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Biomedical subjects

M Johnston

Publications and source records attributed to M Johnston.

At least 19 recordsLinked to original sources

A safer way to aspirate a quinsy.

Quinsies (peritonsillar abscesses) are routinely treated in all ENT departments. This paper outlines a technique for safe aspiration of a quinsy, which minimizes the risk to adjacent structures.

Humans↗

Removal of C-spine protection by A&E triage nurses: a prospective trial of a clinical decision making instrument.

OBJECTIVE: To investigate if triage nurses could safely apply a set of clinical criteria, removing hard collars and spinal boards at initial triage assessment. METHODS: The Nexus clinical decision rules were applied by trained triage nurses to patients who attended the department with cervical collars and/or on spinal boards. Patients were excluded if they were felt to be in need of immediate medical assessment. Data were collected on the time to nursing assessment, time to medical assessment and time spent restrained. Patients were followed up until discharge and their radiological diagnosis confirmed. Hospital records were checked to ensure that no patients re-presented with injuries that had been missed at initial assessment. RESULTS: In total, 112 patients were included in the study. Clinical criteria were met in 59 patients and their collar removed at triage assessment. For low risk patients, this reflects a mean reduction in time spent restrained of 23.3 minutes (p<0.005; 95% confidence interval 20.18 to 26.54). No patient who had a collar removed was found to have a significant injury. CONCLUSIONS: Simple criteria can be applied by accident and emergency triage nurses to allow safe removal of cervical collars and spinal boards. The reduced time patients spent immobilised represents an important improvement in patient care.

Adolescent↗

Using human error theory to explore the supply of non-prescription medicines from community pharmacies.

BACKGROUND: The importance of theory in underpinning interventions to promote effective professional practice is gaining recognition. The Medical Research Council framework for complex interventions has assisted in promoting awareness and adoption of theory into study design. Human error theory has previously been used by high risk industries but its relevance to healthcare settings and patient safety requires further investigation. This study used this theory as a framework to explore non-prescription medicine supply from community pharmacies. The relevance to other healthcare settings and behaviours is discussed. METHOD: A 25% random sample was made of 364 observed consultations for non-prescription medicines. Each of the 91 consultations was assessed by two groups: a consensus group (stage 1) to identify common problems with the consultation process, and an expert group (stages 2 and 3) to apply human error theory to these consultations. Paired assessors (most of whom were pharmacists) categorised the perceived problems occurring in each consultation (stage 1). During stage 2 paired assessors from an expert group (comprising patient safety experts, community pharmacists and psychologists) considered whether each consultation was compliant with professional guidelines for the supply of pharmacy medicines. Each non-compliant consultation identified during stage 2 was then categorised as a slip/lapse, mistake, or violation using human error theory (stage 3). RESULTS: During stage 1 most consultations (n = 75, 83%) were deemed deficient in information exchange. At stage 2, paired assessors varied in attributing non-compliance to specific error types. Where agreement was achieved, the error type most often selected was "violation" (n = 27, 51.9%, stage 3). Consultations involving product requests were less likely to be guideline compliant than symptom presentations (OR 0.30, 95% CI 0.10 to 0.95, p = 0.05). CONCLUSIONS: The large proportion of consultations classified as violations suggests that either pharmacy staff are unaware of professional guidelines and thus do not follow them (therefore these acts would not be violations), or that they knowingly violate the guidelines due to reasons that need further research. The methods presented here could be used in other healthcare settings to explore healthcare professional behaviour and to develop strategies to promote patient safety and effective professional practice.

Clinical Competence↗

Factors predicting the guideline compliant supply (or non-supply) of non-prescription medicines in the community pharmacy setting.

BACKGROUND: The reclassification of prescription only medicines to pharmacy and general sales list medicines (also known as non-prescription medicines) provides the public with greater access to medicines that they can purchase for self-care. There is evidence that non-prescription medicines may be associated with inappropriate supply. This study investigated factors predicting evidence-based (guideline compliant) supply or non-supply of non-prescription medicines. METHOD: Secondary analysis of results from a randomised controlled trial of educational interventions to promote the evidence based supply of non-prescription medicines. Ten actors made simulated patient (customer) visits to 60 community pharmacies using seven scenarios reflecting different types of presentations. The dependent variable was appropriate (guideline compliant) supply of antifungal medication for treatment of vaginal candidiasis. RESULTS: No significant association was shown between guideline compliant behaviour and pharmacy type or location, or with the actor making the visit. The likelihood of guideline compliant outcome was significantly greater with symptom presentations than with condition or product presentations (p < 0.001). The likelihood of a guideline compliant outcome increased (a) as more information was exchanged (p < 0.001), (b) with the use of WWHAM (a mnemonic frequently used by medicine counter assistants during consultations for non-prescription medicines) (p < 0.001); (c) when specific WWHAM questions were used (including "description of symptoms" (p < 0.001) and "whether other medication was currently being used" (p < 0.001); and (d) in consultations involving solely pharmacists compared with those involving only medicine counter assistants (p = 0.017). After adjustment for presentation type, a significant association persisted between appropriate outcome and consultations with WWHAM scores of 2 and > or = 3, respectively. CONCLUSIONS: The nature and extent of information exchange between pharmacy staff and customers has a strong influence on the guideline compliant supply of non-prescription medicines. Future interventions to promote the safe and effective use of non-prescription medicines should address the apparent deficit in communication between pharmacy staff in general, and medicine counter assistants in particular, which may reflect both pharmacy staff skills and customer expectations.

Adult↗

Lymph, lymphocytes, and lymphatics.

This is a summary of recent developments regarding the role of the lymphatic system in immune responses. Emphasis is on physiological considerations from experiments in sheep. Cell- and tissue-specific lymphocyte traffic patterns measured over several days are considered. Particular attention is given to recent data on the relationship between the central nervous system and the lymphatic system, to cell labeling in situ, and to the entry of immune cells into afferent lymph from the interstitial tissues.

Animals↗

The agreement between the MedGem indirect calorimeter and a standard indirect calorimeter in anorexia nervosa.

OBJECTIVES: Measurement of the basal metabolic rate (BMR) can be used to estimate the calories required for weight gain during refeeding in anorexia nervosa (AN). The reference method for measuring the BMR is indirect calorimetry. MedGem has developed a new indirect calorimeter that calculates the metabolic rate much more quickly than standard indirect calorimeters. This study compared the BMR measured by the MedGem and standard indirect calorimetry in an AN population. METHODS: We measured the BMR using the Deltatrac metabolic cart followed immediately by the MedGem indirect calorimeter in 27 subjects (12 patients and 15 controls). RESULTS: Bland-Altman plots show that there is poor agreement between the BMR reported by the MedGem compared to the Deltatrac. DISCUSSION: Until better agreement with standard indirect calorimetry can be shown the MedGem should not be used for calorimetry in AN. Possible factors that may limit the MedGem's reliability include patient discomfort with the mouthpiece, use of a fixed RQ, and the short sampling period.

Adult↗

Heparin compromises streptokinase-induced arterial patency in rabbits.

INTRODUCTION: Little is known with regard to efficacy of heparin as an adjunct to fibrinolytics under conditions of severe vascular damage. In this study, we compared the effects of unfractionated heparin (UH), low-molecular weight heparin (LMWH), and recombinant desulfohirudin (HIR) in combination with streptokinase (SK) in such settings. MATERIALS AND METHODS: We used an established rabbit model, in which thrombosis, critical stenosis, and vascular wall damage were introduced to a segment of the abdominal aorta and the effects of the respective therapies were assessed by time to patency (TTP in minutes), cumulative patency (CP (%)), lysis of original clot (CL (%)), and net clot accretion (NCA (%)). Treatments were administered over 90 min at the following doses: SK: 33,000 U/kg, UH: 125-250 U/kg, LMWH: 1.25-2.5 mg/kg, HIR: 0.25-0.55 mg/kg. RESULTS: Unexpectedly, UH and LMWH had a paradoxical and detrimental effect on SK-mediated recanalization as measured by both TTP and CP. Thus, administration of SK vs. SK+UH or SK+LMWH resulted in TTP values of 43+/-8 min vs. 70+/-11 min (p<0.05) and 67+/-12 min. (p<0.08), respectively. For CP, the corresponding values were 21+/-7%, 0.5+/-0.3% and 9+/-8%. This delay in vessel recanalization occurred despite excessive systemic anticoagulation (activated partial thromboplastin time (aPTT) and thrombin clotting time (TCT) ratios >6 and >34, respectively). Of interest, both heparinoids completely inhibited SK-induced fibrinogen consumption (FC). In contrast, recombinant desulfohirudin (HIR) shortened SK-induced TTP (4.97+/-0.81 min) without preserving fibrinogen. CONCLUSIONS: Our findings suggest that caution needs to be exercised, when using the combination of SK and heparinoids for the treatment of arterial thrombosis under conditions of severe vascular damage and stenosis.

Animals↗

Glucose as a hormone: receptor-mediated glucose sensing in the yeast Saccharomyces cerevisiae.

Because glucose is the principal carbon and energy source for most cells, most organisms have evolved numerous and sophisticated mechanisms for sensing glucose and responding to it appropriately. This is especially apparent in the yeast Saccharomyces cerevisiae, where these regulatory mechanisms determine the distinctive fermentative metabolism of yeast, a lifestyle it shares with many kinds of tumour cells. Because energy generation by fermentation of glucose is inefficient, yeast cells must vigorously metabolize glucose. They do this, in part, by carefully regulating the first, rate-limiting step of glucose utilization: its transport. Yeast cells have learned how to sense the amount of glucose that is available and respond by expressing the most appropriate of its 17 glucose transporters. They do this through a signal transduction pathway that begins at the cell surface with the Snf3 and Rgt2 glucose sensors and ends in the nucleus with the Rgt1 transcription factor that regulates expression of genes encoding glucose transporters. We explain this glucose signal transduction pathway, and describe how it fits into a highly interconnected regulatory network of glucose sensing pathways that probably evolved to ensure rapid and sensitive response of the cell to changing levels of glucose.

Fermentation↗

Predictors of emotional outcomes of intensive care.

Negative emotional outcomes (anxiety, depression and post-traumatic stress) have been identified in patients discharged from intensive care. The aims of this prospective, longitudinal study were to assess levels of and changes in emotional outcome after intensive care, and to explore how these relate to objective and subjective indicators of the intensive care experience. Emotional outcome was assessed using the Hospital Anxiety and Depression and Impact of Event Scales. Anxiety (p = 0.046) and depression (p = 0.001) were reduced subsequently, but not avoidance (p = 0.340) or intrusion (p = 0.419). Most objective (age, gender, length of ICU and hospital stay) and subjective indicators (as measured by the Intensive Care Experience Questionnaire) of the intensive care experience were related to negative emotional outcome. Subjective interpretation of the intensive care experience emerged as a consistent predictor of adverse emotional outcome, in both the short- and the long-term.

Adult↗

Subarachnoid injection of Microfil reveals connections between cerebrospinal fluid and nasal lymphatics in the non-human primate.

Based on quantitative and qualitative studies in a variety of mammalian species, it would appear that a significant portion of cerebrospinal fluid (CSF) drainage is associated with transport along cranial and spinal nerves with absorption taking place into lymphatic vessels external to the central nervous system. CSF appears to convect primarily through the cribriform plate into lymphatics associated with the submucosa of the olfactory and respiratory epithelium. However, the significance of this pathway for CSF absorption in primates has never been established unequivocally. In past studies, we infused Microfil into the subarachnoid compartment of numerous species to visualize CSF transport pathways. The success of this method encouraged us to use a similar approach in the non-human primate. Yellow Microfil was injected post mortem into the cisterna magna of 6 years old Barbados green monkeys (Cercopithecus aethiops sabeus, n = 6). Macroscopic and microscopic examination revealed that Microfil was (1) distributed throughout the subarachnoid compartment, (2) located in the perineurial spaces associated with the fila olfactoria, (3) present within the olfactory submucosa, and (4) situated within an extensive network of lymphatic vessels in the nasal submucosa, nasal septum and turbinate tissues. We conclude that the Microfil distribution patterns in the monkey were very similar to those observed in many other species suggesting that significant nasal lymphatic uptake of CSF occurs in the non-human primate.

Animals↗

The incidence and prognostic significance of elevated cardiac troponins in patients with submassive pulmonary embolism.

Although the incidence and prognostic significance of elevated cardiac troponins are known in patients with massive pulmonary embolism (PE), few studies have addressed this issue in patients with hemodynamically stable, submassive PE, who comprise the majority of patients presenting with PE. This prospective cohort study was, therefore, designed to determine the incidence and prognostic significance of elevated cardiac troponins in patients with submassive PE. Consecutive patients with acute, symptomatic, submassive PE that was confirmed by objective diagnostic testing were studied. All patients received treatment with either unfractionated heparin or fondaparinux followed by a coumarin derivative and underwent clinical follow-up for 3 months. Cardiac troponin I (cTnI) levels were measured within 24 h of clinical presentation. An elevated cTnI was defined as > 0.5 microg L(-1) and indicated myocardial injury. Major myocardial injury, that is associated with myocardial infarction, was defined by a cTnI > 2.3 microg L(-1). The clinical outcomes were recurrent venous thromboembolism and all-cause death. In 458 patients with submassive PE, the incidence of cTnI > 0.5 microg L(-1) was 13.5%[95% confidence interval (CI): 10.4-16.7], and the incidence of cTnI > 2.3 microg L(-1) was 3.5% (95% CI: 2.0-5.6). An elevated cTnI > 0.5 microg L(-1) was associated with an increased risk of all-cause death [odds ratio (OR) = 3.5; 95% CI: 1.0-11.9], but did not appear to confer an increased risk of recurrent venous thromboembolism (OR = 1.1; 95% CI: 0.2-4.9). In patients who present with submassive PE, an elevated cTnI occurs in about one in seven patients and is associated with a 3.5-fold increased risk of all-cause death.

Aged↗

Making psychological theory useful for implementing evidence based practice: a consensus approach.

BACKGROUND: Evidence-based guidelines are often not implemented effectively with the result that best health outcomes are not achieved. This may be due to a lack of theoretical understanding of the processes involved in changing the behaviour of healthcare professionals. This paper reports the development of a consensus on a theoretical framework that could be used in implementation research. The objectives were to identify an agreed set of key theoretical constructs for use in (1) studying the implementation of evidence based practice and (2) developing strategies for effective implementation, and to communicate these constructs to an interdisciplinary audience. METHODS: Six phases of work were conducted to develop a consensus: (1) identifying theoretical constructs; (2) simplifying into construct domains; (3) evaluating the importance of the construct domains; (4) interdisciplinary evaluation; (5) validating the domain list; and (6) piloting interview questions. The contributors were a "psychological theory" group (n = 18), a "health services research" group (n = 13), and a "health psychology" group (n = 30). RESULTS: Twelve domains were identified to explain behaviour change: (1) knowledge, (2) skills, (3) social/professional role and identity, (4) beliefs about capabilities, (5) beliefs about consequences, (6) motivation and goals, (7) memory, attention and decision processes, (8) environmental context and resources, (9) social influences, (10) emotion regulation, (11) behavioural regulation, and (12) nature of the behaviour. CONCLUSIONS: A set of behaviour change domains agreed by a consensus of experts is available for use in implementation research. Applications of this domain list will enhance understanding of the behaviour change processes inherent in implementation of evidence-based practice and will also test the validity of these proposed domains.

Evidence-Based Medicine↗

Effectiveness of strategies to disseminate and implement clinical guidelines for the management of impacted and unerupted third molars in primary dental care, a cluster randomised controlled trial.

OBJECTIVE: To investigate the effectiveness and cost-effectiveness of different guideline implementation strategies, using the Scottish Intercollegiate Guidelines Network (SIGN) Guideline 42 "Management of unerupted and impacted third molar teeth" (published 2000) as a model. DESIGN: A pragmatic, cluster RCT (2x2 factorial design). SUBJECTS: Sixty-three dental practices across Scotland. Clinical records of all 16-24-year-old patients over two, four-month periods in 1999 (pre-intervention) and 2000 (post-intervention) were searched by a clinical researcher blind to the intervention group. Data were also gathered on the costs of the interventions. INTERVENTIONS: Group 1 received a copy of SIGN 42 Guideline and had an opportunity to attend a postgraduate education course (PGEC). In addition to this, group 2 received audit and feedback (A and F). Group 3 received a computer aided learning (CAL) package. Group 4 received A and F and CAL. PRINCIPAL OUTCOME MEASUREMENT: The proportion of patients whose treatment complied with the guideline. RESULTS: The weighted t-test for A and F versus no A and F (P=0.62) and CAL versus no CAL (P=0.76) were not statistically significant. Given the effectiveness results (no difference) the cost effectiveness calculation became a cost-minimisation calculation. The minimum cost intervention in the trial consisted of providing general dental practitioners (GDPs) with guidelines and the option of attending PGEC courses. Routine data which subsequently became available showed a Scotland-wide fall in extractions prior to data collection. CONCLUSION: In an environment in which pre-intervention compliance was unexpectedly high, neither CAL nor A and F increased the dentists' compliance with the SIGN guideline compared with mailing of the guideline and the opportunity to attend a postgraduate course. The cost of the CAL arm of the trial was greater than the A and F arm. Further work is required to understand dental professionals' behaviour in response to guideline implementation strategies.

Adolescent↗

Neither baseline tests of molecular hypercoagulability nor D-dimer levels predict deep venous thrombosis in critically ill medical-surgical patients.

OBJECTIVE: Predicting patients who are harboring asymptomatic deep venous thrombosis (DVT), or who are at particular risk of developing DVT, is a desirable clinical goal since prevention or early treatment of DVT might reduce the risk of fatal pulmonary embolism. Thus validation of simple laboratory tests that reliably predict venous thromboembolism (VTE) would be clinically very important. Tests that might be useful for these applications include markers of hypercoagulability (predicting patients at risk of DVT) and D-dimer (predicting which patients may have acute DVT). METHODS: In a prospective cohort study we measured a panel of hypercoagulability markers at the time of ICU admission, and six commercial D-dimer assays were performed serially during the ICU stay in medical-surgical ICU patients who were screened for DVT with biweekly lower limb compression ultrasonography. Ultrasonography was also performed at the time of any clinically suspected DVT events. We matched cases with DVT with controls without DVT for length of stay in the ICU to generate receiver operating characteristics (ROC) curves. RESULTS: One hundred ninety-seven patients were enrolled. Blood was collected on a total of 763 occasions (median number of occasions per patient: 3, range 1-21). None of the assays predicted DVT, as indicated by the areas under the ROC curves, that did not differ significantly from 50%. CONCLUSION: In critically ill patients, neither tests of hypercoagulability nor D-dimer levels predict patients at risk of DVT and thus they should not be used to guide diagnostic testing for DVT.

Aged↗

Integrating the roles of extracranial lymphatics and intracranial veins in cerebrospinal fluid absorption in sheep.

At relatively low cerebrospinal fluid (CSF) pressures, the majority of CSF drainage in 6- to 8-month-old sheep occurs through the cribriform plate into lymphatic vessels in the nasal submucosa. As CSF pressures are elevated, other absorption sites are recruited and these may include transport through arachnoid projections. To test for the transport of CSF directly into the venous sinus, the concentration of a tracer (131I-human serum albumin [HSA]) administered into the CSF compartment was measured in the confluence of the intracranial venous sinuses (torcular) and in the peripheral blood (inferior vena cava). CSF pressures were adjusted to favor absorption. Enrichment of the CSF tracer in the cranial venous system was most evident when the CSF-venous sinus pressure gradients were high. Peak concentration differences occurred 90 s after the CSF pressures were elevated. When pressure gradients approached 30 cm H(2)O, tracer concentrations in the torcular were approximately twofold higher than those observed in peripheral blood. The greatest concentration differences favoring the torcular were obtained when the CSF-venous sinus pressure gradients were elevated to high levels (20- to 40 cm H(2)O) and when CSF access to the paranasal lymphatics and CSF transport into the spinal subarachnoid compartment were prevented. In conjunction with previous studies, these results are compatible with the view that CSF absorption in the adult animal can occur directly into the cranial venous system. However, contrary to the established view, this pathway may represent a secondary system that is recruited to compliment lymphatic transport when global absorption capacity is stressed or compromised.

Absorption↗

Comparison of 1 month with 3 months of anticoagulation for a first episode of venous thromboembolism associated with a transient risk factor.

BACKGROUND: The risk of recurrence is lower after treatment of an episode of venous thromboembolism associated with a transient risk factor, such as recent surgery, than after an episode associated with a permanent, or no, risk factor. Retrospective analyses suggest that 1 month of anticoagulation is adequate for patients whose venous thromboembolic event was provoked by a transient risk factor. METHODS: In this double-blind study, patients who had completed 1 month of anticoagulant therapy for a first episode of venous thromboembolism provoked by a transient risk factor were randomly assigned to continue warfarin or to placebo for an additional 2 months. Our goal was to determine if the duration of treatment could be reduced without increasing the rate of recurrent venous thromboembolism during 11 months of follow-up. RESULTS: Of 84 patients assigned to placebo, five (6.0%) had recurrent venous thromboembolism, compared with three of 81 (3.7%) assigned to warfarin, resulting in an absolute risk difference of 2.3%[95% confidence interval (CI) - 5.2, 10.0]. The incidence of recurrent venous thromboembolism after discontinuation of warfarin was 6.8% per patient-year in those who received warfarin for 1 month and 3.2% per patient-year in those who received warfarin for 3 months (rate difference of 3.6% per patient-year; 95% CI - 3.8, 11.0). There were no major bleeds in either group. CONCLUSION: Duration of anticoagulant therapy for venous thromboembolism provoked by a transient risk factor should not be reduced from 3 months to 1 month as this is likely to increase recurrent venous thromboembolism without achieving a clinically important decrease in bleeding.

Adult↗