Access to primary eye care for people living with dementia: a call to action for primary care practitioners to 'think vision'

Access to allied health services offers significant benefits for people living with dementia, yet access is currently fragmented and inconsistent. The 2023-2024 budget allocated AU$445million to further enable general practice-led, multidisciplinary teams, with integrated care located within practices, including employment of allied health professionals. Such team care models are recognised by The Royal Australian College of General Practitioners as vital to delivery of high-quality care for older adults. They are especially relevant for over 250,000 Australians who live with dementia in the community. However, not all allied health professionals are currently based within general practices. Future, sustainable general practice-led models of multidisciplinary care that connect patients with external allied health providers could be considered for a comprehensive and collaborative approach to care. Our focus is on people living with dementia, who are at greater risk of preventable vision impairment. Poor vision and/or ocular health can be detected and managed through regular eye examinations, which are predominantly delivered by community-based optometrists in Australia, in a primary care capacity. However, people living with dementia are also less likely to have regular eye examinations. In this paper, we highlight the value of ensuring access to primary eye care services as part of post-diagnosis dementia care. We illustrate the important role of primary care practitioners in building and sustaining connections with allied health professions, like optometry, through effective referral and interprofessional communication systems. This can help break down access barriers to dementia-friendly eye care, through promoting the importance of regular eye tests for people living with dementia.

A rapid review of challenges and opportunities related to diversity and inclusion as experienced by early and mid-career academics in the medicine, dentistry and health sciences fields

BACKGROUND

Early- and mid-career academics in medicine, dentistry and health sciences are integral to research, education and advancement of clinical professions, yet experience significant illbeing, high attrition and limited advancement opportunities.

OBJECTIVES

Identify and synthesise published research investigating challenges and opportunities related to diversity and inclusion, as experienced by early and mid-career academics employed in medicine, dentistry and health sciences disciplines.

DESIGN

Rapid review.

DATA SOURCES

OVID Medline, Embase, APA PsycInfo, CINAHL and Scopus.

METHODS

We systematically searched for peer reviewed published articles within the last five years, investigating challenges and opportunities related to diversity and inclusion, as experienced by early and mid-career academics employed in medicine, dentistry and health sciences. We screened and appraised articles, then extracted and synthesised data.

RESULTS

Database searches identified 1162 articles, 11 met inclusion criteria. Studies varied in quality, primarily reporting concepts encompassed by professional identity. There were limited findings relating to social identity, with sexual orientation and disability being a particularly notable absence, and few findings relating to inclusion. Job insecurity, limited opportunities for advancement or professional development, and a sense of being undervalued in the workplace were evident for these academics.

CONCLUSIONS

Our review identified overlap between academic models of wellbeing and key opportunities to foster inclusion. Challenges to professional identity such as job insecurity can contribute to development of illbeing. Future interventions to improve wellbeing in academia for early- and mid-career academics in these fields should consider addressing their social and professional identity, and foster their inclusion within the academic community.

REGISTRATION

Open Science Framework ( https://doi.org/10.17605/OSF.IO/SA4HX ).

A novel tool for quantitative measurement of distortion in keratoconus

Background

Keratoconus is associated with thinning and anterior protrusion of the cornea resulting in the symptoms of blurry and distorted vision. The commonly used clinical vision tests such as visual acuity and contrast sensitivity may not reflect the symptoms experienced in keratoconus and there are no quantitative tools to measure visual distortion. In this study, we used a quantitative test based on vernier alignment and field matching techniques to quantify visual distortion in keratoconus and assess its relation to corneal structural changes.

Methods

A total of 50 participants (25 keratoconus and 25 visually normal) completed the experiment where they aligned supra-threshold white target circles in opposite field in reference to guidelines and circles to complete a square structure monocularly. The task was repeated five times and the global distortion index (GDI) and global uncertainty index (GUI) were calculated as the mean and standard deviation respectively of local perceived misalignment of target circles over five trials.

Results

Both GDI and GUI were higher in participants with keratoconus compared to controls (p < 0.01). Both parameters correlated with the best corrected visual acuity, maximum corneal curvature (K_max), topographical keratoconus classification (TKC) and central corneal thickness (CCT).

Conclusion

Our findings show that the quantitative measure of distortion could be a useful tool for behavioural assessment of progressive keratoconus.

Feasibility of an automated interview grounded in multiple mini interview (MMI) methodology for selection into the health professions: an international multimethod evaluation

OBJECTIVES

Global, COVID-driven restrictions around face-to-face interviews for healthcare student selection have forced admission staff to rapidly adopt adapted online systems before supporting evidence is available. We have developed, what we believe is, the first automated interview grounded in multiple mini-interview (MMI) methodology. This study aimed to explore test-retest reliability, acceptability and usability of the system.

DESIGN, SETTING AND PARTICIPANTS

Multimethod feasibility study in Physician Associate programmes from two UK and one US university during 2019-2020.

PRIMARY, SECONDARY OUTCOMES

Feasibility measures (test-retest reliability, acceptability and usability) were assessed using intraclass correlation (ICC), descriptive statistics, thematic and content analysis.

METHODS

Volunteers took (T1), then repeated (T2), the automated MMI, with a 7-day interval (±2) then completed an evaluation questionnaire. Admission staff participated in focus group discussions.

RESULTS

Sixty-two students and seven admission staff participated; 34 students and 4 staff from UK and 28 students and 3 staff from US universities. Good-excellent test-retest reliability was observed at two sites (US and UK2) with T1 and T2 ICC between 0.65 and 0.81 (p<0.001) when assessed by individual total scores (range 80.6-119), station total scores 0.6-0.91, p<0.005 and individual site (≥0.79 p<0.001). Mean test re-test ICC across all three sites was 0.82 p<0.001 (95% CI 0.7 to 0.9). Admission staff reported potential to reduce resource costs and bias through a more objective screening tool for preselection or to replace some MMI stations in a 'hybrid model'. Maintaining human interaction through 'touch points' was considered essential. Users positively evaluated the system, stating it was intuitive with an accessible interface. Concepts chosen for dynamic probing needed to be appropriately tailored.

CONCLUSION

These preliminary findings suggest that the system is reliable, generating consistent scores for candidates and is acceptable to end users provided human touchpoints are maintained. Thus, there is evidence for the potential of such an automated system to augment healthcare student selection.

Eye health profile of affordable eye care service users

CLINICAL RELEVANCE

Knowledge of the typical eye health profile of patients experiencing social or economic disadvantage is useful for health care modelling.

BACKGROUND

The aim of this work is to profile the ocular health and sociodemographic characteristics of Australian College of Optometry service users of all ages and to explore the relationships between key sociodemographic characteristics and eye health.

METHODS

For 3093 eye examinations, best-corrected distance visual acuity and mean spherical equivalent refractive error were tested non-parametrically by clinic category, remoteness area, number of co-morbidities, gender and indigenous status, also correlated against age and socioeconomic advantage/disadvantage. Covariates of interest were entered into linear mixed models of visual acuity and mean spherical equivalent refractive error, controlling for age. Risk estimates are reported for visual impairment (defined as ≤6/12 best-corrected distance visual acuity in one or both eyes) and ocular diagnoses.

RESULTS

Visual impairment is more prevalent amongst service users examined in domiciliary settings. Increasing co-morbidities were associated with poorer best-corrected distance visual acuity. Aboriginal and Torres Strait Islander service users had lower visual impairment prevalence overall but proportionally fewer aged ≥50 years attended for eye care, compared to non-indigenous.

CONCLUSIONS

Domiciliary eye examinations detect remediable visual impairment. Federal public health interventions delivered by the Australian College of Optometry for Aboriginal and Torres Strait Islander eye care appear effective but may not reach all aged ≥ 50 years; further research is required. Identification of multiple co-morbidities should prompt optometrists to tailor public health messages and signpost to low vision services earlier.

Posterior Circulation Endovascular Thrombectomy for Large-Vessel Occlusion: Predictors of Favorable Clinical Outcome and Analysis of First-Pass Effect

BACKGROUND AND PURPOSE

Successful vessel recanalization in posterior circulation large-vessel occlusion is considered crucial, though the evidence of clinical usefulness, compared with the anterior circulation, is not still determined. The aim of this study was to evaluate predictors of favorable clinical outcome and to analyze the effect of first-pass thrombectomy.

MATERIALS AND METHODS

A retrospective, multicenter, observational study was conducted in 10 high-volume stroke centers in Europe, including the period from January 2016 to July 2019. Only patients with an acute basilar artery occlusion or a single, dominant vertebral artery occlusion ("functional" basilar artery occlusion) who had a 3-month mRS were included. Clinical, procedural, and radiologic data were evaluated, and the association between these parameters and both the functional outcome and the first-pass effect was assessed.

RESULTS

A total of 191 patients were included. A lower baseline NIHSS score (adjusted OR, 0.77; 95% CI, 0.61-0.96; P = .025) and higher baseline MR imaging posterior circulation ASPECTS (adjusted OR, 3.01; 95% CI, 1.03-8.76; P = .043) were predictors of better outcomes. The use of large-bore catheters (adjusted OR, 2.25; 95% CI, 1.08-4.67; P = .030) was a positive predictor of successful reperfusion at first-pass, while the use of a combined technique was a negative predictor (adjusted OR, 0.26; 95% CI, 0.09-0.76; P = .014).

CONCLUSIONS

The analysis of our retrospective series demonstrates that a lower baseline NIHSS score and a higher MR imaging posterior circulation ASPECTS were predictors of good clinical outcome. The use of large-bore catheters was a positive predictor of first-pass modified TICI 2b/3; the use of a combined technique was a negative predictor.

Use of Cangrelor in Cervical and Intracranial Stenting for the Treatment of Acute Ischemic Stroke: A "Real Life" Single-Center Experience

BACKGROUND AND PURPOSE

In cases of large-vessel-occlusion strokes due to an underlying tandem internal carotid artery occlusion or intracranial atherosclerotic disease, concomitant stent placement may be needed. Immediate platelet inhibition is necessary, but to date, a standardized approach for antiplatelet inhibition in acute settings is still missing. Here we report our single-center experience about the safety and efficacy of periprocedural administration of cangrelor in patients with acute ischemic stroke due to intracranial or cervical artery occlusion undergoing stent placement.

MATERIALS AND METHODS

We retrospectively evaluated all cases of acute ischemic stroke that needed acute stent implantation and were treated with periprocedural administration of cangrelor between January 2019 and April 2020 at our institution. All patients who needed either extracranial or intracranial artery stent placement (in either the anterior or posterior circulation) were included.

RESULTS

We evaluated 38 patients in whom cangrelor was administered IV periprocedurally. Their mean age was 64 years (range, 26-85 years), with 25/38 male subjects and 13/38 female patients. In 26 patients (68.4%), a tandem occlusion was present and was treated with carotid artery stent placement, while 12 patients (31.6%) required an intracranial stent implantation. In 4 subjects (10.5%), an intracerebral hemorrhage occurred after the procedure. All patients in the series were alive 1 week after the procedure.

CONCLUSIONS

Although larger, multicentric randomized studies are strongly warranted, our results support the hypothesis of a possible role of cangrelor as a valuable therapeutic option in the management of platelet inhibition in acute ischemic stroke procedures after intra- or extracranial stent placement.

Binocular Vision, Visual Function, and Pupil Dynamics in People Living With Dementia and Their Relation to the Rate of Cognitive Decline and Structural Changes Within the Brain: Protocol for an Observational Study

BACKGROUND

Visual impairment is a common comorbidity in people living with dementia. Addressing sources of visual difficulties can have a significant impact on the quality of life for people living with dementia and their caregivers. Depth perception problems are purportedly common in dementia and also contribute to falls, visuomotor task difficulties, and poorer psychosocial well-being. However, depth perception and binocular vision are rarely assessed in dementia research. Sleep fragmentation is also common for people living with dementia, and binocular cooperation for depth perception can be affected by fatigue. Pupillary responses under cognitive load also have the potential to be a risk marker for cognitive decline in people living with dementia and can be combined with the above measures for a comprehensive evaluation of clinical visual changes in people living with dementia and their relation to changes in cognitive status, sleep quality, and cortical structure or function.

OBJECTIVE

This study aims to characterize the nature of clinical visual changes and altered task-evoked pupillary responses that may occur in people living with dementia and evaluate whether these responses relate to changes in cognitive status (standardized Mini Mental State Examination [MMSE] score), Pittsburgh sleep quality index, and cortical structure or function.

METHODS

This proposed exploratory observational study will enroll ≤210 people with recently diagnosed dementia (within the last 24 months). The following parameters will be assessed on 3 occasions, 4 months apart (plus or minus 2 weeks): visual function (visual acuity and contrast sensitivity), binocular function (motor fusion and stereopsis), task-evoked pupillary responses (minimum and maximum pupil size, time to maximum dilation, and dilation velocity), cognitive status (MMSE score), and sleep quality (Pittsburgh Sleep Quality Index). A subset of patients (n=30) with Alzheimer disease will undergo structural and functional magnetic resonance imaging at first and third visits, completing a 10-day consensus sleep diary to monitor sleep quality, verified by sleep actimetry.

RESULTS

This research was funded in February 2018 and received National Health Service Research Ethics Committee approval in September 2018. The data collection period was from October 1, 2018, to November 30, 2019. A total of 24 participants were recruited for the study. The data analysis is complete, with results expected to be published before the end of 2020.

CONCLUSIONS

Findings will demonstrate how often people with dementia experience binocular vision problems. If frequent, diagnosing and treating them could improve quality of life by reducing the risk of falls and fine visuomotor task impairment and by relieving psychosocial anxiety. This research will also demonstrate whether changes in depth perception, pupillary responses, and quality of vision relate to changes in memory or sleep quality and brain structure or function. If related, these quick and noninvasive eye tests help monitor dementia. This would help justify whether binocular vision and pupillary response testing should be included in dementia-friendly eye-testing guidelines.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/16089.

Cranial nerve deficits in giant cavernous carotid aneurysms and their relation to aneurysm morphology and location

BACKGROUND

Giant cavernous carotid aneurysms (GCCAs) usually exert substantial mass effect on adjacent intracavernous cranial nerves. Since predictors of cranial nerve deficits (CNDs) in patients with GCCA are unknown, we designed a study to identify associations between CND and GCCA morphology and the location of mass effect.

METHODS

This study was based on data from the prospective clinical and imaging databases of the Giant Intracranial Aneurysm Registry. We used magnetic resonance imaging and digital subtraction angiography to examine GCCA volume, presence of partial thrombosis (PT), GCCA origins, and the location of mass effect. We also documented whether CND was present.

RESULTS

We included 36 GCCA in 34 patients, which had been entered into the registry by eight participating centers between January 2009 and March 2016. The prevalence of CND was 69.4%, with one CND in 41.7% and more than one in 27.5%. The prevalence of PT was 33.3%. The aneurysm origin was most frequently located at the anterior genu (52.8%). The prevalence of CND did not differ between aneurysm origins (p = 0.29). Intracavernous mass effect was lateral in 58.3%, mixed medial/lateral in 27.8%, and purely medial in 13.9%. CND occurred significantly more often in GCCA with lateral (81.0%) or mixed medial/lateral (70.0%) mass effect than in GCCA with medial mass effect (20.0%; p = 0.03). After adjusting our data for the effects of the location of mass effect, we found no association between the prevalence of CND and aneurysm volume (odds ratio (OR) 1.30 (0.98-1.71); p = 0.07), the occurrence of PT (OR 0.64 (0.07-5.73); p = 0.69), or patient age (OR 1.02 (95% CI 0.95-1.09); p = 0.59).

CONCLUSIONS

Distinguishing between medial versus lateral location of mass effect may be more helpful than measuring aneurysm volumes or examining aneurysm thrombosis in understanding why some patients with GCCA present with CND while others do not.

CLINICAL TRIAL REGISTRATION NO

NCT02066493 ( clinicaltrials.gov ).

Cancer Survivors' Experience With Telehealth: A Systematic Review and Thematic Synthesis

BACKGROUND

Net survival rates of cancer are increasing worldwide, placing a strain on health service provision. There is a drive to transfer the care of cancer survivors-individuals living with and beyond cancer-to the community and encourage them to play an active role in their own care. Telehealth, the use of technology in remote exchange of data and communication between patients and health care professionals (HCPs), is an important contributor to this evolving model of care. Telehealth interventions are "complex," and understanding patient experiences of them is important in evaluating their impact. However, a wider view of patient experience is lacking as qualitative studies detailing cancer survivor engagement with telehealth are yet to be synthesized.

OBJECTIVE

To systematically identify, appraise, and synthesize qualitative research evidence on the experiences of adult cancer survivors participating in telehealth interventions, to characterize the patient experience of telehealth interventions for this group.

METHODS

Medline (PubMed), PsychINFO, Cumulative Index for Nursing and Allied Health Professionals (CINAHL), Embase, and Cochrane Central Register of Controlled Trials were searched on August 14, 2015, and March 8, 2016, for English-language papers published between 2006 and 2016. Inclusion criteria were as follows: adult cancer survivors aged 18 years and over, cancer diagnosis, experience of participating in a telehealth intervention (defined as remote communication or remote monitoring with an HCP delivered by telephone, Internet, or hand-held or mobile technology), and reporting qualitative data including verbatim quotes. An adapted Critical Appraisal Skill Programme (CASP) checklist for qualitative research was used to assess paper quality. The results section of each included article was coded line by line, and all papers underwent inductive analysis, involving comparison, reexamination, and grouping of codes to develop descriptive themes. Analytical themes were developed through an iterative process of reflection on, and interpretation of, the descriptive themes within and across studies.

RESULTS

Across the 22 included papers, 3 analytical themes emerged, each with 3 descriptive subthemes: (1) influence of telehealth on the disrupted lives of cancer survivors (convenience, independence, and burden); (2) personalized care across physical distance (time, space, and the human factor); and (3) remote reassurance-a safety net of health care professional connection (active connection, passive connection, and slipping through the net). Telehealth interventions represent a convenient approach, which can potentially minimize treatment burden and disruption to cancer survivors' lives. Telehealth interventions can facilitate an experience of personalized care and reassurance for those living with and beyond cancer; however, it is important to consider individual factors when tailoring interventions to ensure engagement promotes benefit rather than burden.

CONCLUSIONS

Telehealth interventions can provide cancer survivors with independence and reassurance. Future telehealth interventions need to be developed iteratively in collaboration with a broad range of cancer survivors to maximize engagement and benefit.

Embolization of Intracranial Dural Arteriovenous Fistulas Using PHIL Liquid Embolic Agent in 26 Patients: A Multicenter Study

BACKGROUND AND PURPOSE

The introduction of liquid embolic agents has revolutionized endovascular approach to cranial vascular malformations. The aim of the study was to retrospectively assess the efficacy and safety of Precipitating Hydrophobic Injectable Liquid (PHIL), a new nonadhesive liquid embolic agent, in the treatment of patients with cranial dural arteriovenous fistulas. The primary end point was the rate of complete occlusion of dural arteriovenous fistulas. Secondary end points included the incidence of adverse events and clinical status at 3-month follow-up.

MATERIALS AND METHODS

This was a retrospective multicenter study. Twenty-six consecutive patients with dural arteriovenous fistulas (de novo or previously treated) treated by injection of PHIL only or with PHIL in combination with other embolization products (such as Onyx or detachable coils) were included in the study. Recruitment started in August 2014 and ended in September 2015.

RESULTS

Twenty-two (85%) patients were treated with PHIL only, with 3 patients treated with both PHIL and Onyx, and 1, with both PHIL and coils. Immediate complete angiographic occlusion was achieved in 20 (77%) patients. Of the 6 patients with residual fistulas, 3 were retreated with PHIL and 1 achieved angiographic cure. An adverse event was seen in 1 patient who developed worsening of preexisting ataxia due to acute thrombosis of the draining vein.

CONCLUSIONS

PHIL appears to be safe and effective for endovascular treatment of cranial dural arteriovenous fistulas. Short-term angiographic and clinical results are comparable with those of Onyx, with the added advantage of easier preparation and improved homogeneous cast visualization. The use of iodine as a radio-opacifier also produces considerably less artifacts on CT compared with tantalum-based embolic materials.

A pilot study examining density of suppression measurement in strabismus

PURPOSE

Establish whether the Sbisa bar, Bagolini filter (BF) bar, and neutral density filter (NDF) bar, used to measure density of suppression, are equivalent and possess test-retest reliability. Determine whether density of suppression is altered when measurement equipment/testing conditions are changed.

METHODS

Our pilot study had 10 subjects aged ≥18 years with childhood-onset strabismus, no ocular pathologies, and no binocular vision when manifest. Density of suppression upon repeated testing, with clinic lights on/off, and using a full/reduced intensity light source, was investigated. Results were analysed for test-retest reliability, equivalence, and changes with alteration of testing conditions.

RESULTS

Test-retest reliability issues were present for the BF bar (median 6 filter change from first to final test, p = 0.021) and NDF bar (median 5 filter change from first to final test, p = 0.002). Density of suppression was unaffected by environmental illumination or fixation light intensity variations. Density of suppression measurements were higher when measured with the NDF bar (e.g. NDF bar = 1.5, medium suppression, vs BF bar = 6.5, light suppression).

CONCLUSIONS

Test-retest reliability issues may be present for the two filter bars currently still under manufacture. Changes in testing conditions do not significantly affect test results, provided the same filter bar is used consistently for testing. Further studies in children with strabismus having active amblyopia treatment would be of benefit. Despite extensive use of these tests in the UK, this is to our knowledge the first study evaluating filter bar equivalence/reliability.

Use of atropine penalization to treat amblyopia in UK orthoptic practice

PURPOSE

To compare clinical practice patterns regarding atropine penalization use by UK orthoptists to the current evidence base and identify any existing barriers against use of AP as first-line treatment.

METHODS

An online survey was designed to assess current practice patterns of UK orthoptists using atropine penalization. They were asked to identify issues limiting their use of atropine penalization and give opinions on its effectiveness compared to occlusion. Descriptive statistics and content analysis were applied to the results.

RESULTS

Responses were obtained from 151 orthoptists throughout the United Kingdom. The main perceived barriers to use of atropine penalization were inability to prescribe atropine and supply difficulties. However, respondents also did not consider atropine penalization as effective as occlusion in treating amblyopia, contrary to recent research findings. Patient selection criteria and treatment administration largely follow current evidence. More orthoptists use atropine penalization as first-line treatment than previously reported.

CONCLUSIONS

Practitioners tend to closely follow the current evidence base when using atropine penalization, but reluctance in offering it as first-line treatment or providing a choice for parents between occlusion and atropine still remains. This may result from concerns regarding atropine's general efficacy, side effects, and risk of reverse amblyopia. Alternatively, as demonstrated in other areas of medicine, it may reflect the inherent delay of research findings translating to clinical practice changes.

Treatment of cavernous sinus aneurysms with flow diversion: results in 44 patients

BACKGROUND AND PURPOSE

Aneurysms of the cavernous segment of the ICA are difficult to treat with standard endovascular techniques, and ICA sacrifice achieves a high rate of occlusion but carries an elevated level of surgical complications and risk of de novo aneurysm formation. We report rates of occlusion and treatment-related data in 44 patients with cavernous sinus aneurysms treated with flow diversion.

MATERIALS AND METHODS

Patients with cavernous segment aneurysms treated with flow diversion were selected from a prospectively maintained data base of patients from 2009 to the present. Demographic information, treatment indications, number/type of flow diverters placed, outcome, complications (technical or clinical), and clinical/imaging follow-up data were analyzed.

RESULTS

We identified 44 patients (37 females, 7 males) who had a flow diverter placed for treatment of a cavernous ICA aneurysm (mean age, 57.2; mean aneurysm size, 20.9 mm). The mean number of devices placed per patient was 2.2. At final angiographic follow-up (mean, 10.9 months), 71% had complete occlusion, and of those with incomplete occlusion, 40% had minimal remnants (<3 mm). In symptomatic patients, complete resolution or significant improvement in symptoms was noted in 90% at follow-up. Technical complications (which included, among others, vessel perforation in 4 patients, groin hematoma in 2, and asymptomatic carotid occlusion in 1) occurred in approximately 36% of patients but did not result in any clinical sequelae immediately or at follow-up.

CONCLUSIONS

Our series of flow-diversion treatments achieved markedly greater rates of complete occlusion than coiling, with a safety profile that compares favorably with that of carotid sacrifice.

Amperometric lactate biosensor for flow injection analysis based on a screen-printed carbon electrode containing Meldola's Blue-Reinecke salt, coated with lactate dehydrogenase and NAD+

A biosensor for the measurement of lactate in serum has been developed, which is based on a screen-printed carbon electrode, modified with Meldola's Blue-Reinecke Salt (MBRS-SPCE), coated with the enzyme lactate dehydrogenase NAD(+) dependent (from Porcine heart), and NAD(+). A cellulose acetate layer was deposited on the top of the device to act as a permselective membrane. The biosensor was incorporated into a commercially available, thin-layer, amperometric flow cell operated at a potential of only +0.05 V vs. Ag/AgCl. The mobile phase consisted of 0.2 M phosphate buffer pH 10 containing 0.1 M potassium chloride solution; a flow rate of 0.8 ml min(-1) was used throughout the investigation. The biosensor response was linear over the range 0.55-10 mM lactate; the former represents the detection limit. The precision of the system was determined by carrying out 10 repeat injections of 10 mM l(+)lactic acid standard; the calculated coefficient of variation was 4.28%. It was demonstrated that this biosensor system could be applied to the direct measurement of lactate in serum without pre-treatment; therefore, this would allow high throughput-analysis, at low cost, for this clinically important analyte.

A flow injection system, comprising a biosensor based on a screen-printed carbon electrode containing Meldola's Blue-Reinecke salt coated with glucose dehydrogenase, for the measurement of glucose

A biosensor for the measurement of glucose in serum has been developed, based on a screen-printed carbon electrode modified with Meldola's Blue-Reinecke salt, coated with the enzyme glucose dehydrogenase (from Bacillus sp.), and nicotinamide adenine dinucleotide coenzyme (NAD+). A cellulose acetate layer was deposited on top of the device to act as a permselective membrane. The biosensor was incorporated into a commercially available, thin-layer, amperometric flow cell operated at a potential of only +0.05 V versus Ag/AgCl. The mobile phase consisted of 0.2 M phosphate buffer (pH 7.0) containing 0.1 M potassium chloride solution, and a flow rate of 0.8 ml min(-1) was used throughout the investigation. The biosensor response was linear over the range of 0.075-30 mM glucose, with the former representing the detection limit. The precision of the system was determined by carrying out 20 repeat injections of a 5-mM glucose standard, and the calculated coefficient of variation was 3.9%. It was demonstrated that this biosensor system could be applied to the direct measurement of glucose in serum without pretreatment. Therefore, this would allow high-throughput analysis, at low cost, for this clinically important analyte.