Late Diagnosis of Residual Major Aortopulmonary Collateral in a Patient with Tetralogy of Fallot

•Residual MAPCAs result in post-tricuspid shunt and PH. •Distinction between PH and conduit stenosis requires attention to TTE findings. •Management of complex adult CHD should be reserved for centers with expertise. •A multimodal imaging approach is often required to complete this understanding.

Echocardiographic measured shunt velocity does not predict pulmonary blood flow in patients with Blalock-Thomas-Taussig shunt

INTRODUCTION

Catheterisation is the gold standard used to evaluate pulmonary blood flow in patients with a Blalock-Thomas-Taussig shunt. It involves risk and cannot be performed frequently. This study aimed to evaluate if echocardiographic measurements obtained in a clinical setting correlate with catheterisation-derived pulmonary blood flow in patients with a Blalock-Thomas-Taussig shunt as the sole source of pulmonary blood flow.

METHODS

Chart review was performed retrospectively on consecutive patients referred to the catheterisation lab with a Blalock-Thomas-Taussig shunt. Echocardiographic parameters included peak, mean, and diastolic gradients across the Blalock-Thomas-Taussig shunt and forward and reverse velocity time integral across the distal transverse aorta. In addition to direct correlations, we tested a previously published formula for pulmonary blood flow calculated as velocity time integral across the shunt × heart rate × Blalock-Thomas-Taussig shunt area. Catheterisation parameters included pulmonary and systemic blood flow as calculated by the Fick principle.

RESULTS

18 patients were included. The echocardiography parameters and oxygen saturation did not correlate with catheterisation-derived pulmonary blood flow, systemic blood flow, or the ratio of pulmonary to systemic blood flow. As the ratio of reverse to forward velocity time integral across the transverse aorta increased, the probability of shunt stenosis decreased.

CONCLUSION

Echocardiographic measurements obtained outside the catheterisation lab do not correlate with catheterisation-derived pulmonary blood flow. The ratio of reverse to forward velocity time integral across the transverse aortic arch may be predictive of Blalock-Thomas-Taussig shunt narrowing; this finding should be investigated further.

Memory support training and lifestyle modifications to promote healthy aging in persons at risk for Alzheimer's disease: a digital application supported intervention (Brain Boosters)

BACKGROUND

Evidence-based interventions to protect against cognitive decline among older adults at risk for Alzheimer's disease and related dementias (ADRD) are urgently needed. Rehabilitation approaches to support memory and behavioral/lifestyle interventions are recognized as promising strategies for preserving or improving cognitive health, although few previous interventions have combined both approaches. This paper describes the protocol of the Brain Boosters intervention, which synergistically combines training in compensatory and healthy lifestyle behaviors and supports implementation and tracking of new behaviors with a digital application.

METHODS

The study utilizes a single-site, single-blinded, randomized controlled design to compare a structured lifestyle and compensatory aid intervention to an education-only self-guided intervention. We plan to enroll 225 community-dwelling adults (25% from underrepresented groups) aged 65 + who endorse subjective cognitive decline (SCD) and low baseline levels of healthy lifestyle behaviors. Both interventions will be administered in group format, consisting of 15 two-hour classes that occur weekly for ten weeks and taper to bi-monthly and monthly, for an intervention duration of 6 months. Participants in both interventions will receive education about a variety of memory support strategies and healthy lifestyle behaviors, focusing on physical and cognitive activity and stress management. The structured intervention will also receive support in adopting new behaviors and tracking set goals aided by the Electronic Memory and Management Aid (EMMA) digital application. Primary outcomes include global cognition (composite of memory, attention, and executive function tests) and everyday function (Everyday Cognition Questionnaire). Data will be collected at baseline and outcome visits, at approximately 6, 12, and 18 months. Qualitative interviews, self-report surveys (e.g., indicators of self-determination, health literacy) and EMMA data metrics will also be used to identify what components of the intervention are most effective and for whom they work.

DISCUSSION

Successful project completion will provide valuable information about how individuals with SCD respond to a compensation and preventative lifestyle intervention assisted by a digital application, including an understanding of factors that may impact outcomes, treatment uptake, and adherence. The work will also inform development, scaling, and personalization of future interventions that can delay disability in individuals at risk for ADRD.

TRIAL REGISTRATION

ClinicalTrials.gov. (NCT05027789, posted 8/30/2021).

Left Atrial Hypertension and Respiratory Failure Requiring Venoarterial ECMO After Transcatheter Pulmonary Valve Replacement

A 33-year-old woman with aortic valve stenosis status-post Ross at age 6 years developed symptomatic right heart failure from right ventricle to pulmonary artery conduit stenosis. Conduit rehabilitation and transcatheter pulmonary valve replacement resulted in acute left atrial hypertension and respiratory failure requiring venoarterial extracorporeal membrane oxygenation and atrial septal defect creation as a bridge to recovery.

Echocardiogram-Guided Balloon Valvuloplasty of the Aortic Valve in Neonates and Infants Reduces Contrast Exposure with Maintained Efficacy and Less Aortic Regurgitation

Balloon aortic valvuloplasty (BAV) is performed in children with significant aortic stenosis (AS). Traditionally, contrast angiography measures the annulus and assesses aortic regurgitation (AR) after each dilation. Echocardiographic guidance is hypothesized to reduce contrast and radiation exposure, without compromising efficacy or safety. Patients < 10 kg undergoing BAV from 2013 to 2022 were retrospectively investigated. Agreement between echocardiographic and angiographic annulus measurements was assessed. Echocardiogram-guided (eBAV) and traditional angiogram-guided (tBAV) outcomes were compared controlling for weight, critical AS, and other congenital heart disease (CHD). Twelve eBAV and 19 tBAV procedures were performed. The median age was 33 days, median weight was 4.3 kg, 7 patients (23%) had critical AS, and 9 patients (29%) had other CHD. Annulus measurements by intraprocedural echocardiography and angiography displayed excellent correlation (ICC 0.95, p < 0.001). eBAV patients received less contrast (0.5 vs 3.5 ml/kg, p < 0.01). Five recent eBAV procedures were performed contrast free. Radiation exposure was not statistically different between the eBAV and tBAV groups (155 vs 313 µGy·M², p = 0.12). One eBAV patient (8%) and 3 tBAV patients (16%, p = 0.62) experienced serious adverse events. Technical success (gradient < 35 mmHg and increase in AR by ≤ 1 grade) occurred in 11 eBAV patients (92%) and 16 tBAV patients (84%, p = 0.22). AR increased in 2 eBAV patients (17%) and 8 tBAV patients (44%, p = 0.02). eBAV was associated with similar efficacy and significantly lower contrast exposure and risk of aortic regurgitation. There was strong agreement between aortic valve annulus measurements by intraprocedural echocardiography and angiography, ultimately permitting contrast free BAV.

The influence of frailty on outcomes for older adults admitted to hospital with benign biliary disease: a single-centre, observational cohort study

INTRODUCTION

The prevalence and complications of biliary disease increase with age. Frailty has been associated with adverse outcomes in the hospital setting. We describe the prevalence of frailty in older patients hospitalised with benign biliary disease and its association with duration of hospital stay, and 90-day and 1-year mortality.

METHODS

We performed a retrospective cohort study of patients aged 75 years and over admitted with acute biliary disease between 17 September 2014 and 20 March 2017. Clinical Frailty Scale (CFS) score was recorded on admission.

RESULTS

We included 200 patients with a median age of 82 (75-99) years, 60% were female; 154 (77%) were independent for personal activities of daily living (ADLs) and 99 (49.5%) for instrumental ADLs. Cholecystitis was the most common diagnosis (43%) followed by cholangitis (36%) and pancreatitis (21%). Ninety-nine patients were non frail (NF; CFS 1-4) and 101 were frail (F; CFS 5-9). Some 104 patients received medical treatment only. Surgery was more common in NF patients (11% vs F 2%), percutaneous drainage more frequently performed in F patients (15% vs NF 5%) and endoscopic cholangiopancreatography was similar in both groups (F 32% vs NF 31%). Frailty was associated with worse clinical outcomes in F vs NF: functional deconditioning (34% vs 11%), increased care level (19% vs 3%), length of stay (12 vs 7 days), 90-day mortality (8% vs 3%) and 1-year mortality (48% vs 24%).

CONCLUSIONS

Half of patients in our cohort were frail and spent longer in hospital, were less likely to undergo surgery and were less likely to remain alive at 1 year after discharge.

Imaging Breast Microcalcifications Using Dark-Field Signal in Propagation-Based Phase-Contrast Tomography

Breast microcalcifications are an important primary radiological indicator of breast cancer. However, microcalcification classification and diagnosis may be still challenging for radiologists due to limitations of the standard 2D mammography technique, including spatial and contrast resolution. In this study, we propose an approach to improve the detection of microcalcifications in propagation-based phase-contrast X-ray computed tomography of breast tissues. Five fresh mastectomies containing microcalcifications were scanned at different X-ray energies and radiation doses using synchrotron radiation. Both bright-field (i.e. conventional phase-retrieved images) and dark-field images were extracted from the same data sets using different image processing methods. A quantitative analysis was performed in terms of visibility and contrast-to-noise ratio of microcalcifications. The results show that while the signal-to-noise and the contrast-to-noise ratios are lower, the visibility of the microcalcifications is more than two times higher in the dark-field images compared to the bright-field images. Dark-field images have also provided more accurate information about the size and shape of the microcalcifications.

Data registration for multi-method qualification of additive manufactured components

This work refines surface registration methods for metrological datasets to improve the multi-method qualification accuracy of additively manufactured (AM) lattices. Datasets acquired from X-ray computed tomography and a coordinate measurement machine of an AM lattice were aligned using derived geometry datum features based on a theoretical supplemental surface definition, which has been established in recent draft standards, but has had limited examination using complex AM structures. A refined sampling registration approach for lattice geometry based on spatially-dependent subsampling is derived and shown to statistically decrease variation between measurement sources. This importance of well-defined sampling practice and definition is highlighted. The applicability of this approach for multi-method qualification of complex AM parts is discussed. This work lays the foundation of utilizing specifications under consideration in a new standard with possible verification techniques that can be employed.

Measuring High-Order Phonon Correlations in an Optomechanical Resonator

We use single photon detectors to probe the motional state of a superfluid ^{4}He resonator of mass ∼1  ng. The arrival times of Stokes and anti-Stokes photons (scattered by the resonator's acoustic mode) are used to measure the resonator's phonon coherences up to the fourth order. By postselecting on photon detection events, we also measure coherences in the resonator when ≤3 phonons have been added or subtracted. These measurements are found to be consistent with predictions that assume the acoustic mode to be in thermal equilibrium with a bath through a Markovian coupling.

Hospital and community care costs for people newly diagnosed of living with HIV in London, UK

This study of people newly diagnosed of living with HIV (ND-PLHIV) calculated the use, cost and outcome of HIV services at a London HIV centre. ND-PLHIV were followed July 2017-October 2018. Hospital data included inpatient days (IP), outpatient (OP), dayward (DW) visits, tests and procedures, and anti-retroviral drugs (ARVs). Community services were recorded in daily diaries. Mean per patient-year (MPPY) use was multiplied by unit costs. 13.6 MPPY (95%CI 12.4-14.9) OP visits, 0.4 MPPY (95%CI 0.1-0.7) IP days, 0.09 MPPY (95%CI 0.01-0.2) DW visits and 4.6 MPPY community services (95%CI 3.4-5.8). Total annual costs per patient-year (CPPY) was £11,483 (95%CI £10,369-12,597): ARVs comprised 63% and community services 2%. White participants used fewer hospital and more community services compared with minority ethnic community (MEC) participants. Costs for White ND-PLHIV was £10,778 CPPY (95%CI £9629-11,928); £13,214 (95%CI £10,656-15,772) for MEC ND-PLHIV (p < 0.06). Annual costs were inversely related to CD4 count at entry (r = -5.58, p = 0.02); mean CD4 count was 476 cells/mm³ (95%CI 422-531) versus 373 cells/mm³ (95%CI 320-425) for White and MEC participants respectively (p = 0.03). Annual costs for ND-PLHIV with CD4 ≤ 350 cells/mm³ was £2478 PPY higher compared with CD4 count >350 cells/mm³ (p = 0.04).

A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log₁₀ increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

Computerised decision support in veterinary medicine, exemplified in a canine idiopathic epilepsy care pathway

Computerised decision support is of emerging and increasing importance in human medicine, but as yet has not been thoroughly applied or evaluated in veterinary medicine. In this essay, the authors report on the first example of a veterinary care pathway, a specific form of computerised decision support, which guides clinicians through a clinical workflow and incorporates individual patient data to inform patient-specific decision recommendations. The veterinary care pathway was designed using consensus statements and specialist neurologist opinion to create a decision support tool concerning canine idiopathic epilepsy. The authors evaluated the care pathway by comparing 35 clinical decisions made by referral clinicians in historical cases of idiopathic epilepsy to decisions recommended by the care pathway when presented with the same clinical case. Their results show that in 77.1% (95% confidence interval [59.9, 89.6]) of cases the care pathway recommended a decision that was the same or similar to a specialist neurologist's decision. Whilst further studies are needed to explore the potential use of such technology in clinical practice, the authors believe this first application provides great promise of a new and alternative method of clinical decision support.

513 THE INFLUENCE OF FRAILTY ON OUTCOMES FOR OLDER ADULTS ADMITTED TO HOSPITAL WITH BENIGN BILIARY AND PANCREATIC DISEASE

Introduction

The prevalence and complications of biliary disease increase with age. We describe the prevalence of frailty in older patients hospitalised with benign biliary and pancreatic disease and establish its association with mortality and duration of hospital stay.

Methods

Prospective observational cohort study of patients aged 75 years and over admitted with a diagnosis of acute biliary disease to a surgical hospital unit between 17/09/2014 and 20/03/2017. Clinical Frailty Scale (CFS) score was recorded on admission.

Results

We included 200 patients with a median age of 82 (75–99), 60% females, 89% lived in their homes, 154 (77%) were independent for personal and 99 (49.5%) for instrumental ADLs, 95% mobilised independently, 17.5% had memory impairment and 8% low mood. Acute cholecystitis was the most common diagnosis (43%) followed by acute cholangitis (36%) and acute pancreatitis (21%). 99 patients were non-frail (NF = CFS 1–4) and 101 were frail (F = CFS ≥5). 104 patients received medical treatment only. Surgery was more common in non-frail (F 2% vs. NF 11%), percutaneous drainage more frequently carried out in frail patients (15% vs. NF 5%) and endoscopic cholangiopancreatography (ERCP) was similar in both groups (F 32%vs. NF 31%). Frailty was associated with worse clinical outcomes in F vs. NF: functional deconditioning (34% vs. 11%), increased care level (19% vs 3%), length of stay (12 vs. 7 days), 90-day (8% vs. 3%) and 1 year-mortality (48% vs. 24%).

Conclusion

Half of patients in our cohort of older adults hospitalised with acute biliary disease were frail. Higher scores of frailty are associated with increased mortality. Compared with non-frail patients, individuals living with frailty were less likely to undergo surgical treatment, spent longer in hospital and were less likely to remain alive at 12 months after hospital discharge.

472 A PILOT COLORECTAL AND GERIATRIC MEDICINE (CGM) CLINIC FOR OLDER, FRAIL PATIENTS REFERRED VIA A 2 WEEK WAIT PATHWAY

Introduction

The two week wait (2ww) colorectal referral pathway was introduced to expedite referrals where cancer is suspected, facilitating prompt diagnosis +/− intervention. Older frail patients are referred via this 2ww pathway even when invasive testing and intervention may not be appropriate. These patients may benefit more from holistic assessment than a universally surgical approach. A Colorectal and Geriatric Medicine (CGM) 2ww referral clinic was piloted, delivered by an urgent referral colorectal specialist nurse and an advanced clinical practitioner in geriatric medicine.

Method

Patients &gt;65 years with a Clinical Frailty Scale (CFS) score of 5 or more at referral were directed to the CGM clinic. A telephone consultation was undertaken, incorporating both 2ww assessment and aspects of comprehensive geriatric assessment.

Results

42-patients were reviewed in the clinic. Mean age was 86.1 years and mean CFS 6. 12-patients underwent CT, and 2 CT virtual colonoscopy. No patients underwent endoscopic investigation and 28-patients declined any investigation. Of those who underwent investigation, no cancers were identified. 1 patient was referred on for endosocpic mucosal resection of polyps. 5-patients had severe diverticular disease, which accounted for their symptoms. Medication recommendations were made for 30-patients, some of which led to symptom cessation. Onward referrals were made to a community geriatrician, diabetes and continence teams, and palliative care specialists. 9-patients were identified as meeting criteria for advance care planning. This was commenced during the consultation and communicated back to the referring clinician for further action.

Conclusion

Older, frail patients are often not able, nor wish to undergo, invasive investigations but should not be disadvantaged or delayed in their pathway. Further work is needed to determine the most appropriate referral pathway for this group of patients. Holistic assessment that leads to improvement in symptoms and future planning may not be achievable through a solely surgical assessment.

Adsorption trajectories of nonspherical particles at liquid interfaces

The adsorption of colloidal particles at liquid interfaces is of great importance scientifically and industrially, but the dynamics of the adsorption process is still poorly understood. In this paper we use a Langevin model to study the adsorption dynamics of ellipsoidal colloids at a liquid interface. Interfacial deformations are included by coupling our Langevin dynamics to a finite element model while transient contact line pinning due to nanoscale defects on the particle surface is encoded into our model by renormalizing particle friction coefficients and using dynamic contact angles relevant to the adsorption timescale. Our simple model reproduces the monotonic variation of particle orientation with time that is observed experimentally and is also able to quantitatively model the adsorption dynamics for some experimental ellipsoidal systems but not others. However, even for the latter case, our model accurately captures the adsorption trajectory (i.e., particle orientation versus height) of the particles. Our study clarifies the subtle interplay between capillary, viscous, and contact line forces in determining the wetting dynamics of micron-scale objects, allowing us to design more efficient assembly processes for complex particles at liquid interfaces.

Tolerability of four-drug antiretroviral combination therapy in primary HIV-1 infection

Objectives

Rapid initiation of antiretroviral therapy (ART) is important for individuals with high baseline viral loads, such as in primary HIV‐1 infection (PHI). Four‐drug regimens are sometimes considered; however, data are lacking on tolerability. We aimed to evaluate the tolerability of four‐drug regimens used in the Research in Viral Eradication of HIV‐1 Reservoirs (RIVER) study.

Methods

At enrolment, ART‐naïve adult participants or those newly commenced on ART were initiated or intensified to four‐drug regimens within 4 weeks of PHI. Rapid start was defined as pre‐confirmation or ≤ 7 days of confirmed diagnosis. Primary and secondary outcomes were patient‐reported adherence measured by 7‐day recall and regimen switches between enrolment and randomization, respectively.

Results

Overall, 54 men were included: 72.2% were of white ethnicity, with a median age of 32 years old, 42.6% had a viral load of ≥ 100 000 HIV‐1 RNA copies/mL, and in 92.6% sex with men was the mode of acquisition of HIV‐1. Twenty (37%) started a four‐drug regimen and 34 (63%) were intensified. Rapid ART initiation occurred in 28%, 100% started in ≤ 4 weeks. By weeks 4, 12, and 24, 37.0%, 69.0%, and 94.0% were undetectable (viral load < 50 copies/mL), respectively. Adherence rates of 100% at weeks 4, 12, 22 and 24 were reported in 88.9%, 87.0%, 82.4% and 94.1% of participants, respectively. Five individuals switched to three drugs, four changed their regimen constituents, and two switched post‐randomization.

Conclusions

Overall, four‐drug regimens were well tolerated and had high levels of adherence. Whilst their benefit over three‐drug regimens is lacking, our findings should provide reassurance if a temporarily intensified regimen is clinically indicated to help facilitate treatment.

Combined HIV Adolescent Prevention Study (CHAPS): comparison of HIV pre-exposure prophylaxis regimens for adolescents in sub-Saharan Africa-study protocol for a mixed-methods study including a randomised controlled trial

BACKGROUND

HIV remains a major public health issue, especially in Eastern and Southern Africa. Pre-exposure prophylaxis is highly effective when adhered to, but its effectiveness is limited by cost, user acceptability and uptake. The cost of a non-inferiority phase III trial is likely to be prohibitive, and thus, it is essential to select the best possible drug, dose and schedule in advance. The aim of this study, the Combined HIV Adolescent PrEP and Prevention Study (CHAPS), is to investigate the drug, dose and schedule of pre-exposure prophylaxis (PrEP) required for the protection against HIV and the acceptability of PrEP amongst young people in sub-Saharan Africa, and hence to inform the choice of intervention for future phase III PrEP studies and to improve strategies for PrEP implementation.

METHODS

We propose a mixed-methods study amongst young people aged 13-24 years. The first component consists of qualitative research to identify the barriers and motivators towards the uptake of PrEP amongst young people in South Africa, Uganda and Zimbabwe. The second component is a randomised clinical trial (ClinicalTrials.gov NCT03986970, June 2019) using a novel ex vivo HIV challenge method to investigate the optimal PrEP treatment (FTC-TDF vs FTC-TAF), dose and schedule. We will recruit 144 amongst HIV-negative uncircumcised men aged 13-24 years from voluntary male medical circumcision clinics in two sites (South Africa and Uganda) and randomise them into one of nine arms. One group will receive no PrEP prior to surgery; the other arms will receive either FTC-TDF or FTC-TAF, over 1 or 2 days, and with the final dose given either 6 or 20 h prior to surgery. We will conduct an ex vivo HIV challenge on their resected foreskin tissue.

DISCUSSION

This study will provide both qualitative and quantitative results to help decide the optimum drug, dose and schedule for a future phase III trial of PrEP. The study will also provide crucial information on successful strategies for providing PrEP to young people in sub-Saharan Africa.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03986970 . Registered on 14 June 2019.

Integrating connectivity theory within watershed modelling part II: Application and evaluating structural and functional connectivity

Integrating connectivity theory within watershed modelling is one solution to overcome spatial and temporal shortcomings of sediment transport prediction, and Part I and II of these companion papers advance this overall goal. In Part II of these companion papers, we investigate sediment flux via connectivity formula discretized over many catchments and then integrated via sediment routing; and we advance model evaluation technology by using hysteresis of sensor data. Model evaluation with hysteresis indices provides nearly a 100% increase in model statistics. Hysteresis loop evaluation shows a shift from near linear behavior at low to moderate events and then clock-wise loops for larger events indicating the importance of proximal sediment sources. Catchment-scale sediment flux varies as function of the probability of timing and extent of connectivity of an individual catchment. Watershed-scale sediment flux shows self-similarity for the main stem of the river channel as the 181 catchments are integrated moving down gradient. Sediment flux varies from event-to-event as a function of the most sensitive connected pathways, including ephemeral gullies and roadside ditches in this basin. These sensitive pathways contribute disproportionately large amounts to overall sediment yield regardless of the total rainfall depth. Prediction requires the connectivity formula, erosion formula and sediment routing formula; and the probability of connectivity alone was a poor predictor for sediment transport. The result highlights the importance of coupling connectivity simulations with sediment transport formula, and our method provides one such approach.

Integrating connectivity theory within watershed modelling part I: Model formulation and investigating the timing of sediment connectivity

Integrating connectivity theory within watershed modelling is one solution to overcome spatial and temporal shortcomings of sediment transport prediction, and Part I and II of these companion papers advance this overall goal. In Part I of these companion papers, we present the theoretical development of probability of connectivity formula considering connectivity's magnitude, extent, timing and continuity that can be applied to watershed modelling. Model inputs include a high resolution digital elevation model, hydrologic watershed variability, and field connectivity assessments. We use the model to investigate the dependence of the probability of connected timing and spatial connectivity on sediment transport predictors. Results show the spatial patterns of connectivity depend on both structural and functional characteristics of the catchment, such as hillslope gradient, upstream contributing area, soil texture, and stream network configuration (structural) and soil moisture content and runoff generation (functional). Spatial connectivity changes from catchment-to-catchment as a function of soil type and drainage area; and it varies from event-to-event as a function of runoff depth and soil moisture conditions. The most sensitive connected pathways provide the stencil for the probability of connectivity, and pathways connected from smaller hydrologic events are consistently reconnected and built upon during larger hydrologic events. Surprisingly, we find the probability of connected timing only depends on structural characteristics of catchments, which are considered static over the timescales analyzed herein. The timing of connectivity does not statistically depend on functional characteristics, which relaxes the parameterization across events of different magnitudes. This result occurs because the pathway stencil accumulates sediment from adjacent soils as flow intensity increases, but this does not statistically shift the frequency distribution.

An Infant Sonicguide Intervention Program for a Child with a Visual Disability

The purpose of the study reported here was to teach a preschool child with a visual impairment and significant developmental delay to reach out and locate objects systematically and accurately from a sitting position and to locate and move toward given objects in the environment using the Infant Sonicguide. Although the child achieved the first goal, time constraints prevented him from reaching the second goal.

Enzymatic-Ultraviolet Method for Measuring Lactose in Milk: Collaborative Study

Collaborators in 8 dairy and food industry laboratories performed one lactose determination on each of 8 unknown samples of milk, lowfat milk, or skim milk, as 3 pairs of blind duplicates. Two known samples were provided to gain experience prior to analysis of the unknown samples. All of the above samples were also analyzed for lactose content by the official AOAC gravimetric method (16.507) by a commercial laboratory. From the overall mean of results on all samples, determinations by the enzymatic method averaged 0.49% lower than by the AOAC method. This difference was significant by the t-test (P = 0.05), which indicated a lack of agreement between the compared methods in determining lactose content. Standard deviations were similar for the 3 sets of blind duplicates which ranged between 3.67 and 4.55% lactose content. F-values revealed that variations between means obtained by laboratories differed significantly as compared with variations within laboratory means. The method has been adopted official first action.

Propagation-based x-ray phase-contrast tomography of mastectomy samples using synchrotron radiation

PURPOSE

Propagation-based phase-contrast computed tomography (PB-CT) is a method for three-dimensional x-ray imaging that utilizes refraction, as well as absorption, of x rays in the tissues to increase the signal-to-noise ratio (SNR) in the resultant images, in comparison with equivalent conventional absorption-only x-ray tomography (CT). Importantly, the higher SNR is achieved without sacrificing spatial resolution or increasing the radiation dose delivered to the imaged tissues. The present work has been carried out in the context of the current development of a breast CT imaging facility at the Australian Synchrotron.

METHODS

Seven unfixed complete mastectomy samples with and without breast cancer lesions have been imaged using absorption-only CT and PB-CT techniques under controlled experimental conditions. The radiation doses delivered to the mastectomy samples during the scans were comparable to those approved for mammographic screening. Physical characteristics of the reconstructed images, such as spatial resolution and SNR, have been measured and compared with the results of the radiological quality assessment of the complete absorption CT and PB-CT image stacks.

RESULTS

Despite the presence of some image artefacts, the PB-CT images have outperformed comparable absorption CT images collected at the same radiation dose, in terms of both the measured objective image characteristics and the radiological image scores. The outcomes of these experiments are shown to be consistent with predictions of the theory of PB-CT imaging and previous reported experimental studies of this imaging modality.

CONCLUSIONS

The results presented in this paper demonstrate that PB-CT holds a high potential for improving on the quality and diagnostic value of images obtained using existing medical x-ray technologies, such as mammography and digital breast tomosynthesis (DBT). If implemented at suitable synchrotron imaging facilities, PB-CT can be used to complement existing imaging modalities, leading to more accurate breast cancer diagnosis.

C-MAC© videolaryngoscopy: The anaesthetic assistant's view

Although videolaryngoscopy plays a major role in the 2015 Difficult Airway Society guidelines, the impact on anaesthetic assistant working practices and training has not previously been reported. We surveyed anaesthetic assistants in our hospital to document their experience with using the C-MAC^© videolaryngoscope (48 practitioners, 100% response rate). Improvements in the following were reported: patient safety 100%; ability to see whether laryngoscopy is difficult 98%; ability to anticipate the 'next step' 98%; team-working and human factors 96%; ability to call a senior anaesthetist more quickly 94%; assessment or adjustment of cricoid force application 92%, understanding of laryngeal anatomy 92%; training in intubation 98%; training in cricoid force application 87%. Concerns were primarily about local issues such as decontamination and blade availability. Ninety percent reported that the clinical benefit outweighed any additional workload. In conclusion, the C-MAC^© videolaryngoscope is judged by anaesthetic assistants to confer numerous advantages for their working practice and training.

Predicting in-hospital mortality in older general surgical patients

Introduction A significant number of emergency general surgical admissions occur in older patients. Clinical decision making in this group is challenging and current risk prediction tools extrapolate data from cohorts of younger patients. This is the first UK study to examine risk factors predicting in-hospital mortality in older acute surgical patients undergoing comprehensive geriatric assessment. Methods This was a prospective study of consecutive patients aged ≥75 years admitted non-electively to general surgery wards between September 2014 and February 2017 who were reviewed by an elderly medicine in-reach service. Results A total of 577 patients were included with a mean age of 82.9 years. There was a female predominance (56%). The majority were living at home alone or with carers (93%) and most were independent in basic activities of daily living (79%). Over two-thirds (69%) were mobile with no walking aids or use of a walking stick and overt here-quarters (79%) had no cognitive impairment. Seventy-seven per cent of patients were managed non-operatively. The in-hospital mortality rate was 6.9%. Female sex (p=0.031), dependence in activities of daily living (p<0.001), cognitive impairment (p<0.001) and incontinence (p<0.001) were predictors of in-hospital mortality. ASA (American Society of Anesthesiologists) grade ≥3 was also associated with increased in-hospital mortality (odds ratio: 5.3, 95% confidence interval: 2.6-10.7). Conclusions Older general surgical patients present a high level of complexity. This study highlights the predictive role of mobility, functional and cognitive impairment when assessing this population. Accurate risk stratification requires global assessment by teams experienced in care of the older patient rather than the traditional focus on co-morbidities.

Knowledge Acquisition for Expert Systems: Experience in Leukaemia Diagnosis

EMYCIN was used to develop an expert system for the interpretation of immunological data obtained in the cell surface phenotyping of leukaemia. Access to a recognised expert, and a large quantity of data on the leukaemias, has facilitated a systematic study of knowledge acquisition and knowledge base refinement based on tape recorded commentaries made by the expert. System performance was analysed at six stages in its development, and ways in which it differed from that of the human diagnostician were identified. Among the most suggestive observations were differences in the way that “undiagnosable” patients were treated and a failure of the elicitation technique to reveal structural aspects of the task. The tools and techniques of knowledge engineering are a significant advance, but a better methodology for developing high quality knowledge bases is needed.

Abstract P4-08-01: Not presented

This abstract was not presented at the symposium.

Alternatives to Bayes?

Recent proposals have suggested that rule-based systems of diagnostic inference are an attractive medium for computer-aided diagnosis, in part because clinicians find their behaviour easy to understand. Bayesian systems have been more prominent in this field to date, but no direct comparison of their clinical abilities has been reported. A rule-based system that was closely modelled on clinical thinking is described and a quantitative comparison with a successful Bayesian system for the diagnosis of »dyspepsia« is presented. The results suggest that the rule-based approach may have considerable potential as an efficient alternative to Bayesian inference.

RAGs: A Novel Approach to Computerized Genetic Risk Assessment and Decision Support from Pedigrees

Objectives: To assist general practitioners in evaluating patients’ genetic risk of cancer on the basis of family history data.

Methods: A new computer application, RAGs (Risk Assessment in Genetics), has been developed to help doctors create graphical family trees and assess the genetic risk of breast and colorectal cancer. RAGs possesses two features that distinguish it from similar software: (i) a user-centred design, which takes into account the requirements of the doctor-patient encounter; (ii) effective and accessible risk reporting by employing qualitative evidence for or against increased risk, which is more easily understood than numerical probabilities. The system allows any rule-based genetic risk guideline to be implemented, and may be readily modified to cater for the varying degrees of information required by different specialists.

Results: RAGs permits fast, accurate data entry, and results in more appropriate management decisions than those made via other techniques. In addition, RAGs enables both the clinician and the patient to understand how it arrives at its conclusions, since the use of qualitative evidence allows the program to provide explanations for its reasoning.

Conclusions: The RAGs system promises to help practitioners be more effective gatekeepers to genetic services. It may empower doctors both to make an informed choice when deciding to refer patients who are at increased genetic risk of breast or colorectal cancer, and to reassure those who are at low risk.