Turner's syndrome. On two occasions she showed an abnormal response of GH release during insulin induced hypoglycaemia. Her response to GH treatment was poor, but this was commenced at a very late bone-age. It is possible that autoimmunity is a new aetiological factor for GH deficiency in some cases.

Adolescent↗
PubMed1980

Management of long-standing cardiocutaneous fistulas after resection of left ventricular aneurysms.

Cardiocutaneous fistulas arising from pledgets used in the closure of resected left ventricular aneurysms are rare but have serious implications. The case histories of four patients, each managed in a somewhat different manner, are presented. From this experience we recommend an aggressive approach to remove the infected pledgets once scar formation is complete and before erosion of the pledgets into the left ventricular cavity can occur.

Adult↗
PubMed1979

Diverticula in association with the proximal left subclavian artery: a cause of mediastinal mass lesions.

The case reports of 5 patients with an aortic arch diverticulum associated with the proximal left subclavian artery are presented. In 3 patients, the left subclavian artery arose from a diverticulum off a right aortic arch and traversed the retroesophageal area to the opposite arm. In 1 patient, the left subclavian artery arose from a diverticulum off a left aortic arch; this represents the second instance of this anomaly to be reported in the literature. In 1 patient, the left subclavian artery was not attached to the aorta, and a diverticulum was present in the expected area of attachment. Confusion of these anomalies with solid mediastinal mass lesions and with aortic aneurysms may occur. Treatment is predicted on symptomatology, and resection is usually not indicated. It is necessary to remain cognizant of aortic diverticula and to differentiate them from other mediastinal mass lesions.

Adult↗
PubMed1979

A guideline for anticipated blood usage during elective surgical procedures.

A realistic guideline for transfusion therapy was prepared, with the cooperation of the departments of anesthesiology and surgery, in order to reduce excessive crossmatching. The guideline recommends an ABO-Rh type and an antibody screen, instead of the ""routine'' two-unit crossmatch, for elective surgical procedures where blood is seldom used. For those operations normally necessitating hemotherapy, the number of units suggested for the preoperative crossmatch was determined by examination of the average number of units transfused in the past for that particular procedure. The guideline provides the anesthesiologic and surgical staff with the knowledge of how much blood was usually used during a particular elective surgical procedure and therefore how much blood should be preoperatively crossmatched for that procedure. Implementation of this guideline allows the blood bank to distribute its limited blood resources more efficiently and also decreases patient and laboratory costs.

ABO Blood-Group System↗