Chronic subdural haematoma: the role of peri-operative medicine in a common form of reversible brain injury.

Epidemiological studies project a significant rise in cases of chronic subdural haematoma over the next 20 years. Patients with this condition are frequently older and medically complex, with baseline characteristics that may increase peri-operative risk. The intra-operative period is only a small portion of a patient's total hospital stay, with a majority of patients in the United Kingdom transferred between institutions for their surgical and rehabilitative care. Definitive management remains surgical, but peri-operative challenges exist which resonate with other surgical cohorts where multidisciplinary working has become the gold standard. These include shared decision-making, medical optimisation, the management of peri-operative anticoagulation and the identification of key points of equipoise for examination in the future trials. In this narrative review, we use a stereotyped patient journey to provide context to the recent literature, highlighting where multidisciplinary expertise may be required to optimise patient care and maximise the benefits of surgical management. We discuss the triage, pre-operative optimisation, intra-operative management and immediate postoperative care of patients undergoing surgery for a chronic subdural haematoma. We also discuss where adjunctive medical management may be indicated. In so doing, we present the current and emerging evidence base for the role of an integrated peri-operative medicine team in the care of patients with a chronic subdural haematoma.

Incidence of chronic subdural haematoma: a single-centre exploration of the effects of an ageing population with a review of the literature.

BACKGROUND: Chronic subdural haematoma (cSDH) is a common neurosurgical pathology frequently occurring in older patients. The impact of population ageing on cSDH caseload has not been examined, despite relevance for health system planning. METHODS: This is a single-centre study from the UK. Operated cases of cSDH (n = 446) for 2015-2018 were identified. Crude and directly standardised incidence rates were calculated. Medline and EMBASE were systematically searched to identify studies reporting on the incidence of cSDH by year, so an estimate of rate of incidence change could be determined. Local incidence rates were then applied to population projections for local catchment area to estimate operated cSDH numbers at 5 yearly intervals due to shifting demographics. RESULTS: We identified nine studies presenting incidence estimates. Crude estimates for operative cases ranged from 1.3/100,000/year (1.4-2.2) to 5.3/100,000/year (4.3-6.6). When non-operated cases were included, incidence was higher: 8.2/100,000/year (6.0-11.2) to 48/100,000/year (37.7-61.1). Four pairs of studies demonstrated incidence rate increases of 200-600% over the last 50 years, but data was deemed too heterogeneous to generate formal estimate of incidence change. Local crude incidence of operated cSDH was 3.50/100,000/year (3.19-3.85). Directly standardised incidence was 1.58/100,000/year (1.26-1.90). After applying local incidence rates to population projections, case numbers were predicted to increase by 53% over the next 20 years. CONCLUSIONS: The incidence of cSDH is increasing. We project a 53% increase in operative caseload within our region by 2040. These are important findings for guiding future healthcare planning.

Management of infected nonunion of the long bones by a multidisciplinary team.

Infected nonunion of a long bone continues to present difficulties in management. In addition to treating the infection, it is necessary to establish bony stability, encourage fracture union and reconstruct the soft-tissue envelope. We present a series of 67 infected nonunions of a long bone in 66 patients treated in a multidisciplinary unit. The operative treatment of patients suitable for limb salvage was performed as a single procedure. Antibiotic regimes were determined by the results of microbiological culture. At a mean follow-up of 52 months (22 to 97), 59 patients (88%) had an infection-free united fracture in a functioning limb. Seven others required amputation (three as primary treatment, three after late failure of limb salvage and one for recalcitrant pain after union). The initial operation achieved union in 54 (84%) of the salvaged limbs at a mean of nine months (three to 26), with recurrence of infection in 9%. Further surgery in those limbs that remained ununited increased the union rate to 62 (97%) of the 64 limbs treated by limb salvage at final follow-up. The use of internal fixation was associated with a higher risk of recurrent infection than external fixation.

The use of a biodegradable antibiotic-loaded calcium sulphate carrier containing tobramycin for the treatment of chronic osteomyelitis: a series of 195 cases.

We report our experience using a biodegradable calcium sulphate antibiotic carrier containing tobramycin in the surgical management of patients with chronic osteomyelitis. The patients were reviewed to determine the rate of recurrent infection, the filling of bony defects, and any problems with wound healing. A total of 193 patients (195 cases) with a mean age of 46.1 years (16.1 to 82.0) underwent surgery. According to the Cierny-Mader classification of osteomyelitis there were 12 type I, 1 type II, 144 type III and 38 type IV cases. The mean follow-up was 3.7 years (1.3 to 7.1) with recurrent infection occurring in 18 cases (9.2%) at a mean of 10.3 months post-operatively (1 to 25.0). After further treatment the infection resolved in 191 cases (97.9%). Prolonged wound ooze (longer than two weeks post-operatively) occurred in 30 cases (15.4%) in which there were no recurrent infection. Radiographic assessment at final follow-up showed no filling of the defect with bone in 67 (36.6%), partial filling in 108 (59.0%) and complete filling in eight (4.4%). A fracture occurred in nine (4.6%) of the treated osteomyelitic segments at a mean of 1.9 years (0.4 to 4.9) after operation. We conclude that Osteoset T is helpful in the management of patients with chronic osteomyelitis, but the filling of the defect in bone is variable. Prolonged wound ooze is usually self-limiting and not associated with recurrent infection.

Perceptual compromise between apparent and veridical motion indices: the unchained-dots illusion.

A new motion illusion based on dot-trajectory misperception is presented. The illusory effect can not be explained by the aperture problem unlike some previous illusions characterised by misperception of motion direction. We propose an explanation in terms of 'perceptual compromise' between an original type of apparent motion and the veridical motion. Several demonstrations are presented in support of that hypothesis.

Estimating hourly anaesthetic and surgical reimbursement from private medical insurers' benefit maxima: implications for pricing services and for incentives.

While some speculation surrounds annual private practice incomes of anaesthetists, little is known of the hours of work needed to generate any presumed income (the hourly rate). The benefit maxima of five private medical insurers are published in fee schedules and data on the duration of common operations are now also known. In this study we combined these to generate estimates for hourly rates of reimbursement across 78 common operations in eight surgical subspecialties, for anaesthetists and surgeons. We expected to find significant differences between insurers as a result of market competition, and we expected differences between anaesthetists and surgeons. The median (IQR [range]) rate of reimbursement for anaesthetists was pound167 (132-211 [68-570]).h(-1) with significant variation across subspecialties (p < 0.001); for example, cardiac surgery was best reimbursed at pound283 (257-308 [229-398]).h(-1) and orthopaedics the least at pound146 (133-159 [81-246]).h(-1). Contrary to expectations, the rates of payment to anaesthetists by insurers were similar (p > 0.17). Patterns of reimbursement for surgeons were similar to those for anaesthetists, except that surgeons were reimbursed at about twice the rate. We conclude there is a confluence of insurer reimbursement levels and we discuss potential implications of this finding. Our results also have implications for how incentives between the NHS and private practice, or within a private practice group, might be optimally managed.

Measuring the quantitative performance of surgical operating lists: theoretical modelling of 'productive potential' and 'efficiency'.

We previously defined surgical list 'efficiency' as: maximising theatre utilisation, minimising over-running, and minimising cancellations. 'Efficiency' maximises output for input; 'productivity' emphasises total output. We define six criteria that any measure of productivity (better termed 'quantitative performance') needs to satisfy. We then present a theoretical analysis that fulfils these by incorporating: 'speed' of surgery (with reference to average speeds), 'patient contact' (synonymous with minimising gaps between cases), and 'efficiency' (as previously defined). 'Speed' and 'patient contact' together constitute a 'productive potential'. Our formula satisfies the pre-set criteria and yields plausible results in both hypothetical and real data sets, To be productive in these quantitative terms, teams in any specialty need to achieve minimum quality standards defined by their sub-specialty; to plan their lists to utilise the time available with no cancellations or over-runs and to work at least as fast as average with minimal gaps between cases. 'Productive potential' combined with 'efficiency' yielding 'actual productivity' in our theoretical analysis more completely describes quantitative surgical list performance than any other single measure.

Perception of linear and nonlinear trends: using slope and curvature information to make trend discriminations.

This study investigated several factors influencing the perception of nonlinear relationships in time series graphs. To model real-world data, the graphed data represented different underlying trends and included different sample sizes and amounts of variability. Six trends (increasing and decreasing linear, exponential, asymptotic) were presented on four graph types (histogram, line graph, scatterplot, suspended bar graph). The experiment assessed how these factors affect trend discrimination, with the overall goal of judging what types of graphs lead to better discrimination. Six participants (two psychology professors, four psychology graduate students) viewed graphs on a computer screen and identified the underlying trend. All participants were familiar with the types of trends presented and were aware of the purpose of the experiment. Analysis indicated higher accuracy when variability was lower and sample size was higher. Choice accuracy was higher for nonlinear trends and was highest when line graphs were used.

Clues from digital radio regarding biomolecular recognition.

Frequency-offset immunosensors based on acoustic wave devices are known to provide extremely high sensitivity and selectivity where the target is detected and identified based on the amount of frequency shift. We propose a new method to further classify chemically similar molecules extrapolating on the concept of in-phase (I) and quadrature (Q) domain used for the detection of orthogonal M-ary signals in digital telecommunication systems. We performed a series of detection experiments using samples of explosives such as cyclotrimethylene trinitramine [or royal demolition explosive (RDX)] and trinitrotoluene (TNT), containing nitrous oxide (NO2) groups and chemically analogous substances (e.g., musk oil). This detection scheme involves the use of semi-orthogonal monoclonal anti-TNT and anti-RDX antibodies immobilized onto two separate sensor surfaces. The term semi-orthogonal represents the co-option of a term used heavily in digital radio for the purpose of describing chemical orthogonality. The antibody to TNT which we use has some reactivity with RDX, and other nitrous oxide compounds. This feature of an antibody is referred to in the literature as antibody promiscuity. The antibody for RDX which we use shows very little cross reactivity with other molecules and, hence, the chemical responsiveness of the two antibodies is not quite orthogonal. Their responses are then chemically semi-orthogonal. The two semi-orthogonal immunosensor responses were then monitored and the baseline frequency shifts were recorded. After remapping the measured frequency data of the analytes onto a new 2-D domain by setting the TNT-specific sensor as the (I) or real component and the RDX-specific sensor as the (Q) or imaginary component, we could observe that all the substances were detected and mapped out to distinct regions on the I-Q plot. We assert that there is a strong resemblance between digital radio system quadrature detection techniques and our I-Q mapping scheme of the semi-orthogonal immunosensor signatures.

A new set of illusions--the dynamic luminance-gradient illusion and the breathing light illusion.

A novel set of illusions that break brightness constancy and size constancy at the same time is reported. The illusions occur when observers move towards or away from these patterns. Many variations of these phenomena and a possible explanation are discussed.

In vivo evaluation of resorbable bone graft substitutes in a rabbit tibial defect model.

Calcium sulfate as a bone graft substitute is rapidly resorbed in vivo releasing calcium ions but fails to provide long-term three-dimensional framework to support osteoconduction. The setting properties of calcium sulfate however allow it to be applied in a slurry form making it easier to handle and apply in different situations. This study examines the in vivo response of calcium sulfate alone and as a carrier for a coralline hydroxyapatite in an established bilateral corticocancellous defect model in rabbits. Defects were filled flush to the anterior cortex with a resorbable porous ceramic alone and in combination with calcium sulfate slurry, calcium sulfate slurry alone or calcium sulfate pellets and examined at time points up to 52 weeks. Specimens where assessed using Faxitron X-ray, light and electron microscopy. Calcium sulfate in either slurry or pellet form does indeed support new bone formation alone however, complete filling of the bone defect is not observed. Calcium sulfate in slurry form does however improve the surgical handling of particulate bone graft substitutes such as Pro Osteon 200 R, which remained as an osteoconductive scaffold for up to 52 weeks and may have played an important role in the ultimate closure of the cortical windows.

Investigation of cocaine plumes using surface acoustic wave immunoassay sensors.

Vapor sensors, aka electronic noses, are becoming an increasingly popular analytical tool for detection and identification of small molecules in the gas phase. In this paper, we present the results of a series of experiments demonstrating real-time vapor phase detection of cocaine molecules. A distinctive response or signature was observed under laboratory conditions in which the cocaine vapors were presented using an INEL vapor generator and under "field" conditions facilitated by the Georgia Bureau of Investigation (GBI) Crime Lab. For these experiments, the sensor component was a two-port resonator on ST-X quartz with a center frequency of approximately 250 MHz. On this cut of quartz, a temperature-compensated surface acoustic wave is generated via an interdigital transducer. Antibenzoylecgonine (anti-BZE) antibodies are attached to the electrodes on the device surface via a protein-A cross linker. We observed a large transient frequency shift accompanied by baseline shift with the anti-BZE coated sensor. After repeated experiments and the use of numerous controls, we believe that we have achieved real time molecular recognition of cocaine molecules.

Constructing knowledge. The role of graphs and tables in hard and soft psychology.

Because graphs provide a compact, rhetorically powerful way of representing research findings, recent theories of science have postulated their use as a distinguishing feature of science. Studies have shown that the use of graphs in journal articles correlates highly with the hardness of scientific fields, both across disciplines and across sub-fields of psychology. In contrast, the use of tables and inferential statistics in psychology is inversely related to subfield hardness, suggesting that the relationship between hardness and graph use is not attributable to differences in the use of quantitative data in subfields or their commitment to empiricism. Enhanced "graphicacy" among psychologists could contribute to the progress of psychological science by providing alternatives to significance testing and by facilitating communication across subfields.

Gas phase activity of anti-FITC antibodies immobilized on a surface acoustic wave resonator device.

In this paper we present the results of a series of experiments on the activity of antibodies in a vapor phase sensor. For these experiments the sensor component was a ST-Quartz resonator with a center frequency of approximately 250 MHz. Anti-FITC antibodies were attached to the electrodes on the device surface via a protein-A crosslinker. Surface acoustic wave (SAW) resonator devices with various coatings were mounted in TO-8 packages, inserted into our sensor head module and subjected to various fluorescent analyte gases. Numerous controls were performed including the use of coated and uncoated devices along with devices coated with antibodies which were not specific for the target analyte. The SAW immunosensor response was monitored and a baseline frequency shift was observed when the analyte being presented was the antigen for the immobilized antibody. To provide an independent measure of antibody/antigen binding, the devices were removed from the sensor head, washed with a buffer solution to remove any unbound analyte, and then inspected using a confocal laser scanning microscope (CLSM). Since all the analytes being used in these experiments were fluorescent this afforded us the opportunity to visualize the attachment of the analyte to the antibody film. Given the high resolution of the CLSM, we were able to identify the location of the attachment of the fluorescent analytes relative to the 1.5 microm wide electrodes of the SAW device. We believe that these experiments demonstrate that we have achieved real time molecular recognition of these small molecules in the vapor phase.

Graph use in psychology and other sciences.

Since the early 19th century, graphs have been recognised as an effective method of analysing and representing scientific data. However, levels of graph use have varied widely since then, partly due to increasing reliance on inferential statistics in some fields. Recent studies indicate that graph use is closely related to the 'hardness' of scientific disciplines, and that this finding holds for journal articles and textbooks across the subfields of psychology. In the area of animal behaviour, journals devote about one-sixth of their page space to graphs, a level of graph use approximating that of biology and physics. Implications for the training of scientists in the use of visual displays are considered.

The perceptions of managers and accident subjects in the service industries towards slip and trip accidents.

Slips and trips are a major cause of injury and lost time, and remain so despite specific initiatives. The work presented here focuses on how accident subjects and their managers each perceive the circumstances of an accident with respect to causal responsibility. To investigate this issue, a research questionnaire was designed, piloted and then applied to 33 occupational slip and trip accidents reported to a Local Authority Inspectorate. The results showed important differences in the attribution of causal responsibility between those who experience and those who investigate slips and trip accidents. The levels of agreement between individual accident subjects and their managers was at best fair (using kappa). The consequences of this and the limited scope of investigation carried out by managers is highlighted and the need for improved training and the development of a practical model of risk assessment and investigation for managers is advanced.

Six-year effect of depressive symptoms on the course of physical disability in community-living older adults.

BACKGROUND: Late-life depression affects physical health and impedes recovery from physical disability. But whether milder symptoms that occur frequently in the general population increase the risk of developing a disability or decrease the likelihood of recovery remains unclear. OBJECTIVE: To examine the effect of mild symptoms of depression, assessed by a reduced version (10 items, ranging from 0-10) of the Center for Epidemiological Studies-Depression Scale, on the course of physical disability, assessed by items from the Katz Activities of Daily Living Scale, the Rosow-Breslau Functional Health Scale, and the Nagi Index. METHODS: A population-based longitudinal study was conducted, with 6 follow-up interviews of 3434 community-dwelling persons aged 65 years and older in East Boston, Mass. RESULTS: The likelihood of becoming disabled increased with each additional symptom of depression (for the Katz measure: odds ratio, 1.16 per symptom; 95% confidence interval, 1.13-1.19; for the Rosow-Breslau measure: odds ratio, 1.14; 95% confidence interval, 1.11-1.16; and for the Nagi measure: odds ratio, 1.17; 95% confidence interval, 1.14-1.19). As the number of depressive symptoms increased, the likelihood of recovering from a physical disability decreased (for the Katz measure: odds ratio, 0.96; 95% confidence interval, 0.93-0.99; for the Rosow-Breslau measure: odds ratio, 0.86; 95% confidence interval, 0.84-0.89; and for the Nagi measure: odds ratio, 0.89; 95% confidence interval, 0.87-0.91). This effect was not accounted for by age, sex, level of educational attainment, body mass index, or chronic health conditions. CONCLUSION: Mild depressive symptoms in older persons (those aged > or =65 years) are associated with an increased likelihood of becoming disabled and a decreased chance of recovery, regardless of age, sex, and other factors that contribute to physical disability.

Complementary and alternative therapies to manage HIV-related symptoms.

Persons with HIV infection report substantial use of complementary and alternative medical (CAM) therapies for symptom management. Anecdotal reports from patients indicate that CAM approaches are helpful; however, there is limited scientific information on the safety and efficacy of these therapies in the HIV population. The purpose of this review is to critically appraise the scientific evidence for selected CAM therapies that are used by HIV-infected persons to manage three common symptoms: nutritional alterations, pain, and depression.