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S Backhouse

Publications and source records attributed to S Backhouse.

6 recordsLinked to original sources
PubMed1999

Transport and temperature effects on measurement of serum and plasma potassium.

Transport of blood samples from general practice to a central laboratory can result in spuriously high or low potassium concentrations. The importance of this phenomenon was studied in a general practice serving a population of 15,000 patients, 27 km from the pathology laboratory that routinely measured serum potassium. The design involved comparison of potassium levels between control serum (plain gel-separation serum tubes centrifuged in the surgery), routine serum (plain gel-separation tubes centrifuged in the laboratory) and routine plasma samples (lithium-heparin tubes centrifuged in the laboratory). Complete triple sets of data were obtained for 371 samples. Altman and Bland plots for the control serum vs routine serum samples showed a mean difference of +0.1 mmol/L with limits of agreement (+/- 2SD) +0.6 mmol/L, -0.4 mmol/L and for control serum vs routine plasma a mean difference of +0.2 mmol/L with limits of agreement +0.8 mmol/L, -0.4 mmol/L. There was a negative association between mean weekly routine plasma potassium levels with mean weekly temperatures achieved. Regression analysis indicated that both maximum temperature achieved and time to centrifugation significantly contributed to differences observed in the routine plasma samples, but not with the routine serum samples. For plasma samples exposed to high temperatures a clinically significant lowering of potassium concentrations can arise. These results confirm that spurious lowering of potassium concentrations occurs in plasma samples collected in a primary care setting. The preferred method is to centrifuge samples soon after venepuncture. Where this is not possible, collection into plain gel-separation tubes (serum) ensures less variation due to temperature and time to centrifugation than does collection into lithium-heparin tubes (plasma).

Blood Preservation↗
PubMed1997

Validation of current practice and a near patient testing method for oral-anticoagulant control in general practice.

When oral anticoagulant control is monitored in general practice, venous blood samples are usually transported to a central laboratory for determination of international normalized ratio (INR). An alternative is near patient testing by a commercial method. In a rural general practice 27 km from a central haematology laboratory, whole blood samples were drawn from patients receiving oral anticoagulants and analysed by three methods: after centrifugation, plasma separated and frozen in liquid nitrogen, transported to the laboratory, thawed and immediately analysed (control); courier transport of citrated sample to the laboratory for analysis (routine); near patient testing of whole blood sample (NPT). Maximum temperature achieved and time to analysis for routine samples were recorded. 306 complete sets of data were obtained. Comparison between the routine method and the control method revealed acceptable agreement. On multiple regression analysis, maximum temperature achieved did not contribute to differences observed but time to analysis of over 5 hours did make a significant contribution. Comparison between the NPT method and control method showed acceptable agreement, with persistent under-recording by the NPT method. The routine method for INR determination was validated as robust and reproducible with the proviso that needle-to-analysis time should be kept below 5 hours. The NPT method was valid under conditions of normal general practice. Strict quality control of NPT methods is essential if performance is to be comparable with that of established methods.

Anticoagulants↗
PubMed1997

Patterns of hospital attendance with epistaxis.

The age and sex distribution of epistaxis admissions to hospital was examined. A retrospective analysis of 6,885 patients admitted to hospitals in the whole of Wales was performed, over a period of five years. The findings were compared with data from the 1991 National Population Census for the same region, thus providing a more representative estimate of the behaviour of this disease. A clear age relationship is demonstrated, with the incidence of epistaxis increasing rapidly after the age of 40 years. The female-to-male ratio is also age dependent. In the group aged between 20 to 49 years twice as many males as females were admitted, where no sex difference was expected from the population data. This difference was not present in the group aged 50 years and over where the ratio was similar to that in the underlying population. There was a 1.6 fold difference between the sex ratios of the two groups (95% confidence intervals of 1.9 to 1.4; p < 0.0001). It is possible that the female pre-menopausal state may provide a significant protection from this disease. The mechanism for this is unknown, but may be secondary to a direct effect of oestrogen on the nasal mucosa or vasculature, or the healing of vessels in this region. Alternatively, this observation may simply be a reflection of protection the pre-menopausal state provides against cardiovascular disease in general.

Adolescent↗
PubMed1995

The relationship between hassles, uplifts and irritable bowel syndrome: a preliminary study.

In a preliminary study, 30 sufferers of irritable bowel syndrome filled in daily symptom sheets and the combined Hassles and Uplifts questionnaire for five weeks. Initially, analyses were carried out for each symptom separately. Results showed that ratings on the hassles and symptoms questionnaires completed in the same week were more highly associated than ratings for hassles and symptoms in different weeks. No one symptom in any week was significantly associated with the following week's hassles. Similarly, hassles in any one week were not associated with the following week's symptoms. However, total symptoms were found to be significantly associated with hassles in the following weeks, whereas the association between hassles and total symptoms in the following weeks was not significant. The study suggests that there is a cumulative effect of symptoms such that an increase in the severity of the combined effect of symptoms is associated with an increase in severity of stress in the next week. Increased hassles do not appear to exacerbate symptoms. There was no evidence of an association between uplifts and IB symptoms.

Adult↗
PubMed1993

Towards a better understanding of patients with irritable bowel syndrome.

This study was undertaken by sending a questionnaire to 148 people suffering from irritable bowel syndrome (IBS). The respondents all were members of the IBS Network, a national independent organization formed to help alleviate the suffering and distress of people diagnosed as having irritable bowel. They were asked about their symptoms, the medical tests they had undergone, how they felt about the treatment they received, and how IBS affected their lives. The study found that IBS affected all aspects of their lives: work, leisure, travel and relationships. Sufferers indicated that they felt they would have coped better if they had been provided with more information about IBS, its possible causes and treatment, and greater sensitivity from members of the medical profession in dealing with them.

Activities of Daily Living↗