Preoperative autologous blood donation for bone marrow harvests: Are we wasting donors' time and blood?

Predeposit autologous blood donation (PAD) is frequently offered to bone marrow donors, but its cost-effectiveness is dubious. We assessed the impact of PAD and bone marrow donation on transfusion requirements; and the use of donated blood units in a retrospective study of 61 bone marrow donors. The mean haemoglobin (Hb) concentration fell from 12.9 to 11.8 g dL(-1) in women who predonated one unit and from 13.2 to 10.9 g dL(-1) in those who predonated two units. In men who donated two units of blood, the Hb concentration decreased to 12.9 g dL(-1). Bone marrow harvest led to a further decline in Hb concentration by 2.3 g dL(-1) in women and by 2.4 g dL(-1) in men. The postharvest Hb fell to <or=9.0 g dL(-1) in 39% of female and in 6% of the male donors; all but one of them had predonated blood. The utilization rate of autologous units was 45.6%, with 55% of women and 24% of men receiving autologous blood. In females, 59% of transfused autologous units were given with the donor's Hb of >or= 9.0 g dL(-1); overtransfusion was even more apparent in men: 71% units were given with a Hb >or= 10.0 g dL(-1). PAD in bone marrow donors is associated with high wastage and increases the likelihood of requiring a transfusion. We recommend that PAD should not be routinely offered to bone marrow donors.

Tracheo-innominate artery fistula after percutaneous tracheostomy: three case reports and a clinical review

Tracheo-innominate artery fistula (TIF) is an uncommon yet life threatening complication after a tracheostomy. Rates of 0.1-1% after surgical tracheostomy have been reported, with a peak incidence at 7-14 days post procedure. It is usually fatal unless treatment is instituted immediately. Initial case reports of TIF resulted from surgically performed tracheostomies. We present three fatalities attributable to TIF, confirmed by histopathology, after percutaneous dilatational tracheostomy (PDT). The use of PDT has resulted in tracheostomies being performed by specialists from different backgrounds and the incidence of this complication may be increasing. Pressure necrosis from high cuff pressure, mucosal trauma from malpositioned cannula tip, low tracheal incision, radiotherapy and prolonged intubation are all implicated in TIF formation. Massive haemorrhage occurring 3 days to 6 weeks after tracheostomy is a result of TIF until proven otherwise. We present a simple algorithm for management of this situation. The manoeuvres outlined will control bleeding in more than 80% of patients by a direct tamponade effect. Surgical stasis is obtained by debriding the innominate artery proximally, then transecting and closing the lumen. Neurological sequelae are few. Post-mortem diagnosis of TIF may be difficult, but specific pathology request should be made to assess innominate artery abnormalities.

Trimetazidine for stable angina

BACKGROUND

Patients with stable angina not controlled by monotherapy with nitrates, beta blockers, or calcium channel blockers are often treated with combinations of these drugs. There may be adverse effects from, or contraindications to, the use of combinations. In low risk groups, medical treatment appears to be as good an option as percutaneous transluminal coronary angioplasty in terms of averting myocardial infarction, death, or subsequent revascularization. Revascularization procedures are too costly or inaccessible for many patients in developing countries therefore effective and safe medical treatment is needed. Trimetazidine is a less well known anti-anginal drug that controls myocardial ischaemia through intracellular metabolic changes. Trimetazidine has been reported, in some studies, to be better tolerated than combined anti-anginal therapy; however it is not considered in published guidelines.

OBJECTIVES

To determine the efficacy and tolerability of trimetazidine in patients with stable angina.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, LILACS and SCISEARCH, without language restriction, from inception to October 2003. Experts in the field were contacted to locate unpublished studies.

SELECTION CRITERIA

Randomised studies comparing trimetazidine with placebo, or other anti-angina drug in adults with stable angina.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied the inclusion criteria, assessed trial quality and extracted data.

MAIN RESULTS

Twenty-three studies (1378 patients) met the inclusion criteria. There was a paucity of information about mortality, cardiovascular events and quality of life. Trimetazidine, compared with placebo, reduced the number of weekly angina attacks ( mean difference -1.44, 95% CI -2.10 to -0.79; P < 0.0001), reduced weekly nitroglycerin tablet consumption (95% CI -1.47 to -2.20, -0.73; P < 0.0001) and improved exercise time to 1 mm segment depression (P=0.0002). Four small trials (263 patients) compared trimetazidine against other anti-anginal agents. One favoured trimetazidine over nitrates. Three tended to favour alternative regimens but with confidence intervals consistent with both major increases and decreases in frequency of angina episodes. In this subgroup, adverse events were considered in 5 trials (448 patients) and totals of 2 versus 12 drop outs due to adverse events were observed in the trimetazidine and alternative regimens respectively, but this was mostly driven by a single trial.

AUTHORS' CONCLUSIONS

Trimetazidine is effective in the treatment of stable angina compared with placebo, alone or combined with conventional anti-anginal agents. Trimetazidine may result in fewer dropouts due to adverse events. Large, long term trials comparing trimetazidine with other anti-anginal drugs assessing clinically relevant important outcomes are required to establish its role in clinical management.

Attenuated response to purified protein derivative in patients with rheumatoid arthritis: study in a population with a high prevalence of tuberculosis

BACKGROUND

The purified protein derivative (PPD) skin test is the only widely used method which detects latent tuberculosis infection (LTBI) and is dependent on a normal T cell function. In rheumatoid arthritis (RA) the T cell function is altered, which may result in an inability to develop an adequate PPD reaction.

OBJECTIVES

To evaluate the response to PPD in patients with RA and to compare it with that of control subjects.

METHODS

112 patients with RA and 96 healthy controls were studied. PPD 5 U was applied using the Mantoux method, and skin reaction was measured at 72 hours. The reaction was considered negative for PPD <5 mm.

RESULTS

There were no significant differences in age, sex, history of bacille Calmette-Guerin vaccination, or tuberculosis contact between the two groups. The median size of the PPD induration in the patients with RA was significantly less than that in the control group (4.5 v 11.5 mm, p<0.01). 79 (70.6%) patients with RA compared with 25 (26%) of the control group had a negative reaction to PPD (p<0.01), a response not influenced by disease activity or duration of disease in the patients with RA.

CONCLUSION

A PPD skin test is not an appropriate test for recognising LTBI in patients with RA in our population.

Risk of silicosis in cohorts of Chinese tin and tungsten miners and pottery workers (II): Workplace-specific silica particle surface composition

BACKGROUND

It is hypothesized that surface occlusion by alumino-silicate affects the toxic activity of silica particles in respirable dust. In conjunction with an epidemiological investigation of silicosis disease risk in Chinese tin and tungsten mine and pottery workplaces, we analyzed respirable silica dusts using a multiple-voltage scanning electron microscopy-energy dispersive X-ray spectroscopy (MVSEM-EDS).

METHODS

Forty-seven samples of respirable sized dust were collected on filters from 13 worksites and were analyzed by MVSEM-EDS using high (20 keV) and low (5 keV) electron beam accelerating voltages. Changes in the silicon-to-aluminum X-ray line intensity ratio between the two voltages are compared particle-by-particle with the 90th percentile value of the same measurements for a ground glass homogeneous control sample. This provides an index that distinguishes a silica particle that is homogeneously aluminum-contaminated from a clay-coated silica particle.

RESULTS

The average sample percentages of respirable-sized silica particles alumino-silicate occlusion were: 45% for potteries, 18% for tin mines, and 13% for tungsten mines. The difference between the pottery and the metal mine worksites accounted for one third of an overall chi-square statistic for differences in change in measured silicon fraction between the samples.

CONCLUSION

The companion epidemiological study found lower silicosis risk per unit cumulative respirable silica dust exposure for pottery workers compared to metal miners. Using these surface analysis results resolves differences in risk when exposure is normalized to cumulative respirable surface-available silica dust.

Measuring the extent and effectiveness of protected areas as an indicator for meeting global biodiversity targets

There are now over 100000 protected areas worldwide, covering over 12% of the Earth's land surface. These areas represent one of the most significant human resource use allocations on the planet. The importance of protected areas is reflected in their widely accepted role as an indicator for global targets and environmental assessments. However, measuring the number and extent of protected areas only provides a unidimensional indicator of political commitment to biodiversity conservation. Data on the geographic location and spatial extent of protected areas will not provide information on a key determinant for meeting global biodiversity targets: 'effectiveness' in conserving biodiversity. Although tools are being devised to assess management effectiveness, there is no globally accepted metric. Nevertheless, the numerical, spatial and geographic attributes of protected areas can be further enhanced by investigation of the biodiversity coverage of these protected areas, using species, habitats or biogeographic classifications. This paper reviews the current global extent of protected areas in terms of geopolitical and habitat coverage, and considers their value as a global indicator of conservation action or response. The paper discusses the role of the World Database on Protected Areas and collection and quality control issues, and identifies areas for improvement, including how conservation effectiveness indicators may be included in the database to improve the value of protected areas data as an indicator for meeting global biodiversity targets.

Mechanical evaluation of mandibular defects reconstructed using osteogenic protein-1 (rhOP-1) in a sheep model: a critical analysis

Osteoinductive bone morphogenetic proteins (BMPs) have been used extensively in experimental and clinical orthopaedic research. It is a natural progression for these growth regulators to be tested in the craniofacial region. The aim of this investigation was to analyse the mechanical properties of the sheep mandibles reconstructed using recombinant human osteogenic protein type 1 (rhOP-1). A unilateral 35 mm osteoperiosteal continuity defect was created at the parasymphyseal region of the mandible in six adult sheep. The animals were sacrificed 3 months after surgery and mechanical properties of the regenerated bone at the operated sides (OS) were compared to the corresponding bone at the non-operated side (NOS). The regenerated tissue at the OS were then submitted for histological and histomorphometric analysis. Although all the animals achieved complete bony union, a wide range of mechanical properties was found. The rhOP-1-induced bone achieved a mean of 36% of the strength of the bone at the NOS (P < 0.05). The mean value of the stiffness of the OS was 24% of the NOS (P < 0.05). While half of the samples of the OS had 'weak' mechanical properties (9-25% strength compared to NOS) and a low stiffness (6-18%), the rest showed relatively higher strength (47-63%) and were stiffer (35-47%). Unlike the NOS, the operated sides failed under tensile stresses and cracks initiated at the superior border of the mandible. The wide mechanical variations suggest that further basic bone biology research is needed to provide better understanding of the cellular and molecular events which take place during the process of osteoinduction.

Colonization and maintenance of murine embryonic stem cells on poly(alpha-hydroxy esters)

The aim of this study was to determine the ability of various poly(alpha-hydroxy esters) to support the in vitro propagation of murine embryonic stem (ES) cells in an undifferentiated state. To this end, ES cell colonization, growth and Oct-4 immunoreactivity following a 48 h culture period upon poly((D,L)-lactide), poly((L)-lactide), poly(glycolide) and poly((D,L)-lactide-co-glycolide) (PLGA) were assessed. By the analysis of live and dead cell number indices and Oct-4 immunoreactivity, ES cell colonization rate during a 48 h culture period was found to be significantly greater on PLGA compared to all the other unmodified poly(alpha-hydroxy esters) tested. Surface treatment of all polymers with 0.1m potassium hydroxide revealed a significant increase in ES cell live numbers when compared to all unmodified polymers, thus revealing a correlation between polymer content, hydrophilicity and colonization rate. These data suggest that surface treated poly(alpha-hydroxy esters) may be employed for ES cell scale up procedures and in tissue engineering applications requiring the colonization of scaffolds by ES cells in an undifferentiated state. According to such applications, once the designated scaffold has been colonized, ES cell directed differentiation into the desired and fully differentiated, functional adult tissue may then be effected.

Sintered hydroxyfluorapatites--IV: The effect of fluoride substitutions upon colonisation of hydroxyapatites by mouse embryonic stem cells

Biodegradable scaffolds serve a central role for tissue engineering scaffolds and guiding tissue regeneration. Some of these scaffolds, including apatites, display a significant effect upon cell adhesion and cell proliferation. The incorporation of scaffold technology with the developing embryonic stem (ES) cell field and the capacity of ES cells for self-renewal and differentiation are believed to hold enormous potential for applications in biomedical research and regenerative medicine. The purpose of this work was to determine the effect of hydroxyapatite (HAP) and fluoride substitutions of HAP upon ES cell growth and colonisation. Sintered hydroxyfluorapatite discs were found to support cellular proliferation and colonisation, and the ES cells displayed a tendency for differentiation on the apatite surface as determined by reductions in colony Oct4 immunoreactivity. Fluoride-containing HAPs were found to provide equivalent support to gelatin in terms of cell numbers, yet superior support for cellular colonisation when compared to HAP. This study indicates that fluoride substitutions of HAP may represent a viable strategy for the development of certain engineered tissue replacements and tissue regeneration systems using ES cells.

Assessing investment in manual handling risk controls: a scoring system for use in observational studies

Most UK hospitals now have manual handling policies, but few studies have assessed their impact. To facilitate such research, a system for ranking the investment in manual handling risk controls was devised and applied to 109 acute hospitals in the UK. High scoring hospitals performed well on all aspects of manual handling risk management. Low scoring hospitals had a manual handling policy and recorded accidents and sickness absence, but had limited resource for expert manpower and equipment.

Manual handling risk controls in hospitals (MARCH): a cross-sectional survey of UK hospitals

Injury and ill health among healthcare staff associated with handling patients is an important area of risk for UK National Health Service (NHS) employers. Since the introduction of a specific legal duty to control this risk in 1992, many Trusts have developed manual handling risk management strategies. Anecdotally, however, practice varies between Trusts and there is no published description of common practice among NHS employers. The latter would be useful as a benchmark for risk managers. Therefore, we undertook a cross-sectional survey of 158 UK trusts (81% of those invited) using a structured interviewer-administered questionnaire to collect information about manual handling risk controls. Most Trusts had basic systems for risk management, including defined management accountability, written policies, provision of handling equipment, training, expert advice about manual handling and access to occupational health services and physiotherapy for injured employees. However, there was wide variation in important aspects, including the extent of expert manpower and criteria for referral to occupational health. Arrangements for monitoring risk controls were generally poor, and the variation in practice was a cause for concern. These data will help NHS employers by providing a benchmark against which to measure and develop risk management systems for manual handling. Future research should aim to develop standards through consensus opinion and ultimately evidence of effectiveness of risk controls.

Access to the internet in an acute care area: experiences of nurses

The internet is expected to play a key role in delivering evidence-based practice (Department of Health (DoH), 1997, 1998a; Beyea, 2000). In the UK, poor access to the internet and a lack of knowledge and confidence have been identified as barriers to nurses accessing evidence via the internet. The study described here aimed to evaluate how open access to the internet in an acute ward area had an impact upon the evidence-based practice of nurse and allied health professionals. The study was funded by the Department of Health. It incorporated a survey of over 200 staff, semi-structured interviews and monitoring of internet use. The results indicate that the ward-based internet facilities were valued and used by nurses. However, time, support and training are required for nurse to realize the full potential of the internet. Future partnerships between health science libraries and the NHS are recommended to help staff to access and use the internet in order to answer clinically derived questions.

Development of guidelines for improved hydraulic design of waste stabilisation ponds

Pond hydraulic behaviour is influenced by the inlet/outlet configuration, baffles and wind, but design information relating to these factors is still very limited. This paper reviews the development of "Guidelines for the Improved Hydraulic Design of Waste Stabilisation Ponds" and summarises some of the key findings and recommendations. This work was based on review of previous research, laboratory experimentation, field studies and mathematical modelling using computational fluid dynamics. The inlet design can have a significant influence on the flow regime in a pond. Poorly considered positioning of the inlet and the outlet can create hydraulic short-circuiting problems. As an example of the nature of the work undertaken in this project, the use of a small horizontal inlet pipe was compared against a vertical inlet design. A practical method of assessing the relative significance of wind versus inlet power input was presented. The application of this analysis may allow engineers to size inlet pipes to help control the flow patterns in ponds for efficient performance. Extensive testing has been undertaken on a wide range of baffle configurations. An example of this research showed how short stub baffles could provide similar improvements to longer "traditional" baffle designs, potentially offering significant savings in construction costs. For traditional baffle designs a minimum of two baffles is recommended. For the pond modelled in this work, it was found that any more than four baffles gave only marginal improvements.

Integration of coliform decay within a CFD (computational fluid dynamic) model of a waste stabilisation pond

CFD mathematical modelling offers the potential to predict the actual flow pattern in a pond rather than generalising its mixing and mass transport as either an ideal flow reactor or, in the case of the non-ideal flow reactor, as a single dispersion number. However, perhaps the greatest benefit that CFD offers over the previous approaches is its ability to directly account for physical influences on the pond hydraulics such as the addition of baffles for example. In addition to solving the equations of fluid flow, CFD modelling also allows incorporation of other equations. The next logical development is, therefore, the integration of a reaction model within its solution domain. This potential has been recognised by several researchers, but to date no such work has been published. The primary aim of this paper was to present a CFD model of a field pond that incorporates the first order decay equation for coliforms. Experimental monitoring of the field pond gave an average effluent concentration of 3,710 f.c./100 mL, while the CFD model predicted 4,600 f.c./100 mL. Considering the pond provides an order of magnitude decrease in faecal coliform concentration, the integrated CFD model has clearly predicted the treatment efficiency very well. The secondary aim of this paper was to demonstrate the potential application of this technique. A typical pond was designed and modelled along with two variations incorporating two baffles and six baffles respectively. As is typically found in pond systems, the standard design suffered from severe short-circuiting with the model predicting a value of 6.2 x 10(6) f.c./100 mL at the outlet. The simulations of the baffled designs illustrate how treatment efficiency was improved by reducing the short-circuiting through the pond. The model predicted values of 6.0 x 10(3) f.c./100 mL for the 2-baffle design and 5.7 x 10(2) f.c./100 mL for the 6-baffle design.

Implementation of statutory occupational respiratory health surveillance

Health surveillance is required by UK regulations in certain circumstances, and is usually provided through an occupational health organization. Although there are studies assessing the provision of health surveillance across the country, there are no published studies addressing the practical application of legislation, guidelines and medical research to respiratory health surveillance programmes. An audit of a multidisciplinary health surveillance programme was carried out, using review of occupational health records, occupational hygiene reports and managers' risk assessments, to compare the implementation of health surveillance in different organizations and under different contractual relationships. Sixty-six per cent of National Health Service (NHS) and 56% of industrial workplaces were able to provide risk assessments but were unable to link these with appropriate health surveillance. Twenty-seven per cent of NHS employees potentially exposed to respiratory sensitizers had baseline surveillance, compared with 87% in industry. Fifty-five per cent of Medical Research Council questionnaires were inappropriately administered by the employee themselves, rather than an interviewer as recommended. Other follow-up questionnaires in use had not been formally validated. Non-regular lung function assessment using spirometry was the predominant tool used for follow-up surveillance. There was no overall strategic approach to respiratory health surveillance in the organization studied. Health surveillance programmes should focus on disease prevention without becoming a repetitious application of unvalidated tools. Clinical governance demands quality assurance standards that will effectively implement a coordinated approach to health surveillance.