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Biomedical subjects

M Keaney

Publications and source records attributed to M Keaney.

18 recordsLinked to original sources
PubMed1999

Auditing the implementation of SIGN (Scottish Intercollegiate Guidelines Network) clinical guidelines.

Clinical practice guidelines are increasingly being recognised as integral to the clinical effectiveness agenda. According to the recent Scottish White Paper, Scotland "leads the way in clinical effectiveness". The Scottish Intercollegiate Guidelines Network (SIGN), established in 1993, has produced over 20 clinical practice guidelines, and plans to produce at least as many more, while reviewing existing guidelines at a minimum of every two years. This represents a substantial investment of NHS resources. This paper investigates whether this investment is being recouped in Scottish NHS acute trusts via the implementation of SIGN guidelines, and whether their implementation is being audited properly. It is argued that without clinical audit, guideline implementation is unlikely to succeed. This has important ramifications for the implementation of clinical governance.

Accreditation↗
PubMed1998

Health and efficiency: clinical effectiveness dissected.

If the exclusive promotion of values inimical to our basic humanity extends to the health care policy arena, we face a defensive, restricted, impersonal and ultimately impoverished health care system. Americans known it already as 'managed-care'. This is why it is crucial for health policy analysts to make explicit the role of values in policy-making, especially that involving the input of 'value-neutral' economics. The nature of any clinical effectiveness policy will be determined by the understanding of cost-effectiveness employed in its design and implementation. Given that cost-effectiveness is nowadays usually defined according to health economists' criteria, the battle over the meaning of clinical effectiveness is a significant development in health economics' move to assume control of the NHS.

Clinical Competence↗
PubMed1997

Can economics be bad for your health?

The increasing popularity of economic evaluation methods, especially cost effectiveness analysis, brings with it the danger of decisions being made on the basis of faulty criteria. This paper explores the underlying faults of orthodox economics, and offers tentatively an alternative means of decision appraisal via John Dewey's philosophy of instrumentalism and the methods of institutionalist economics.

Cost-Benefit Analysis↗
PubMed1995

Responses of systemic and pulmonary veins to the presence of an intravascular stent in a swine model.

The outcome of stent implantation for children with pulmonary venous obstruction has been characterized by late reocclusion associated with a marked vessel neointimal proliferation. The purpose of this study was to compare the responses of the systemic vein and pulmonary vein to the presence of an intravascular stent, using a Yorkshire swine (N = 10) model. Under cardiopulmonary bypass, a single Palmaz stent was placed in the inferior vena cava (IVC) and right lower pulmonary vein (PV) with sacrifice at 4.9-6.1 months. Angiography and hemodynamic data were determined at 1 and 3 months post-stent implant and prior to euthanasia. All stents were found to be patent, with no difference in degree of thrombosis or neointimal formation. No statistical difference was found in the initial and final stent diameter for both inferior vena cava and pulmonary vein stents (PV initial 6.8 +/- 0.9; final 7.1 +/- 0.6) (IVC initial 10.4 +/- 1.2; final 10.4 +/- 1.2). Electron microscopy demonstrated smooth endothelialization of both pulmonary and systemic venous stent devices. No thrombosis was found on gross morphology. The data indicate that there is no intrinsic difference in the response of the pulmonary vein to the presence of a stent device. The clinical experience of restenosis following stent implantation for pulmonary vein stenosis appears to be more related to variables of final stent diameter combined with the marked intrinsic abnormal vessel architecture, as seen with this condition.

Angiography↗
PubMed1995

Assessment of the cytotoxicity of the photosensitizing drug BPD verteporfin using human vascular smooth muscle cells in culture.

Photosensitizing drugs are selectively taken up by lipid-rich lesions such as atheromatous plaque which when exposed to light render the drugs cytotoxic. However, skin photosensitivity which persists for many weeks is a significant side effect. We investigated the cytotoxicity of a new photosensitizing drug, the benzoporphyrin derivative BPD verteporfin (Quadra Logic Technologies), which does not have this deleterious side effect. Vascular smooth muscle cells (VSMC) from normal human mammary and diseased human coronary arteries were grown in culture from explants and characterized with respect to their growth rates. The sensitivity to BPD with and without light was assessed by measuring viability after treatment. The lethal dose of drug for 50% viability loss (LD50) for BPD with light was approximately 12.5 ng/ml for mammary artery, with 52 +/- 8% cell survival (n = 6). The coronary artery VSMC from all patient sources, although differing significantly in growth rate, had a survival of 44 +/- 6% (n = 12) at the same concentration of BPD used for the mammary artery SMC (p = NS). Our results established the LD50 for BPD using human arterial sources of SMC and showed that the growth rates of the cells did not affect the cytotoxicity of the drug.

Cell Survival↗
PubMed1993

Transcutaneous energy transfer system performance evaluation.

A transcutaneous energy transfer (TET) system has been developed to power implantable devices such as artificial hearts, defibrillators, and electrical stimulators. Transcutaneous coupling of power to these implanted devices remains a favorable alternative as percutaneous lines are avoided in order to eliminate the potential of infection and allow patient mobility. In vitro, in vivo, ex vivo, and human cadaver studies of the electrohydraulic ventricular assist device TET have demonstrated that power can be transmitted over a range of skin thicknesses of 3-15 mm and can tolerate radial misalignments of up to 20 mm. Sensitivity to coil separation and radial misalignment variations has been addressed by the development of an auto-tuning TET. The system has only a 10% attenuation in secondary coil voltage when metallic objects are in contact with the primary coil. The system has demonstrated a power transfer efficiency of 60-80% for power demands from 5 to 70 W. The TET secondary coil will provide an output voltage of 10-25 V for current demands from 0.5 to 4.0 A. TET chronic studies in porcine models have demonstrated no adverse effect to the tissue when up to 40 W of power can be delivered to an implanted load without the tissue-contacting surface of the coil exceeding 42 degrees C. In conclusion, the TET is a feasible alternative for tether-free power transmission.

Cadaver↗
PubMed1987

Intravenous or intraperitoneal vancomycin for the treatment of continuous ambulatory peritoneal dialysis associated gram-positive peritonitis?

A clinical and pharmacokinetic study was carried out to determine whether an intraperitoneal (IP) loading dose of vancomycin was as effective as an intravenous (IV) load in the treatment of continuous ambulatory peritoneal dialysis (CAPD)-associated gram-positive peritonitis. Each patient continued a 14-day treatment on IP maintenance doses. All cases of peritonitis (10 in each group) were eradicated. Side effects occurred in 3 patients following IV vancomycin and in none following IP vancomycin. Serum and peritoneal vancomycin concentrations equilibrated fully and rapidly with each route. It is concluded that an IP loading dose of vancomycin, followed by IP maintenance doses, is as effective as and produces fewer side effects than an IV loading dose in the treatment of CAPD peritonitis.

Bacterial Infections↗
PubMed1986

In vivo and in vitro dielectric properties of feline tissues at low radiofrequencies.

The dielectric constant and conductivity of muscle, liver, spleen and kidney of cats in vivo and in situ immediately following the animal's death were measured at frequencies from 10 kHz to 100 MHz. A novel multi-ring capacitive sensor and a computer-controlled automatic network analyser (ANA) were employed. The results were compared with the data available from literature for the same species in the frequency range between 10 and 100 MHz. It was found that at frequencies from 10 to 100 kHz the in vitro dielectric constant for all tissues except spleen was smaller than the in vivo one. In contrast, in the range from 1 to 100 MHz the in vitro dielectric constant was larger than the in vivo one. At intermediate frequencies from 0.1 to 1 MHz both the dielectric constant in vivo and in vitro were the same within the experimental uncertainty. The dielectric constant of the spleen in vivo was quite similar to that in vitro. The in vivo conductivity of all tissues appeared to be higher than in vitro from 10 kHz to 10 MHz, while at frequencies above 10 MHz the two conductivities were within the experimental uncertainty.

Animals↗
PubMed1985

Discrete lesions of the area postrema abolish radiation-induced emesis in the dog.

Studies carried out in several mammalian species during the 1950's led to the concept of a 'vomiting center' located in the dorsolateral reticular formation and a 'chemoreceptor trigger zone' (CTZ) within or near the area postrema (AP). This early work suggested that the AP was essential for vomiting induced by a variety of chemical emetics and by ionizing radiation. However, the lesion techniques used often produced significant damage to neural tissue underlying the AP, as well as to the AP itself, making localization of function very difficult. In the present study, electrolytic lesions confined to the AP abolished both radiation- and apomorphine-induced emesis in dogs. Thus, in addition to its postulated function in osmoreception and central cardiovascular regulation, the AP also appears to have a key role in vomiting initiated by chemical emetics and by ionizing irradiation.

Animals↗
PubMed1982

Ketoconazole versus nystatin plus amphotericin B for fungal prophylaxis in severely immunocompromised patients.

72 patients severely immunocompromised by their underlying disease (marrow aplasia, acute leukaemia, or solid tumour) or by the treatment they were receiving, or both, were randomised to receive antifungal prophylaxis with either oral ketoconazole or conventional doses of oral amphotericin B and nystatin. All patients also had gut decontamination with non-absorbable antibiotics, skin antisepsis, sterile food, and oral cotrimoxazole. Protection against fungal infection was significantly superior with ketaconazole. When patients who had received allogeneic bone-marrow transplant were studied separately, there was no significant difference between the two treatments, probably because there was a fall-off in ketoconazole absorption from the end of the third week after the transplant. However, ketoconazole greatly reduced the likelihood of fungal infection in non-transplant patients.

Amphotericin B↗
PubMed1980

The antibody-dependent cell-mediated cytotoxic reaction. II. The effect of the concentration of anti-target cell antibodies on the identity of the human effector cells.

The circulating leucocytes of normal adults (lymphocytes, monocyte-lymphocyte mixtures and neutrophils) were investigated for their capacity to induce antibody-dependent cell-mediated cytotoxicity (ADCC). The target cell was the rabbit antibody-sensitized chicken erythrocyte. Under conditions of optimal target cell sensitization by anti-target cell antibodies, ADCC cytotoxic activity was exhibited by the neutrophils and lyphocytes to the apparent exclusion of the monocytes. The lymphocytes exhibit activity more rapidly than do the neutrophils and they are more active on an equal cell basis. However, when the effector cells were investigated using target cells sensitized with the anti-target cell antiserum in a threshold concentration, the monocyte and not the lymphocyte or neutrophil displayed ADCC cytotoxic activity. It was concluded that the effector cells in the circulation are heterogeneous and include subclasses of lymphocytes, monocytes and neutrophils and that the identity of the cytotoxic effector cells appears to vary with the concentration of anti-target cell antibodies.

Antibodies↗
PubMedDate not supplied

Evolution of an electrohydraulic ventricular assist device through in vivo testing. The EVAD Team.

A totally implantable intrathoracic electrohydraulic ventricular assist device has been developed at the University of Ottawa Heart Institute. In vivo testing has been instrumental in its progressive development. A total of 15 experiments (4 acute, 11 performance) have been performed using male calves (62-117 kg). Data from the acute experiments, human fit trials, fluid dynamic studies, and hydraulic/energy efficiency analyses formed the basis for the development of a compact, single piece ventricular assist device called the Unified System in which the volume displacement chamber, motor, and blood chamber are housed within a compact 600 cc, 740 g unit. The performance experiments indicated that the unified system could support calves for periods up to 96 hr. The mean postoperative cardiac output was 7.1 +/- 0.7 L/ min (range = 4.9-11), mean blood pressure was 99.7 +/- 5.8 mmHg, and mean pulmonary artery pressure was 32.1 +/- 1.2 mmHg. The operative technique for intrathoracic implantation has been developed. The major problems encountered were of respiratory failure, improved by device repositioning in the calf; decreased blood inflow to the device that was improved by cannula redesign; circuit board fracture corrected by design modification; and a power supply problem that was limited to a single unit. The preliminary experiments have helped in the design modifications of the Unified System. The improved version of the system will undergo formal performance, reliability, and chronic in vivo testing before human implantation.

Animals↗
PubMedDate not supplied

In vivo evaluation of an intrathoracic ventricular assist device.

In this series of experiments, the Unified System components of the HeartSaver Ventricular Assist Device (VAD) version 5.0 were isolated from the controller and power supply for independent assessment. Five systems with external controller/power supply via a percutaneous lead configuration were tested in 13 male calves (101.8+/-4.3 kg). Two studies were ended acutely because of improper filling and air embolism, respectively. Duration of support was from 2.2 hours to 30 days (mean, 99+/-62 hours). The 30 day survivor was euthanized electively. Study termination was related to postoperative complications in five calves: two with bleeding/tamponade, one with thromboembolism caused by inadequate anticoagulation, and two with respiratory insufficiency. Other causes of termination were: one caused by main building power failure, two from errors in communication between the device and controller, and two caused by hydraulic fluid loss related to housing defects. From these experiments, an intrathoracic position for the calf has been defined, the procedure for implantation without cardiopulmonary bypass has been developed, refinements to the controller have been made, and inflow and outflow cannulae have been reinforced. Hydraulic fluid losses will be solved by proceeding with use of a titanium housing instead of polyurethane. In conclusion, the development of the HeartSaver VAD is progressing, in part because of these experimental and informative animal studies. Further in vivo evaluation of the final version will be conducted before clinical trials.

Animals↗