Evaluation of urinary chloride dipsticks for the rapid estimation of hydration status in patients receiving artificial nutrition: Feasibility study

BACKGROUND AND AIMS

The home parenteral nutrition (HPN) population face many challenges, especially with respect to fluid balance management. A low urinary sodium concentration of <20 mmol/L is commonly used as an indicator of dehydration that requires clinical assessment in these patients. The Quantab titrator dipstick measures chloride concentration of a solution and correlates with sodium concentration. We assessed whether it would be feasible to use the Quantab dipstick in the HPN population and explored relationships between Quantab dipstick estimated chloride concentration and quality of life (QOL).

METHODS

Patients on HPN were asked to collect urine samples at 5 specific times points (day 0,7,14, 21 and 28) to send to the laboratory for formal electrolyte analysis. The participant and a member of laboratory staff tested these samples with the Quantab dipstick to estimate urinary chloride concentration. Participants were instructed to complete a QOL questionnaire at each of the 5 time-points in addition to a baseline demographic questionnaire and an end-of-study questionnaire. Six participants completed an interview at the end of the study period. The relationship between participant-derived and laboratory-derived data was assessed using rank correlation coefficients. QOL assessment was correlated with urine dipstick measurements.

RESULTS

10 patients on HPN completed the study. Data on chloride concentration as estimated by the dipstick (assessed by participants and by the laboratory) and sodium concentration from the laboratory were available for 47 urine samples. There was a positive relationship between participant dipstick estimated chloride concentration and laboratory sodium (Kendall's τ = 0.45; P < 0.001; Spearman's r_s = 0.58 P < 0.001; 47 pairs). There was a strong correlation between chloride concentrations estimated by dipstick in the laboratory and by participants (Kendall 0.58 p < 0.001, Spearman's 0.69 p < 0.001; 47 pairs). In exploratory analyses, there was no relationship between QOL and dipstick estimated chloride concentration. Participants had no issues collecting urine samples but some difficulties were reported with determining the dipstick reading.

CONCLUSIONS

Patients on HPN are able to collect urine specimens, complete QOL questionnaires, and are capable of using the Quantab dipstick to estimate urinary chloride concentration. The Quantab dipstick correlates with laboratory measured sodium and chloride concentrations. Further work is required to fully establish whether this point-of-care test could be used to guide fluid balance management in the HPN population.

Estimating the diagnostic accuracy of the ankle-brachial pressure index for detecting peripheral arterial disease in people with diabetes: A systematic review and meta-analysis

AIM

To systematically evaluate research investigating the accuracy of the ankle-brachial index (ABI) for diagnosing peripheral artery disease (PAD) in people with diabetes, as the accuracy is thought to be reduced in this cohort.

METHODS

A database search of EBSCO Megafile Premier, Embase and The Cochrane Library was conducted to 28 February 2019. Prospective and retrospective investigations of the diagnostic accuracy of the ABI for PAD in people with diabetes using an imaging reference standard were eligible. Sensitivity and specify of the ABI and bivariate meta-analysis against reference tests, or a standard summary receiver operating curve analysis (SROC) was performed.

RESULTS

Thirty-three studies met the inclusion criteria. ABI was compared with angiography in 12 studies and with colour duplex ultrasound (CDUS) in 21 studies. A SROC analysis of studies using angiography as the reference standard found a diagnostic odds ratio (DOR) of 9.06 [95% confidence interval (CI) 3.61 to 22.69], and area under the curve (AUC) of 0.76 (95% CI 0.66 to 0.86). Bivariate analysis of studies using CDUS demonstrated mean sensitivity of 0.60 (95% CI 0.48 to 0.71; P = 0.097) and mean specificity of 0.87 (95% CI 0.78 to 0.92; P < 0.001) with a DOR of 9.76 (95% CI 5.24 to 18.20; P < 0.0001) and AUC 0.72.

CONCLUSIONS

These results suggest the ABI has a high specificity but lower sensitivity in detecting imaging diagnosed PAD in people with diabetes. The low probability of the testing being able to rule diagnosis in or out suggest that the ABI has limited effectiveness for early detection of PAD in this cohort.

The development of a theory informed behaviour change intervention to improve adherence to dietary and physical activity treatment guidelines in individuals with familial hypercholesterolaemia (FH)

BACKGROUND

Familial hypercholesterolaemia (FH) is a genetic condition characterised by elevated levels of low-density lipoprotein cholesterol (LDL-C) and an increased risk of cardiovascular disease (CVD). Following dietary and physical activity guidelines could help minimise this risk but adherence is low. Interventions to target these behaviours are therefore required. A comprehensive understanding of the target behaviours and behaviour change theory should drive the process of intervention development to increase intervention effectiveness and scalability. This paper describes the application of a theoretical framework to the findings of a qualitative evidence synthesis (QES) to inform the content and delivery of an intervention to improve adherence to dietary and physical activity guidelines in individuals with FH.

METHODS

The Behaviour Change Wheel (BCW) was used to guide intervention development. Factors influencing dietary and physical activity behaviours were identified from an earlier QES and mapped onto factors within the BCW. A comprehensive behavioural diagnosis of these factors was conducted through application of the theoretical domains framework (TDF). Using these data, the most appropriate intervention functions and behaviour change techniques (BCTs) for inclusion in the intervention were identified. Decision making was guided by evaluation criteria recommended by BCW guidance and feedback from individuals with FH.

RESULTS

Factors influencing dietary and physical activity behaviours mapped onto twelve of the fourteen TDF domains, with seven intervention functions deemed suitable to target the domains' theoretical constructs. Twenty-six BCTs were identified as being appropriate for delivery within these functions and were included in the intervention. For instance, within the enablement intervention function, the BCT problem solving was incorporated by inclusion of a 'barriers and solutions' section. Guided by evaluation criteria and feedback from individuals with FH, the intervention will be delivered as an hour-long family-based appointment, followed up with four telephone calls.

CONCLUSIONS

The novel application of the BCW and TDF to the results of a QES has enabled the development of a theory and evidence informed behaviour change intervention. This systematic approach facilitates evaluation of the intervention as part of an ongoing feasibility trial. The transparent approach taken can be used to guide intervention development by researchers in other fields.

Prevalence of ankle equinus and correlation with foot plantar pressures in people with diabetes

BACKGROUND

An association between equinus and plantar pressure may be important for people with diabetes, as elevated plantar pressure has been linked with foot ulcer development. To determine the prevalence of equinus in community dwelling people with diabetes and to examine any association between presence of equinus and forefoot plantar pressures.

METHODS

Barefoot (Tekscan HR Mat™) and in-shoe (Novel Pedar-X®) plantar pressure variables, non-weight bearing ankle range of motion and neuropathy status were assessed in 136 adults with diabetes (52.2% male; 47.8% with neuropathy; mean (standard deviation) age and diabetes duration: 68.4 (11.5) and 14.6 (11.1) years respectively).

FINDINGS

Equinus, when measured as ≤5° dorsiflexion, was present in 66.9% of the cohort. There was a significant correlation between an equinus and barefoot (r = 0.247, p = 0.004) and in-shoe forefoot pressure time integrals (r = 0.214, p = 0.012) and in-shoe forefoot alternate pressure time integrals (r = 0.246, p = 0.004). Significantly more males (p < 0.01) and people with neuropathy (p = 0.02) or higher glycated haemoglobin levels (p < 0.01) presented with an equinus.

INTERPRETATION

Community dwelling adults with diabetes have a high rate of ankle equinus which is associated with increased forefoot pressure time integrals and a two-fold increased risk of high in-shoe peak pressures. Clinical assessment of an ankle equinus may be a useful screening tool to identify adults at increased risk of diabetic foot complications.

Prenatal diagnosis and implications of microphthalmia and anophthalmia with a review of current ultrasound guidelines: two case reports

BACKGROUND

Microphthalmia and anophthalmia are rare congenital fetal abnormalities. The combined incidence is estimated at 1 in 10,000 births. These two conditions arise from complex and incompletely understood genetic and/or environmental causes. Prenatal diagnosis is neither frequent nor easy and relies on precise, high-quality ultrasonography. Current antenatal ultrasound protocols for imaging of the fetal eye are inconsistent and inadequate to screen for the spectrum of ocular malformations, and there are no clear guidelines on detection of these rare abnormalities. Our study of two cases highlights the importance of early detection, and we review current practice and suggest a definitive fetal imaging protocol.

CASE PRESENTATION

We present two antenatal cases, one each of microphthalmia and anophthalmia, both diagnosed at the morphology scan at our tertiary fetal medicine unit. In both cases, the parents (a 36-year-old woman of Mauritanian ethnicity and a non-consanguineous partner of Nepalese descent, and a 31-year-old Caucasian woman and non-consanguineous Caucasian partner) elected to terminate their pregnancies and made unremarkable recoveries. Subsequent fetal autopsy confirmed the ultrasound scan findings.

CONCLUSIONS

We recommend that antenatal ultrasound guidelines are updated to specify use of a curvilinear transducer (2-9 MHz) to image both orbits in the axial and coronal planes, aided by use of a transvaginal probe when the transabdominal approach is inadequate to generate these images. When applicable, three-dimensional reverse-face imaging should be obtained to aid the diagnosis. The presence, absence, or non-visualization of lenses and hyaloid arteries should be documented in reports and these cases referred for a tertiary-level ultrasound scan and fetal medicine review. Imaging of the orbits should occur from 12 weeks' gestation. Magnetic resonance imaging and amniocentesis with chromosome microarray testing may provide additional genetic and structural information that may affect the overall morbidity associated with a diagnosis of microphthalmia or anophthalmia.

Weight bearing versus non-weight bearing ankle dorsiflexion measurement in people with diabetes: a cross sectional study

Background

Accurate measurement of ankle dorsiflexion is important in both research and clinical practice as restricted motion has been associated with many foot pathologies and increased risk of ulcer in people with diabetes. This study aimed to determine the level of association between non-weight bearing versus weight bearing ankle dorsiflexion in adults with and without diabetes, and to evaluate the reliability of the measurement tools.

Methods

One hundred and thirty-six adults with diabetes and 30 adults without diabetes underwent ankle dorsiflexion measurement non-weight bearing, using a modified Lidcombe template, and weight bearing, using a Lunge test. Pearson product-moment correlation coefficients, intraclass correlation coefficients (ICCs) with 95% confidence intervals, standard error of measurement and minimal detectable change were determined.

Results

There was a moderate correlation (r = 0.62–0.67) between weight and non-weight bearing tests in the non-diabetes group, and a negligible correlation in the diabetes group(r = 0.004–0.007). Intratester reliability was excellent in both groups for the modified Lidcombe template (ICC = 0.89–0.94) and a Lunge test (ICC = 0.83–0.89). Intertester reliability was also excellent in both groups for the Lidcombe template (ICC = 0.91) and a Lunge test (ICC = 0.88–0.93).

Conclusions

We found the modified Lidcombe template and a Lunge test to be reliable tests to measure non-weight bearing and weight bearing ankle dorsiflexion in adults with and without diabetes. While both methods are reliable, further definition of weight bearing ankle dorsiflexion normative ranges may be more relevant for clinical practice.

Potential of electric bicycles to improve the health of people with Type 2 diabetes: a feasibility study

AIM

To explore in a feasibility study whether 'e-cycling' was acceptable to, and could potentially improve the health of, people with Type 2 diabetes.

METHODS

Twenty people with Type 2 diabetes were recruited and provided with an electric bicycle for 20 weeks. Participants completed a submaximal fitness test at baseline and follow-up to measure predicted maximal aerobic power, and semi-structured interviews were conducted to assess the acceptability of using an electric bicycle. Participants wore a heart rate monitor and a Global Positioning System (GPS) receiver in the first week of electric bicycle use to measure their heart-rate during e-cycling.

RESULTS

Eighteen participants completed the study, cycling a median (interquartile range) of 21.4 (5.5-37.7) km per week. Predicted maximal aerobic power increased by 10.9%. Heart rate during electric bicycle journeys was 74.7% of maximum, compared with 64.3% of maximum when walking. Participants used the electric bicycles for commuting, shopping and recreation, and expressed how the electric bicycle helped them to overcome barriers to active travel/cycling, such as hills. Fourteen participants purchased an electric bicycle on study completion.

CONCLUSIONS

There was evidence that e-cycling was acceptable, could increase fitness and elicited a heart rate that may lead to improvements in cardiometabolic risk factors in this population. Electric bicycles have potential as a health-improving intervention in people with Type 2 diabetes.

Association between ankle equinus and plantar pressures in people with diabetes. A systematic review and meta-analysis

BACKGROUND

Diabetes is one of the most common chronic diseases in the world and is associated with a life-time risk of foot ulcer of 12-25%. Diabetes related restriction in ankle joint range of dorsiflexion is proposed to contribute to elevated plantar pressures implicated in the development of foot ulcers.

METHODS

A systematic search of EBSCO Megafile Premier (containing MEDLINE, CINAHL, SPORTSdiscus and Academic Search Complete) and The Cochrane Library was conducted to 23rd November 2016. Two authors independently reviewed and selected relevant studies. Meta-analysis of study data were conducted where possible.

FINDINGS

Fifteen studies met the inclusion criteria. Three studies were eligible to be included in the meta-analysis which found that equinus has a significant, but small, effect on increased plantar pressures (ES=0.26, CI 95% 0.11 to 0.41, p=0.001). Of the remaining studies, eight found evidence of an association between limited ankle dorsiflexion and increased plantar pressures while four studies found no relationship.

INTERPRETATION

Limited ankle joint dorsiflexion may be an important factor in elevating plantar pressures, independent of neuropathy. Limited ankle dorsiflexion and increased plantar pressures were found in all the studies where the sample population had a history of neuropathic foot ulceration. In contrast, the same association was not found in those studies where the population had neuropathy and no history of foot ulcer. Routine screening for limited ankle dorsiflexion range of motion in the diabetic population would allow for early provision of conservative treatment options to reduce plantar pressures and lessen ulcer risk.

A pragmatic randomised controlled trial to evaluate the cost-effectiveness of a physical activity intervention as a treatment for depression: the treating depression with physical activity (TREAD) trial

OBJECTIVE

The TREAting Depression with physical activity (TREAD) study investigated the cost-effectiveness of a physical activity intervention, in addition to usual general practitioner care, as a treatment for people with depression.

DESIGN

An individually randomised, pragmatic, multicentre randomised controlled trial with follow-up at 4, 8 and 12 months. A subset of participants took part in a qualitative study that investigated the acceptability and perceived benefits of the intervention.

SETTING

General practices in the Bristol and Exeter areas.

PARTICIPANTS

Aged 18-69 years with an International Statistical Classification of Diseases and Related Health Problems, 10th Edition (ICD-10) diagnosis of depression and scoring ≥ 14 on the Beck Depression Inventory (BDI). Those who were unable to complete self-administered questionnaires in English, with medical contraindications to physical activity or with psychosis, bipolar disorder or serious drug abuse were excluded.

INTERVENTIONS

We devised an intervention designed to encourage choice and autonomy in the adoption of physical activity. It consisted of up to three face-to-face and ten telephone contacts delivered by a trained physical activity facilitator over an 8-month period.

MAIN OUTCOME MEASURES

The primary outcome was the BDI score measured at 4 months. Secondary outcomes included depressive symptoms over the 12 months and quality of life, antidepressant use and level of physical activity.

RESULTS

The study recruited 361 patients, with 182 randomised to the intervention arm and 179 to the usual care arm; there was 80% retention at the 4-month follow-up. The intervention group had a slightly lower BDI score at 4 months [-0.54, 95% confidence interval (CI) -3.06 to 1.99] but there was no evidence that the intervention improved outcome for depression. Neither was there any evidence to suggest a difference in the prescription of or self-reported use of antidepressants. However, the amount of physical activity undertaken by those who had received the intervention was increased (odds ratio 2.3, 95% CI 1.3 to 3.9) and was sustained beyond the end of the intervention. From a health-care perspective, the intervention group was more costly than the usual care group, with the cost of the intervention £220 per person on average. It is therefore extremely unlikely that the intervention is cost-effective as a treatment for depression using current willingness-to-pay thresholds.

CONCLUSIONS

This physical activity intervention is very unlikely to lead to any clinical benefit in terms of depressive symptoms or to be a cost-effective treatment for depression. Previous research has reported some benefit and there are three possible reasons for this discrepancy: first, even though the intervention increased self-reported physical activity, the increase in activity was not sufficiently large to lead to a measurable influence; second, only more vigorous activity might be of benefit; and third, previous studies had recruited individuals with a pre-existing commitment to physical activity. Future research is needed to identify and explain the mechanisms by which depression might be effectively treated, including, in particular, specific guidance on the optimum type, intensity and duration of physical activity required to produce a therapeutic effect.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN16900744.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 16, No. 10. See the HTA programme website for further project information.

Coping style and depression influence the healing of diabetic foot ulcers: observational and mechanistic evidence

AIMS/HYPOTHESIS

Experimental evidence suggests that the healing of diabetic foot ulcers is affected by psychosocial factors such as distress. We examined this proposal in a prospective study, in which we considered the role of psychological distress and coping style in the healing of diabetic foot ulcers over a 24 week period. We also explored the role of salivary cortisol and matrix metalloproteinases (MMPs) as potential mechanisms.

METHODS

For this prospective observational study we recruited 93 (68 men; mean age 60 years) patients with neuropathic or neuroischaemic diabetic foot ulcers from specialist podiatry clinics in secondary care. Clinical and demographic determinants of healing, psychological distress, coping, salivary cortisol and both MMP2 and MMP9 were assessed at baseline. Ulcers were assessed at baseline and at 6, 12 and 24 weeks post-baseline. The primary outcome was ulcer status at 24 weeks, i.e. healed vs not healed.

RESULTS

After controlling for clinical and demographic determinants of healing, ulcer healing at 24 weeks was predicted by confrontation coping, but not by depression or anxiety. Patients with unhealed ulcers exhibited greater confrontation coping (model including depression: OR 0.809, 95% CI 0.704-0.929, p = 0.003; model including anxiety: OR 0.810, 95% CI 0.704-0.930, p = 0.003). However, change in ulcer size over the observation period was associated with depression only (p = 0.04, d = 0.31). Healed ulcers by 24 weeks were also associated with lower evening cortisol, higher precursor MMP2 and a greater cortisol awakening response.

CONCLUSIONS/INTERPRETATION

Confrontation coping and depression predict ulcer healing. Our preliminary enquiry into biological mechanisms suggests that cortisol and precursor MMP2 may underlie these relationships.

The current role of tissue engineering in head and neck reconstruction

Tissue engineering is an emerging field that has the potential to revolutionize the field of reconstructive surgery by providing off-the-shelf replacement products. The literature has become replete with tissue engineering studies, and the aim of this article is to review the contemporary application of tissue-engineered products. The use of tissue-engineered cartilage, bone and nerve in head and neck reconstruction is discussed.

Alliance and compliance in tuberculosis treatment of older Pakeha people in Auckland, New Zealand

SETTING

A community-based ethnography of tuberculosis (TB) treatment of 'European' New Zealanders in Auckland was completed in 2003.

OBJECTIVE

To document and analyse the nature of the process of care in this population where the majority of patients are older with other health and social complications.

DESIGN

Data collection included repeated semi-structured interviews with all patients who were willing and able to give consent, semi-structured interviews on health and TB with matched participants without TB, discussions with health care providers, participant observation with TB patients, readings of patient records and monitoring of TB in the media. Reiterative inductive analyses were made of transcripts, field notes and textual materials.

RESULTS

Eight patients from 2003 (out of a possible nine) and one patient from 1997 participated. All were aged 47-75 years. They represent a wide socio-economic range. All completed treatment. The contribution of multidimensional care, from initial acceptance through exigencies of treatment to successful recovery, is evident in the participants' narratives. The public health nurse is a key support and a lynchpin in the patients' support network.

CONCLUSION

A model of care including alliances between patients and care givers as part of treatment is clearly successful in this population group. This study has implications for older cohorts in other low-incidence countries.

Phenotype of autosomal dominant cone–rod dystrophy due to the R838C mutation of the GUCY2D gene encoding retinal guanylate cyclase-1

AIMS

To describe the phenotype of members of a large Caucasian British family affected by autosomal dominant cone-rod dystrophy due to an R838C mutation in the guanylate cyclase 2D (GUCY2D) gene encoding retinal guanylate cyclase-1 (RETGC-1).

METHODS

Retrospective review of 29 patients from four generations of the same family.

RESULTS

Visual symptoms usually commenced in childhood. Only two patients, aged 14 and 25 years, had visual acuity compatible with driving. Of the 12 patients aged over 40 years, eight (66%) had vision of counting fingers or worse and were eligible for blind registration in the UK. Of the 29 patients, 18 (62%) had myopia greater than 5 D in at least one eye. Most had discernible macular changes on biomicroscopy, which varied from subtle RPE change to gross macular atrophy. All patients who underwent computerised perimetry exhibited a central or paracentral scotoma with normal peripheral field of vision. Of the 21 patients who underwent electrodiagnostic testing, all exhibited decreased cone function, but rod function was normal in 12 (57%) patients.

CONCLUSION

We believe this report highlights the importance of phenotype-genotype correlation in cone and cone-rod dystrophies. Increased understanding of the varying phenotypes associated with different genetic mutations allows appropriate counselling of patients. In addition, the phenotypic characterisation of the natural history of these conditions may prove valuable in the future should therapeutic interventions become available.

Psychosocial and clinical determinants of compliance with occlusion therapy for amblyopic children

AIMS

The objective of this study was to determine the extent that psychosocial and clinical variables influence parental compliance with occlusion therapy (eye patching) in children with amblyopia.

METHODS

Children (n = 151) receiving occlusion therapy (eye patching) for the treatment of amblyopia were recruited from five orthoptic clinics in Bristol, UK. Parents completed a questionnaire based on Rogers' (1983) Protection Motivation Theory (PMT). The parents (n = 105) were also followed up 2 months later. Clinical data, including measures of visual acuity, were also recorded. Compliance with eye patching was assessed through self-report accounts of parents. Stepwise regression analyses were used to determine the factors predictive of compliance with eye patching.

RESULTS

Self-reported compliance with eye patching at study entry revealed that only 54% of parents were achieving orthoptists' recommendations to patch their child. Perceived self-efficacy was positively associated with compliance and perceived prohibition of the child's activities were negatively associated with compliance. At follow-up, past behaviour accounted for the largest proportion of explained variance in patching behaviour followed by response efficacy, and prohibition of the child's activities.

CONCLUSION

The present findings may serve to inform interventions aimed at enhancing current orthoptic practice to improve compliance in amblyopic children. The importance of 'self-efficacy' and past behaviour suggests that consultations with parents exhibiting higher levels of success with patching may elicit strategies that could be shared with parents experiencing difficulties with patching their children. In addition, it is possible that the perceived efficacy of the treatment could be enhanced if orthoptists emphasised evidence of improvements in visual acuity which may, in turn, foster the maintenance of eye patching.

Effect of luminance level on electro-encephalogram alpha-wave synchronisation

A control system for the remote activation of electronic devices, based on alpha-wave synchronisation, must be robust over a wide range of lighting conditions. This study investigates the effect that low light levels have on the increase in amplitude of the occipital alpha-wave component of the human electro-encephalogram spectrum in response to eye closure. Measurements of the time required for the amplitude of the occipital alpha wave to increase above a predetermined threshold, upon eye closure, were taken from 21 subjects and at four illuminances, ranging from 2 x 10(-1) lx to 2 x 10(-5) lx. The light source used to provide these illuminances was a featureless, uniformly illuminated white paper that subtended 30 degrees of the visual field. Statistical analysis showed that the time to exceed threshold (TTET) upon eye closure was not independent (p< 0.001) of illuminance, and that the main source of this lack of independence occurred at the lowest illuminance, 2 x 10(-5) lx. At this luminance, the median TTET value was 15.0s. However, at 2 x 10(-4) lx, the median value of the TTET was 4.2s. This is a sufficiently short time for device activation, and therefore a control system based on alpha-wave synchronisation is functional at very low light levels.

Detection of alpha electro-encephalogram onset following eye closure using four location-based techniques

Detection of alpha activity in the electro-encephalogram (EEG) has been used extensively in neurophysiological studies. Previously applied alpha parameterisation techniques, which utilise the amplitude information from a pair of differential electrodes, are often susceptible to interference from artifact signals. This is an issue if the purpose of detecting the change in alpha wave synchronisation is the basis of an environmental control system (ECS). An alternative approach to alpha activity detection is proposed that utilises the information from an array of electrodes on the scalp to estimate the apparent location of alpha activity in the brain. Four methods are described that successfully detect the onset of alpha EEG increase following eye closure by monitoring the apparent location of alpha activity in the head. The methods use Bartlett beamforming, a four-sphere anatomical head model, the MUSIC algorithm and a new 'power vector' technique. Of the methods described, the power vector technique is found to be the most successful. The power vector technique detects the alpha increase associated with eye closure in times that are, on average, 33% lower than previously applied alpha detection methods.

The effectiveness of activating electrical devices using alpha wave synchronisation contingent with eye closure

Increases in alpha wave amplitude occur with eye closure (EC) and decreases occur when the eyes are opened (EO). The research reports in this paper emphasise effectiveness of people using these alpha wave changes to activate electrical devices. Effectiveness was measured in terms of time taken and errors made when selecting the correct device. Ten non-disabled subjects significantly decreased the time taken and errors made to activate correctly a device using a six-option environmental control system (ECS) in the laboratory. In addition, a severely disabled person was shown to use the ECS successfully to control her television in her home environment. This research demonstrates that alpha wave manipulation contingent with EC and EO can be the basis for a reliable and quick switching system for controlling electrical devices. Applications to disability are discussed.

A direct comparison of wet, dry and insulating bioelectric recording electrodes

Alternatives to conventional wet electrode types are keenly sought for biomedical use and physiological research, especially when prolonged recording of biosignals is demanded. This paper describes a quantitative comparison of three types of bioelectrode (wet, dry and insulating) based on tests involving electrode impedance, static interference and motion artefact induced by various means. Data were collected simultaneously, and in the same physical environment for all electrode types. Results indicate that in many situations the performance of dry and insulating electrodes compares favourably with wet electrodes. The influence of non-stationary electric fields on shielded dry and insulating electrode types was compared to wet types. It was observed that interference experienced by dry and insulating electrode types was 40 dB and 34 dB less than that experienced by wet electrode types. Similarly, the effect of motion artefact on dry and insulating electrodes was compared to wet types. Artefact levels for dry and insulating electrodes were significantly higher than those for wet types at the beginning of trials conducted. By the end of the trial periods artefact levels for dry and insulating types were lower than wet electrodes by an average of 8.2 dB and 6.8 dB respectively. The reservations expressed in other studies regarding the viability of dry and insulating electrodes for reliable sensing of biosignals are not supported by the work described here.

Real time impedance plots with arbitrary frequency components

Temporal changes in the impedance spectra of bioelectrodes in contact with skin provide useful data for comparisons between differing electrode materials and skin preparation methods. Traditional impedance measuring systems employ swept frequency methods which will distort results in the impedance spectra of a sample which has nonstationary electrical characteristics. The system reported here obtains impedance spectra by applying a digitally constructed waveform consisting of many frequency components. This allows impedance values to be measured at a number of frequencies simultaneously. Sample data are provided and compared with data obtained using similar square wave techniques.

Improving the donor site cosmesis of the latissimus dorsi flap

A modification in the design of the pedicled latissimus dorsi musculocutaneous flap is described that aims to minimize the cosmetic morbidity of its donor site. The implications of this variation are discussed with particular reference to use of the flap in postmastectomy reconstruction.

Three methods compared for detecting the onset of alpha wave synchronization following eye closure

Recent work indicates that the variation in the occipital alpha wave component of the EEG spectrum, controlled through eye closure, can be used by an untrained person to effect reliable activation of electrical devices. Here we describe and compare three real-time strategies, based on analogue and digital signal processing methods, of detecting the onset of alpha wave synchronization during eye closure. The goal of this work is to establish a method which satisfies the condition of rapid detection of alpha wave enhancement, thereby allowing for the efficient activation of devices, while simultaneously registering few or no false positives due to the natural variation in the alpha signal with eyes open. This work, based on measurements on 15 subjects in the age range 12 to 40 years, indicates that renal-time analysis of the EEG power spectrum provides for rapid detection of the onset of alpha wave synchronization while maintaining low counts of false positives.

EEG-based system for rapid on-off switching without prior learning

Details are reported of an EEG-based system that permits a person rapidly and reliably to switch on and off electrical devices without prior learning. The system detects and utilises increases in the amplitude of the alpha component of the EEG spectrum that occur when people close their eyes for more than 1 s. In addition to conventional signal-processing elements, the system incorporates a module for suppressing switching at the output of the system when predetermined noise threshold levels (such as those due to sources of EMG) are exceeded. This work indicates that a majority, perhaps in excess of 90%, of the adult population can demonstrate the control necessary to operate an electrical device or appliance using this system. It is indicated that multi-level switching and quasi-continuous control options are feasible with further development of the system. This work has implications for the design of a system that could be used, for example, to assist the infirm or severely physically disabled to effect greater control over their environment.

Measles appendicitis

Measles is a common disorder in the United Kingdom, due partly to the decreasing incidence of vaccination in children of a susceptible age. We report a case of abdominal pain in a child caused by the measles virus.

In situ determination of the molecular weight of hepatic gamma-glutamyl transferase and gamma-glutamyl hydrolase activities

The molecular weight of gamma-glutamyl transferase from normal rat liver and hepatoma tissue was determined by radiation-inactivation and found to be approx 100000 in each case. The molecular weight previously reported for the subunit containing the gamma-glutamyl binding site (22000) is considerably less than that of the holoenzyme, suggesting that in situ the large subunit is implicated in both transferase and hydrolase activities.