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Biomedical subjects

W R Webb

Publications and source records attributed to W R Webb.

At least 217 records · Page 12Linked to original sources
PubMed1979

Experimental pulmonary edema. The effect of unilateral PEEP on the accumulation of lung water.

The effect of PEEP in retarding the development of pulmonary edema produced by elevation of left atrial (LA) pressure to 25cm water was studied in dogs, Using two synchronized volume respirators connected to a double lumen endotracheal tube, 10 or 25cm H2O PEEP was applied to one lung while the contralateral lung was ventilated with an equal tidal volume without PEEP. LA pressure was then elevated by inflating a Foley catheter ballon in the LA until the desired LA pressure was reached. After three hours of pulmonary edema with ventilation of one lung with PEEP lung water was quantitated by wet-to-dry weights. There were no differences in wet to dry weights of PEEP and nonPEEP lungs at either 10 or 25cm H2O level. Additional blood flow studies showed that 25cm H2O of PEEP reduced blood flow to the PEEP lung by 25% and to the nonPEEP lung by 7%. This study shows that PEEP will not mechanically retard the accumulation of lung water due to increased pulmonary capillary hydrostatic pressure.

Animals↗
PubMed1979

Post-traumatic respiratory distress syndrome.

During the past two decades there has been recognition of the role of acute respiratory failure in the deaths of patients with shock from any cause. Leaky capillaries are the common pathophysiologic event. The pulmonary capillary bed is affected by the toxic action of vasoactive substances, gastric aspirates, and fat embolism; by the obstructive action of platelet, fibrin, and leukocyte clots; and by changes in the balance between perfusion pressures and oncotic pressures. This is complicated by increases in pulmonary vascular pressures from associated heart disease or overenthusiastic replacement of blood volume. The early treatment of the shock state, early intubation and ventilation, and the use of agents designed to improve capillary integrity have led to a significant reduction in mortality from this common problem.

Adult↗
PubMed1978

Diagnosis and management of spontaneous aortoenteric fistulas.

Spontaneous aortoenteric fistulas are rare but appear to be increasing. They may occur anywhere from the esophagus to the rectum but most often between the duodenum and an infrarenal abdominal aortic aneurysm. Four patients (two with aortoesophageal, one with aortoduodenal, and one with aortocolic fistulas) are presented. The patient usually presents with the clinical triad of aortic aneurysm, pain suggesting aortic disruption, and gastrointestinal hemorrhage. The final exsanguinating hemorrhage is usually preceded by prodomal hemorrhages of varying severity which may be present for weeks to months. Endsocopy is the most helpful diagnostic procedure. Prompt aggressive surgical therapy is the only hope for survival. Successful reconstruction requires placement of the graft in uninfected tissue--often in an extraanatomic position--and interposition of healthy tissues between the graft and the repaired enteric tract.

Aged↗
PubMed1978

Experimental pulmonary edema: the effect of positive end-expiratory pressure on lung water.

The effect of 10 cm of positive end-expiratory pressure (PEEP) on lung water was studied during pulmonary edema induced in dogs by inflating a Foley balloon placed in the left atrium. Colloid oncotic pressure (COP) was measured directly. Intrapleural pressure (IPP) was measured after surgical closure of the chest. Transmural left atrial (LA) pressure (LA minus IPP) minus COP was considered to be the net force driving water out of the capillaries. LA pressure was elevated so that transmural LA pressure minus COP averaged +7.5 mm Hg. Water accumulation was expressed as the ratio of wet to dry weight. The control ratio of wet to dry lung weight was 4.30 +/- 0.10 (+/- SE). After 2 hours of standardized pulmonary edema and ventilation without PEEP, wet-to-dry lung weight was 5.63 +/- 0.24. In animals ventilated with 10 cm of PEEP through 2 hours of pulmonary edema the ratio was 5.36 +/- 0.14. Animals ventilated with 10 cm of PEEP showed a significant increase in functional residual capacity and decreased intrapulmonary shunt. Ten centimeters of PEEP, however, had no statistically significant effect on water accumulation during experimental pulmonary edema.

Animals↗
PubMed1978

Pulmonary complications of renal transplantation: a survey of patients treated by low-dose immunosuppression.

Sixty-eight episodes of pulmonary complication developed in 52 of 416 renal transplant recipients treated with low-dose immunosuppression. Twenty-four complications were noninfectious (20 were pulmonary edema due to transplant rejection). Forty-four complications were infectious (75% of were wholly bacterial). Nine patients died from their pulmonary complications; 7 had bacterial pneumonia, but other infections were also present in 5. Several patterns were seen radiographically. Cardiomegaly, vascular congestion, and patchy consolidation indicated pulmonary edema. Segmental and labor consolidations were usually bacterial in origin. Large cavitary nodules, small nodules, and generalized consolidation were often due to diseases requiring biopsy for diagnosis.

Adolescent↗
PubMed1978

The pleural tail sign.

The pleural tail sign is widely thought to indicate malignancy. However, of 18 patients with the tail sign, 9 had benign disease. Bronchioloalveolar carcinoma was the most common malignant tumor, but adenocarcinoma, squamous-cell carcinoma, and metastatic adenocarcinoma of the colon were also found. The location of nodules and the radiographic characteristics of the pleural tails did not help differentiate benign from malignant lesions. However, nodules 2 cm or larger were malignant while those 1 cm or smaller were benign. Histologically, pleural tails reflected thickened, fibrotic connective tissue septae with indrawing of the visceral pleura. Their occurrence with neoplasm reflects desmoplastic reaction or scar carcinoma.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1978

Prevention of pulmonary insufficiency through prophylactic use of PEEP and rapid respiratory rates.

This study evaluated the effectiveness of prophylactic positive end-expiratory pressure (PEEP) rapid respiratory rates (RRR), and high tidal volume (HTV) in prevention of congestive atelectasis. Measurements of pulmonary hemodynamics, mechanics, gas exchange, functional residual capacity (FRC), pathology, and cinemicroscopy were performed in 45 anesthetized dogs subjected to hemorrhagic hypotension. Randomly, the animals received control ventilation, HTV (20 ml. per kilogram), RRR (32 breaths per minute), or PEEP (5 cm. of water). Carbon dioxide was added as needed to maintain normocapnia. Control and HTV animals showed characteristic changes of congestive atelectasis (capillary congestion, stasis, interstitial edema, periarterial hemorrhage, alveolar edema, and hemorrhage). These microscopic and cinemicroscopic changes were prevented by PEEP and RRR and correlated with decreased physiological shunting (PEEP 10 percent, RRR 13 percent, HTV 22 percent; p less than 0.01) in the postshock phase. PEEP increased FRC by 40 percent (p less than 0.02) and reduced the pulmonary artery--small pulmonary vein gradient (PA-SPV), suggesting a direct effect on the capillary bed. RRR did not affect FRC but minimized the SPV-LA gradient. This effect on the pulmonary venules theoretically could be mediated by stimulating lymphatic flow, thereby decreasing interstitial edema. Thus PEEP and RRR are beneficial when used prophylactically but may work by widely differing mechanisms.

Animals↗
PubMed1978

Pulmonary hemorrhage in systemic lupus erythematosus.

Pulmonary hemorrhage is a rare and often fatal manifestation of systemic lupus erythematosus (SLE), and enters the differential diagnosis of diffuse lung disease in patients with SLE. Pulmonary hemorrhage results from deposit of immune complexes in the alveolar basement membrane, which in turn damages capillary endothelium. Similar immune-complex deposition is present in the glomerular basement membrane of patients with systemic lupus erythematosus and pulmonary hemorrhage.

Adult↗
PubMed1977

Ventricular septal defect due to septal infarction after repair of tetralogy of fallot.

A case is reported of ventricular septal defect resulting from septal infarction following repair of a tetralogy of Fallot. The infarct probably resulted from division of a septal coronary artery during resection of the hypertrophied infundibulum. The superficial position of the septal artery on the right side of the septum in tetralogy makes it surprising that this complication has not been previously reported.

Child↗
PubMed1977

Fibrosing alveolitis in patients with neurofibromatosis.

Fibrosing alveolitis, or interstitial pulmonary fibrosis, is a common manifestation of neurofibromatosis, and was observed in 7 of 70 patients with the disease. Though neurofibromatosis is congenital, fibrosing alveolitis does not appear until adulthood, and occurs in 20% of patients with the disease who are over 30 years old. Characteristic radiographic findings include linear, interstitial density, and large upper lobe bullae; this combination limits the differential diagnosis. Pathological examination demonstrates alveolar wall thickening progressing to fibrosis and lung destruction. Pulmonary function tests can show obstructive or restrictive lung disease.

Adolescent↗
PubMed1977

Thoracic metastasis in malignant melanoma. A radiographic survey of 65 patients.

Sixty-five patients with malignant melanoma metastatic to the thorax were evaluated retrospectively. Chest x-ray films showed abnormalities in 63 patients and provided the first evidence of dissemination in 42 of the 62 with widespread metastasis. Frequent radiographic follow-up evaluations of patients with primary melanoma is necessary to detect metastasis at an early stage. Pulmonary metastasis was seen radiographically in almost 90 percent of the patients. Snowstorm metastasis denotes a poorer prognosis than other patterns of pulmonary involvement. Enlargement of mediastinal lymph nodes, bronchial obstruction with atelectasis, pleural effusion, bone metastasis with an extrapleural mass, and cardiomegally were also seen. Follow-up chest x-ray films are of limited value in evaluating patients once they are found to have thoracic metastasis. The rate of growth of metastatic lesions or the regression of the metastasis does not correlate with survival.

Adolescent↗
PubMed1977

Transpleural abdominal systemic artery-pulmonary artery anastomosis in patients with chronic pulmonary infection.

Systemic-pulmonary artery anastomoses commonly occur in lung diseases characterized by inflammation and decreased pulmonary artery perfusion. Three cases are reported in which anastomotic branches arose within the abdomen and crossed the pleural space. Arteriography differentiated acquired abdominal systemic artery supply from that seen in sequestration. In each case an inferior phrenic artery was involved, and a tangle of anastomotic branches was present at the pleural surface. Intensive medical therapy prior to lobectomy may be indicated in such patients.

Abdomen↗