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Biomedical subjects

I Schofield

Publications and source records attributed to I Schofield.

At least 19 recordsLinked to original sources
PubMed2006

Amplitude, area and duration of the compound muscle action potential change in different ways over the length of the ulnar nerve.

OBJECTIVE: To study physiological changes of the compound muscle action potential (CMAP) obtained from stimulation at different sites over the full length of a motor nerve and to study possible effects of anthropometrical factors. METHODS: Multicentre study of ulnar motor nerve conduction in five segments to Erb's point performed bilaterally on 100 healthy subjects aged 17-83 years. RESULTS: CMAP amplitude decreased linearly with conduction distance (0.31%/cm) from wrist to Erb's point. CMAP area decreased with the square of conduction distance. Decrease in area was smaller than decrease in amplitude especially distally. CMAP duration increased linearly (0.17%/cm). Amplitude decay correlated with age, height and BMI and dispersion correlated with age and height. There were no correlations between area decay and anthropometrical factors. There was no significant inter-examiner variation. CONCLUSIONS: Area decay may be preferred to amplitude decay in the evaluation of conduction block over short segments due to smaller physiological changes and independence of anthropometrical factors. The absence of inter-examiner variation indicates that the results are robust and may be used by other laboratories. SIGNIFICANCE: This study provides knowledge of physiological changes of CMAP parameters that may be of importance in the evaluation of nerve pathology, in particular conduction block.

Action Potentials↗
PubMed2005

Multivariate prediction of major adverse cardiac events after 9914 percutaneous coronary interventions in the north west of England.

OBJECTIVE: To develop a multivariate prediction model for major adverse cardiac events (MACE) after percutaneous coronary interventions (PCIs) by using the North West Quality Improvement Programme in Cardiac Interventions (NWQIP) PCI Registry. SETTING: All NHS centres undertaking adult PCIs in north west England. METHODS: Retrospective analysis of prospectively collected data on 9914 consecutive patients undergoing adult PCI between 1 August 2001 and 31 December 2003. A multivariate logistic regression analysis was undertaken, with the forward stepwise technique, to identify independent risk factors for MACE. The area under the receiver operating characteristic (ROC) curve and the Hosmer-Lemeshow goodness of fit statistic were calculated to assess the performance and calibration of the model, respectively. The statistical model was internally validated by using the technique of bootstrap resampling. MAIN OUTCOME MEASURES: MACE, which were in-hospital mortality, Q wave myocardial infarction, emergency coronary artery bypass graft surgery, and cerebrovascular accidents. RESULTS: Independent variables identified with an increased risk of developing MACE were advanced age, female sex, cerebrovascular disease, cardiogenic shock, priority, and treatment of the left main stem or graft lesions during PCI. The ROC curve for the predicted probability of MACE was 0.76, indicating a good discrimination power. The prediction equation was well calibrated, predicting well at all levels of risk. Bootstrapping showed that estimates were stable. CONCLUSIONS: A contemporaneous multivariate prediction model for MACE after PCI was developed. The NWQIP tool allows calculation of the risk of MACE permitting meaningful risk adjusted comparisons of performance between hospitals and operators.

Adult↗
PubMed2003

An open-label phase II study of low-dose thalidomide in androgen-independent prostate cancer.

The antiangiogenic effects of thalidomide have been assessed in clinical trials in patients with various solid and haematological malignancies. Thalidomide blocks the activity of angiogenic agents including bFGF, VEGF and IL-6. We undertook an open-label study using thalidomide 100 mg once daily for up to 6 months in 20 men with androgen-independent prostate cancer. The mean time of study was 109 days (median 107, range 4-184 days). Patients underwent regular measurement of prostate-specific antigen (PSA), urea and electrolytes, serum bFGF and VEGF. Three men (15%) showed a decline in serum PSA of at least 50%, sustained throughout treatment. Of 16 men treated for at least 2 months, six (37.5%) showed a fall in absolute PSA by a median of 48%. Increasing levels of serum bFGF and VEGF were associated with progressive disease; five of six men who demonstrated a fall in PSA also showed a decline in bFGF and VEGF levels, and three of four men with a rising PSA showed an increase in both growth factors. Adverse effects included constipation, morning drowsiness, dizziness and rash, and resulted in withdrawal from the study by three men. Evidence of peripheral sensory neuropathy was found in nine of 13 men before treatment. In the seven men who completed six months on thalidomide, subclinical evidence of peripheral neuropathy was found in four before treatment, but in all seven at repeat testing. The findings indicate that thalidomide may be an option for patients who have failed other forms of therapy, provided close follow-up is maintained for development of peripheral neuropathy.

Aged↗
PubMed2003

Variation in the classification of polyneuropathies among European physicians.

OBJECTIVE: Considerable debate still exists regarding the classification of polyneuropathies (PNPs) into predominantly demyelinating, predominantly axonal loss, mixed or unclassified. This study was designed to determine the variation among physicians in the classification of PNPs by using the European Standardized Telematic tool to Evaluate Electromyography knowledge-based systems and Methods (ESTEEM) multicenter database. METHODS: Seven physicians from 6 laboratories in Europe sent a total of 156 prospectively collected cases of PNP with electromyography (EMG) data including diagnosis (examination diagnosis) to the database. Each physician interpreted the electrophysiological data from all cases (interpretation diagnosis) and a final diagnosis was given at the consensus meetings of the group (consensus diagnosis). RESULTS: Comparison of each physician's examination diagnosis with his/her interpretation diagnosis, i.e. intra-physician variation, showed a change towards less classified PNPs (P < 0.05). Interpretation diagnoses showed large inter-physician variation in the classification of PNPs. The consensus group was more cautious than individual physicians in classifying PNPs as mixed and axonal. The probability of the consensus diagnosis increased with increasing number of abnormal motor and sensory segments tested. CONCLUSIONS: Recognition of variation in classification of PNP as shown in this study and suggesting standards of good clinical practice developed by a consensus group may increase the quality of EMG practice.

Consensus↗
PubMed1999

Variation in diagnostic strategy of the EMG examination--a multicentre study.

OBJECTIVES: In order to improve the universal quality of the EMG examination, knowledge about the variation among physicians is needed. METHODS: The variation among physicians in diagnostic strategy or criteria for diagnosing was analysed from a multicentre database with 940 EMG examinations sampled by seven physicians from six laboratories in Europe. RESULTS: For the whole group of patients as well as for the subgroup of patients with polyneuropathy, variation among physicians in examination techniques, number of examined structures per patient and number of abnormal structures per patient required for a diagnosis was found. Some of the variation may be explained by use of different techniques, which showed differences in sensitivity, while some of the variation may be due to differences in diagnostic strategy and criteria for diagnosing. CONCLUSIONS: The study indicates a need for development and revision of international guidelines for EMG practice although implementation of standards requires caution.

Decision Making↗
PubMed1999

Influenza vaccination.

Nurses have an important part to play in dispelling myths about influenza vaccination and in actively encouraging older people to attend for vaccination. Irene Schofield discusses the issues.

Aged↗
PubMed1998

Can medical audit change electromyographic practice?

Considerable variation in EMG practice has been described previously. Since 1992, 7 clinical neurophysiologists from 6 European countries prospectively collected electromyographic (EMG) examinations. The aim of this study was to examine whether several years of mutual influence among physicians using medical audit resulted in a more uniform EMG practice. We studied whether there was a change in the number of examinations per patient and the techniques used from the first 12 to the last 12 EMG examinations on patients with polyneuropathy. For F-wave studies and motor nerve studies, there was a clear change towards a more uniform practice. For sensory nerve conduction studies and muscle studies, there were only minor changes. With regard to examination techniques, there was a reduction in the use of more time-consuming examination techniques (near-nerve sensory studies and quantitative muscle studies). It seems possible to change the EMG practice of individual physicians by international collaboration and medical audit. However, until now most changes have been minor and large differences in European EMG practices persist. The diversity of practices suggests a need for studies on the optimal application of existing examination techniques.

Electromyography↗
PubMed1997

A small exploratory study of the reaction of older people to an episode of delirium.

Delirium or an acute confusional state, occurs as a result of disease or physiological imbalance secondary to impaired brain function. One of its main clinical features is widespread cognitive impairment, which causes patients to become disconnected from their immediate surroundings and misinterpret reality. It has a sudden onset and its duration is relatively brief. Some authors take the view that delirium might be interpreted as a precursor to dementia. The aim of the study was to retrospectively explore older peoples' experience of an episode of delirium. In particular, whether they knew what had caused and cured it; and whether it had left them with any unresolved feelings of anxiety. A cross sectional design using grounded theory methodology was chosen, as being the most appropriate method for exploring this issue. A sample of 19 patients was selected using predetermined criteria, and engaged in a semi-structured interview with the researcher, in the ward environment. The interviews were audiotaped, transcribed, and analysed using the constant comparison method. Those interviewees who had illusions and hallucinations, were often able to describe their experiences in detail. They ranged from being pleasant and entertaining, to horrible and frightening. They were also able to remember short verbal commands from nurses during the episode of altered perception. Others remembered, or chose not to remember, very little. Few interviewees appeared to know exactly what had caused and cured the delirium, although some were able to tentatively connect the experience to their present medical condition. There also appeared to be little evidence of therapeutic communication with nursing staff once the episode of delirium had resolved. Although no one connected the experience with dementia, there did seem to be some evidence of mildly disturbed feelings, on reflecting back over the episode. As interviewees were generally willing to discuss their experiences with the researcher, it suggests that it would be helpful for nurses to provide opportunities to do so. Nevertheless, interviewees appeared to regard the episode simply as a transitory event in the overall context of illness, admission to hospital and their future welfare. The latter was of prime concern; yet again it appeared that they did not always receive the information they required to maintain control over their personal destinies.

Adaptation, Psychological↗
PubMed1997

An analysis of CPR decision-making by elderly patients.

Traditionally clinicians have determined their patients' resuscitation status without consultation. This has been condemned as morally indefensible in cases where not for resuscitation (NFR) orders are based on quality of life considerations and when the patient's true wishes are not known. Such instances would encompass most resuscitation decisions in elderly patients. Having previously involved patients in CPR decision-making, we chose formally to explore the reasons behind the choices made. Although the patients were not upset, and readily decided at the time of initial consultation, on later analysing the decision-making we found poor understanding of the procedure, poor recall of information given and in some cases evidence of harm. This may be attributed to impaired decision-making capacity of elderly hospitalised patients as previously shown, or to the discomfort precipitated by having to contemplate the apparent immediacy of cardiac arrest by these patients. We propose that subscribing to autonomy as a general principle needs to be balanced against particular cases where distress may be caused by, or result in, diminished competence and limited autonomy.

Aged↗
PubMed1995

Variation in performance of the EMG examination at six European laboratories.

The quality of the EMG examination might be improved by standardization. However, knowledge about interlaboratory differences in the performance of the EMG examination is a prerequisite for standardization. The aim of this study was to describe differences in EMG techniques used and number of muscles and nerves examined per patient at 6 European EMG laboratories. The EMG results of 595 patients were prospectively sampled. The average number of muscles examined per patient in different disorders varied from laboratory to laboratory, for example from 3.0 to 10.8 muscles in anterior horn cell disorders and from 2.0 to 5.5 muscles in myopathies. The average number of muscles examined by quantitative EMG varied from 0 to 4.3 in anterior horn cell disorders and from 0.0 to 4.5 in myopathies. Also the average number of nerve segments examined per patient varied from laboratory for example from 2.7 to 17.7 for motor segments and from 3.1 to 9.0 for sensory segments in polyneuropathies. The laboratories that used needle electrodes for nerve conduction studies and quantitative analysis of individual motor unit potentials examined a smaller number of muscles and nerves than laboratories using surface electrodes for nerve conduction studies and qualitative EMG studies. The results of this study may have impact on guidelines and examination protocols as well as on quality assurance.

Electromyography↗
PubMed1995

Inter- and intraobserver variation in the interpretation of electromyographic tests.

This study was undertaken with the aim of evaluating inter- and intraobserver variation on the pathophysiological interpretation of individual electromyographic (EMG) tests on muscles and nerve segments. Seven physicians from 6 European EMG laboratories independently interpreted 81 EMG studies comprising 735 muscle tests and 726 tests on nerve segments. Pathophysiological conclusions were inferred from findings of these tests without considering clinical information. For most combinations of findings, both the inter- and intraobserver variations on the interpretation were low, suggesting that common criteria for pathophysiological interpretations were used and that these were used consistently. For some combinations of findings, however, there was disagreement on whether these indicated specific or unspecific pathophysiological changes. In particular disagreement on whether findings indicated demyelination may be of clinical significance. A large part of the intraobserver variation may be explained by a change towards more cautious interpretations during the study for most of the physicians. It is concluded that there is a need to seek for consensus on the pathophysiological interpretation of individual findings and for incentives to ensure consistency in interpretations. The fact that experienced physicians changed their ways to interpret findings during the study suggests that agreement may be improved globally.

Data Interpretation, Statistical↗
PubMed1995

Quality assurance in clinical neurophysiology: the ESTEEM project example.

This paper describes the current status of the utilisation of clinical practice guidelines (protocols) in the ESTEEM project as one form of the clinical quality assurance procedures considered in the project. The performance of electrodiagnostic studies, in terms of which types of conclusions need to be inferred during the examination plan, is briefly described. The main focus of the paper is a description of an European multicentre clinical audit in the field of Clinical Neurophysiology, using a common data-entry protocol for prospective EMG case collection and assessment with the ultimate objective of building up a multicentre reference database of EMG cases.

Computer Communication Networks↗
PubMed1994

Differences in the handling of the EMG examination at seven European laboratories.

This study was undertaken to analyse epidemiological and methodological differences in referral pattern, examination techniques and distribution of diagnoses among different European EMG laboratories. Seven European EMG laboratories filled in questionnaires and sampled 700 cases retrospectively. The use of needle or surface electrodes for nerve studies and the selection of quantitative techniques for muscle studies exhibited considerable variation. The pattern of referral varied with respect to the type of referral source and the neurological expertise of the referring physician. The proportion of patients without any neurophysiological abnormality ranged from 16 to 33%. The 3 most common diagnostic groups were mononeuropathies, polyneuropathies and radiculopathies although a great inter-laboratory variation was found. The proportion of patients with multiple diagnoses varied from 0 to 23% and most of these diagnoses were from a few known combinations. The presence of an inter-laboratory variation suggests that the quality of the EMG examination may be improved by focussing on the use of techniques, strategies and diagnostic criteria.

Electromyography↗