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Biomedical subjects

J D Murphy

Publications and source records attributed to J D Murphy.

At least 19 recordsLinked to original sources
PubMed2006

A technical, economic, and environmental analysis of energy production from newspaper in Ireland.

The production of newspaper corresponds to 37 kg per person per annum in Ireland. Newspaper becomes a waste product in a short period of time; only 13% of domestic waste paper is recycled (data on newspaper is not available). Four scenarios, which generate energy from newspaper, are analysed. These scenarios may be summarised as follows: lignocellulosic biomass conversion to ethanol (transport fuel); co-digestion with the organic fraction of municipal solid waste and production of CH4-enriched biogas (transport fuel); co-firing with the residue of municipal solid waste in an incinerator; and gasification of newspaper as a sole fuel. Two of the scenarios involve transport fuel production; two involve the production of electricity and heat. Two of the scenarios involve newspaper as the sole ingredient; two involve co- utilisation of newspaper with another waste stream. Assuming no economic market for heat, then only the transport scenarios have the potential to be economic; indeed the biogas scenario is shown to be extremely competitive generating a potential profit of euro 227/t newspaper. A greenhouse-gas analysis indicates that the biogas scenario generated the best net greenhouse-gas savings. However when a market for heat is available, gasification was shown to be most advantageous.

Bioelectric Energy Sources↗
PubMed2006

Wildfire effects on soil nutrients and leaching in a tahoe basin watershed.

A wildfire burned through a previously sampled research site, allowing pre- and post-burn measurements of the forest floor, soils, and soil leaching near Lake Tahoe, Nevada. Fire and post-fire erosion caused large and statistically significant (P < or = 0.05) losses of C, N, P, S, Ca, and Mg from the forest floor. There were no statistically significant effects on mineral soils aside from a decrease in total N in the surface (A11) horizon, an increase in pH in the A11 horizon, and increases in water-extractable SO4(2-) in the A11 and A12 horizons. Burning caused consistent but nonsignificant increases in exchangeable Ca2+ in most horizons, but no consistent or statistically significant effects on exchangeable K+ or Mg2+, or on Bray-, bicarbonate-, or water-extractable P concentrations. Before the burn, there were no significant differences in leaching, but during the first winter after the fire, soil solution concentrations of NH4+, NO3-, ortho-P, and (especially) SO4(2-) were elevated in the burned area, and resin lysimeters showed significant increases in the leaching of NH4+ and mineral N. The leaching losses of mineral N were much smaller than the losses from the forest floor and A11 horizons, however. We conclude that the major short-term effects of wildfire were on leaching whereas the major long-term effect was the loss of N from the forest floor and soil during the fire.

Calcium↗
PubMed2001

Allopurinol neurocardiac protection trial in infants undergoing heart surgery using deep hypothermic circulatory arrest.

OBJECTIVE: This pharmacologic protection trial was conducted to test the hypothesis that allopurinol, a scavenger and inhibitor of oxygen free radical production, could reduce death, seizures, coma, and cardiac events in infants who underwent heart surgery using deep hypothermic circulatory arrest (DHCA). DESIGN: This was a single center, randomized, placebo-controlled, blinded trial of allopurinol in infant heart surgery using DHCA. Enrolled infants were stratified as having hypoplastic left heart syndrome (HLHS) and all other forms of congenital heart disease (non-HLHS). Drug was administered before, during, and after surgery. Adverse events and the clinical efficacy endpoints death, seizures, coma, and cardiac events were monitored until infants were discharged from the intensive care unit or 6 weeks, whichever came first. RESULTS: Between July 1992 and September 1997, 350 infants were enrolled and 348 subsequently randomized. A total of 318 infants (131 HLHS and 187 non-HLHS) underwent heart surgery using DHCA. There was a nonsignificant treatment effect for the primary efficacy endpoint analysis (death, seizures, and coma), which was consistent over the 2 strata. The addition of cardiac events to the primary endpoint resulted in a lack of consistency of treatment effect over strata, with the allopurinol treatment group experiencing fewer events (38% vs 60%) in the entire HLHS stratum, compared with the non-HLHS stratum (30% vs 27%). In HLHS surgical survivors, 40 of 47 (85%) allopurinol-treated infants did not experience any endpoint event, compared with 27 of 49 (55%) controls. There were fewer seizures-only and cardiac-only events in the allopurinol versus placebo groups. Allopurinol did not reduce efficacy endpoint events in non-HLHS infants. Treated and control infants did not differ in adverse events. CONCLUSIONS: Allopurinol provided significant neurocardiac protection in higher-risk HLHS infants who underwent cardiac surgery using DHCA. No benefits were demonstrated in lower risk, non-HLHS infants, and no significant adverse events were associated with allopurinol treatment.congenital heart defects, hypoplastic left heart syndrome, induced hypothermia, ischemia-reperfusion injury, neuroprotective agents, allopurinol, xanthine oxidase, free radicals, seizures, coma.

Allopurinol↗
PubMed2000

Use of a bow tie stent occluder for transcatheter closure of a large anomalous vein.

Percutaneous occlusion of superfluous vascular connections, which are short and have large caliber, is technically difficult. We report use of a composite device (consisting of a Palmaz stent, a Gianturco Grifka vascular occlusion device, and multiple platinum detachable embolization coils) to close a large left superior vena cava draining to the pulmonary venous atrium.

Cardiac Catheterization↗
PubMed2000

Preoperative risk-of-death prediction model in heart surgery with deep hypothermic circulatory arrest in the neonate.

OBJECTIVE: Our goal was to generate a preoperative risk-of-death prediction model in selected neonates with congenital heart disease undergoing surgery with deep hypothermic circulatory arrest. METHODS: We completed a single-center, prospective, randomized, double-blind, placebo- controlled neuroprotection trial in selected neonates with congenital heart disease requiring operations for which deep hypothermic circulatory arrest was used. An extensive database was generated that included preoperative, intraoperative, and postoperative variables. Variables (delivery, maternal, and infant related) were evaluated to produce a preoperative risk-of-death prediction model by means of logistic regression. An operative risk-of-death prediction model including duration of deep hypothermic circulatory arrest was also generated. RESULTS: Between July 1992 and September 1997, 350 (74%) of 473 eligible infants were enrolled with 318 undergoing deep hypothermic circulatory arrest. The mortality was 52 of 318 (16.4%), unaffected by investigational drug. The resulting preoperative risk model contained 4 variables: (1) cardiac anatomy (two-ventricle vs single ventricle surgery, with/without arch obstruction), (2) 1-minute Apgar score (</=5 vs >5), (3) presence of genetic syndrome, and (4) age at hospital admission for surgery (</=5 or >5 days). Mortality for two-ventricle repair was 3.2% (4/130). Mortality for single ventricle palliation was 25.5% (48/188) and was significantly influenced by Apgar score, genetic diagnosis, and admission age. The preoperative model had a prediction accuracy of 80%. The operative risk model included duration of deep hypothermic circulatory arrest, which significantly (P =.03) increased risk of death, with a prediction accuracy of 82%. CONCLUSIONS: In this selected population, postoperative mortality risk is significantly affected by preoperative conditions. Identification of infants with varying mortality risks may affect family counseling, therapeutic intervention, and risk stratification for future study designs.

Cardiac Surgical Procedures↗
PubMed2000

Transcatheter closure of fenestrations and excluded hepatic veins after fontan: versatility of the Amplatzer device.

BACKGROUND: The aim of this study was to evaluate the Amplatzer septal occluder (ASO) for transcatheter closure of fenestrations and excluded hepatic veins in patients after modified Fontan operations. Residual right-to-left shunts have improved surgical results of the Fontan operation. Shunt closure may eventually be desirable to eliminate hypoxemia and reduce risk of embolic complications. METHODS AND RESULTS: Ten patients with hypoxemia caused by residual shunts after Fontan procedures were evaluated for closure. After favorable results of test occlusion, all shunts were closed with the use of the ASO. Eight ASOs were used to close fenestrations in 7 patients with 6F transvenous sheaths. Three ASOs were used to close excluded hepatic veins in 3 patients with 6F venous sheaths and transbaffle punctures. Fluoroscopy and transesophageal echocardiography were used to guide device placement. Device placement in all patients was successful. All shunts were closed by angiography after device placement. While breathing room air, systemic oxygen saturation rose from 87.9% +/- 3.0% to 96.3% +/- 0. 9% (P <.001) in the patients. There were no complications of the implant procedures and none noted in outpatient follow-up. CONCLUSIONS: This experience suggests that the ASO is safe and effective for closing surgical shunts after Fontan procedures. The ASO design allows closure of excluded hepatic veins and has advantages over other devices in closure of fenestrations.

Adolescent↗
PubMed1998

Abciximab therapy in percutaneous intervention: economic issues in the United States.

Whether abciximab therapy should be the standard of care during percutaneous intervention in the United States depends on its efficacy, safety, and economics. In view of the EPIC, CAPTURE, and EPILOG data, few question the superior efficacy and relative safety of abciximab compared with conventional high-dose heparin therapy during percutaneous intervention. Economic considerations have been the major issue limiting its use. Review of the economic data demonstrates that the incremental direct medical care cost of abciximab therapy is $290 to $600 per patient treated in the EPIC and EPILOG populations. In the patients with acute myocardial infarction and unstable angina, abciximab appears to reduce direct medical costs (produce cost savings) at 6 months. Given abciximab's significant incremental effectiveness, its relatively small incremental cost yielded a highly cost-effective therapy in the EPIC and EPILOG patient populations. Additional economic issues relate to minimizing bleeding complications, indirect costs, reduced frequency of emergency procedures, and rationalizing provider/payor policies and incentives to produce the optimal individual patient and societal outcomes. The currently available data concerning the efficacy, safety, and cost provide a compelling argument for embracing abciximab therapy in the treatment of patient subsets where it will be a cost-saving or cost-neutral adjunct to percutaneous coronary intervention. In other subsets, the direct medical cost will likely not be fully recouped, but the incremental cost-effectiveness will compare favorably to other widely accepted therapies.

Abciximab↗
PubMed1998

Autonomous epicardial and endocardial boundary detection in echocardiographic short-axis images.

An autonomous endocardial and epicardial boundary detection (ABD) method is reported. One hundred ten cycles from 55 clinical studies were selected retrospectively. Image sequences were digitized at 512 x 480 pixel resolution. The point-by-point boundary positions of the ABD and the areas enclosed were compared with positions and enclosed areas drawn by three independent observers. Correlation coefficients for epicardial end-diastolic (ED) and end-systolic (ES) areas, endocardial ED and ES areas, muscle area, and fractional area change were 0.970, 0.976, 0.951, 0.985, 0.887, and 0.878, respectively. Bland-Altman analysis showed negligible biases with standard deviations comparable to those of the observers. The mean difference between the ABD border and the consensus observer border positions in 64 directions falls within the mean range of interobserver border positions, suggesting that shape is also well defined by the ABD.

Echocardiography↗
PubMed1998

Significance of radiographic cardiomegaly in orthotopic heart transplant recipients.

OBJECTIVE: The purpose of this study is to evaluate the clinical significance of radiographic cardiomegaly in orthotopic heart transplant recipients and to identify causative anatomic and physiologic parameters. MATERIALS AND METHODS: We retrospectively compared the cardiothoracic ratio (CTR) measured using standard posteroanterior chest radiography with left ventricular end-diastolic diameter and left ventricular ejection fraction measured on two-dimensional echocardiography; right ventricular systolic pressure; and systolic, diastolic, and mean blood pressure measured at biopsy in 46 heart transplant recipients. RESULTS: Twenty-eight (61%) of the 46 patients had radiographic cardiomegaly. When we compared heart transplant recipients who had a CTR greater than 0.5 with recipients who had a CTR less than or equal to 0.5, we found no significant difference between their respective left ventricular end-diastolic diameters, left ventricular ejection fractions, right ventricular systolic pressures, systolic blood pressures, or mean blood pressures. A statistically significant difference existed between the mean values of diastolic blood pressure for transplant recipients with and without radiographic cardiomegaly. We found no significant correlation between CTR and left ventricular end-diastolic diameter, left ventricular ejection fraction, systolic blood pressure, diastolic blood pressure, or mean blood pressure. CONCLUSION: The statistically significant difference between the mean values of diastolic blood pressure of transplant recipients with and without radiographic cardiomegaly is clinically insignificant and unlikely to account for the finding of radiographic cardiomegaly. We conclude that radiographic cardiomegaly, which occurs frequently in heart transplant recipients, does not correlate with anatomic or physiologic parameters obtained under the same conditions. Radiographic cardiomegaly in heart transplant recipients does not connote allograft dysfunction or heart failure.

Adult↗
PubMed1998

Abciximab therapy in percutaneous intervention: economic issues in the United States.

Whether abciximab therapy should be the standard of care during percutaneous intervention in the United States depends on its efficacy, safety, and economics. In view of the EPIC, CAPTURE, and EPILOG data, few question the superior efficacy and relative safety of abciximab compared with conventional high-dose heparin therapy during percutaneous intervention. Economic considerations have been the major issue limiting its use. Review of the economic data demonstrates that the incremental direct medical care cost of abciximab therapy is $290 to $600 per patient treated in the EPIC and EPILOG populations. In the patients with acute myocardial infarction and unstable angina, abciximab appears to reduce direct medical costs (produce cost savings) at 6 months. Given abciximab's significant incremental effectiveness, its relatively small incremental cost yielded a highly cost-effective therapy in the EPIC and EPILOG patient populations. Additional economic issues relate to minimizing bleeding complications, indirect costs, reduced frequency of emergency procedures, and rationalizing provider/payor policies and incentives to produce the optimal individual patient and societal outcomes. The currently available data concerning the efficacy, safety, and cost provide a compelling argument for embracing abciximab therapy in the treatment of patient subsets where it will be a cost-saving or cost-neutral adjunct to percutaneous coronary intervention. In other subsets, the direct medical cost will likely not be fully recouped, but the incremental cost-effectiveness will compare favorably to other widely accepted therapies.

Abciximab↗
PubMed1997

Pulmonary AV malformations after superior cavopulmonary connection: resolution after inclusion of hepatic veins in the pulmonary circulation.

BACKGROUND: A high incidence of pulmonary arteriovenous malformations (PAVMs) has been reported in patients who have polysplenia and congenital heart disease after superior cavopulmonary anastomosis. Interruption of hepatic venous return to the pulmonary circulation is believed to potentiate the development of PAVMs. Surgical inclusion of hepatic flow in the pulmonary circulation may result in their resolution. METHODS: We reviewed 3 patients with congenital heart disease and polysplenia in whom PAVMs developed and who had subsequent hepatic vein inclusion in the pulmonary circulation. RESULTS: Patients underwent superior cavopulmonary connection at a median age of 8 months. The PAVMs were diagnosed at a median duration of 8 months after operation (arterial saturation <75% in room air). Hepatic venous flow was included in the pulmonary circulation at operation. Resolution of PAVMs occurred at a median duration of 7 months after operation (arterial saturation >90% in room air). CONCLUSIONS: Surgical inclusion of hepatic venous blood in the pulmonary circulation results in the resolution of PAVMs. Electively associating the hepatic veins with the pulmonary vasculature may prevent the development of PAVMs in patients who are at risk.

Arteriovenous Malformations↗
PubMed1997

Dobutamine echocardiography for prediction of ischemic events in heart transplant recipients.

The purpose of this study was to assess the use of dobutamine stress echocardiography in predicting cardiac events in heart transplant recipients. Dobutamine echocardiography was performed in 63 consecutive heart transplant recipients, 52 males and 11 females ranging in age from 12 to 77 years (mean 54), undergoing routine yearly evaluation. Twenty-one patients had abnormal wall motion at baseline or during dobutamine infusion. Over a mean follow-up of 8 months (range 4 to 14), there were six major cardiac events: five occurred among patients with abnormal echocardiography study results; only one event occurred in a patient with a normal echocardiography result. These data suggest that normal wall motion during dobutamine echocardiography identifies a subset of heart transplant recipients at low risk for development of cardiac events, whereas an abnormal study result serves as an important predictor of subsequent cardiac events.

Adolescent↗
PubMed1996

Early reduction of the volume work of the single ventricle: the hemi-Fontan operation.

BACKGROUND: In hearts with a functional single ventricle, cavity volume and myocardial muscle mass increase as a consequence of the excessive volume work associated with parallel pulmonary and systemic circulations. The hemi-Fontan operation was conceived as a means of accomplishing early reduction of the volume work of the single ventricle. METHODS: All patients presenting in infancy with single-ventricle physiology were managed by early hemi-Fontan operation in anticipation of a subsequent completion Fontan operation. Between May 1989 and August 1995, 400 patients less than 2 years of age underwent hemi-Fontan operations. Mean age at operation was 8.5 months (range, 2 months to 24 months). The hemi-Fontan operation included association of superior vena(e) cava(e) with the branch pulmonary arteries, augmentation of the central pulmonary arteries, occlusion of the inflow of the superior vena cava into the right atrium, and elimination of other sources of pulmonary blood flow. RESULTS: Operative mortality ( < 30 days) was 31 of 400 patients (7.8%). For the last 200 patients, operative mortality was 8 of 200 (4.0%). Younger age at operation was not an independent risk factor for operative mortality. Urgent operation in the presence of a hemodynamic burden requiring concomitant procedures was associated with increased mortality. CONCLUSIONS: The hemi-Fontan operation can be accomplished with low operative mortality in young patients, achieving early reduction of the volume work of the single-ventricle heart.

Age Factors↗
PubMed1995

Transhepatic central venous access for cardiac catheterization and radiologic intervention.

We describe a technique of direct puncture and catheterization of the hepatic veins for cardiac catheterization and radiologic intervention in children who lack conventional access routes. Four patients underwent eight direct hepatic vein punctures to allow cardiac catheterization (3 patients) and 5-12 F sheath insertions for balloon dilatation of hepatic vein stenoses (1 liver transplant patient). Gelfoam was injected in the sheath tract for hemostasis. All procedures were successful, including five hepatic vein dilatations and right heart access for three cardiac catheterizations. There were no complications. When conventional venous access is precluded, direct percutaneous catheterization of hepatic veins is easy, effective, and probably low risk.

Cardiac Catheterization↗
PubMed1995

Avoidance of subaortic obstruction in staged management of single ventricle.

BACKGROUND: Subaortic obstruction is a frequent accompaniment of single-ventricle anatomy. Most often, the aorta arises from an outflow chamber that is connected to the single ventricle by a bulboventricular foramen or ventricular septal defect. This connection may be restrictive of flow at birth, or may become obstructive after surgical procedures that reduce the volume work of the ventricle. Subaortic obstruction is recognized as a risk factor for reconstructive surgical procedures for single ventricle. METHODS: To prevent the consequences of subaortic obstruction, we have routinely amalgamated the proximal main pulmonary artery with the ascending aorta and arch early in the management of these patients. From September 1990 through September 1994, 29 neonates and infants with single ventricle and established or potential subaortic obstruction underwent staged reconstructive surgical procedures. The initial operation in the newborn period was a Norwood procedure (18 patients) or a pulmonary artery band (5 patients). All survivors underwent a hemi-Fontan procedure at approximately 6 months. RESULTS: Eighteen patients have undergone a completion Fontan operation with no deaths. Five await completion Fontan. None has subaortic obstruction, and none has pulmonary valve insufficiency that is graded more than mild. CONCLUSIONS: Early association of the proximal main pulmonary artery with the ascending aorta appears to obviate the risks and complications associated with subaortic obstruction in patients with single ventricle.

Cardiac Surgical Procedures↗
PubMed1995

Results of Norwood's operation for lesions other than hypoplastic left heart syndrome.

Norwood's operation provides satisfactory palliation for neonates with hypoplastic left heart syndrome. The dominant physiologic features of hypoplastic left heart syndrome, ductal dependency of the systemic circulation and parallel pulmonary and systemic circulations, are shared by a multitude of other less common congenital heart malformations. Theoretically, these should be equally amenable to palliation by Norwood's operation. Between January 1990 and June 1994, 60 neonates with malformations other than hypoplastic left heart syndrome underwent initial surgical palliation by Norwood's procedure. Diagnoses included single left ventricle with levo-transposition of the great arteries (12); critical aortic stenosis (8); complex double-outlet right ventricle (8); interrupted aortic arch with ventricular septal defect and subaortic stenosis (7); ventricular septal defect, subaortic stenosis, and coarctation of the aorta (7); aortic atresia with large ventricular septal defect (6); tricuspid atresia with transposition of the great arteries (6); heterotaxy syndrome with subaortic obstruction (3); and other (3). There were 10 hospital deaths and 50 survivors (83% survival). After the introduction of inspired carbon dioxide therapy into the postoperative management protocol (1991), 42 of 47 patients survived (89% survival). Mortality was independent of diagnosis and essentially the same as that for hypoplastic left heart syndrome. With minor technical modifications, Norwood's operation provides satisfactory initial palliation for a wide variety of malformations characterized by ductal dependency of the systemic circulation in anticipation of either a Fontan procedure or a biventricular repair.

Aorta, Thoracic↗