A Multielectrode Nerve Cuff for Chronic Velocity Selective Recording in a sheep model

Supra-sacral spinal cord injury (SCI) causes loss of bladder fullness sensation and bladder over-activity, leading to retention and incontinence respectively. Velocity selective recording (VSR) of nerve roots innervating the bladder might enable identification of bladder activity. A 10-electrode nerve cuff for sacral nerve root VSR was developed and tested in a sheep model during acute surgeries and chronic implantation for 6 months. The cuff performed well, with 5.90±1.90 kΩ electrode, and <~800 Ω tissue impedance after 189 days implantation with a stable device and tissues. This is important information for assessing the feasibility of chronic VSR.Clinical Relevance-This demonstrates the manufacturing and performance of a neural interface for chronic monitoring of bladder nerve afferents with applications in urinary incontinence and retention management following SCI.

Closed-loop optogenetic control of the dynamics of neural activity in non-human primates

Electrical neurostimulation is effective in the treatment of neurological disorders, but associated recording artefacts generally limit its applications to open-loop stimuli. Real-time and continuous closed-loop control of brain activity can, however, be achieved by pairing concurrent electrical recordings and optogenetics. Here we show that closed-loop optogenetic stimulation with excitatory opsins enables the precise manipulation of neural dynamics in brain slices from transgenic mice and in anaesthetized non-human primates. The approach generates oscillations in quiescent tissue, enhances or suppresses endogenous patterns in active tissue and modulates seizure-like bursts elicited by the convulsant 4-aminopyridine. A nonlinear model of the phase-dependent effects of optical stimulation reproduced the modulation of cycles of local-field potentials associated with seizure oscillations, as evidenced by the systematic changes in the variability and entropy of the phase-space trajectories of seizures, which correlated with changes in their duration and intensity. We also show that closed-loop optogenetic neurostimulation could be delivered using intracortical optrodes incorporating light-emitting diodes. Closed-loop optogenetic approaches may be translatable to therapeutic applications in humans.

Silicone encapsulation of thin-film SiOx, SiOxNyand SiC for modern electronic medical implants: a comparative long-term ageing study

Objective.Ensuring the longevity of implantable devices is critical for their clinical usefulness. This is commonly achieved by hermetically sealing the sensitive electronics in a water impermeable housing, however, this method limits miniaturisation. Alternatively, silicone encapsulation has demonstrated long-term protection of implanted thick-film electronic devices. However, much of the current conformal packaging research is focused on more rigid coatings, such as parylene, liquid crystal polymers and novel inorganic layers. Here, we consider the potential of silicone to protect implants using thin-film technology with features 33 times smaller than thick-film counterparts.Approach.Aluminium interdigitated comb structures under plasma-enhanced chemical vapour deposited passivation (SiO_x, SiO_xN_y, SiO_xN_y+ SiC) were encapsulated in medical grade silicones, with a total of six passivation/silicone combinations. Samples were aged in phosphate-buffered saline at 67 ^∘C for up to 694 days under a continuous ±5 V biphasic waveform. Periodic electrochemical impedance spectroscopy measurements monitored for leakage currents and degradation of the metal traces. Fourier-transform infrared spectroscopy, x-ray photoelectron spectroscopy, focused-ion-beam and scanning-electron- microscopy were employed to determine any encapsulation material changes.Main results.No silicone delamination, passivation dissolution, or metal corrosion was observed during ageing. Impedances greater than 100 GΩ were maintained between the aluminium tracks for silicone encapsulation over SiO_xN_yand SiC passivations. For these samples the only observed failure mode was open-circuit wire bonds. In contrast, progressive hydration of the SiO_xcaused its resistance to decrease by an order of magnitude.Significance.These results demonstrate silicone encapsulation offers excellent protection to thin-film conducting tracks when combined with appropriate inorganic thin films. This conclusion corresponds to previous reliability studies of silicone encapsulation in aqueous environments, but with a larger sample size. Therefore, we believe silicone encapsulation to be a realistic means of providing long-term protection for the circuits of implanted electronic medical devices.

The Effects of the Presence of Multiple Conduction Velocities in the Analysis of Electrically-Evoked Compound Action Potentials (eCAPs)

New methods for the analysis of electrically-evoked compound action potentials (eCAPs) are described. Mammalian nerves tend to have broad multi-modal distributions of fibre diameters, which translates into a spread of conduction velocities. The method of velocity selective recording (VSR) is unable to distinguish between this spectral spread and the transfer function of the system. The concept of the velocity impulse function (VIF) is introduced as a tool to differentiate between these signal and system attributes. The new methods enable separate estimates of velocity spectral broadening and signal-to-noise ratio (SNR) to be obtained.

Selective Recording of Urinary Bladder Fullness from the Extradural Sacral Roots. Annu Int Conf IEEE Eng Med Biol Soc 2020;2020:3873-3876. [PMID: 33018846 DOI: 10.1109/embc44109.2020.9176038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Managing the urinary bladder is of primary importance to clinicians and patients after trauma to the spinal cord. Sacral Anterior Root Stimulators that control the bladder have been available as clinical technology for many years, however these devices cannot measure the fullness of the urinary bladder or detect the onset of reflex voiding. In order to address this fundamental limitation, it is necessary to develop a method for recording the neural signals that encode bladder fullness. This paper presents a proof of concept technique for recording bladder afferents from the extradural sacral roots using a multiple electrode cuff. Results are provided from acute in-vivo experiments performed in sheep.

Apparatus to investigate the insulation impedance and accelerated life-testing of neural interfaces

Objective. Neural interfaces and other implantable micro-devices that use polymer-encapsulated integrated circuits will only be allowed in medical devices when their lifetimes can be estimated from experimental data. An apparatus has been developed and tested that allows hundreds of insulated samples (interdigitated combs) to be aged under accelerated conditions of high temperature and voltage stress. Occasionally, aging is paused while the sample’s impedance is measured; the impedance spectrogram may show degradation as it progresses before failure. Approach. The design was based on practical considerations which are reviewed. A Solartron Modulab provides the frequency response analyser and the femtoammeter. The apparatus can accommodate batches of samples at several temperatures and with different aging voltage waveforms. It is important to understand features of the spectra that are not due to comb–comb leakage, but come from other places (for example substrate-solution leakage); some have been observed and investigated using SPICE. Main results. The design is described in detail and test results show that it is capable of making measurements over long periods, at least up to 67 °C. Despite the size of the apparatus, background capacitance is about 1 pF and comb–comb capacitances of about 30 pF can be measured down to 10 mHz, an impedance of about 100 GΩ. An important discovery was the advantage of grounding the bathing solution, primarily in that it raises the measurement ceiling. Observation and SPICE simulation shows that leakage from the substrate to the bathing solution can give phase lags  >90°, in contrast to comb–comb leakage which reduces phase lag to  <90°. Significance. The value of this paper is that it will facilitate research into the endurance of small implanted devices because, given a description of a proven apparatus, researchers can start building their own apparatus relatively quickly and with confidence.

Lessons learned on recruitment and retention in hard-to-reach families in a phase III randomised controlled trial of preparatory information for children undergoing general anaesthesia

BACKGROUND

Recruitment and retention are documented as two of the most difficult elements of conducting clinical trials. These issues are even more challenging in paediatric trials, particularly when the families being recruited and retained are deemed 'hard to reach'.

METHODS

Through the authors' own reflection on the conduct of the trial this paper examines recruitment and retention with hard to reach families from the perspective of a recently completed clinical trial on preparatory information for children undergoing general anaesthesia for tooth extractions in which approximately 83% of those approached and eligible agreed to participate.

RESULTS

The lessons learned for recruitment include: the importance of children's assent; maximising limited resources when screening and approaching potential participants; valuing families' time; and developing effective professional relationships. The retention rate was 83-85.5% at follow up time points up to 3.5 weeks following recruitment, insights into how this was accomplished include: ensuring continuity of care; determination to connect via telephone; valuing families' time; and close monitoring of appointment date changes.

CONCLUSIONS

Implications for future paediatric trials with hard to reach families are discussed.

TRIAL REGISTRATION

ISRCTN18265148 ; NIHR Portfolio 10,006. Date of Registration: 29 November 2013. The trial was registered after commencement but before completion of data collection.

Motivation to study dental professions in one London Dental Institute

INTRODUCTION

While past research has explored dental students' motivation to study, there is limited understanding in the reasons behind career choice for hygienists/therapists and dental nurses. The aim of this study was to investigate simultaneously the views of students of dentistry, hygiene/therapy and dental nursing in King's College London and explore similarities or differences in career choice.

METHODS

All first-year students were invited to the questionnaire survey, exploring motivation to study using a 23-item instrument. Data were analysed using SPSS v18; statistical analysis included one-way analyses of variance and factor analysis.

RESULTS

The overall response rate to the study was 75% (n = 209). Ten out of 23 factors were considered important by more than 80% of respondents, with 'job security' (93.8%), 'desire to work with people' (88%) and 'degree leading to recognised job' (87.5%) being top three. Analysis suggested that 52% of the total variation in motivating influences was explained by four factors: 'features of the job' (26%), 'education/skills' (11%), 'public service' (8%) and 'careers-advising' (7%); at group level 'features of the job' were significantly more important for the direct entrants to dentistry (P = 0.001).

DISCUSSION

The findings suggest that across groups students were motivated to study by common influences reflecting altruistic, but also pragmatic and realistic motives, while 'features of the job' were more important for the direct entrants to dentistry.

Corrosion of silicon integrated circuits and lifetime predictions in implantable electronic devices

Corrosion is a prime concern for active implantable devices. In this paper we review the principles underlying the concepts of hermetic packages and encapsulation, used to protect implanted electronics, some of which remain widely overlooked. We discuss how technological advances have created a need to update the way we evaluate the suitability of both protection methods. We demonstrate how lifetime predictability is lost for very small hermetic packages and introduce a single parameter to compare different packages, with an equation to calculate the minimum sensitivity required from a test method to guarantee a given lifetime. In the second part of this paper, we review the literature on the corrosion of encapsulated integrated circuits (ICs) and, following a new analysis of published data, we propose an equation for the pre-corrosion lifetime of implanted ICs, and discuss the influence of the temperature, relative humidity, encapsulation and field-strength. As any new protection will be tested under accelerated conditions, we demonstrate the sensitivity of acceleration factors to some inaccurately known parameters. These results are relevant for any application of electronics working in a moist environment. Our comparison of encapsulation and hermetic packages suggests that both concepts may be suitable for future implants.

The effect of counselling, graded exercise and usual care for people with chronic fatigue in primary care: a randomized trial

BACKGROUND

To evaluate the effectiveness of graded exercise therapy (GET), counselling (COUNS) and usual care plus a cognitive behaviour therapy (CBT) booklet (BUC) for people presenting with chronic fatigue in primary care.

METHOD

A randomized controlled trial in general practice. The main outcome measure was the change in the Chalder fatigue score between baseline and 6 months. Secondary outcomes included a measure of global outcome, including anxiety and depression, functional impairment and satisfaction.

RESULTS

The reduction in mean Chalder fatigue score at 6 months was 8.1 [95% confidence interval (CI) 6.6-10.4] for BUC, 10.1 (95% CI 7.5-12.6) for GET and 8.6 (95% CI 6.5-10.8) for COUNS. There were no significant differences in change scores between the three groups at the 6- or 12-month assessment. Dissatisfaction with care was high. In relation to the BUC group, the odds of dissatisfaction at the 12-month assessment were less for the GET [odds ratio (OR) 0.11, 95% CI 0.02-0.54, p=0.01] and COUNS groups (OR 0.13, 95% CI 0.03-0.53, p=0.004).

CONCLUSIONS

Our evidence suggests that fatigue presented to general practitioners (GPs) tends to remit over 6 months to a greater extent than found previously. Compared to BUC, those treated with graded exercise or counselling therapies were not significantly better with respect to the primary fatigue outcome, although they were less dissatisfied at 1 year. This evidence is generalizable nationally and internationally. We suggest that GPs ask patients to return at 6 months if their fatigue does not remit, when therapy options can be discussed further.

Colonoscopic high frequency mini-probe ultrasound is more accurate than conventional computed tomography in the local staging of colonic cancer

AIM

Colonoscopic high frequency mini-probe ultrasound was compared prospectively with CT in the local staging of colonic cancer.

METHOD

Consecutive patients undergoing surgical resection for colonic cancer were recruited. Preoperative 64-slice CT staging with multiplanar reconstruction was compared with colonoscopic high frequency mini-probe ultrasound using 12 MHz and 20 MHz probes. The three methods of staging (CT, 12 MHz ultrasound and 20 MHz ultrasound) were compared with the histological stage of the resected specimen. This was done using weighted kappa coefficients where weights of 0.7-0.8 were given to penalize disagreements of one level in either direction and weights of zero were given to penalize disagreements of more than one level in any direction.

RESULTS

In total, 38 patients with colonic cancer were included. They were located in the sigmoid (n = 20), descending (n = 5), ascending (n = 2) and transverse colon (n = 1) and in the caecum (n = 7) and splenic (n = 2) and hepatic (n = 1) flexure. Histopathological assessment revealed seven pT1, four pT2, 25 pT3 and two pT4 cancers. In relation to the pathology the weighted kappa coefficients were 0.36 (SE = 0.14), 0.81 (SE = 0.16) and 0.81 (SE = 0.17) for CT, ultrasound 12 MHz and ultrasound 20 MHz. Histopathologically 15 (39.5%) patients were lymph node positive. The sensitivity, specificity and kappa coefficient for detection of nodal disease for CT were 80%, 47.8% and 0.25 (SE = 0.14) compared with 80%, 82.5% and 0.62 for 12 MHz ultrasound (SD = 0.14) and 23%, 90.5% and 0.15 (SD = 0.13) for 20 MHz ultrasound.

CONCLUSION

Colonoscopic ultrasound is significantly more accurate than CT for T staging of colonic cancers. With respect to nodal status, 12 MHz ultrasound offers superior accuracy to CT or 20 MHz ultrasound.

An assessment of oral health promotion programmes in the United Kingdom

BACKGROUND

Improving oral health and reducing tooth decay is a key area for action, both in the United Kingdom (UK) and overseas. The World Health Organization (WHO) has highlighted the unique advantage schools have in promoting oral health.

AIM

We summarise current oral health promotion strategies in the United Kingdom and estimate the spread of their use as well as their impact on oral health and influence on the oral health-related knowledge and behaviour in a patient population.

METHODS

A structured overview of published papers, government publications, official government websites and policy reports. A cross-sectional study of patients referred for a tooth extraction in one dental surgery in south-east London. Statistical methods consisted of logistic and ordinal regressions to model the likelihood of exposure to oral health promotion and of obtaining higher levels of knowledge of oral health issues, respectively. Linear regression was used to model the level of oral health and knowledge of oral health issues.

RESULTS

We found three main promotion programmes, namely, National Healthy Schools (NHS), Sure Start and Brushing for life plus a small number of local initiatives. Sure Start targets disadvantaged areas, but is limited. In our observational study, 34% of the patients reported exposure to a settings-based oral health education programme: Sure Start (5%), NHS (7%) and other (22%). This exposure was not influenced by age or gender, but an association with education was detected. Although oral health promotion was not found to influence the actual knowledge of oral health issues, it was found to influence some oral health-related attitudes and perceptions.

CONCLUSIONS

Participation in an oral health promotion programme was found to be significantly associated with the patients' education, their belief that they can prevent oral disease and the subjective perception of their own oral health. The WHO principles need to be embedded across all schools to achieve a true national oral health promotion programme for the United Kingdom. The National Healthy Schools programme provides the perfect platform.

High-power integrated stimulator output stages with floating discharge over a wide voltage range for nerve stimulation

Two integrated nerve stimulator circuits are described. Both generate passively charge-balanced biphasic stimulating pulses of 1 to 16 mA with 10-¿s to 1-ms widths from 6- to 24-V supplies for implanted book electrodes. In both circuits, the electrodes are floating during the passive discharge anywhere within the range of the power rails, which may be up to 24 V. The first circuit is used for stimulation only. It uses a floating depletion transistor to enable continuous discharge of the electrodes, except when stimulating, without using power. The second circuit also allows neural signals to be recorded from the same tripole. It uses a modified floating complementary metal-oxide semiconductor (CMOS) discharge switch capable of operating over a range beyond the gate-to-source voltage limits of its transistors. It remains off for long periods using no power while recording. A 0.6-¿m silicon-on-insulator CMOS technology has been used. The measured performance of the circuits has been verified using multiple tripoles in saline.

Study of the factors affecting health-related quality of life in adolescents after liver transplantation

The aim of the study was to identify factors affecting health-related quality of life (HRQL) in adolescents after liver transplantation. HRQL was measured using the CHQ-CF87 in 55 adolescents, aged 12-18 years. Factors associated with HRQL included allograft morbidity, psychological and family-related variables measured through standardized questionnaires. The domains of the CHQ-CF87 were reduced using factor analysis to give physical, psychological and social domains. Impacting factors were identified through stepwise, multiple regression analysis. Adolescents had significantly lower HRQL in every domain except for role/social-behavior and family cohesion compared to the general population. Adolescents experienced median 18 (range 4-31) symptoms related to immunosuppression, 40(75%) had one or more chronic illnesses related to immunosuppression and 12(22%) had a history of emotional difficulties. Self-esteem and emotional health were similar to the general population but behavior and aspects of family function were lower. Following regression analysis, the factors associated with HRQL were: age at transplant, secondary chronic illness, symptom distress, headaches, history of emotional difficulties, self-esteem and family conflict. These explained 57% of the variance in physical function, 61% of psychological function and 39% of social function. HRQL is significantly reduced in adolescents after transplantation, which could be related to immunosuppression and psychosocial factors.

An Integrated Implantable Stimulator That is Fail-Safe Without Off-Chip Blocking-Capacitors

We present a neural stimulator chip with an output stage (electrode driving circuit) that is fail-safe under single-fault conditions without the need for off-chip blocking-capacitors. To miniaturize the stimulator output stage two novel techniques are introduced. The first technique is a new current generator circuit reducing to a single step the translation of the digital input bits into the stimulus current, thus minimizing silicon area and power consumption compared to previous works. The current generator uses voltage-controlled resistors implemented by MOS transistors in the deep triode region. The second technique is a new stimulator output stage circuit with blocking-capacitor safety protection using a high-frequency current-switching (HFCS) technique. Unlike conventional stimulator output stage circuits for implantable functional electrical stimulation (FES) systems which require blocking-capacitors in the microfarad range, our proposed approach allows capacitance reduction to the picofarad range, thus the blocking-capacitors can be integrated on-chip. The prototype four-channel neural stimulator chip was fabricated in XFAB's 1-mum silicon-on-insulator CMOS technology and can operate from a power supply between 5-18 V. The stimulus current is generated by active charging and passive discharging. We obtained recordings of action potentials and a strength-duration curve from the sciatic nerve of a frog with the stimulator chip which demonstrate the HFCS technique. The average power consumption for a typical 1-mA 20-Hz single-channel stimulation using a book electrode, is 200 muW from a 6 V power supply. The silicon area occupation is 0.38 mm(2) per channel.

Prevalence of Neisseria gonorrhoeae infection in young subjects attending community clinics in South London

OBJECTIVES

To describe the prevalence and epidemiology of gonococcal infection in young subjects attending community clinics in South-East London.

METHODS

Subjects <25 years of age participating in the National Chlamydia Screening Programme were tested for gonococcal infection using a nucleic acid amplification test (strand displacement amplification assay).

RESULTS

10 523 tests were performed in 7369 patients (82% female) over a 2-year period in 2004 and 2005. Specimens used for tests were self-taken vulvovaginal swabs (43%), cervical swabs (40%), urine (16%) and urethral swabs (0.9%). Reasons for tests were: screening (67%), diagnosis (27%) and contacts of patients with chlamydia or gonococcus infection (7%). A significantly higher percentage of male subjects were tested as contacts (19% male vs 4% female; p<0.001). Of the 10 117 cases with definite results, 414 were positive (prevalence 4.1%, 95% CI 3.7% to 4.5%). There was a significantly higher prevalence in male subjects (5.7% male v 3.8% female; p<0.001). The average number of tests was 1.4 per patient (range 1-10). Contacts had a significantly higher prevalence (15.5%, p<0.001) than those tested for diagnostic (3.6%) or screening (3.1%) purposes. Multivariate regression analysis confirmed that there was a significantly higher prevalence in black Caribbean (5.8%, OR 2.44), black British/other black (5.6%, OR 2.33) and mixed (5.5%, OR 2.25) than white (2.4%) ethnic groups (p<0.001). Increasing age was significantly associated with lower prevalence (OR = 0.87; 95% CI 0.84 to 0.91; p<0.001). The odds of a positive test decreased by 13% for every year older.

CONCLUSION

A community-screening programme has detected a high prevalence of Neisseria gonorrhoeae in South London, especially in teenagers, male subjects and certain ethnic groups.

Energetics of paraplegic cycling: a new theoretical framework and efficiency characterisation for untrained subjects

Complete lower-limb paralysis resulting from spinal cord injury precludes volitional leg exercise, leading to muscle atrophy and physiological de-conditioning. Cycling can be achieved using phased stimulation of the leg muscles. With training there are positive physiological adaptations and health improvement. Prior to training, however, power output may not be sufficient to overcome losses involved in rotating the legs and little is known about the energetics of untrained paralysed muscles. Here we propose efficiency measures appropriate to subjects with severe physical impairment performing cycle ergometry. These account for useful internal work (i.e. muscular work done in moving leg mass) and are applicable even for very low work rates. Experimentally, we estimated total work efficiency of ten untrained subjects with paraplegia to be 7.6 +/- 2.1% (mean +/- SD). This is close to values previously reported for anaesthetised able-bodied individuals performing stimulated cycling exercise, but is less than 1/3 of that of able-bodied subjects cycling volitionally. Correspondingly, oxygen cost of the work (38.8 +/- 13.9 ml min(-1) W(-1)) was found to be approximately 3.5 times higher. This indicates the need, for increased power output from paralysed subjects, to maximise muscle strength through training, and to improve efficiency by determining better methods of stimulating the individual muscles involved in the exercise.

The effect of noninvasive ventilation on ALS patients and their caregivers

BACKGROUND

Noninvasive ventilation (NIV) reduces mortality and improves some aspects of quality of life (QoL) in ALS. However, concerns remain that progressive disability may negate these benefits and unnecessarily burden caregivers.

METHODS

Thirty-nine patients requiring NIV were offered treatment. Twenty-six were established on NIV, but 13 declined or could not tolerate NIV. Fifteen patients without respiratory muscle weakness (RMW) but with similar ALS severity and age were studied in parallel. Caregivers of 21 NIV, 7 untreated, and 10 patients without RMW participated. Patients and caregivers had detailed QoL measurements for 12 months. NIV patients underwent cognitive testing before and after treatment.

RESULTS

RMW correlated with lower QoL. The median survival of untreated patients (18 days; 95% CI 11 to 25 days) was shorter than for NIV patients (298 days; 95% CI 192 to 404 days) and non-RMW patients (370 days; 95% CI 278 to 462 days; log rank test [2 df] = 81, p = 0.00001). A wide range of QoL measures improved within 1 month of starting NIV, and improvements were maintained for 12 months. QoL of non-RMW patients declined as RMW progressed. Caregivers of NIV and non-RMW patients showed similar increases in burden, but NIV patient caregivers developed a deterioration in the Short Form-36 Vitality score. No improvements were found on measures of learning and recall in the NIV patients.

CONCLUSIONS

Respiratory muscle weakness has a greater impact on quality of life (QoL) than overall ALS severity. Noninvasive ventilation (NIV) improves QoL despite ALS progression. NIV has no impact on most aspects of caregiver QoL and does not significantly increase caregiver burden or stress.

An Audit of Pain/Discomfort Experienced during Image-Guided Breast Biopsy Procedures

A prospective audit of 221 breast biopsies was carried out to assess the pain/discomfort experienced during image-guided breast biopsies. The only significant factor in pain scores was the size of the needle used. Fine-needle aspiration cytology using a 21-gauge needle was found to cause the most discomfort.

Noise from implantable Cooper cable

Cooper cable is made for implanted devices, usually for connection to stimulating electrodes. An experiment has been performed to see whether these cables would be satisfactory for recording electroneurogram (ENG) signals from cuffs. Four cables were subjected to continuous flexion at 2 Hz while submerged in saline. The cables were connected to a low-noise amplifier, and the noise was measured using a spectrum analyser. These cables had not fractured after 184 million flexions, and the noise in the neural band (500-5000 Hz) had not increased owing to age. Noise in the ENG band increased by less than 3 dB owing to the motion. A fifth, worn cable did fail during the experiment, the conductors becoming exposed to the saline, but this was only apparent by extra noise when the cable was in motion. After 184 million flexions, the four cables were given a more severe test: instead of being connected to the amplifier reference node, two of the four cores of each cable were connected to 18V batteries. Two of the cables were then noisier, but only when in motion, presumably because of leakage between cores. Cooper cables are excellent for transmitting neural signals alone; transmission in one cable of neural signals and power supplies should be avoided if possible.

A randomised controlled comparison of alternative strategies in stroke care

OBJECTIVES

To compare outcomes between stroke patients managed on the stroke unit, on general wards with stroke team support or at home by specialist domiciliary team and to derive prognostic variables that will identify patients most suitable for management by each strategy. To describe organisational aspects of individual strategies of stroke care and to evaluate cost-effectiveness of each strategy and its acceptability to patients, carers and professionals.

DESIGN

Prospective single-blind randomised controlled trial undertaken in patients recruited from a community-based stroke register.

SETTING

Suburban district in south-east England.

PARTICIPANTS

Patients with disabling stroke who could be supported at home.

INTERVENTIONS

The stroke unit gave 24-hour care provided by specialist multidisciplinary team based on clear guidelines for acute care, prevention of complications, rehabilitation and secondary prevention. The stroke team provided management on general wards with specialist team support. The team undertook stroke assessments and advised ward-based nursing and therapy staff on acute care, secondary prevention and rehabilitation aspects. Domiciliary care involved management at home under the supervision of a GP and stroke specialist with support from specialist team and community services. Support was provided for a maximum of 3 months.

MAIN OUTCOME MEASURES

The primary measure was death or institutionalisation at 1 year. Secondary measures were dependence, functional abilities, mood, quality of life, resource use, length of hospital stay, and patient, carer and professional satisfaction.

RESULTS

Of the 457 patients randomised, 152 patients were allocated to the stroke unit; 152 patients to stroke team and 153 patients to domiciliary stroke care (average age 76 years, 48% women). The groups were well matched for baseline characteristics, stroke type and severity, level of impairment and initial disability. Fifty-one (34%) patients in the domiciliary group were admitted to hospital after randomisation. Mortality and institutionalisation at 1 year were lower on stroke unit compared with stroke team or domiciliary care. Significantly fewer patients on the stroke unit died compared with those managed by the stroke team. The proportion of patients alive without severe disability at 1 year was also significantly higher on the stroke unit compared with stroke team or domiciliary care. These differences were present at 3 and 6 months after stroke. Stroke survivors managed on the stroke unit showed greater improvement on basic activities of daily living compared with other strategies. Achievement of higher levels of function was not influenced by strategy of care. Quality of life at 3 months was significantly better in stroke unit and domiciliary care patients. There was greater dissatisfaction with care on general wards compared with stroke unit or domiciliary care. Poor outcome with domiciliary care and on general wards was associated with Barthel Index <5, incontinence and, on general wards, age over 75 years. The total costs of stroke per patient over the 12-month period were pound 11,450 for stroke unit, pound 9527 for stroke team and pound 6840 for home care. However, the mean costs per day alive for the stroke unit were significantly less than those for the specialist stroke team patients, but no different from domiciliary care patients. Costs for the domiciliary group were significantly less than for those managed by the specialist stroke team on general wards.

CONCLUSIONS

Stroke units were found to be more effective than a specialist stroke team or specialist domiciliary care in reducing mortality, institutionalisation and dependence after stroke. A role for specialist domiciliary services for acute stroke is not supported by this study. Management of patients with strokes on general medical wards, even with specialist team input, is not supported by this study. The stroke unit intervention was less costly per patient day alive and more effective than the stroke team intervention. The stroke unit was more effective and of equivalent cost when compared to home care. Hence, the stroke unit is a more cost-effective intervention than either stroke team or home care. Further research is needed to understand processes contributing to the reduction in mortality on stroke units and to determine the generalisability of these results and the factors that will influence the implementation of the findings of this study in clinical practice.

Phentolamine re-dosing during penile dynamic colour Doppler ultrasound: a practical method to abolish a false diagnosis of venous leakage in patients with erectile dysfunction

Increased sympathetic tone may cause an equivocal response to a prostaglandin E1 (PGE1) penile Doppler ultrasound (US) examination interpreted as a venous leak. We evaluated the US parameters and erectile response to the addition of phentolamine to a PGE1 penile Doppler US examination to ascertain whether addition of phentolamine would abolish a suboptimal response. 32 patients (median age 29 years, range 17-70 years) with either a previous Doppler US pattern of venous leakage or a clinical suspicion of venogenic impotence, underwent Doppler US after a total dose of 20 microg of PGE1. Peak systolic velocity (PSV), end diastolic velocity (EDV) and grade of erection were documented. If erectile response was suboptimal irrespective of the EDV measurement, 2 mg-intracavernosal phentolamine was administered and measurements repeated. Six patients had a normal erectile response, the remaining 26 received phentolamine. A significant increase in PSV between baseline and 20 microg PGE1 (p<0.001) was observed in all cases. Following phentolamine there was a significant increase in grade of erection (p=0.0001) and a significant reduction in the EDV (p=0.0001). A reduction of the EDV to below 0.0 cm s(-1) was observed in 16 patients. Four patients with EDV <5.0 cm s(-1) but >0.0 cm s(-1) had improved erectile response following phentolamine while six showed persistent EDV elevation >5 cm s(-1). No priapism was documented. It is essential to ensure cavernosal relaxation using phentolamine before a Doppler US diagnosis of venous leak is made. This two-stage assessment will allow this to be done efficiently and with a low risk of priapism.

Multiple-electrode nerve cuffs for low-velocity and velocity-selective neural recording

In the paper, a method using multiple-electrode nerve cuffs is presented that enables electroneurographic signals (ENG) to be recorded selectively by action potential velocity. The theory uses a one-dimensional model of the electrodes in the cuff. Using this model, the transfer function for a single tripole is derived, and it is shown that more than one tripole signal can be recorded from within a cuff. When many tripole signals are available and are temporally aligned by artificial delays and summed, there is a significant increase in the amplitude of the recorded action potential, depending on the cuff length and the action potential velocity, with the greatest gain occurring for low velocities. For example, a cuff was considered that was constrained by surgical considerations to 30 mm between the end electrodes. For action potentials with a velocity of 120 m s(-1), it was shown that, as the number of tripoles increased from one, the peak energy spectral density of the recorded output increased by a factor of about 1.6 with three tripoles, whereas, for 20 m s(-1), the increase was about 19, with ten tripoles. The time delays and summation act as a velocity-selective filter. With consideration of the energy spectral densities at frequencies where these are maximum (to give the best signal-to-noise ratio), the tuning curves are presented for these velocity-selective filters and show that useful velocity resolution is possible using this method. For a 30 mm cuff with nine tripoles, it is demonstrated that it is possible to resolve at least five distinct velocity bands in the range 20-120m s(-1).

Experimental determination of compound action potential direction and propagation velocity from multi-electrode nerve cuffs

Information extracted from whole-nerve electroneurograms, recorded using electrode cuffs, can provide signals to neuroprostheses. However, the amount of information that can be extracted from a single tripole is limited. This communication demonstrates how previously unavailable information about the direction of action potential propagation and velocity can be obtained using a multi-electrode cuff and that the arrangement acts as a velocity-selective filter. Results from in vitro experiments on frog nerves are presented.

Effect of salmeterol on respiratory muscle activity during exercise in poorly reversible COPD

BACKGROUND

Some patients with irreversible chronic obstructive pulmonary disease (COPD) experience subjective benefit from long acting bronchodilators without change in forced expiratory volume in 1 second (FEV(1)). Dynamic hyperinflation is an important determinant of exercise induced dyspnoea in COPD. We hypothesised that long acting bronchodilators improve symptoms by reducing dynamic hyperinflation and work of breathing, as measured by respiratory muscle pressure-time products.

METHODS

Sixteen patients with "irreversible" COPD (<10% improvement in FEV(1) following a bronchodilator challenge; mean FEV(1) 31.1% predicted) were recruited into a randomised, double blind, placebo controlled, crossover study of salmeterol (50 micro g twice a day). Treatment periods were of 2 weeks duration with a 2 week washout period. Primary outcome measures were end exercise isotime transdiaphragmatic pressure-time product and dynamic hyperinflation as measured by inspiratory capacity.

RESULTS

Salmeterol significantly reduced the transdiaphragmatic pressure-time product (294.5 v 348.6 cm H(2)O/s/min; p = 0.03), dynamic hyperinflation (0.22 v 0.33 litres; p = 0.002), and Borg scores during endurance treadmill walk (3.78 v 4.62; p = 0.02). There was no significant change in exercise endurance time. Improvements in isotime Borg score were significantly correlated to changes in tidal volume/oesophageal pressure swings, end expiratory lung volume, and inspiratory capacity, but not pressure-time products.

CONCLUSIONS

Despite apparent "non-reversibility" in spirometric parameters, long acting bronchodilators can cause both symptomatic and physiological improvement during exercise in severe COPD.

The TG5 thyroglobulin gene test for a marbling quantitative trait loci evaluated in feedlot cattle

The TG5 (thyroglobulin 5′ leader sequence) single nucleotide polymorphism has been associated with marbling in cattle fed for periods longer than 250 days. To test whether the association could be detected in diverse cattle, fed for less than 250 days, and to measure the size of the effect, we sampled 1750 cattle from the AMH Toowoomba feedlot. These cattle were sampled on 28 separate days, over 9 months. Their marbling scores covered the complete range. We found that the TG5 single nucleotide polymorphism was associated with marbling scores (P<0.05) and estimated that TG5 genotypes explained 6.5% of the residual deviance for the marbling phenotype. We also found that the '3' allele was more frequent in animals with higher marbling scores. The consistency of the allelic association between studies and, in particular, the association found in diverse cattle, indicate that the TG5 polymorphism can be used as a breeding tool and possibly a feedlot entry tool. To estimate the size of the genetic region in which the marbling quantitative trait loci are located, we tested the nearby DNA markers CSSM66 and BMS1747. These do not show allelic associations to marbling. The consistency of the allelic association between studies, the lack of association to nearby DNA markers and the complementary information on gene action of genes near Thyroglobulin suggest that DNA sequence variations, in or near the Thyroglobulin gene sequence, are the likely causes for the marbling quantitative trait loci. Further studies of single nucleotide polymorphism in and near the Thyroglobulin DNA sequence should allow causal mutations for the effect to be identified.

Can differences in management processes explain different outcomes between stroke unit and stroke-team care?

BACKGROUND

Stroke units reduce mortality and dependence, but the reasons are unclear. We have compared differences in management and complications of patients with acute stroke who were admitted to a stroke unit or to a general ward as part of a previously reported randomised trial.

METHODS

304 patients had been randomly assigned to stroke units (n=152) or to general wards supported by a specialist stroke team (152). We used a structured format to gather prospective data on the frequency of prespecified interventions in each of the major aspects of stroke care. Observations were undertaken daily for the first week and every week for the next 3 months by independent observers. The effect of differences in management on outcome at 3 months was assessed with the modified Rankin score, dichotomised to good (0-3) and poor (4-6) outcome.

FINDINGS

Patients in the stroke unit were monitored more frequently (odds ratio 2.1 [1.3-3.4]) and more patients received oxygen (2.0 [1.3-3.2]), antipyretics (6.4 [1.5-27.5]), measures to reduce aspiration (6.0 [2.3-15.5]), and early nutrition (14.4 [5.1-40.9]) than those in general wards. Complications were less frequent in patients in the stroke unit than those in general wards (0.6 [0.2-0.7]), with fewer patients having progression of stroke, chest infection, or dehydration. Measures to prevent aspiration, early feeding, stroke unit management, and frequency of complications independently affected outcome.

INTERPRETATION

Differences in management and complications between the stroke unit and general wards differ substantially, even when specialist support is provided. Such differences could be responsible for the more favourable outcome seen in patients on stroke units than those on general wards.

Respiratory muscle strength and ventilatory failure in amyotrophic lateral sclerosis

Although ventilatory failure is the most common cause of death in amyotrophic lateral sclerosis (ALS) and measurement of respiratory muscle strength (RMS) has been shown to have prognostic value, no single test of strength can predict the presence of hypercapnia reliably. RMS was measured in 81 ALS patients to evaluate the relationship between tests of RMS and the presence of ventilatory failure, defined as a carbon dioxide tension > or = 6 kPa. We studied the predictive value of vital capacity (VC), static inspiratory and expiratory mouth pressures (MIP, MEP), maximal sniff oesophageal (sniff P(oes)), transdiaphragmatic (sniff P(di)) and nasal (SNP) pressure, cough gastric (cough P(gas)) pressure and transdiaphragmatic pressure after bilateral cervical magnetic phrenic nerve stimulation (CMS P(di)) to identify the risk of ventilatory failure in the whole group and in subgroups of patients with and without significant bulbar involvement. For patients without significant bulbar involvement, sniff P(di) had greatest predictive power [odds ratio (OR) 57] with specificity, sensitivity and positive and negative predictive values (PPV, NPV) of 87, 90, 74 and 95%, respectively Of the less invasive tests, per cent predicted SNP had greater overall predictive power (OR 25, specificity 85%, sensitivity 81%) than per cent predicted VC (9, 89%, 53%) and per cent predicted MIP (6, 83%, 55%). No test had significant predictive power for the presence of hypercapnia when used to measure RMS in a subgroup of patients with significant bulbar weakness. Thirty-five patients underwent polysomnography. CMS P(di), sniff P(di) and per cent predicted SNP were significantly correlated with the apnoea/hypopnoea index (AHI) (P = 0.035, 0.042 and 0.026, respectively). The correlations between AHI and per cent predicted MIP and VC were less strong (both non-significant). In ALS patients without significant bulbar involvement, novel tests of RMS have greater predictive power than conventional tests to predict hypercapnia. In particular, the non-invasive SNP is more sensitive than VC and MIP, suggesting that it could usefully be included in tests of respiratory muscle strength in ALS and will be helpful in assessing the risk of ventilatory failure. In patients with significant bulbar involvement, tests of respiratory muscle strength do not predict hypercapnia. Sleep-disordered breathing is correlated with RMS and the novel tests of RMS having the strongest relationship with the degree of sleep disturbance.

A response to California's mandated nursing ratios

PURPOSE

To explore the need for evidence-based health policy, as illustrated by the mandatory staffing bill passed by the California state legislature in 1999.

DESIGN

Prospective data were collected from a voluntary sample of California acute care hospital representatives to describe selected patient safety and clinical outcomes and nurse staffing variables at the patient-care unit level.

METHODS

Data for descriptive analysis were collected on hospital nurse staffing, patient falls, and pressure ulcers from 257 medical, surgical, medical-surgical combined, step-down, 24-hour observation units, and critical care patient care units in 38 California acute care hospitals from June 1998 to June 1999.

FINDINGS

Nursing staffing ratios varied among the 257 units. RNs provided 91% of the nursing care in critical care units. Patients in medical-surgical units received 59% of their care from RNs, 11% from licensed vocational nurses, and 30% from other caregivers. Preliminary data showed no relationships between reported staffing ratios in these hospitals and the incidence of patient falls or hospital-acquired pressure ulcers.

CONCLUSIONS

California Nursing Outcomes Coalition (CalNOC) data showed wide variations in staffing ratios, patient falls, and hospital-acquired pressure ulcers among nursing units and hospitals. These early findings indicate the need for additional research before determining minimal RN staffing requirements. Analysis of multiple sources of data may be necessary to determine safe staffing ratios and to provide evidence-based data for public policy.

A prospective study of quality of life in ALS patients treated with noninvasive ventilation

Noninvasive positive pressure ventilation prolongs survival in ALS but its effect on quality of life is unknown. The authors prospectively studied quality of life using the SF-36 questionnaire in a cohort of 16 ventilated patients with ALS. Noninvasive positive pressure ventilation improved scores in the "Vitality" domain by as much as 25%, for periods of up to 15 months, despite disease progression. Noninvasive positive pressure ventilation did not cause reduced quality of life, as any fall in scores in the ventilated group were comparable to those seen in a control group. In conclusion, noninvasive positive pressure ventilation enhances quality of life when used to treat sleep-disordered breathing in patients with ALS.

Hospital nursing benchmarks: the California Nursing Outcomes Coalition project

The California Nursing Outcomes Coalition (CalNOC) project is an initiative that has become the largest ongoing nursing quality measurement repository in the nation. Launched in 1996 by California nursing leaders concerned with trends in hospital care, CalNOC has created reliable quality benchmark data to define patient safety thresholds in California. This article describes CalNOC's effort, which aligns with the strategy of the National Quality Forum for measuring and reporting healthcare quality. By tracing the evolution of the CalNOC project and its future potential, we hope to encourage other grassroots efforts to build the database repositories needed for healthcare quality measurement in the 21st century.

Survival patterns in biliary atresia and comparison of quality of life of long-term survivors in Japan and England

BACKGROUND/PURPOSE

Portoenterostomy is an accepted method of achieving bile drainage in biliary atresia, but there is a paucity of data, including formal quality-of-life (QoL) studies, on long-term survivors. This report includes survival analysis and QoL studies from the world's largest series of cases treated in Japan (1951 to 1998). The Japanese QoL results are compared with a matched group of UK patients from King's College Hospital, London.

METHODS

One hundred fifteen Japanese surviving portoenterostomy patients were studied and comparison of trends in survival calculated from 6-year period cohorts. Liver function and hematologic status in a group of 30 long-term survivors (14 to 24 years) were compared with 25 patients from England, (14 to 23 years). Twenty-five Japanese and 21 UK patients (SF-36) completed a QoL questionnaire.

RESULTS

Median survival times in Japanese patients before 1975 were less than 1 year but increased to 18 years after 1975. Hematologic and liver function test results did not show any significant differences between the Japanese and UK patients. QoL studies in the UK patients showed no significant difference from normative, general population data. Japanese patients underperformed in general health (P = .01), role emotional (P = .05) and role physical (P = .07) but, overall, there was no significant difference between the Japanese and UK patients except for marginal differences in indices of general health and vitality (P = .06 and .04, respectively).

CONCLUSIONS

Long-term survival rate in the Japanese patients increased dramatically from 1 year to 17 years after 1975. The QoL of survivors was comparable in Japan and England. The satisfactory comparison with normative population data suggests that we should continue to use portoenterostomy as the primary treatment for biliary atresia. J Pediatr Surg 36:892-897.

Hospital referrals to a hospice: timing of referrals, referrers' expectations, and the nature of referral information

Hospital referrals to Mary Potter Hospice were reviewed prior to the implementation of a new hospital palliative care support service. The hospital palliative care service aims to improve the communication between health professionals in the acute hospital and hospice, and to advise the hospital staff on its management of terminally ill patients. The purpose of this review was to provide baseline information that would assist the hospice with the planning and future evaluation of the new service. Information included the timing of the referrals, the type of referral information provided by hospital doctors, and their expectations of hospice care. One fifth of patients were referred near to death. While medical information was nearly always provided on referral, information on the psychological, spiritual and social dimensions of care was often absent. A third of hospital doctors expressed their expectation of the hospice as "to take over" the patient's care. This suggests the hospital palliative care support service should encourage health professionals to take a more active role in caring for dying patients. The findings are discussed in relation to the goals of the new hospital palliative care support service.

FES cycling may promote recovery of leg function after incomplete spinal cord injury

STUDY DESIGN

Single subject pilot.

OBJECTIVES

(i) To see whether strength and endurance for recreational cycling by functional electrical stimulation (FES) are possible following spinal cord injury (SCI). (ii) To develop the equipment for FES-cycling.

SETTING

England.

METHODS

Near-isometric or cycling exercise was performed by the incomplete SCI subject at home.

RESULTS

After training for an average of 21 min per day for 16 months, the stimulated muscles increased in size and the subject was able to cycle for 12 km on the level. Surprisingly, there was a substantial increase in the measured voluntary strength of the knee extensors and the subject reports improved leg function.

CONCLUSION

FES-cycling may promote recovery after incomplete spinal cord injury. If so, it offers the possibility of being a convenient method for widespread use.

Alternative strategies for stroke care: a prospective randomised controlled trial

BACKGROUND

Organised specialist care for stroke improves outcome, but the merits of different methods of organisation are in doubt. This study compares the efficacy of stroke unit with stroke team or domiciliary care.

METHODS

A single-blind, randomised, controlled trial was undertaken in 457 acute-stroke patients (average age 76 years, 48% women) randomly assigned to stroke unit, general wards with stroke team support, or domiciliary stroke care, within 72 h of stroke onset. Outcome was assessed at 3, 6, and 12 months. The primary outcome measure was death or institutionalisation at 12 months. Analyses were by intention to treat.

FINDINGS

152 patients were allocated to the stroke unit, 152 to stroke team, and 153 to domiciliary stroke care. 51 (34%) patients in the domiciliary group were admitted to hospital after randomisation. Mortality or institutionalisation at 1 year were lower in patients on a stroke unit than for those receiving care from a stroke team (21/152 [14%] vs 45/149 [30%]; p<0.001) or domiciliary care (21/152 [14%] vs 34/144 [24%]; p=0.03), mainly as a result of reduction in mortality. The proportion of patients alive without severe disability at 1 year was also significantly higher on the stroke unit compared with stroke team (129/152 [85%] vs 99/149 [66%]; p<0.001) or domiciliary care (129/152 [85%] vs 102/144 [71%]; p=0.002). These differences were present at 3 and 6 months after stroke.

INTERPRETATION

Stroke units are more effective than a specialist stroke team or specialist domiciliary care in reducing mortality, institutionalisation, and dependence after stroke.

An improved configuration for the reduction of EMG in electrode cuff recordings: a theoretical approach

A theoretical investigation of different electroneurogram recording techniques using electrode cuffs is presented. A new screened tripole arrangement is proposed with a higher inherent signal to interference ratio than the true tripole, which also allows the nulling of the residual electromyogram signal. The reduction in interference is small because the electrode impedance is large compared to the source resistance.

Prospective cohort study to determine if trial efficacy of anticoagulation for stroke prevention in atrial fibrillation translates into clinical effectiveness

OBJECTIVE

To determine whether trial efficacy of prophylaxis with warfarin for patients with atrial fibrillation at high risk of stroke translates into effectiveness in clinical practice.

DESIGN

Two year prospective cohort study.

SETTING

District general hospital.

PARTICIPANTS

167 patients with atrial fibrillation and at high stroke risk who were eligible for anticoagulation.

INTERVENTIONS

Long term anticoagulation with warfarin at adjusted doses to maintain an international normalised ratio of 2.0-3.0.

MAIN OUTCOME MEASURES

Comparison of patient characteristics, comorbidity, anticoagulation control, stroke rate, and haemorrhagic complications with pooled data from five randomised controlled trials.

RESULTS

Patients in the study group were seven years older (95% confidence interval 4 to 10) and comprised 33% more women than patients in the pooled trials. The international normalised ratio was in the target range for 61% of the time (range 37%-85%), below for 26% of the time (range 8%-32%), and above for 13% of the time (range 6%-26%). The time that patients in the study group spent in the target range was significantly less than in the pooled analysis. The incidence of stroke in the study group (2.0% per year, 0.7% to 4. 4%) was comparable to that of patients receiving warfarin in pooled studies (1.4%, 0.8% to 2.3%). Per year the incidence of major (1.7% v 1.6%) and minor (5.4% v 9.2%) bleeding complications was also similar.

CONCLUSION

Rates of stroke and major haemorrhage after anticoagulation in clinical practice were comparable to those obtained from pooled data from randomised controlled studies for patients with atrial fibrillation at high risk of stroke.

Sequential re-analysis of a phase-III clinical trial in non-small cell lung cancer

This paper presents a reanalysis of a randomized clinical trial conducted by the Cancer and Leukemia Group B (CALGB, Bethesda, MD, USA). This trial found a significant benefit of combination chemotherapy followed by irradiation (CTRT) in comparison to radiotherapy alone (RT) for the treatment of nonsmall cell lung cancer. The validity of the results obtained and the decision to terminate taken by the CALGB, were assessed using sequential methods. The reliability and efficiency of sequential methods were also assessed for this study. Two sequential designs were used: the triangular and the restricted procedure. Initial analyses were conducted with the data from patients actually recruited, adjusting for important prognostic variables at any interim analysis. As a confirmatory technique, a continuation of the trial was simulated, sampling extra patients under the assumption of no treatment difference, preserving the effect of the prognostic variables. Using the results from the 155 patients recruited by the CALGB (88 deaths at termination and 136 after follow-up), the sample path stayed within the continuation region of both sequential designs considered. An underpowered sequential analysis showed significant superiority of CTRT over RT (95% confidence interval (95% CI) 0.50-0.96, p=0.03 for the triangular; 95% CI 0.37-0.88, p=0.01 for the restricted procedure). Conventional analysis of the follow-up data also showed significant superiority of CTRT. The trial extended with simulated data ended at 60 months with 251 patients (178 deaths), showing significant superiority of CTRT under both designs (95% CI for hazard ratio 0.55-0.97). The two sequential procedures would have led to the same conclusion as that reached by the Cancer and Leukemia Group B, still achieving considerable savings in patients recruited and time over the conventional design. The data simulated under the rather conservative null hypothesis did not reverse the positive result claimed by the Cancer and Leukemia Group B.

Experiments with CHRELMS patient-driven stimulator controllers for the restoration of function to paralysed legs

This paper examines the control of electrical stimulators for restoring the standing function to paraplegics. Patient-driven controllers are based on the knowledge that standing, using support handles, is guided by the neurologically intact natural motor control system, acting through the arms. One category of patient-driven controller is CHRELMS (Control by Handle Reactions of Leg Muscle Stimulation). The first experiments with patient-driven controllers are reported. Experiments in the CHRELMS control of one volunteer are described. Proportional control did not allow the subject to stand up because of the strategy he used, but integral control was successful. With it, he could stand up and sit down slowly, entirely guided by himself, as well as making other manoeuvres. Without changing controller mode, and by leaning forwards and backwards, he could 'posture switch' his support muscles. These are significant achievements and justify a larger study of patient-driven controllers. The subject's control strategies are discussed.