Search PubMed⌕ Search

Biomedical subjects

R E Clark

Publications and source records attributed to R E Clark.

At least 307 records · Page 17Linked to original sources
PubMed1976

The indications for pericardiectomy in the uremic pericardial effusion.

Uremic pericarditis developed in 37 of 295 patients (8 percent) admitted to the chronic hemodialysis program at our institution. Sixteen patients (43%) underwent limited pericardiectomy through a left anterior thoracotomy approach with no operative deaths and minimal morbidity (19%). Twenty-one patients (57%) were treated successfully with intensive hemodialysis. The use of pericardiocentesis did not avert cardiac tamponade in any patient in our series. The procedure was associated with two life-threatening complications and its use, therefore, has been limited in the therapy of uremic pericarditis. We recommend surgical intervention in all patients with hemodynamic instability and echocardiographic evidence of enlarging effusions or an effusion unchanged in size following 10 days of intensive hemodialysis.

Adult↗
PubMed1976

Infection control in cardiac surgery.

This report relates the results of a multifaceted, 4 year program directed toward reduction of infection in patients undergoing cardiac operations and extracorporeal circulation in a large teaching hospital. Retrospective analysis of all superficial and deep wound infections and prosthetic valve infections for the period of 1966 to 1970 and a prospective study of the period of 1970 to 1974 were made. The multifaceted program begun in 1970 consisted of (1) renovation of a cardiac operating room with incorporation of a high flow, vertical unidirectional ventilation system, (2) change in the gown and draping material for improvement of barriers to bacteriologic shedding, (3) frequent steam sterilization of prosthetic valves, (4) routine use of an antistaphylococcal agent in patients receiving valve replacement, and (5) an unannounced bacteriologic monitoring program of the cardiac operating room personnel. Studies of airborne particulates and bacteria and adequacy of skin preparation and hair removal also were conducted. The studies showed that (1) a high-flow HEPA filtered vertical ventilation system and altered operating room clothing reduced the concentration of airborne particles and the concentration of bacteria at the wound by a factor of 10 compared to conventional operating rooms, (2) the incidence of markedly contaminated scrubbed and unscrubbed hands decreased, (3) shedders and carriers were identified, and (4) current patient skin preparation and hair removal practices were satisfactory. The results of the program were a reduction of the deep wound infection rate from 2.9 to 0.6 percent (p less than 0.01) and a concomitant total wound infection decrease from 6.6 to 3.3 percent. Prosthetic valve infection rates decreased fourfold, from 5.6 to 1.4 percent. It is concluded that careful attention to possible endogenous sources of infection from the patient and a multifaceted program directed to exogenous sources of infection can lower infection rates in cardiac surgical patients.

Air Microbiology↗
PubMed1976

Continuous detection of microemboli during cardiopulmonary bypass in animals and man.

A device that continuously and accurately detects solid and gaseous microemboli (75-100 muM) during cardiopulmonary bypass is described. A continuous ultrasonic standingwave field was generated between two parallel piezoelectric crystals. Extremely high sensitivity to small changes in ultrasonic attenuation was achieved with a transmission oscillator ultrasonic spectrometer (TOUS). The device was relatively insensitive to variations in flow rate, gradual temperature changes, hematocrit, protein content, and pressure. The system was tested with 100, 200, and 300 muM microspheres. Animal perfusions demonstrated high initial counts that were markedly reduced by an arterial line filter. Furthermore, high cardiotomy suction rates, use of nitrogen, and physical disturbances of the oxygenator increased the microemboli rate. Of 30 clinical perfusions, 15 had complete data for analysis. There was a statistically significant difference (P less than 0.01) in the total number of microemboli between the first 10 minutes (4398 +/- 1132) versus the second 10 minutes of perfusion (2739 +/- 1195). It is concluded that an accurate device that continuously measures the number of microemboli may provide data that will lead to significant improvements in the quality of extracorporeal circulation in the future.

Animals↗
PubMed1975

Experimentally reversed pulmonary blood flow. Implications for the surgical management of complex forms of congenital heart disease.

Blood flow to the right lung was reversed in 28 dogs, 14 of which survived more than 1 month. Four successful long-term survivors (1 years to 4 years 7 months) were repeatedly studied by cardiac catheterization, angiography, and ventilation/perfusion scans as well as hemodynamically when they were killed. Hemodynamics and gas transfer were normal up to 4 1/2 years after the procedure, and the histology of the right lung was essentially normal. The application of reversed pulmonary blood flow is proposed in the surgical management of forms of congenital heart disease in which the right ventricle is diminutive. The procedure consists of repartitioning of the atria to allow venous blood to flow into the lung through the pulmonary veins and exit to the left atrium through the pulmonary artery.

Animals↗
PubMed1975

Small atrophic kidney secondary to renal vein thrombosis: report of a case diagnosed arteriographically.

Although rena vein thrombosis usually presents with a large or normal-sized kidney radiographically, a small atrophic kidney may be the end stage result of complete renal vein thrombosis with subsequent hemorrhagic infarction. A small atrophic kidney secondary to renal vein thrombosis (probably of neonatal origin) was diagnosed by selective renal arteriography in a 31-year-old woman being studied for hypertension of unknown etiology.

Adult↗
PubMed1975

Cerebral metastatic choriocarcinoma: a postpartum cause of "stroke".

This case presentation is that of a 23-year-old woman who developed a "stroke" shortly after delivering a normal full-term infant. Evacuation of an intracerebral hematoma was required and an underlying nidus of choriocarcinoma was discovered. The patient responded dramatically to chemotherapy and irradiation. Because this metastatic tumor is potentially curable, we emphasize the importance of considering this diagnosis in young women who present with "stroke" symptoms, and we outline the appropriate laboratory and radiographic investigations.

Adult↗
PubMed1975

Fat and solid filtration in clinical perfusions.

The purpose of this study was to define the fat filtration characteristics of a packed polyester wool filter when used alone in the cardiotomy suction (12 cases) and the arterial lines (10 cases) during clinical hemodilution, extracorporeal circulation. The pressure gradient-flow relationship and the efficiency of removal of fibrin microparticles were first ascertained in vitro. Total fat was extracted from the polyester wool with a Soxhlet device. Whole blood and plasma lipids were measured before and after bypass. The results showed a 23 mm. Hg pressure drop across a wool filter with a water flow rate of 5 L. per minute and a 40 to 52 percent efficiency for fibrin microparticles 15 to 250 mu. The total lipid extracted from the cardiotomy filters averaged 376 plus or minus 72 mg. compared with 512 plus or minus 95 mg. in the arterial line filters, although there was no statistically significant difference. Additionally 245 plus or minus 101 mg. of nonlipid material were extracted from the arterial line filters. The postperfusion whole blood contained a higher concentration of lipid than the preperfusion blood when corrected for dilution. It was concluded that significant quantities of solids, two thirds of which were fat, were removed by packed polyester wool filters during total body perfusions. Most of the fat was derived from the cardiotomy suction system. The amount of filtered fat and solids increased with perfusion time. These findings endorse the concept of cardiotomy filtration during extracorporeal circulation.

Blood↗
PubMed1975

Close-range stereophotogrammetry and coupled stress analysis as tools in the development of prosthetic devices.

The combination of molding at physiologic pressures, close-range stereophotogrammetric processing, geometric smoothing, finite element analysis, leaflet thickness measurements, and a knowledge of leaflet properties have provided a description of asymmetric geometry and stress patterns within a normal human aortic leaflet which are consistent with anatomic observations. A predominantly circumferential, tensile pattern of stress resultants was found. The higher values of stress resultants coincide with thinner regions of the leaflet. And those in a coronary leaflet. A design stress magnitude of 80 Gm/mm2 for a long pressure of 110 mm Hg, based on the actual thickness of the leaflet, was considerably greater than that previously reported in the literature. Those responsible for device development in the future must consider the mechanical properties and asymmetric geometries in design. Future generation devices will depend on the ability of the designer and the fabricator to incorporate features of asymmetry, anisotrophy, and deformation characteristics which match those of living tissue. Through such efforts more durable devices will result.

Aortic Valve↗