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Biomedical subjects

R Greene

Publications and source records attributed to R Greene.

At least 19 recordsLinked to original sources
PubMed1992

Successful extended lung preservation with UW solution.

Maximum preservation times of 4-6 hr continue to plague lung transplantation. The high-potassium colloid University of Wisconsin solution (UWS) has proved superior to the crystalloid modified Eurocollins' solution (ECS) for preservation of the liver, kidney, and pancreas. The purpose of this study was to compare UWS and ECS for extended lung preservation using a technique of combined pulmonary and bronchial artery perfusion. Simultaneous pulmonary artery and bronchial artery (via a closed aortic segment) perfusion was employed to harvest the lungs of ten mongrel dogs (wt 25-35 kg) using either UWS (n = 5) or ECS (n = 5) preservation solutions. Following 17 hr of cold (4 degrees C) pulmoplegic storage, the lungs were placed in an isolated perfused working lung (IPWL) apparatus. Seven freshly harvested lungs served as a control group (CON). Lung aerodynamics and gas exchange were evaluated at standard intervals until failure of the lung on the IPWL apparatus. Time until failure (mean +/- SEM) for each group was: CON = 209 +/- 14 min; UWS = 227 +/- 26 min; and ECS = 123 +/- 29 min. Only one of the ECS lungs lasted longer than 90 min. UWS-preserved lungs displayed a gas exchange efficiency equal to the CON group and better than that in the ECS-preserved lungs (lower A-aDO2, lower intrapulmonary shunt), suggesting better protection of the alveolar capillary membrane. Although the UWS lungs were initially less compliant than the ECS lungs, at no time was there a significant difference in the total work of respiration between the two groups. We conclude that UWS provides superior protection of the alveolar capillary membrane. The aerodynamic disadvantages of UWS preservation did not effect lung survival or total work of respiration.

Adenosine↗
PubMed1992

Lactic acidosis: effect of treatment on intracellular pH and energetics in living rat heart.

Systemic acidemia may impair cardiac contractility and predispose to arrhythmias. Moreover, bicarbonate treatment may further depress cardiac performance and increase mortality. Whether changes in myocardial intracellular pH or energy metabolism underlie this diminished performance has not been clarified in the in vivo setting. Thus we investigated the effect of lactic acidosis and two proposed treatments on myocardial energetics and intracellular pH in anesthetized living rats. A previously validated 31P-labeled nuclear magnetic resonance (31P-NMR) spectroscopic technique using saturating pulses was used to follow myocardial intracellular pH, phosphocreatine (PCr), ATP, and inorganic phosphate (Pi). After obtaining baseline values, we infused lactic acid to achieve a level greater than 5 mM. We then added an infusion of either bicarbonate (n = 7) or saline (n = 5). During lactic acid infusion, arterial pH declined (from 7.27 to 7.07, P less than 0.0001), but myocardial intracellular pH did not change (7.13 vs. 7.07, P not significant). The ratio of PCr to Pi, however, decreased with acidemia (from 3.13 to 2.24, P = 0.004), suggesting impaired energy metabolism. Compared with saline, bicarbonate infusion restored systemic pH (from 7.08 to 7.29), but myocardial pH was unaltered. In addition, PCr/Pi declined further following bicarbonate treatment (1.41 vs. 2.42, P = 0.08) but not following saline. Thus, despite reversal of systemic acidemia, bicarbonate treatment was associated with more severe impairment of energy metabolism than saline. This suggests a mechanism for previously reported adverse cardiac effects of bicarbonate treatment.

Acidosis, Lactic↗
PubMed1992

Fleischner Lecture. Imaging the respiratory system in the first few years after discovery of the X-ray: contributions of Francis H. Williams, M.D.

Imaging of the respiratory system developed with exceptional rapidity in North America during the spring of 1896, after Roentgen's discovery of X-rays in November 1895, largely because of the efforts of a unique physicians, Francis H. Williams. With great zeal, this pioneer used fluoroscopy for early detection of tuberculosis and other life-threatening chest disorders. By the summer of 1896, he had accumulated more than 100 volumes containing tracings of clinical chest fluoroscopy. As a result of his extensive clinical experience, his dedication to patients' welfare, and his sense of scientific inquiry, several inventions and many landmark clinical observations were made in the first few years after the discovery of the X-ray. These included (1) the invention of a "densitometer" for standardized measurements of relative X-ray attenuation of the lung, (2) the invention of a "seehear" device to correlate auscultative findings and fluoroscopic observations, (3) the recognition that fluoroscopy was more accurate than percussion for estimating mediastinal displacement, (4) the discovery that clinically occult tuberculosis and congestive heart failure could be detected with fluoroscopy, (5) the documentation that unilateral chest disease caused decreased ipsilateral ventilatory compliance and increased contralateral ventilation, (6) the identification of the classical imaging characteristics of tuberculosis, pneumonia, pneumothorax, tension pneumothorax, pleural effusion, hydropneumothorax, emphysema, congestive heart failure, and air trapping. In April 1896, Dr. Williams described the "air bronchogram" in a radiograph of a patient with pneumonia.

History, 19th Century↗
PubMed1992

Short-term and long-term results of experimental wrapping techniques for bronchial anastomosis.

Major complications of bronchial anastomoses for either transplantation or sleeve resection include early leak, fistula formation, granulation tissue, and stenosis. To evaluate the impact of technique on these complications, we designed a nonimmunocompromised canine model with a totally ischemic bronchial segment. We wished to discover the prevalence of early and late complications of a telescoping anastomosis and if wrapping techniques modify them. We autotransplanted 25 mm of left main-stem bronchus by telescoping 1 mm of proximal into distal bronchus sutured with interrupted 4-0 polyglactin sutures. The animals were divided into four groups: no wrap; omental pedicle wrap; detached-free omental wrap; and Gelfoam sponge soaked in porcine omental extract. Weekly bronchoscopic studies assessed airway patency. After the animals were put to death at 70 days, the luminal areas of the proximal anastomoses were compared with the origin of the left main bronchus. No air leak, bronchial disruption, or infection occurred in any group at any time. Luminal narrowing occurred in all four groups but was most pronounced in the three groups in which wrapping techniques were used. We conclude that wrapping of a telescoped anastomosis is not necessary to prevent early complications. However, no method completely eliminates stenosis. Further experiments should determine the effects of immunomodulation in this model.

Anastomosis, Surgical↗
PubMed1991

Asbestos-related disease in public school custodians.

A cross-sectional prevalence study of 120 public school custodians was carried out. The purposes were 1) to investigate the prevalence of asbestos-related disease in a group of custodians at risk for asbestos exposure in public schools and 2) to determine the proportion with disease attributable to exposures in school buildings. Medical and occupational histories, flow-volume loops, and posterior-anterior, lateral, and anterior oblique (AO) chest radiographs were obtained. Single breath DLCO was measured and chest auscultation performed. Mean age of subjects was 57 years and mean duration of work as a custodian, 27 years. Fifty-seven (47.5%) had no known or likely exposure to asbestos outside of their work as a school custodian (NOE). Pleural plaques (PP) occurred in 40 (33%) of the total group and 12 (21%) of the group with NOE. Pulmonary restriction (FVC less than 80% predicted, FEV1/FVC% greater than or equal to 70) occurred in 22 (18%) of the total group and 10 (17%) of those with NOE. DLCO was lower in the group with restriction. Multivariate analysis revealed significant associations (p less than 0.05) between both PP and restriction and duration of asbestos exposure. AO radiographs increased PP detection by a factor of 1.9. Our results reveal PP prevalence in excess of background and pulmonary restriction in the study population, and indicate that PP are attributable to asbestos in schools. Findings with regard to pulmonary restriction need further investigation. Prudent management of asbestos in buildings is indicated for the prevention of related disease.

Adult↗
PubMed1991

Endoscopic thoracic sympathectomy: evaluation of pulsatile laser, non-pulsatile laser, and radiofrequency-generated thermocoagulation.

We describe a modified technique for percutaneous denervation of the thoracic sympathetic chain by laser to treat selected cases of sympathetic causalgia of the upper extremities. The technique involves transpleural ablation with laser under thoracoscopic guidance through the second or third intercostal space-anterior axillary line. We also compare four different modalities of endoscopic denervation: A xenon chloride excimer laser (308 nm, 35 mJ/pulse, 20 pulses/sec, 2.2 mm catheter tip), CO2 laser (14 W, CW, 2 mm spot size), Nd:YAG laser (88 W, CW, 3 mm spot size), and radiofrequency-generated thermocoagulation (3 W, CW, 2.1 mm catheter tip) by performing bilateral thoracic sympathectomy on 12 mongrel dogs (three dogs each). Criteria analyzed included duration of exposure, power density, total energy output, laser penetration and spread, gross morphology, and scanning electron microscopy (SEM) of the destroyed neural tissue. Total ablation of the inferior segment of the stellate ganglion and the T1-T2 nerve roots by excimer laser required 83 +/1 1 Joules over an exposure period of 118 seconds. Ablation by CO2 and Nd:YAG laser required 153 +/- 13 Joules and 554 +/- 47 Joules delivered over 11 and 6 seconds respectively. In contrast, ablation of the same volume of nerve tissue by RF required 810 +/- 50 Joules over 270 seconds. SEM evaluation revealed that excimer and CO2 laser lesions were narrower in configuration compared to RF and Nd:YAG lesions which showed more lateral spread. The actual depth of penetration per 1 second exposure was similar for Excimer and CO2 (1.5 mm) and RF (1.3 mm), but deeper for Nd:YAG (3 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Mediastinal abnormalities: detection with storage phosphor digital radiography.

Conventional film radiography (FR) and six postprocessing algorithms of isodose storage phosphor digital radiography (SR) (0.2-mm X 10-bit pixel matrix) were compared in the evaluation of 40 mediastinal and 30 pulmonary lesions in 60 patients who underwent computed tomography of the chest. The six SR algorithms varied among each other in only one image parameter. One algorithm approximated conventional image characteristics. The other five algorithms were designed to optimize imaging of the mediastinum and tested the effects of gray-scale reversal, adjustment of optical density, a linear instead of a sigmoid gradation curve, and moderate edge enhancement of high and medium spatial frequencies. Performance was evaluated by calculating the average area under the receiver operating characteristic curve (Az) of 5,040 observations by six readers. Post-processing with high-frequency edge enhancement and density optimization for the mediastinum significantly improved performance of SR over FR in the detection of mediastinal lesions (Az = .80 +/- .02 vs .73 +/- .01, respectively). Gray-scale reversal significantly decreased performance (Az = .64 +/- .03). All SR algorithms that were postprocessed to optimize imaging of the mediastinum were significantly inferior to FR in the detection of pulmonary lesions.

Algorithms↗
PubMed1991

Interstitial lung disease: impact of postprocessing in digital storage phosphor imaging.

The ability to resolve the fine linear structures of interstitial lung disease is one measure of the limiting performance characteristics of an imaging system. Conventional screen-film radiography was compared with six algorithms of isodose storage phosphor digital radiography (0.2-mm x 10-bit pixel matrix) in the detection of interstitial lung abnormality documented by means of computed tomography in 40 patients with abnormalities and 25 healthy control subjects. Performance was evaluated with an analysis of variance (the Fisher paired comparison test; P less than .05) of the average receiver operating characteristic area of 2,730 observations by six readers. The moderately and the more markedly high-frequency edge-enhanced algorithms of storage phosphor digital radiographs were equivalent in performance to screen-film radiography. The default mode, low- and medium-frequency edge-enhanced algorithms, and gray scale reversed mode of storage phosphor digital radiography were inferior to screen-film radiography. The authors conclude that high-frequency edge-enhanced algorithms can perform as well as screen-film radiography in the detection of interstitial disease.

Algorithms↗
PubMed1991

Coronary vasoconstriction induced by vasopressin. Production of myocardial ischemia in dogs by constriction of nondiseased small vessels.

BACKGROUND: We studied the effect of intracoronary administration of arginine-8-vasopressin on blood flow in nondiseased coronary arteries and determined whether this vasoconstriction was severe enough to produce ischemia in 30 dogs. METHODS AND RESULTS: In group 1 (n = 6), after vasopressin administration coronary blood flow was decreased by 41% (p less than 0.002) without changes in heart rate or aortic pressure, and left ventricular ejection fraction measured by radionuclide angiocardiography was decreased by 18% (p less than 0.0005). In group 2 (n = 6), ischemia was confirmed by measurement of transmural pH changes. Administration of vasopressin decreased subendocardial pH of the infused zone from 7.40 +/- 0.03 to 7.31 +/- 0.07 (p less than 0.01). The subendocardial pH of the zone not infused with vasopressin did not change. To overcome the intrinsic regulation of blood flow, operating primarily in small coronary arteries, we hypothesized that vasopressin must increase resistance primarily in large rather than small coronary arteries. After intracoronary infusion in group 3 (n = 6), however, most (94%) of the increase in resistance during vasopressin administration was explained by an increase of resistance in small coronary arteries. In group 4 (n = 9), vasopressin decreased coronary blood flow by 50% and decreased local shortening by 90% at a time when systemic hemodynamics were unchanged. Coronary constriction induced by vasopressin, or the recovery from it, also was not altered by cyclooxygenase blockade. CONCLUSIONS: Thus, vasopressin produces myocardial ischemia by constricting small, nondiseased coronary arteries severely enough to overcome the competition from normal coronary regulation, and this ischemic event is not mediated by prostaglandin products.

Animals↗
PubMed1991

Bilateral reexpansion pulmonary edema following unilateral pleurocentesis.

Acute ipsilateral pulmonary edema following reexpansion of the lung after pleurocentesis or pneumothorax is a well described entity. We report the unusual occurrence of bilateral pulmonary edema following unilateral pleurocentesis in a young male without heart disease. Various hypotheses regarding the mechanism of reexpansion pulmonary edema include increased capillary permeability due to hypoxic injury, decreased surfactant production, altered pulmonary perfusion and mechanical stretching of membranes. This case suggests that forces leading to ipsilateral reexpansion pulmonary edema also affect the contralateral lung.

Acute Disease↗
PubMed1991

Detection of bullous lung disease: conventional radiography vs digital storage phosphor radiography.

The detection of fine linear contours and altered aeration are requirements for the radiologic diagnosis of bullous lung disease and are severe measures of the spatial and contrast resolution of chest imaging systems. We compared plain film radiography with five postprocessing algorithms of storage phosphor digital radiography (2144 x 1744 x 10 bit matrix with 0.2-mm pixel size) in the detection of CT-proved bullous lung disease (35 patients and 25 normal control subjects). Receiver-operating-characteristic analysis of 2160 observations by six interpreters was done to evaluate the observers' performance. By analysis of variance (p less than .05), we found that the default digital algorithm and the three edge-enhancing algorithms of high and medium frequencies performed less well than plain films did, but the differences fell short of statistical significance. Gray-scale reversal was the only digital algorithm that performed significantly less well than plain films did. We conclude that any differences between digital algorithms and plain films in the detection of bullous lung disease were too small to be detected in this study. Any difference between the two methods in providing clinically important, diagnostic information is likely to be insignificant.

Algorithms↗
PubMed1991

Contribution of the bronchial circulation to lung preservation.

Short preservation time still severely limits lung transplantation. To determine the effect of bronchial arterial flush preservation, we studied 54 dogs using the isolated perfused working lung model. After baseline measurements, lungs were flushed with lactated Ringer's solution (60 ml/kg at 8 degrees C) by one of three methods: pulmonary artery perfusion, bronchial artery perfusion through a 15 cm closed aortic segment, or simultaneous pulmonary-bronchial artery perfusion. These groups were further subdivided and tested after 0, 4, and 17 hours of storage at 4 degrees C (n = 6 each). Lungs were ventilated (flow rate 140 ml/kg/min; inspired oxygen fraction 0.21) and continuously reperfused with normothermic deoxygenated autologous blood in a closed loop. Measured variables were hemodynamics, aerodynamics, and leukocytes in bronchoalveolar lavage. Survival time was determined from initial reperfusion to failure of the lung to oxygenate. After 0 and 4 hours of storage, there was no significant difference in survival times. After 17 hours, lungs subjected to pulmonary-bronchial artery perfusion survived longer than those perfused via either the pulmonary or bronchial arteries alone (120 +/- 24 versus 38 +/- 14 or 52 +/- 16 minutes; p less than 0.01). Pulmonary artery pressure and resistance in all groups except at failure were never different from baseline values in the intact animal. Shunts in the pulmonary-bronchial artery perfusion groups were closest to baseline at onset (8% +/- 4%) and remained lower throughout reperfusion than in the groups subjected to pulmonary or bronchial artery perfusion alone. After 17 hours, static compliance of pulmonary artery-perfused lungs was worse than baseline (1.1 +/- 0.2 x 10(-2) versus 3.2 +/- 0.7 x 10(-2) L/cm H2O/sec; p less than 0.05), whereas compliance in the pulmonary-bronchial artery perfusion groups remained constant (3.6 +/- 1.5 x 10(-2) L/cm H2O/sec). Elastic work performed by lungs subjected to pulmonary-bronchial artery flushing at onset was significantly lower when these lungs were reperfused immediately (201 +/- 14 versus 295 +/- 35 gm-m/min for pulmonary artery-flushed lungs) or after 4 hours of storage (229 +/- 30 versus 290 +/- 24 gm-m/min for pulmonary artery-flushed lungs). Bronchoalveolar lavage after 17 hours in the group subjected to pulmonary bronchial artery flushing demonstrated leukocyte counts similar to those of intact lungs (45 +/- 5 versus 29 +/- 8/mm3) and significantly less than in lungs subjected to pulmonary or bronchial artery flushing (137 +/- 18 or 82 +/- 10/mm3, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗