Man vs. Machine (Learning): Comparing Speed and Cost-Effectiveness of Manual vs. Deep Learning Segmentation-Aided Volume Delineation for Head and Neck Lymph Node Targets

PURPOSE/OBJECTIVE(S)

The purposes of the following study were to: 1) compare the time required to delineate head and neck lymph nodal volumes using a manual versus deep learning segmentation (DLS) - aided approach and 2) investigate the potential cost-savings per scan.

MATERIALS/METHODS

10 de-identified head and neck CT simulation datasets were randomly selected for segmentation and analysis. Using published consensus definitions of 27 total lymph node regions1, 1 radiation oncologist manually segmented all 10 CT datasets. For each patient, the time required to contour and review the dataset was recorded. Next, for each dataset, the time required to generate and modify DLS-generated volumes via a proprietary software was recorded, including image export from treatment planning system (TPS), uploading to DLS software, volume generation, downloading volumes, importing volumes into the TPS, and manual edits required. Mean and standard deviations for each treatment modality were calculated. Using two-sided t-test, the statistical difference between the measured outcomes were compared. Finally, assuming a salary of $500,000 per year, average cost savings per scan were calculated.

RESULTS

Time required to segment each dataset manually (mean = 59.32 min, SD = 9.16) versus DLS-aided (mean = 14.55 min, SD = 3.16) was statistically significant (p-value = 1.91E-07). Estimated cost required to segment each dataset manually (mean = $237.67, SD = $36.69) versus DLS-aided (mean = $58.27, SD = $12.64) was also statistically significant (p-value = 1.91E-07). The DLS-aided approach resulted in a $179.40 savings per CT dataset segmented, as well as an absolute time savings of 44.78 minutes per scan.

CONCLUSION

This preliminary study shows that using a DLS-aided approach to head and neck lymph node stations can be feasibly implemented within a standard radiation oncology workflow and has the potential for significant time and cost savings.

Biomolecular characterization of 3500-year-old ancient Egyptian mummification balms from the Valley of the Kings

Ancient Egyptian mummification was practiced for nearly 4000 years as a key feature of some of the most complex mortuary practices documented in the archaeological record. Embalming, the preservation of the body and organs of the deceased for the afterlife, was a central component of the Egyptian mummification process. Here, we combine GC-MS, HT-GC-MS, and LC-MS/MS analyses to examine mummification balms excavated more than a century ago by Howard Carter from Tomb KV42 in the Valley of the Kings. Balm residues were scraped from now empty canopic jars that once contained the mummified organs of the noble lady Senetnay, dating to the 18th dynasty, ca. 1450 BCE. Our analysis revealed balms consisting of beeswax, plant oil, fats, bitumen, Pinaceae resins, a balsamic substance, and dammar or Pistacia tree resin. These are the richest, most complex balms yet identified for this early time period and they shed light on balm ingredients for which there is limited information in Egyptian textual sources. They highlight both the exceptional status of Senetnay and the myriad trade connections of the Egyptians in the 2nd millennium BCE. They further illustrate the excellent preservation possible even for organic remains long removed from their original archaeological context.

Epidemiology and impact of frailty in patients with atrial fibrillation in Europe

BACKGROUND

Frailty is a medical syndrome characterised by reduced physiological reserve and increased vulnerability to stressors. Data regarding the relationship between frailty and atrial fibrillation (AF) are still inconsistent.

OBJECTIVES

We aim to perform a comprehensive evaluation of frailty in a large European cohort of AF patients.

METHODS

A 40-item frailty index (FI) was built according to the accumulation of deficits model in the AF patients enrolled in the ESC-EHRA EORP-AF General Long-Term Registry. Association of baseline characteristics, clinical management, quality of life, healthcare resources use and risk of outcomes with frailty was examined.

RESULTS

Among 10,177 patients [mean age (standard deviation) 69.0 (11.4) years, 4,103 (40.3%) females], 6,066 (59.6%) were pre-frail and 2,172 (21.3%) were frail, whereas only 1,939 (19.1%) were considered robust. Baseline thromboembolic and bleeding risks were independently associated with increasing FI. Frail patients with AF were less likely to be treated with oral anticoagulants (OACs) (odds ratio 0.70, 95% confidence interval 0.55-0.89), especially with non-vitamin K antagonist OACs and managed with a rhythm control strategy, compared with robust patients. Increasing frailty was associated with a higher risk for all outcomes examined, with a non-linear exponential relationship. The use of OAC was associated with a lower risk of outcomes, except in patients with very/extremely high frailty.

CONCLUSIONS

In this large cohort of AF patients, there was a high burden of frailty, influencing clinical management and risk of adverse outcomes. The clinical benefit of OAC is maintained in patients with high frailty, but not in very high/extremely frail ones.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Eligibility for subcutaneous implantable cardiac defibrillator utilising artificial intelligence and deep learning methods for prolonged screening: where is the cut-off?

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Main author is receiving an unrestricted grant by Boston Scientific

Background

S-ICD eligibility is determined by a single surface ECG analysis in which the suitability of an individual’s ECG vector morphology is assessed. A major predictor of eligibility is the T:R ratio. Current screening tools proposes T: R of 1:3 as a cut-off for eligibility. Inappropriate shocks due to T-wave oversensing (TWO) remains an issue despite screening. EFFORTLESS and PRAETORIAN trials reported inappropriate shock rates of 11.4% and 9.7% respectively, most frequently caused by cardiac oversensing.

Purpose

The cut-off T: R of 1:3 currently used incorporates a safety margin to accommodate for ECG signal amplitudes fluctuations without affecting S-ICD sensing. Prolonged screening using our tool accurately measures the T: R fluctuations. However, utilising a T: R of 1:3 for prolonged screening can unnecessarily exclude appropriate S-ICD candidates. The purpose of our study is to provide groundwork for future trials to find the optimal ratio that identifies patients at risk of TWO and inappropriate shocks while not excluding true S-ICD candidates after prolonged screening.

Methods

Patients were fitted with 24-hour Holter monitors with leads placed to correspond to the vectors of an S-ICD. We used our tool to assess T: R over the recordings utilising Phase Space Reconstruction matrices - to convert the ECG signal into compressed pixel images. A Convolutional Neural Network (CNN) model was trained to accurately predict the T: R from these images resulting in a T: R variation plot for each vector. We then applied multiple T:R ratio cut-offs on the recordings to identify patients at risk of inappropriate shocks due to TWO at each proposed value. A vector with a T: R above the cut-off for 20 consecutive seconds was deemed to have failed screening, the time determined by the current detection, charge, and redetection time of the current S-ICD system. A patient has to have at least one suitable vector to pass the screening at the selected threshold.

Results

37 patients (mean age 54.5 years,64.8% male) were included. 14 had Heart failure, 7 Hypertrophic cardiomyopathy, 7 normal hearts, 6 Adult congenital heart disease and 3 patients who received inappropriate S-ICD shocks due to TWO. Overall, 20 (54%) of patients passed prolonged screening using a 1:3 ratio. All of the patients passed screening with a T: R of 1:1. The only subgroup to wholly pass the screening for all the proposed ratios are the normal hearts group.

Conclusion

We propose adopting prolonged screening to select S-ICD eligible patients with low probability of TWO and inappropriate shocks. However, utilising T: R of 1:3 can unnecessarily exclude otherwise S-ICD eligible patients. The appropriate ratio likely lies between 1:3 - 1:1. Further studies are needed to identify the optimal screening thresholds, particularly in patients that have had inappropriate shocks due to TWO.

A leadless pacemaker matched with a vasovagal syncope: how long can it last?

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Dr.Mohamed ElRefai is receiving an unrestricted grant from Boston Scientific

Introduction

Although a benign condition, patients suffering from frequent vasovagal syncopal episodes need treatment to improve their quality of life. ESC Guidelines consider pacing for patients >40 years old with documented symptomatic asystolic pauses >3 seconds or asymptomatic pauses >6 seconds. Caution is advised with use of pacing in younger patients, due to long-term complications associated with transvenous pacemakers (TV-PPM). The ESC guidelines recommend that Leadless pacemakers (LP) should be considered as an alternative to TV-PPM when there is no appropriate venous access or if the risk of device infection is high, also on a case-by-case basis using shared decision making.

Studies on the use of LPs for cardioinhibitory vasovagal population specifically, concluded that the safety and efficacy of LPs are comparable with TV-PPM, demonstrating a high level of symptom improvement at follow up making them a reasonable option in these patients. In addition, observational studies demonstrated that LPs are associated with better quality of life than TV-PPM.

Purpose

Current practice is to implant another LP after the end of life of the old device without extracting it. There are concerns regards battery longevity specially with the paucity of data on device extraction and the number of concomitant LPs that can be implanted safely, a concern in younger patients’ population potentially requiring decades of pacing therapy. We aim to evaluate the performance of the LPs in the relatively younger vasovagal syncope patients with anticipated very low pacing dependency, with emphasis on battery longevity.

Methods

We conducted a retrospective analysis of the first 100 LP implanted at our tertiary referral centre for cardiac devices in the UK. Demographical data as well as devices parameters at implant and latest follow ups were obtained from the patients’ medical electronic records. We compared the performance of the LPs between patients with vasovagal syncope vs other pacing indications with emphasis on battery longevity in both groups.

Results

A total of 90 patients were included in our analysis after excluding 10 patients due to lack of follow-up data. 14 patients (15.6%) had vasovagal syncope as indication for pacing and 76 patients (84.4%) had other indications. Mean ages were 34±13 years and 62±20 years for the vasovagal and the other group, respectively. There were no complications in the vasovagal group. Pacing % at the last follow up was 1±1 in the vasovagal group and 37±43 for the other group. There was a significant difference in the estimated total battery life between both groups, 15.22±0.35 and 13.65±2.97 years in the vasovagal and the other group respectively.

Conclusion

LPs provide a safe and a reliable treatment for young patients with vasovagal syncope with promising battery performance at the short/intermediate term. Further longer-term follow up data is needed to identify the true battery potential in this patient cohort.

Establishing safe, effective ablation in the diseased human ventricle: an analysis of generator impedance and electrogram attenuation

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Biosense Webster Inc

Background

Predictors of effective and safe lesion delivery in the human left ventricle have not been established. Generator impedance (GI) drop and electrogram (EGM) attenuation are indices which can be used as surrogates for ablation lesion parameters. Tissue pops are a complication of myocardial overheating preceded by a rise in GI and can have adverse consequences.

Purpose

To establish the relationships between Ablation Index (AI), Force Time Integral (FTI) and contact force with GI and EGM attenuation. To establish factors early in ablation that are predictive of a GI rise.

Methods

Patients undergoing ventricular tachycardia ablation were recruited. All ablations were performed with contact force sensing surround flow catheters. Electrograms were collected pre and post ablation, with GI, AI, FTI measured during. Ablations were divided into low (LVM, < 0.50mV), intermediate (IVM, 0.51 – 1.50mV) and normal voltage (NVM, > 1.50mV) based upon pre-ablation bipolar EGM amplitude. Ablations with a 5% rise in GI from maximal drop were noted and predictors of this explored.

Results

In 15 patients, 402 ablations were analysed. Filtered percentage GI drop correlated with AI and FTI, (p < 0.0005, Spearman’s ρ = 0.522 and 0.524) and reached a plateau at 763AI and 713gs, a filtered GI drop of 7.5% (Figure 1). Shallower curves occurred progressively from NVM to IVM to LVM, (p < 0.0005), (Figure 2)

The bipolar EGM significantly attenuated with ablation, (median attenuation 0.14mV, [29.3%], p <0.0005), but percentage attenuation did not correlate with AI or FTI.

Parameters associated with a GI rise during ablation were greater mean CF to maximum GI drop, (p = 0.002), greater initial percentage GI drop at 5 seconds, (p < 0.0005), power of 50W (p = 0.005), and perpendicular orientation, (p = 0.006). Percentage GI drop at 5 seconds was the best predictor of ablations with a GI rise, (AUCROC 0.773; 95% CI 0.708 – 0.838; optimal cut-off 2.44%). Mean contact force to maximum GI drop was a poor predictor of a GI rise (AUCROC 0.647; 95% CI 0.577 – 0.718, optimal cut-off 14.7g).

Conclusion

During left ventricular ablation, AI of 763 and FTI of 713gs should be targeted, with a lower impedance drop observed for more scarred myocardium. A GI drop of <2.5% at 5 seconds and contact force < 15g should be used to optimise ablation safety.

The use of artificial intelligence and deep learning methods in subcutaneous implantable cardioverter defibrillator screening to optimise selection in special patient populations

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Dr.Mohamed ElRefai is receiving an unrestricted grant from Boston Scientific.

Introduction

Adult congenital heart disease (ACHD) and hypertrophic cardiomyopathy (HCM) patients who require defibrillator therapy are often relatively young and may require several generator replacements in their lifetime. The increased risk of complications associated with transvenous ICDs make the subcutaneous (S-ICD) a valuable alternative. However, higher S-ICD ineligibility rates (20-40% in ACHD and 7-38% in HCM) and higher inappropriate shock rates (10.5% in ACHD and 12.5% in HCM) are observed in these populations. Unfavourable T:R ratios and dynamic changes in the R and T wave amplitudes are the primarily factors behind ineligibility and inappropriate shocks, which are most commonly caused by T wave over-sensing.

Purpose

We report a novel application of deep learning methods used to autonomously screen patients for S-ICD eligibility over a longer period than conventional screening. We hypothesise that this screening approach might achieve better patient selection and optimise S-ICD vector selection in challenging patient cohorts.

Methods

Adult patients with ACHD or HCM and a control group of normal subjects were fitted with a 24-hour ambulatory ECG with the leads placed to record their S-ICD vectors. T: R ratio throughout the recordings was analysed utilising phase space reconstruction matrices to convert the ECG signal into compressed pixel images. Whilst a convolutional neural network model was trained to provide an in-depth description of the T: R variation plot for each vector T: R variation was compared statistically using a one-way ANOVA test.

Results

20 patients (age 44.1 ±11.68, 60% male, 7 HCM, 6 ACHD and 7 control subjects) were enrolled. A significant difference was observed in the mean and median T: R values between the three groups (p<0.001). There was no difference observed in the standard deviation of T: R between the control subjects and HCM group. However, there was a statistically significant difference in the standard deviation of T: R between the control subjects and the ACHD group (p= 0.01). [see Figure].

Conclusions

T:R ratio, a main determinant for S-ICD eligibility, is significantly higher in ACHD and HCM when compared to normal hearts and it also has more tendency to fluctuate in ACHD patients when compared to HCM and normal hearts populations. We hypothesise that our novel model could be used to select S-ICD eligible patients by better characterisation of T:R ratio reducing the risk of T wave oversensing and inappropriate shocks particularly in the ACHD patients’ cohort.

A leadless pacemaker in the real-world setting: Patient profile and performance over time

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Medtronic, Inc.

OnBehalf

Micra Acute Performance EMEA Investigators

Background

The first in-man implant of the Micra leadless pacemaker occurred in December 2013. While prior trials demonstrated a high implant success rate and favorable safety and efficacy results; whether the patient population and outcomes have changed over time is not well studied.

Purpose

To characterize the evolution of patient profile and outcomes for patients receiving a leadless pacemaker through the pre-market and post-market environment.

Methods

Patients undergoing a Micra leadless pacemaker implant attempt from the initial Micra Investigational Device Exemption [IDE] and current Micra studies (Micra post-approval registry [PAR], Micra acute performance [MAP] study) were analyzed. Patient characteristics and pericardial effusions regardless of severity were summarized.

Results

The 3466 patients included in the analysis underwent a Micra implant attempt and were enrolled during consecutive timeframes: patients from the Micra IDE study (n = 726) underwent a Micra implant attempt from 2013-2015, patients from the PAR (n = 1814) from 2015-2018, and patients from Micra MAP cohort (n = 926) from 2018 – 2020.  Implant success was >99.0% in all 3 studies. Median age ranged from 78 – 79 years among the 3 studies without significant difference. There were more patients requiring dialysis in the MAP cohort compared to the PAR or IDE cohorts (10.3%, 7.9%, and 3.9%, respectively; P < 0.001), but fewer patients with congestive heart failure (8.3%, 13.1%, and 18.0%; P < 0.001). Pacing indication was significantly different between the studies, with fewer patients in MAP having an indication of bradyarrhythmia associated with atrial fibrillation (AF) and more having an indication associated with atrioventricular block without AF (P < 0.001). The number of patients considered to be precluded for a transvenous pacemaker implant increased significantly from the initial IDE study to the PAR and MAP studies (6.2%, 23.9%, and 44.1%, respectively, P < 0.001).  Implant site placement was mostly apical for the IDE but shifted to mostly septal placement in the PAR and MAP (septal placement: 33.3%, 64.0%, and 79.5%, respectively). The rate of pericardial effusion regardless of severity was 1.79% (n = 13) in the IDE, 0.83% (n = 15) in the PAR, and 0.97% (n = 9) in MAP (figure). Mean pacing thresholds among MAP EMEA patients were low (0.61 ± 0.40V) at implant and remained stable through 12 months (0.62 +/- 0.41V).

Conclusion

Despite patient differences over time, the Micra leadless pacemaker was implanted with a high success rate and a low perforation rate, in-line with prior reports. Abstract Figure. Pericardial effusion rate by study

Leadless pacemakers: where is the device?

Funding Acknowledgements

Type of funding sources: None.

Introduction

Leadless pacemakers (LPs) were designed to avoid lead-related complications associated with transvenous pacing. To minimise the risk of complications, there is preference towards implanting LPs into the septal aspect of the right ventricle rather than the apex or free wall. The Transcatheter Pacing Study (TPS) and the international post-approval registry demonstrated the safety and reliability of the LP systems in real-world settings. The registry demonstrated that more than half of the LPs were implanted into the septum and most required <2 attempts at deployment. We report a radiological method of defining LP position.

Methods

We reviewed the first 100 LPs implanted at our centre. Two independent observers who didn’t implant LPs reviewed the patients’ post-implant fluoroscopy images and/or post-implant CXRs when available. The reviewers assessed the devices’ positions in postero-anterior (PA) and/or right anterior oblique (RAO) views based on conventional fluoroscopic criteria for lead position. We used the proposed criteria interchangeably on fluoroscopic images and post implant CXRs (Figure). Differences in classification of device position were resolved by consensus.

Results

Three experienced operators implanted 100 LPs at our centre. Patients (61% male) 56.6 ± 22.2 years had normal hearts (74%), ischaemic cardiomyopathies (12%), congenital heart diseases (6%), valvular pathologies (5%) and dilated cardiomyopathies (3%). Indications for pacing were symptomatic sinus node dysfunction (36%), followed by high grade atrio-ventricular block (33%), bradyarrhythmia associated with atrial tachyarrhythmias (27%) and other indications for pacing (4%). We had a 100% successful implant rate, 88% required ≤2 attempts and 70% required one attempt. There were no major complications.

We were able to classify the site of the LPs implants in a total of 90 patients who had fluoroscopic projections or chest x-rays that would allow us to classify the implant sites. A total of 32 implants were in the apex (35.6%). 28 were in mid-septum (31.1 %), 15 in the apical septum (16.7%), 14 on the septal aspect of the right ventricular inflow (15.5%) and 1 implant (1.1%) in the septum of the RV outflow tract.

Conclusion

Our proposed method of defining LP position demonstrated that the rate of implants into the true apex at our centre was highly comparable to that of the international registry. It also showed that we had lower rates of implants into the mid-septum in favour of apical septum. There were no pericardial effusions or cardiac perforations resulting from our implant procedures regardless of the site of the implant. We utilised widely used fluoroscopic and chest x-ray criteria for categorisation of the LPs implantation sites. However, a recognised limitation to our analysis is that our findings were not validated using other imaging modalities such as echocardiogram or cardiac computerised tomography (CT). Abstract Figure. Criteria to classify device position

Leadless pacemakers: does location matter?

Funding Acknowledgements

Type of funding sources: None.

Introduction

Leadless pacemakers (LPs) provide a viable alternative for patients who have an indication for pacing where transvenous pacing is not desirable or possible. Registries have demonstrated stable performance associated with LPs. There is preference towards implanting LPs into the trabeculated septum rather than the apex or free wall. We report our experience with the impact of the implantation site on acute and long-term electrical performance of LPs.

Methods

We ran a retrospective analysis on the first 100 LPS implanted at our centre. Two independent observers reviewed the fluoroscopic images and post-implant chest x-rays to classify the LPs’ positions.  We obtained the recorded pacing threshold , R-wave amplitude and impedance of the devices at the time of implant and at the latest available routine device follow-up. We used one-way ANOVA testing to compare the acute and long-term electrical performance of the LPs between different implantation sites.

Results

We were able to classify the site of the LPs implants in a total of 90 patient. 84 Patients (60% male) 57.3± 22.16 years were included .23.8% of the patients presented with syncope.  Indications for pacing were symptomatic sinus node dysfunction (33.3%), high grade AV block (34.5%), bradyarrhythmia associated with atrial tachyarrhythmias (28.6%) and other indications (3.6%). We had a 100% successful implant rate, 85.7% required ≤2 attempts and 71.4% required one attempt. A total of 32 implants were in the apex (38.1%), 26 in mid-septum (30.9 %), 13 in the apical septum (15.5%), 12 on the septal aspect of the right ventricular inflow (14.3%) and 1 implant (1.2%) in the septum of the RV outflow tract.

The follow up period of the 84 patients was 3.09 ± 1.97 years. 100% of the LPs had the pacing thresholds <2.0 V @0.24 ms at the time of implant. Pacing threshold, R-wave amplitude, and impedance averaged at 0.67 ± 0.41 V, 10.86 ± 5.41 mV, and 775 ± 193.28 Ohms respectively at the time of implantation and 0.66 ± 0.39 V, 14.08 ± 6.14 mV, and 564.29 ± 96.76 Ohms at the last device check. There was no statistically significant difference in either the pacing thresholds or the impedance between implant sites. Post hocTukey’s analysis (excluding the outflow tract case) demonstrated significant statistical difference in the R-wave amplitudes between implants at the apex and the mid-septum both at the time of implantation (12.9 ± 6.1 mV and 8.53 ± 2.84 mV; p = 0.0196) and at follow up (15.97 ± 5.35 mV and 11.52 ± 5.01 mV; p = 0.0415). There were no differences between other sites

Conclusions

Our analysis demonstrated that aside from the difference between the sensed R wave amplitudes between LPs implanted at the apex and those implanted at mid-septum , there was no statistically significant difference in the acute or the long term electrical performance of implanted LPs regardless of the implantation site. A limitation to our analysis is the relatively low number of LP implants included in our analysis. Abstract Figure. Mean of parameters by validated position

ACE inhibitors, angiotensin receptor blockers and endothelial injury in COVID-19

BACKGROUND

COVID-19 is caused by the coronavirus SARS-CoV-2, which uses angiotensin-converting enzyme 2 (ACE-2) as a receptor for cellular entry. It is theorized that ACE inhibitors (ACE-Is) or angiotensin receptor blockers (ARBs) may increase vulnerability to SARS-CoV-2 by upregulating ACE-2 expression, but ACE-I/ARB discontinuation is associated with clinical deterioration.

OBJECTIVE

To determine whether ACE-I and ARB use is associated with acute kidney injury (AKI), macrovascular thrombosis and in-hospital mortality.

METHODS

A retrospective, single-centre study of 558 hospital inpatients with confirmed COVID-19 admitted from 1 March to 30 April 2020, followed up until 24 May 2020. AKI and macrovascular thrombosis were primary end-points, and in-hospital mortality was a secondary end-point.

RESULTS

AKI occurred in 126 (23.1%) patients, 34 (6.1%) developed macrovascular thrombi, and 200 (35.9%) died. Overlap propensity score-weighted analysis showed no significant effect of ACE-I/ARB use on the risk of occurrence of the specified end-points. On exploratory analysis, severe chronic kidney disease (CKD) increases odds of macrovascular thrombi (OR: 8.237, 95% CI: 1.689-40.181, P = 0.009). The risk of AKI increased with advancing age (OR: 1.028, 95% CI: 1.011-1.044, P = 0.001) and diabetes (OR: 1.675, 95% CI: 1.065-2.633, P = 0.025). Immunosuppression was associated with lower risk of AKI (OR: 0.160, 95% CI: 0.029-0.886, P = 0.036). Advancing age, dependence on care, male gender and eGFR < 60 mL min^-1 /1.73 m² increased odds of in-hospital mortality.

CONCLUSION

We did not identify an association between ACE-I/ARB use and AKI, macrovascular thrombi or mortality. This supports the recommendations of the European and American Societies of Cardiology that ACE-Is and ARBs should not be discontinued during the COVID-19 pandemic.

Pseudomonas aeruginosa infection in augmented care: the molecular ecology and transmission dynamics in four large UK hospitals

BACKGROUND

Pseudomonas aeruginosa is a common opportunistic pathogen and molecular typing in outbreaks has linked patient acquisition to contaminated hospital water systems.

AIM

To elucidate the role of P. aeruginosa transmission rates in non-outbreak augmented care settings in the UK.

METHODS

Over a 16-week period, all water outlets in augmented care units of four hospitals were sampled for P. aeruginosa and clinical isolates were collected. Outlet and clinical P. aeruginosa isolates underwent whole-genome sequencing (WGS), which with epidemiological data identified acquisition from water as definite (level 1), probable (level 2), possible (level 3), and no evidence (level 4).

FINDINGS

Outlets were positive in each hospital on all three occasions: W (16%), X (2.5%), Y (0.9%) and Z (2%); and there were 51 persistently positive outlets in total. WGS identified likely transmission (at levels 1, 2 and 3) from outlets to patients in three hospitals for P. aeruginosa positive patients: W (63%), X (54.5%) and Z (26%). According to the criteria (intimate epidemiological link and no phylogenetic distance), approximately 5% of patients in the study 'definitely' acquired their P. aeruginosa from their water outlets in the intensive care unit. This study found extensive evidence of transmission from the outlet to the patients particularly in the newest hospital (W), which had the highest rate of positive outlets.

CONCLUSIONS

The overall findings suggest that water outlets are the most likely source of P. aeruginosa nosocomial infections in some settings, and that widespread introduction of control measures would have a substantial impact on infections.

P577Early experience with the first pacemakers to directly connect with smart devices for remote monitoring

Background

Remote monitoring is associated with improved patient outcomes; however, adoption and adherence to remote monitoring via home-based consoles remains suboptimal. BlueSync technology in new generation pacemaker and CRT-P models enables the implanted device to communicate directly with patient-owned, Bluetooth-equipped smartphones/tablets and an app (MyCareLink Heart). The app can automatically retrieve information from the cardiac device and transmit the data to the remote network, eliminating the need for traditional remote monitoring consoles.

Objectives

To characterize the communication process between implanted pacemakers and smart device remote monitoring apps by assessing the success of prescheduled remote transmissions in the first month of follow-up. Additionally, to assess the feedback of both patients and clinicians about the process of device pairing.

Methods

Enrollment in the BlueSync Field Evaluation began in April 2018 and was completed November 2018. Follow-up is ongoing. Prior to enrollment in the evaluation, patients completed the device pairing process with the app using their own compatible smartphone or tablet. Patient and clinician questionnaires were completed at the time of the device pairing process. After enrollment, successful completion of scheduled transmissions occurring in the first month were analyzed.

Results

Preliminary data includes 241 enrolled patients with mean age of 64.7±15.5 yrs (min 20, max 90 yrs), who completed device pairing between their implanted device and their smart device app. Of enrolled patients, 79% felt that the device paring was easy to do, 85% were satisfied with the amount of time it took to complete it, and 93% felt that they would be comfortable using the app. Clinicians reported that 67% of the device pairings took less than 20 minutes and 78% felt patients would be able to use the app independently. At the time of analysis 174 patients had at least one scheduled transmission within the first month, and collectively had a total of 322 scheduled transmissions. Out of these, 309 (96%, 95% CI: 93%-98%) were successfully completed.

MyCareLink Heart App

Conclusions

Initial experience with the world's first app based remote monitoring system for Bluetooth enabled pacemakers demonstrated success to scheduled transmissions in the first month across a wide range of patient ages. Patients and clinicians reported high satisfaction with this novel technology.

Acknowledgement/Funding

Medtronic PLC

5970Morbidity and mortality in patients precluded for transvenous pacemaker implantation: experience with the Micra transcatheter pacemaker

Background

The Micra transcatheter pacemaker has proven to be a safe and effective alternative to transvenous pacemakers (TVPs). However, the safety profile after Micra implantation in patients deemed poor candidates for TVPs is poorly understood.

Purpose

To evaluate the safety and all-cause mortality outcomes in Micra recipients stratified by whether or not they were precluded for therapy with TVP.

Methods

Micra patients from the Micra Transcatheter Pacing (IDE) Study, Continued Access (CA) study, and Post-Approval Registry (PAR) were divided into groups based upon whether or not the implanting physician considered the patient to be precluded from receiving a transvenous pacing system. All-cause mortality was compared between the Micra patient groups and patients receiving a single-chamber transvenous pacing system (SC-TVP) since 2010 from the Medtronic product surveillance registry using univariate and multivariate Cox models.

Results

Among 2,819 patients who underwent a Micra implant attempt, the overall major complication rate through 24 months was 3.5%. In these patients, 548 were deemed precluded from TVP implantation. Prior device infection or bacteremia (38.9%), venous access issues (36.1%) and thrombosis (10.2%) were amongst the most common causes of preclusion for TVP implantation. These patients were younger (71.7 vs. 76.7 years), more frequently on hemodialysis (26.3% vs. 2.5%), and more often had a prior CIED implanted (38.4% vs. 4.4%) than non-precluded patients. Over an average follow-up of 13.5±11.1 months, all-cause mortality was significantly higher in precluded Micra patients compared with SC-TVP patients (HR: 2.16, 95% CI: 1.54–3.2, P<0.001) (Figure 1). However, there was no significant difference in all-cause mortality when comparing non-precluded Micra patients and SC-TVP patients (HR: 1.12, 95% CI: 0.86–1.44, P=0.401). Acute all-cause death (within 1 month) among Micra patients was 2.74% and 1.32% in the precluded and non-precluded TVP groups, respectively. The procedure-related death rate was 0.55% for the TVP precluded group and 0.13% for the not precluded group (P=0.092). The major complication rate through 24-months was similar between the two Micra groups (4.0% vs 3.4%, P=0.630).

All-cause mortality for Micra and SC-TVP

Conclusion

The overall safety profile of Micra remains is in line with previously reported data. All-cause mortality risk (both acute and long term) appears to be higher in patients who were precluded from receiving TVP.

Acknowledgement/Funding

Supported by Medtronic

HIV/HCV/HBV testing in the emergency department: a feasibility and seroprevalence study

OBJECTIVES

The aims of this study were to to assess the feasibility of simultaneous testing for the blood-borne viruses (BBV), HIV, hepatitis C (HCV) and hepatitis B (HBV), in the Emergency Department (ED) and ascertain the seroprevalence for these three viruses in this setting.

METHODS

A pilot BBV testing program was undertaken as part of routine clinical care in the ED. All ED attendees aged between 16 and 65 years old who were able to consent were tested over a 55 week period on an opt out basis. Patients with positive test results were linked to clinical services. Interventions aimed at improving testing rates were implemented and evaluated by quality improvement (QI) methodology.

RESULTS

Of 25,520 age-eligible ED attendees, 6108 (24%) underwent BBV testing; an additional 1160 (4.5%) underwent a standalone HIV test (total of 7268 (28%) individuals).There were 83/7268 (1.1%) non-negative (ie reactive or equivocal) results for HIV and 103/6108 (1.7%) and 32/6108 (0.52%) for anti-HCV IgG and HBsAg, respectively. Of these, 12 (0.17%), 16 (0.26%) and 8 (0.13%) were new reactive tests for HIV, HCV and HBV, respectively, which were able to be confirmed on a second test. Specific QI interventions led to temporary increases in testing rates.

CONCLUSIONS

An opt out BBV testing program in the ED is feasible and effective at finding new cases. However, the testing rate was low at 24%. Although QI interventions led to some improvement in testing rates, further studies are required to identify ways to achieve sustained increases in testing in this setting.

Improving patient outcomes with inguinal hernioplasty-local anaesthesia versus local anaesthesia and conscious sedation: a randomized controlled trial

PURPOSE

Conscious sedation is regularly used in ambulatory surgery to improve patient outcomes, in particular patient satisfaction. We hypothesized that the addition of conscious sedation would provide greater patient satisfaction with inguinal hernioplasty compared to local anesthesia alone.

METHODS

This trial was a single-centre, randomized, placebo-controlled, double-blinded trial where patients undergoing inguinal hernioplasty using local anaesthesia were randomized to receive local anaesthesia alone versus local anaesthesia and conscious sedation. The primary outcome of patient satisfaction was assessed using the Iowa Satisfaction with Anesthesia Scale (ISAS). The study was powered to detect a significant difference in ISAS scores between groups. Comparisons were made using T test and Chi square tests. A p value of less than 0.05 was considered significant.

RESULTS

There were 149 patients randomized: 78 to the local anesthesia (LA) group and 71 to the local anaesthesia and conscious sedation (LACS) group. For the primary outcome measure of patient satisfaction, the mean ISAS score was significantly greater in the LACS group (p = 0.009). The experience of pain and pain severity was greater in the LA group (p = 0.016; p = 0.0162 respectively). No statistically significant difference was found between groups with respect to operative time, time to discharge or postoperative complications.

CONCLUSION

The use of conscious sedation with local anesthesia for inguinal hernioplasty is safe, results in less pain experience and severity and is associated with better patient satisfaction. The use of conscious sedation does not delay patient discharge.

Extensive elemental mapping unlocks Mg/Ca ratios as climate proxy in seasonal records of Mediterranean limpets

Elemental analysis of biogeochemical archives is an established technique used to study climate in a range of applications, including ocean circulation, glacial/interglacial climates, and anthropogenic climate change. Data from mollusc archives are especially important because of their global abundance and sub-annual resolution. Despite this potential, they are underrepresented among palaeoclimate studies, due to enigmatic physiological influences skewing the elemental record. Understanding the patterns behind these influences will improve data interpretation and lead to the development of new climate proxies. Here, we show for the first time that extensive spatial mapping of multiple mollusc specimens using Laser Induced Breakdown Spectroscopy (LIBS) across a wider region can resolve enigmatic patterns within the elemental record caused by physiological influences. 2D elemental (Mg/Ca) maps of whole limpet shells (Patella caerulea) from across the Mediterranean revealed patterns of variability within individual mollusc records as well as within isochronous parts of specimens. By registering and quantifying these patterns, we established previously uninterpretable correlations with temperature (R² > 0.8, p < 0.01). This outcome redefines the possibilities of accessing sub-annual climate proxies and presents the means to assess annual temperature ranges using oxygen isotope analysis requiring only 2 samples per shell.

Zoonotic Transfer of Clostridium difficile Harboring Antimicrobial Resistance between Farm Animals and Humans

The emergence of Clostridium difficile as a significant human diarrheal pathogen is associated with the production of highly transmissible spores and the acquisition of antimicrobial resistance genes (ARGs) and virulence factors. Unlike the hospital-associated C. difficile RT027 lineage, the community-associated C. difficile RT078 lineage is isolated from both humans and farm animals; however, the geographical population structure and transmission networks remain unknown. Here, we applied whole-genome phylogenetic analysis of 248 C. difficile RT078 strains from 22 countries. Our results demonstrate limited geographical clustering for C. difficile RT078 and extensive coclustering of human and animal strains, thereby revealing a highly linked intercontinental transmission network between humans and animals. Comparative whole-genome analysis reveals indistinguishable accessory genomes between human and animal strains and a variety of antimicrobial resistance genes in the pangenome of C. difficile RT078. Thus, bidirectional spread of C. difficile RT078 between farm animals and humans may represent an unappreciated route disseminating antimicrobial resistance genes between humans and animals. These results highlight the importance of the "One Health" concept to monitor infectious disease emergence and the dissemination of antimicrobial resistance genes.

'VIOLET': a fluorescence-based simulation exercise for training healthcare workers in the use of personal protective equipment

Background

Healthcare workers caring for patients with high-consequence infectious diseases (HCIDs) require protection from pathogen exposure, for example by wearing personal protective equipment (PPE). Protection is acquired through the inherent safety of the PPE components, but also their safe and correct use, supported by adequate training and user familiarity. However, the evidence base for HCID PPE ensembles and any associated training is lacking, with subsequent variation between healthcare providers.

Aim

To develop an evidence-based assessment and training tool for evaluating PPE ensembles and doffing protocols, in the assessment of patients with suspected HCIDs.

Methods

VIOLET (Visualising Infection with Optimised Light for Education and Training) comprises a healthcare mannequin adapted to deliver simulated bodily fluids containing UV-fluorescent tracers. On demand and remotely operated, the mannequin projectile vomits (blue), coughs (red), has diarrhoea (yellow) and is covered in sweat (orange). Wearing PPE, healthcare staff participate in an HCID risk assessment and examination of the ‘patient’, thereby becoming exposed to these bodily fluids. Contamination of PPE is visualized and body-mapped under UV light before and after removal. Observational findings and participant feedback, around its use as a training exercise, is also recorded.

Findings

Significant contamination from different exposure events was seen, enabling evaluation of PPE and doffing procedures used. Observational data and participant feedback demonstrated its strengths and success as a training technique.

Conclusion

Simulation exercises using VIOLET provide evidence-based assessment of PPE ensembles, and are a valuable resource for training of healthcare staff in wearing and safe doffing of PPE.

Analysing the impacts of air quality policies on ecosystem services; a case study for Telemark, Norway

There is an increasing interest in considering the effects of air pollution on ecosystem services supply in order to enhance cost-benefit analyses of air pollution policies. This paper presents a generic, conceptual approach that can be used to link atmospheric deposition of air pollutants to ecosystem services supply and societal benefits. The approach is applied in a case study in the Telemark county of Norway. First, we examine the potential effects of four European air quality policy scenarios on N deposition in the ecosystems of this county. Second, we analyse the subsequent impacts on the supply of three ecosystem services: carbon sequestration, timber production and biodiversity. Changes in the supply of the first two services are analysed in both physical and monetary units, biodiversity effects are only analysed in physical terms. The scenarios derive from work conducted in the context of the European National Emissions Ceilings Directive. In the 2010 base case the benefits of carbon sequestration are estimated at 13 million euro per year and the value of timber harvesting at 2.9 million euro per year. Under the examined policy scenarios aiming to reduce nitrogen emissions the societal benefits resulting from these two ecosystem services in Telemark are found to be reduced; the scenarios have little effect on terrestrial biodiversity. Such results cannot be scaled up, individual ecosystem services respond differently to changes in air pollution depending upon type of pollutant, type of ecosystem, type of service, and the magnitude of change. The paper further presents an analysis of the uncertainties that need to be considered in linking air pollution and ecosystem services including those in deposition rates, ecosystem responses, human responses and in the values of ecosystem services. Our conceptual approach is also useful for larger scale analysis of air pollution effects on ecosystem services, for example at national or potentially European scale.

Use of ultraviolet-fluorescence-based simulation in evaluation of personal protective equipment worn for first assessment and care of a patient with suspected high-consequence infectious disease

BACKGROUND

Variations currently exist across the UK in the choice of personal protective equipment (PPE) used by healthcare workers when caring for patients with suspected high-consequence infectious diseases (HCIDs).

AIM

To test the protection afforded to healthcare workers by current PPE ensembles during assessment of a suspected HCID case, and to provide an evidence base to justify proposal of a unified PPE ensemble for healthcare workers across the UK.

METHODS

One 'basic level' (enhanced precautions) PPE ensemble and five 'suspected case' PPE ensembles were evaluated in volunteer trials using 'Violet'; an ultraviolet-fluorescence-based simulation exercise to visualize exposure/contamination events. Contamination was photographed and mapped.

FINDINGS

There were 147 post-simulation and 31 post-doffing contamination events, from a maximum of 980, when evaluating the basic level of PPE. Therefore, this PPE ensemble did not afford adequate protection, primarily due to direct contamination of exposed areas of the skin. For the five suspected case ensembles, 1584 post-simulation contamination events were recorded, from a maximum of 5110. Twelve post-doffing contamination events were also observed (face, two events; neck, one event; forearm, one event; lower legs, eight events).

CONCLUSION

All suspected case PPE ensembles either had post-doffing contamination events or other significant disadvantages to their use. This identified the need to design a unified PPE ensemble and doffing procedure, incorporating the most protective PPE considered for each body area. This work has been presented to, and reviewed by, key stakeholders to decide on a proposed unified ensemble, subject to further evaluation.

The clinical utility of genetic testing of tissues from pregnancy losses

OBJECTIVE

To map the current testing being undertaken following pregnancy loss across the UK and to examine the clinical utility in terms of identifying a cause for the loss and in identifying couples at risk of an unbalanced liveborn child.

DESIGN

Retrospective audit.

SETTING

UK, for the year 2014.

POPULATION

An audit of 6465 referrals for genetic testing of tissue samples following pregnancy loss.

METHODS

Data were obtained by questionnaire from 15 UK regional genetics laboratories.

MAIN OUTCOME MEASURES

Data were analysed with respect to gestational age, the presence of identified fetal anomalies, methodologies used, abnormality rates and the presence of a parental balanced rearrangement.

RESULTS

Of 6465 referrals a genetic cause was identified in 22% of cases (before 12 weeks' gestation, in 47%; at 12-24 weeks, in 14%; after 24 weeks, in 6%). In 0.4% of cases a balanced parental rearrangement was identified where there was a risk of an affected liveborn child in a future pregnancy. Eighty percent of genetic imbalances identified were aneuploidy or triploidy and could be identified by quantitative fluorescence polymerase chain reaction alone. There was significant variation across the UK in acceptance criteria, testing strategies and thus level of resolution of testing.

CONCLUSIONS

Genetic testing of tissues following pregnancy loss identifies a probable cause of fetal demise in 22% of cases, but it is of low clinical utility in identifying couples at risk of a future unbalanced liveborn child. A comprehensive multidisciplinary review is needed to develop proposals for an affordable and equitable service.

TWEETABLE ABSTRACT

UK audit of genetic testing of fetal loss shows variation in access to and resolution of analysis.

Definitive surgical trauma skills: a new skills course for specialist registrars and consultants in general surgery in the United Kingdom

In an era of increasing subspecialization within UK surgical practice, few senior trainees and a diminishing number of consultants feel competent operating outside their chosen specialist eld. General surgery and orthopaedic trainees, however, remain in the front line of trauma management. Subspecialization is, to some degree, affecting training of orthopaedic surgeons; there are some that do not deal with trauma. However, it is in the so-called field of general surgery that subspecialization has had the greatest impact. Many trainees are now more familiar with endoscopic techniques than open laparotomy and, even within the open abdomen, few wish to explore organ systems or regions outside their `zone of comfort’. Trauma, especially that inflicted by rearms, does not respect anatomical or speciality boundaries. This raises the question of how best to train surgeons in the future to manage severe multisystem injury.

To manage trauma competently there is a need to master operative skills that cover the whole of the abdominal cavity, including the pelvis and the retroperitoneum. General surgeons should be competent and confident to carry out trauma thoracotomies and able to cope with central and peripheral vascular trauma. Further skills and knowledge are also required: these encompass trauma epidemiology, critical decision making and, not least, a detailed knowledge of surgical anatomy. Knowledge can be most severely tested when dealing with multi-system trauma! There is also a particular need to give military surgeons the competencies required to deal with battlefield trauma, 90% of which is caused by penetrating injury. Military surgeons, by definition, still need to be `generalists’.

The Raven department of education at the Royal College of Surgeons of England, the Royal Defence Medical College (now the Royal Centre for Defence Medicine, Birmingham), and the Uniformed Services University of the Health Sciences, Washington, have developed a Definitive Surgical Trauma Skills (DSTS) course to meet this specific training need. This tripartite venture was developed in association with the Societe International de Chirugie (SIC) and the International Association for the Surgery of Trauma and Surgical Intensive Care (IATSIC).

Abstract P2-13-12: Implementation of a breast/reconstructive surgery coordinator to reduce preoperative delays for patients undergoing mastectomy with immediate reconstruction

Background

The scheduling of mastectomy with immediate reconstruction (M-IR) procedures requires coordination between breast and plastic surgical teams that can contribute to delays in breast cancer treatment and subsequently impact patient outcomes and satisfaction. The breast center leadership at our comprehensive cancer center established a time-to-treatment target of 28 days from initial consultation with a breast surgical oncologist to M-IR. We sought to determine if a centralized breast surgical coordinator (BC) could reduce preoperative delays.

Methods

We initiated a 60-day pilot program to evaluate the impact of a BC on the workflow, efficiency, and timeliness for patients seen at our breast center. All reconstructive surgery candidates were referred to the BC, who had access to the clinic and operating room schedules of the breast and plastic surgeons. The BC worked with patients and both surgical services to identify the earliest consult and surgery dates and facilitated case booking. Interval days between initial surgical consult and M-IR were calculated. The median time to M-IR and the proportion of M-IR cases that met the time-to-treatment goal was determined. These results were compared to a reference cohort of breast cancer patients undergoing M-IR during the same time period (January-March) in 2013 and 2014, who had their consults and surgeries scheduled independently by breast surgery administrative staff. Patients who received neoadjuvant therapy or did not have a definitive cancer diagnosis at initial consultation were excluded from the time-to-treatment calculation.

Results

A total of 99 patients were referred to the BC (62% cancer, 21% neoadjuvant, and 17% prophylactic) during the pilot period. Focusing exclusively on patients with a definitive breast cancer diagnosis at initial consultation, an 18.5% increase in the percentage of cases that met the target (p=0.04), and a 7 day decrease in the median number of days to M-IR (p=0.02) was observed with the implementation of the BC (Table 1).

Table 1: Days to M-IR Pre and Post Implementation of BCPatients (N)Median Days to M-IR (IQR)% M-IR within 28 daysBaseline (59)40.0 (17.0)23.7%BC (45)33.0 (20.0)42.2%p-value0.020.04

Conclusion

The coordination of care between breast surgical and reconstructive services presents timeliness challenges which may be partially alleviated through the implementation of a BC role. Establishing a centralized position to coordinate co-surgeon cases has improved time-to-treatment for M-IR at our cancer center. Further research is warranted to validate these preliminary findings, and determine the impact the BC has on operational efficiency and workflows.

Citation Format: Losk K, Mallory M, Caterson S, Camuso K, Cutone L, Roberts P, Lin N, Bunnell C, Golshan M. Implementation of a breast/reconstructive surgery coordinator to reduce preoperative delays for patients undergoing mastectomy with immediate reconstruction. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-13-12.

Clostridium difficile-associated diarrhoea in primary joint arthroplasty in Aneurin Bevan University Health Board South

INTRODUCTION

The choice of perioperative antibiotics to reduce the prevalence of infection after joint arthroplasty should be considered carefully to minimise the risk of nosocomial infections. Dramatic increases in the incidence and severity of healthcare-associated Clostridium difficile infection with Clostridium difficile-associated diarrhoea (CDAD) have occurred since 2000.

METHODS

A retrospective audit of patients who underwent total hip and total knee replacement between 1 January 2005 and 31 December 2007 was undertaken in Aneurin Bevan University Health Board South (ABHBS). Stool samples from patients who had diarrhoea <12 months of surgery were recorded. Positive samples for CDAD <1 month of surgery were identified. After the change in practice in June 2010, a re-audit linked joint-replacement patients between 1 July 2010 and 26 June 2013 with infection control-records for CDAD-positive cases.

RESULTS

In the first audit cycle, 1900 joint procedures were carried out in 1845 patients. There were 4 cases of CDAD <1 month of surgery (0.22%). In the re-audit period, 2591 joint procedures were undertaken in 2400 patients: no cases of CDAD <1 month of surgery were recorded. Fisher's exact test gave a two-tailed p=0.036.

CONCLUSIONS

The significant reduction in CDAD cases after the change in perioperative antibiotic regimen for primary joint arthroplasty mirrored a 66% reduction in overall CDAD cases in the ABUHBS between 2008 and 2012. This reduction was accompanied by financial savings in antibiotics and nursing hours.

Freeze-thaw cycles have minimal effect on the mineralisation of low molecular weight, dissolved organic carbon in Arctic soils

Warmer winters in Arctic regions may melt insulating snow cover and subject soils to more freeze–thaw cycles. The effect of freeze–thaw cycles on the microbial use of low molecular weight, dissolved organic carbon (LMW-DOC) is poorly understood. In this study, soils from the Arctic heath tundra, Arctic meadow tundra and a temperate grassland were frozen to −7.5 °C and thawed once and three times. Subsequently, the mineralisation of 3 LMW-DOC substrates types (sugars, amino acids and peptides) was measured over an 8-day period and compared to controls which had not been frozen. This allowed the comparison of freeze–thaw effects between Arctic and temperate soil and between different substrates. The results showed that freeze–thaw cycles had no significant effect on C mineralisation in the Arctic tundra soils. In contrast, for the same intensity freeze–thaw cycles, a significant effect on C mineralisation was observed for all substrate types in the temperate soil although the response was substrate specific. Peptide and amino acid mineralisation were similarly affected by FT, whilst glucose had a different response. Further work is required to fully understand microbial use of LMW-DOC after freeze–thaw, yet these results suggest that relatively short freeze–thaw cycles have little effect on microbial use of LMW-DOC in Arctic tundra soils after thaw.

Diagnosis of fetal submicroscopic chromosomal abnormalities in failed array CGH samples: copy number by sequencing as an alternative to microarrays for invasive fetal testing

OBJECTIVES

Array comparative genomic hybridization (CGH) has become the technology of choice for high-resolution prenatal whole genome analysis. Limitations of microarrays are mainly related to the analog nature of the analysis, and poor-quality DNA can result in failed quality metrics with these platforms. We examined a cohort of abnormal fetuses with failed array CGH results using a next-generation sequencing algorithm, CNV-Seq. We assessed the ability of the platform to handle suboptimal prenatal samples and generate interpretable molecular karyotypes.

METHODS

Nine samples obtained from abnormal fetuses and one from a normal control fetus were sequenced using an Illumina GAIIx. A segmentation algorithm for sequencing data was used to determine regional copy number data on the sequencing datasets.

RESULTS

Phred quality scores were satisfactory for analysis of all samples. CNV-Seq identified both large- and small-scale abnormalities in the cohort, and normal results were obtained for fetuses for which microarray data were previously uninterpretable. No variants of uncertain significance were detected. Analysis of the digital sequencing datasets offered some advantages over array CGH output.

CONCLUSIONS

Using next-generation sequencing for the detection of genomic copy number variants may be advantageous for poor-quality, invasively-acquired prenatal samples. CNV-Seq could become a potential alternative to array CGH in this setting.

Large-scale discovery of novel genetic causes of developmental disorders

Despite three decades of successful, predominantly phenotype-driven discovery of the genetic causes of monogenic disorders, up to half of children with severe developmental disorders of probable genetic origin remain without a genetic diagnosis. Particularly challenging are those disorders rare enough to have eluded recognition as a discrete clinical entity, those with highly variable clinical manifestations, and those that are difficult to distinguish from other, very similar, disorders. Here we demonstrate the power of using an unbiased genotype-driven approach to identify subsets of patients with similar disorders. By studying 1,133 children with severe, undiagnosed developmental disorders, and their parents, using a combination of exome sequencing and array-based detection of chromosomal rearrangements, we discovered 12 novel genes associated with developmental disorders. These newly implicated genes increase by 10% (from 28% to 31%) the proportion of children that could be diagnosed. Clustering of missense mutations in six of these newly implicated genes suggests that normal development is being perturbed by an activating or dominant-negative mechanism. Our findings demonstrate the value of adopting a comprehensive strategy, both genome-wide and nationwide, to elucidate the underlying causes of rare genetic disorders.