Short-term risk prediction after major lower limb amputation: PERCEIVE study

BACKGROUND

The accuracy with which healthcare professionals (HCPs) and risk prediction tools predict outcomes after major lower limb amputation (MLLA) is uncertain. The aim of this study was to evaluate the accuracy of predicting short-term (30 days after MLLA) mortality, morbidity, and revisional surgery.

METHODS

The PERCEIVE (PrEdiction of Risk and Communication of outcomE following major lower limb amputation: a collaboratIVE) study was launched on 1 October 2020. It was an international multicentre study, including adults undergoing MLLA for complications of peripheral arterial disease and/or diabetes. Preoperative predictions of 30-day mortality, morbidity, and MLLA revision by surgeons and anaesthetists were recorded. Probabilities from relevant risk prediction tools were calculated. Evaluation of accuracy included measures of discrimination, calibration, and overall performance.

RESULTS

Some 537 patients were included. HCPs had acceptable discrimination in predicting mortality (931 predictions; C-statistic 0.758) and MLLA revision (565 predictions; C-statistic 0.756), but were poor at predicting morbidity (980 predictions; C-statistic 0.616). They overpredicted the risk of all outcomes. All except three risk prediction tools had worse discrimination than HCPs for predicting mortality (C-statistics 0.789, 0.774, and 0.773); two of these significantly overestimated the risk compared with HCPs. SORT version 2 (the only tool incorporating HCP predictions) demonstrated better calibration and overall performance (Brier score 0.082) than HCPs. Tools predicting morbidity and MLLA revision had poor discrimination (C-statistics 0.520 and 0.679).

CONCLUSION

Clinicians predicted mortality and MLLA revision well, but predicted morbidity poorly. They overestimated the risk of mortality, morbidity, and MLLA revision. Most short-term risk prediction tools had poorer discrimination or calibration than HCPs. The best method of predicting mortality was a statistical tool that incorporated HCP estimation.

Analysis of Spinal Ischemia after Frozen Elephant Trunk for Acute Aortic Dissection: An Observational, Single-Center Study

BACKGROUND

This observational study aimed to evaluate the perioperative risk factors for spinal cord ischemia (SCI) in patients who underwent aortic repair with the frozen elephant trunk technique (FET) after acute aortic Stanford A dissection.

METHODS

From May 2015 to April 2019, 31 patients underwent aortic arch replacement with the FET technique, and spinal ischemia was observed in 4 patients. The risk factors for postoperative SCI were analyzed.

RESULTS

The mean age of patients with acute aortic dissection was 57.1 years, and 29.4% were female. Four patients developed SCI. There were no significant differences in characteristics such as age and body mass index. The female gender was associated with most of the SCI cases in the univariate analysis (75%, p = 0.016). Known perioperative and intraoperative risk factors were not related to postoperative SCI in our study. Patients who developed SCI had increased serum postoperative creatinine levels (p = 0.03). Twenty-four patients showed complete false lumen thrombosis up to zones 3-4, five patients up to zones 5-6 and two patients up to zones 7-9, which correlates with the postoperative development of SCI (p = 0.02). The total number of patent intercostal arteries was significantly reduced postoperatively in SCI patients (p = 0.044).

CONCLUSIONS

Postoperative acute kidney injury, the reduction in patent intercostal arteries after surgery and the extension of false lumen thrombosis up to and beyond zone 5 may play a significant role in the development of clinically relevant spinal cord injury after FET.

Snare-Dragging Technique to Target the Hypogastric Artery in an Iliac Bifurcation Dissection

PURPOSE

To describe snare-assisted vessel targeting to selectively overcome a dissection in the iliac bifurcation and gain antegrade access to the hypogastric artery (HA).

TECHNIQUE

The technique is demonstrated in a 64-year-old woman with an asymptomatic Crawford type III thoracoabdominal aneurysm. A 2-stage endovascular repair, consisting of a thoracic endovascular aortic repair (TEVAR) and a branched endovascular aortic repair was planned. In the control angiography after TEVAR, a disrupted plaque with consequent dissection in the right iliac bifurcation was detected. The perfusion of the common iliac artery and external iliac artery resulted impaired. The targeting of the right HA through a contralateral antegrade approach failed, whereas an ipsilateral retrograde approach was possible but unsuitable for therapeutic purposes. Using the catheter of the retrograde ipsilateral access, a snare from a contralateral crossover was cached and dragged into the HA, allowing the targeting of the vessels and further endovascular therapy with angioplasty and stenting. Follow-up 8 months postoperatively demonstrated the patency of the stents and well-preserved perfusion in the right iliac bifurcation.

CONCLUSION

The snare-dragging technique can be used to gain access to vessels presenting challenging conformations or dissections. This application may be a valuable support for complex endovascular treatment in a variety of patients.

CLINICAL IMPACT

The snare-dragging technique can be used to gain access to vessels presenting challenging conformations or dissections. It allows the catheterization to be establish from the easiest and safest approach and then "transferred" from one access to the other. It avoids the risk of repeated loss of catheterization due to unstable and unfavorable working angles, and it saves time and radiation. It permits different material combinations, adapting to the available resources and materials. We believe that the current technique may increase the strategy spectrum available for endovascular therapy and complex endovascular procedures.

Volume Changes in the Descending Aorta after Frozen Elephant Trunk and Conventional Hemi-Arch Repair after Acute Type A Aortic Dissection

The aim of this study was to compare the mortality rates, re-intervention rates, and volumetric changes in aortas following surgery, in terms of the true lumen and false lumen changes, using conventional hemi-arch repair (CET) and frozen elephant trunk (FET) techniques. During the period from 2015 to 2018, 66 patients underwent surgical treatment for acute aortic dissection (Debakey type 1). Demographic and procedure-related data were evaluated. We measured volumetric change before surgical treatment, at discharge, and at 12- and 24-month time points based on computed tomography angiography. The study cohort was divided into two groups (FET vs. CET). The mean age of the patients was 56.9 ± 9.4 years in the FET group versus 63.6 ± 11 years in the CET group (p = 0.063). The mean follow-up time was 24 ± 6 and 25 ± 5 months for the FET and CET groups, respectively. There were no significant differences between the two groups in terms of the medical histories of the cohorts. The results showed a significant increase in true lumen volume after the FET procedure (within 24 months postoperatively; p = 0.005), and no significant changes in total (p = 0.392) or false lumen (p = 0.659) volumes were noted. After the CET procedure, there were significant increases in total and false lumen volumes (p = 0.013, p = 0.042), while no significant change in true lumen was observed (p = 0.219). The volume increase in true lumen after the FET procedure was higher compared to the CET group at all postoperative time points (at discharge, 12 months, and 24 months) without significant evidence (p = 0.416, p = 0.422, p = 0.268). At two years, the volume increase in false lumen was significantly higher among the CET group compared to the FET group (p = 0.02). The Kaplan–Meier curve analysis showed that patients who underwent the CET procedure underwent significantly more re-interventions due to false lumen expansion of the descending aorta (p = 0.047). Present study results indicate that the true and false lumen changes in the aorta following the FET and CET procedures were different. FET led to a significant increase in true lumen volume, while false lumen volume remained stable; however, after the CET procedure, significant false lumen enlargement was noted at mid-term follow-up time points. The re-intervention rate after CET was higher due to false lumen expansion.

Indocyanine Green to Visualize and Resect Pulmonary Sequestration in Adults

Pulmonary sequestration (PS) is a rare congenital pulmonary dysplasia which presents with recurrent chest infections and haemoptysis. Its diagnosis is difficult and suspected on contrast-enhanced chest CT. The definitive treatment of pulmonary sequestration is surgical resection or endoluminal occlusion of the abnormal feeding vessel. Here, we report an innovative technique in which per-operative indocyanine green guided excision of intra-lobar sequestrated lung parenchyma and ligation of abnormal feeding vessel. The first patient was a 44-year-old gentleman with recurrent bouts of cough for 2 years. Courses of antibiotics failed to resolve it. Fibreoptic bronchoscopy and routine blood tests did not show any abnormality. CECT chest showed multiloculated cystic solid and low density mass in the right lower lung. The area of the lesion received its blood supply from anomalous systemic artery originating from coeliac trunk. Intraoperative, indocyanine green was injected into the atypical vessel, and pulmonary sequestration turned green. A sequential atypical lung resection could be completely removed with parenchyma preservation. The second patient was a 53-year-old lady presenting with chest pain, cough and expectoration for 2 years not responding to general management and antibiotics. CECT showed a low-density mass in the right lower lung lobe, with a feeding arterial vessel arising from the abdominal aorta. This was diagnosed as PS and resected using per-operative indocyanine green with parenchymal preservation and ligation of feeding vessel. Both patients have been followed up for at least 1 year and are symptom free. The intraoperative use of indocyanine green could greatly facilitate the presentation of the extent of a lung sequestration and safe resection.

Single-Center Experience With the Thoraflex™ Hybrid Prosthesis: Indications, Implantation Technique and Results

Objective

The aim of this study was to evaluate the early and mid-term results after the frozen elephant trunk (FET) procedure for the treatment of complex arch and proximal descending aortic disease in a single-center institution.

Methods

From April 2015 to July 2021, 72 patients (25 women, 60.4 ± 10.3 years) underwent Thoraflex™ Hybrid implantation at our institution. The indications were thoracic aortic aneurysm (TAA) (n = 16, 22.2%), post-dissection aneurysm (n = 21, 29.2%), and acute aortic dissection (AAD) (n = 35, 48.6%). Antegrade cerebral perfusion under moderate hypothermia (28°C) was employed in all cases. Eighteen patients (25%) have already been operated due to heart or aortic disease.

Results

Overall in-hospital mortality was 12.5% (9 patients). Rates of permanent neurological dysfunction and spinal cord injury were 9.7 and 5.5%, respectively. The in-hospital mortality rate among patients operated on AAD, TAA, and post-dissection aneurysm were 8.6, 6.2, and 23.8%, respectively. At a mean follow-up of 26 ± 20 months, mortality was 9.7%. Furthermore, 23 patients (31.9%) required a subsequent procedure in distal aorta: endovascular stentgraft extension in 19 patients (26.4%) and open aortic surgery in 4 patients (5.5%). The mid-term survival of patients with type A aortic dissection was 97%.

Conclusions

Our experience with the Thoraflex Hybrid prosthesis demonstrates its surgical applicability for different types of aortic pathologies with promising outcomes during early and midterm follow-up. Our technique and perioperative management lead to comparable or even superior neurological outcomes and mortality in urgent cases considering other high-volume centers.

Open Treatment of Abdominal Aortic Aneurysm in the Endovascular Era

The aim of the study was to analyse outcomes and determine the early and late complications in patients after open surgical treatment of AAA in the endovascular era. Two hundred and fourteen patients between January 2012 and December 2021 with open repair in primary infrarenal and juxtarena aneurysm in elective setting were included in the study. Pre-, intra-, and postoperative clinical data were statistically analysed. The mean age of the 214 patients was 65.5 ± 9.3 years. The mean follow-up was 22.1 ± 2.1 months. Men represented the majority of the studied group (85.5%). The mean aortic diameter was 58.2 ± 13.4. The median ICU (days) stay was 5 ± 4.9 days for infrarenal aneurysm and 6 ± 6.1 days for juxtarenal aneurysm. Four patients died within 30 days, giving an in-hospital mortality rate of 1.9%. In multivariate logistic regression, COPD (p = 0.015) was the only predictor significantly associated with the mortality. A comparison of survival and reintervention using a Kaplan–Meier curve showed no significant difference between the groups in terms of risk stratification and the groups with juxtarenal versus infrarenal aneurysms. In conclusion, open aneurysm repair is in the era of endovascular aneurysm repair, being safe and effective, especially when performed in specialised high-volume centres with large expertise.

Memory, neurogenic protein and oxidative deficits of frontal cortex following chlorpyrifos/dichlorvos exposure in rats

Objective: The use of xenobiotics to boost agricultural productivity has led to toxic chemicals exposure including organophosphates, causing adverse health outcomes including behavioral and neuronal impairments. This study aimed to evaluate the memory indices, possible oxidative and cholinesterase outturnson the frontal cortices of rats exposed to organophosphates.Methodology: Thirty-two Wistar rats were grouped into four. They received 1ml/kg of Normal, 8.8 mg/kg dichlorvos, 14.9 mg/kg chlopyrifos, and 8.8 mg/kg dichlorvos plus 14.9mg/kg chlorpyrifos respectively. They had training trials in the Y Maze paradigm then spatial working memory assessment. They were euthanized 24hours following exposure and tissues excised for analysis.Results: A marked reduction in metabolic markers, Acetylcholine Esterase (AChE) activity, spatial memory indices and proliferative neuron marker (Ki67) were observed. Also, increase in oxidative stress markers in the frontal cortices of the organophosphates exposed rats.Conclusion: The findings demonstrated neurotoxic effects of organophosphates in rats.

Transversal Arch Clamping for Complete Resection of Aneurysms of the Distal Ascending Aorta without Open Anastomosis

BACKGROUND

The extent of aortic replacement for aneurysms of the distal ascending aorta remains controversial and opinions vary between standard cross-clamp resection and open hemiarch anastomosis in circulatory arrest and selective cerebral perfusion. As the deleterious effects of extended circulatory arrest are well-known, borderline indication for distal ascending aorta aneurysm repair must be outweighed against the potential risk of complications related to the open anastomosis. In the present study, we describe our own approach consisting of "transversal arch clamping" for exhaustive resection of aneurysms of the distal ascending aorta without open anastomosis and we present the postoperative outcomes.

METHODS

Between May 2017 and December 2019, 35 patients with aneurysm of the ascending aorta (20 male, 15 female) underwent replacement with repair of the lesser curvature without circulatory arrest. Pre-operative, intraoperative, and postoperative clinical outcomes were retrospectively withdrawn from our institutional database and analyzed.

RESULTS

Maximal diameter of distal ascending aorta was 47.5 mm. Patient median age was 66 years (IQR 14) (range 42-86). Preoperative logistic median EuroSCORE II was 17% (IQR 11.3). Median duration of cardiopulmonary bypass and cardiac arrest were 137 (IQR 64) and 93 (IQR 59) min, respectively. In-hospital and 30-day mortality were 0%. There were no cases with acute low output syndrome, surgical re-exploration for bleeding, kidney injury requiring dialysis, or wound infection. Disabling stroke was observed in one patient (2.9%). There was one case of major ventricular arrhythmia (2.9%).

CONCLUSIONS

Our institutional experience suggests that this novel technique is safe and feasible. It facilitates complete resection of the aortic ascending aneurysm avoiding circulatory arrest, antegrade cerebral perfusion, additional peripheral cannulation, and all related complications.

community pharmacists’ experiences and beliefs towards providing pharmacy services to deaf and hard of hearing patients: a mixed-method study in Riyadh, Saudi Arabia

Introduction

Provision of pharmacy services to patients requires the pharmacist to well communicate with the patients. Research has shown that healthcare providers, including community pharmacists, face many challenges while providing services to deaf and hard-of-hearing patients (DHOH).

Aim

To investigate community pharmacists’ experiences and beliefs about providing pharmacy services to DHOH in Riyadh, Saudi Arabia.

Methods

This was a sequential explanatory mixed-method study involving a survey and semi-structured interviews. At first, a web-based, self-administered survey was disseminated to community pharmacists in Riyadh, Saudi Arabia during the period October to November 2020. The survey was disseminated through the official twitter account of Saudi Pharmaceutical Society. Two reminders were sent. It was made clear that the survey targeted community pharmacists working in Riyadh city. To calculate an appropriate sample size, according to Hair et al, the general rule to have a minimum sample size would be five observations per variable (5:1), and an acceptable sample size would be ten observations per variable (10:1). In this survey, there are 16 items, and hence the acceptable sample size was 160 participants. The semi-structured telephone-based interviews were conducted with a purposive sample of survey respondents to gather in-depth information on experiences, beliefs, and barriers about providing pharmacy services to DHOH. The interviews were conducted until saturation occurred. Survey data was analysed using Statistical Package for Social Sciences (SPSS version 24), and the semi-structured interviews were analysed by Framework analysis.

Results

A total of 175 community pharmacists completed the survey. The majority were: male (84.6%), aged between 25 to 35 years (74.9%). Of the respondents, 32.2% and 29.1% had experience in community pharmacy of 1-5 and 6-10 years, respectively. The number of DHOH patients the pharmacists met during the past 6 months were as follows: 68 (38.9%) pharmacists met 1-2 patients, 71 (40.6%) %) pharmacists met 3-4 patients, and 19 (11%) %) pharmacists met ≥ 5 patients. The provided services included: prescription medications (by 82.9%), counselling on prescription medications (by 56.6%), OTC medication dispensing (by 4.3%), and counselling on OTC medications (by 52.6%). Forty participants (22.8%) reported their awareness of the basics of Saudi sign language (SSL). Of the participants, 101 (57.7%) believed that they have handled communication barriers appropriately, while 61(35%) acknowledged unmanageable communication barriers. Among the main barriers identified were the lack of knowledge of the basics of SSL. (70.9%) and the inability to recognize disability (52.6%). The semi-structured interviews further explored pharmacists’ experiences and views on providing such a service. Of the main themes emerged were: (1) Experience; interviewees preferred written communication with DHOH patients regardless of their literacy level, while spontaneous hand gesturing was the least preferred method of communication, and they also acknowledged that their roles in providing services, to the DHOH, need to be improved (2) Beliefs; interviewees believed that awareness of the basics of SSL is important to ensure safe medication use. The barriers emerged from the interview were classified as pharmacist-related, system-related, and patient-related.

Conclusion

To our knowledge, this is the first study of its kind to be conducted in Saudi Arabia. The study highlighted that when providing pharmacy services to DHOH patients, community pharmacists encountered multiple barriers. These barriers need to be addressed for better support and provision of pharmacy services to DHOH. Further studies with large sample size, are warranted to better understand the situation.

References

(1) Hair J, Black W, Babin B, Anderson R. Multivariate data analysis. 7th ed. Harlow: Pearson Education Limited; 2014

(2) Scheier DB. Barriers to health care for people with hearing loss: a review of the literature. J N Y State Nurses Assoc. 2009 Mar 22;40(1):4-11.

(3) Ferguson MC, Shan L. Survey evaluation of pharmacy practice involving deaf patients. Journal of pharmacy practice. 2016 Oct;29(5):461-6.

257 Comparing Practice Testing to Restudying in the Dissecting Room: An Experimental Study

Aim

Medical students employ many strategies for learning, most commonly restudying. However, evidence suggests that restudying is not as effective as other strategies, namely practice testing. Different studies have compared restudying to practice testing on a variety of subjects. Few studies have assessed the effect of practice testing in anatomy courses. To the best of the authors' knowledge, no studies have investigated practice testing in the dissecting room (DR). In this study, we aim to measure the effect of practice testing in a DR setting, as compared to restudying.

Method

Second-year medical students learning the cardiovascular system were included in the study. Two groups were randomly selected to participate in practice tests taken at the end of DR sessions. The other two groups were asked to restudy the material. At the end of the four-week course, all students took a 15 points multiple-choice exam on learned material. Authors of practice tests were blind to the final exam content and vice versa.

Results

One hundred eight students participated in the study. Fifty-three students were in the practice testing group, and 55 were in the restudying group. The practice testing group performed significantly better than the restudying group (p = .008), with a mean of 8.57 +/- 2.3 for the practice testing group and 7.27 +/- 2.6 for the restudying group.

Conclusions

Practice testing significantly improved retention of Anatomy. We recommend that practice testing is implemented regularly at the end of DR sessions to enhance the learning experience.

259 Effect of Telegram Videos on Anatomy Education Among 2nd Year Medical Students, University of Khartoum, 2021

Aim

COVID-19 had major effect on the health and medical education. In order to oblige with the social distancing and quarantine, universities shifted to online learning. This study aimed to assess the effect of online education on anatomy DR (dissection room) teaching by the use of telegram software.

Method

This was a cross-sectional, prospective interventional study, which was carried out among 2nd year medical students in University of Khartoum. Students undertook initial tests on the heart and anterior abdominal wall modules. Telegram videos, prepared by the author, on the anatomy of the heart and the anterior abdominal wall were distributed to students. Students took a second test after watching the videos. A total number of 41 students attended heart sessions and 40 students attended the anterior abdominal wall sessions were included.

Results

The pre-test mean score for the heart and abdomen modules were 4.56 ± 2.335 and 6.15 ± 2.94, respectively. The post-tests means were 9.98 ± 2.877 and 8.95 ± 3.14, respectively. 90% and 75% of the students were satisfied with these videos, respectively.

Conclusions

This study revealed that Telegram videos as a method of online teaching had a positive effect on the students' performance, which was evidenced by the significant improvement in student's scores after watching the videos. Additionally, most of the students were satisfied with the videos and give positive feedback.

255 An Audit on the Knowledge of Junior Doctors About DKA at a Local Hospital, Khartoum, Sudan

Aim

DKA is the most common cause of death in pediatric patients with insulin-dependent diabetes mellitus (IDDM). Junior doctors have a significant role in the management of those patients. We conducted this audit to assess and improve the knowledge of house officers about the characteristic features and management of DKA.

Method

The audit was conducted in Alshuhada hospital, Khartoum. It consisted of two cycles (2019–2021). A 14 items questionnaire based on Sudan Diabetes Mellitus guidelines 2011 was used for the assessment. All house officers in the department of pediatrics were involved in this study. Teaching sessions were used as an intervention in the first cycle, while poster presentations and teaching sessions were used in the second cycle.

Results

Nine house officers participated in the first cycle, while seven house officers were involved during the second cycle. The correct choice of initial fluid correction was selected by 55.5%, 88.8%, and 100% of the house officers before the first cycle, after the first cycle, and after the second cycle, respectively. The figures for the initial management of cerebral edema also rose from 33.3% to 66.7% after the first cycle and reached 100% after the second cycle. The percentage of house officers who identified Investigations needed in suspected cases of DKA improved with each cycle, from 66% to 77% in the first cycle and increased to 100% after the second cycle.

Conclusions

Teaching sessions and posters helped to improve the knowledge of the House officers about the diagnosis and management of DKA.

Early experience with the Bolton Relay Pro/Plus for physician-modified fenestrated TEVAR

BACKGROUND

Thoracic endovascular aortic repair (TEVAR) can be challenging in cases involving the aortic arch and the visceral segment. We report our initial experience with fenestrated TEVAR (f-TEVAR) for thoracic aortic disease involving aortic branches using physician-modified stent grafts (PMSGs).

MATERIALS AND METHODS

Between February 2019 and November 2020 nine patients were treated with a PMSG. Indication to treatment were a symptomatic acute type B aortic dissection (TBAD) in three cases, a penetrating aortic ulcer in three cases (two in zone 3 and one in zone 6), one case of an endoleak type I A after TEVAR, a chronic TBAD after TEVAR in one case and one case of a contained rupture of a thoracoabdominal aneurysm in zone 3. Pre-, intra- and postoperative clinical data were recorded.

RESULTS

The median patient age was 65 (IQR 60.5-71) years, and 8 (89%) patients were men. Nine stent grafts (six Bolton Relay Plus and three Bolton Relay Pro, Terumo Aortic, Vascutek Ltd., Inchinnan, United Kingdom) were deployed. Small fenestrations (8 mm) were created on table, median duration for on table stent graft modifications was 20 minutes (13-22). The technical success rate was 100%. Median operative time was 188 (116-252) minutes. No major adverse events of any sort occurred during the first 30-day postoperatively. There were no type I or type III endoleaks at the end of the procedure, and no cases of spinal cord ischemia. Two access related complications occurred (22%). After a median of 12 (range 5-12) months all patients survived and all target vessels remained patent with one case of fenestration-related type I endoleak, which required open conversion.

CONCLUSIONS

The results of our initial experience with f-TEVAR using PMSGs with the Bolton Relay stentgraft for the treatment of aortic diseases are acceptable. These results should be confirmed on larger patient cohorts.

Test-Retest Data for the Assessment of Breast MRI Radiomic Feature Repeatability

Background

Radiomic features extracted from breast MRI have potential for diagnostic, prognostic, and predictive purposes. However, before they can be used as biomarkers in clinical decision support systems, features need to be repeatable and reproducible.

Objective

Identify repeatable radiomics features within breast tissue on prospectively collected MRI exams through multiple test–retest measurements.

Study Type

Prospective.

Population

11 healthy female volunteers.

Field Strength/Sequence

1.5 T; MRI exams, comprising T2‐weighted turbo spin‐echo (T2W) sequence, native T1‐weighted turbo gradient‐echo (T1W) sequence, diffusion‐weighted imaging (DWI) sequence using b‐values 0/150/800, and corresponding derived ADC maps.

Assessment

18 MRI exams (three test–retest settings, repeated on 2 days) per healthy volunteer were examined on an identical scanner using a fixed clinical breast protocol. For each scan, 91 features were extracted from the 3D manually segmented right breast using Pyradiomics, before and after image preprocessing. Image preprocessing consisted of 1) bias field correction (BFC); 2) z‐score normalization with and without BFC; 3) grayscale discretization using 32 and 64 bins with and without BFC; and 4) z‐score normalization + grayscale discretization using 32 and 64 bins with and without BFC.

Statistical Tests

Features' repeatability was assessed using concordance correlation coefficient(CCC) for each pair, i.e. each MRI was compared to each of the remaining 17 MRI with a cut‐off value of CCC > 0.90.

Results

Images without preprocessing produced the highest number of repeatable features for both T1W sequence and ADC maps with 15 of 91 (16.5%) and 8 of 91 (8.8%) repeatable features, respectively. Preprocessed images produced between 4 of 91 (4.4%) and 14 of 91 (15.4%), and 6 of 91 (6.6%) and 7 of 91 (7.7%) repeatable features, respectively for T1W and ADC maps. Z‐score normalization produced highest number of repeatable features, 26 of 91 (28.6%) in T2W sequences, in these images, no preprocessing produced 11 of 91 (12.1%) repeatable features.

Data Conclusion

Radiomic features extracted from T1W, T2W sequences and ADC maps from breast MRI exams showed a varying number of repeatable features, depending on the sequence. Effects of different preprocessing procedures on repeatability of features were different for each sequence.

Level of Evidence

2

Technical Efficacy Stage

1

Inorganic nitrate attenuates endothelial dysfunction consequent to systemic inflammation

Introduction

Chronic cardiovascular diseases are characterised by low-grade systemic inflammation and attenuated nitric oxide (NO) bioavailability resulting in endothelial dysfunction. Inorganic nitrate augments NO bioavailability and improves markers of vascular dysfunction in patients with cardiovascular risk factors. However, the exact mechanism of this effect is uncertain.

Purpose

To determine whether inorganic nitrate supplementation alters systemic inflammation-induced endothelial dysfunction.

Methods

62 healthy male volunteers were randomised 1:1 to receive ∼8–10 mmol of dietary inorganic nitrate in beetroot juice or nitrate-free beetroot juice (placebo) once daily for 6 days. Measures of brachial artery flow-mediated dilatation (FMD), brachial blood pressure (BP), pulse wave analysis and carotid-femoral pulse wave velocity (PWV) by Vicorder were taken prior to and at 8 hours after a typhoid vaccine (to induce mild systemic inflammation). Plasma, urine and saliva samples were also collected. Clinicaltrials.gov: NCT02715635.

Results

Baseline characteristics were similar between the two groups. Inorganic nitrate significantly elevated plasma nitrite (placebo = Δ0.02±0.5 μM, inorganic nitrate = Δ0.63±1.2 μM; p=0.01) and nitrate levels (p<0.0001) compared to placebo. There were significant increases in urine nitrite (p<0.0001) and nitrate (p<0.0001) in addition to salivary nitrite (p<0.0001) and nitrate (p<0.0001) compared to placebo. After 8 hours, typhoid vaccine induced an increase in circulating white cells (placebo = Δ3.34±3.37x109/L, inorganic nitrate = Δ2.9±2.78x109/L; p=0.58) that was similar in in both arms. However, there was a significant reduction in the FMD response in the placebo group at 8-hours post vaccine; an effect that was absent in volunteers treated with inorganic nitrate (placebo = Δ−1.33±1.53%, inorganic nitrate = Δ−0.07±1.84%, p=0.005). Importantly, there were no statistically significant differences in baseline vessel diameter (p=0.78), time to peak diameter in response to flow (p=0.87) and peak shear rate (p=0.57) between the groups. When comparing change from baseline to 8 hours after the vaccine, there were no significant differences in brachial systolic BP (p=0.12), central systolic BP (p=0.12) and PWV (p=0.60) between groups, but a significant reduction in brachial diastolic BP in the inorganic nitrate group (p=0.048).

Conclusions

Inflammation-induced endothelial dysfunction was prevented in those receiving dietary inorganic nitrate suggesting that elevating circulating nitrite and delivering NO to the blood vessel wall, through dietary approaches may offer potential therapeutic benefit in those cardiovascular diseases which typically exhibit low grade inflammation and deficiencies in bioavailable NO.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation

280 The Use of Telemedicine in Plastics Surgery During COVID-19: A Single-Centre Correlation Study with Patient Reported Outcome Measures

Aim

With enforcement of social distancing measures during the COVID-19 pandemic, face-to-face patient contact was shifted to telemedicine consultations. There is limited evidence evaluating patient experience of follow-ups and expectations into quality metrics. Our aim was to perform a service evaluation by prospectively evaluating the management and outcomes of plastic surgery patients.

Method

Patients were consecutively assessed over the COVID-19 lockdown period, from March to May 2020. They ranged from urgent cancer cases to burns and trauma. We used a questionnaire to evaluate initial treatment, wound care, complications, and overall service. A validated health-related quality of life (HRQL) survey was used to assess the impact of injury or wound on lifestyle and we also assessed patient enablement. Correlation analysis determined relationships between outcomes, service evaluations and HRQL variables.

Results

77 patients were consecutively treated in our unit, of which 46 completed the questionnaire. 42.2% used multimedia as mode of follow-up, including smart phones for messages and videocalls, and trust e-mails. There was a 3-fold increase in number of infections for non-face-to-face consultations, with a correlation significance of 0.043. We found no correlation between age and wound complication rates. 72.7% of patients found overall service very good or excellent. Although overall service satisfaction was similar for multimedia use and face-to-face consultations (p = 0.02), less patients were confident looking after their wound without face-to-face follow-ups.

Conclusions

COVID-19 has brought upon an unprecedented change in practice in our department. Implementing multimedia use and educating patients on wound care can significantly improve efficiency and service provision.

1255 Crowdedness and Consequences of Long Waiting Time in Public and Private Health Centers Among Patients in Khartoum State, Sudan - 2016

Aim

Waiting time (WT) reflects quality of services delivered by Primary health care level. Long waiting time is due to various causes, among which crowdedness is a main cause. This prolonged time has negative impacts on PHC services utilization as well as patients’ outcomes. The aim of this study is to measure the total WT, assess the crowdedness in PHC centers, and to determine the possible consequences of this long waiting time.

Method

Descriptive cross sectional– health institution-based study done in 40 Health centres across Khartoum state using randomized multi-stage sampling. Patients, doctors and lab technicians were interviewed using three different pre-tested structured questionnaires.

Results

A total of 477 patients were included in the study. The average waiting time was found to be 168 minutes. Crowdedness was one of the main causes of delay in waiting time. The lab was the most perceived crowded service (74.4% of the respondents). This long WT had health consequences on patients, ranging from backache, joint pain, and headaches to hypoglycemic symptoms. These symptoms affected patients' willingness to return to the same center. 36.4% of the affected patients were unwilling to revisit the same center.

Conclusions

WT in this study is longer compared to studies from other countries. Crowdedness is one of the main causes of long WT. Due to this prolonged time, patients experienced physical symptoms. It also affected their future attitude regarding PHC centers utilization. There is a need to understand the underlying causes of this issue and address them appropriately.

Post-implantation syndrome after frozen elephant trunk is associated with the volume of new-onset aortic thrombus

Background

Post-implantation syndrome (PIS) is defined as non-infectious continuous fever and a concomitant rise in inflammatory markers shortly after endovascular aortic repair. PIS occurrence after hybrid procedures, such as the frozen elephant trunk (FET) technique, has not been adequately investigated. The current study aims to define the incidence of PIS after the FET and to identify possible risk factors associated with its occurrence.

Methods

The clinical charts of 59 patients undergoing the FET between February 2015 and April 2020 were reviewed retrospectively. The occurrence of PIS was defined as the presence of fever (>38 °C lasting longer than one day during the hospitalisation) and leucocytosis (white blood cell count >12,000/µL). Patients with concomitant conditions possibly leading to fever and/or leucocytosis were excluded. Beside demographic and procedure-related data, serum/plasma inflammatory markers were evaluated before surgery and daily up to seven days postoperatively. Computed tomography scans (CT) were examined to calculate the volume of pre-existent and new-onset mural thrombus after the FET.

Results

Thirty-eight patients met the inclusion criteria. The study cohort was divided into two groups based on the occurrence of PIS (17 cases; 44.7%). Patients with PIS were significantly younger than those without PIS (53.5±8.9 vs. 62.5±9.6 years; P=0.005). Female patients were less likely to develop PIS (5.2% vs. 26.3%, P=0.018). Patients with PIS had a higher volume of new-onset thrombus in the postoperative CT (P<0.001). Patients treated for post-dissection aneurysm had, postoperatively, significantly more thrombus material developed in a false lumen (P=0.02). Among the PIS markers, CRP (C-reactive protein) levels on the third postoperative day were independently associated with the volume of new-onset thrombus (P=0.011). After multivariate analysis, the volume of new-onset thrombus (P=0.028) and age (P=0.036) remained the variable associated with a statistically significant increased incidence of PIS.

Conclusions

PIS can occur after the frozen elephant trunk procedure. The volume of new-onset thrombus seems to be associated with an increased incidence of PIS. These findings need to be confirmed in larger patient cohorts.

Seasonal bias in global ocean color observations

In this study, we identify a seasonal bias in the ocean color satellite-derived remote sensing reflectances (Rrs(λ);sr-1) at the ocean color validation site, Marine Optical BuoY. The seasonal bias in Rrs(λ) is present to varying degrees in all ocean color satellites examined, including the Visible Infrared Imaging Radiometer Suite, Sea-Viewing Wide Field-of-View Sensor, and Moderate Resolution Imaging Spectrometer. The relative bias in Rrs has spectral dependence. Products derived from Rrs(λ) are affected by the bias to varying degrees, with particulate backscattering varying up to 50% over a year, chlorophyll varying up to 25% over a year, and absorption from phytoplankton or dissolved material varying by up to 15%. The propagation of Rrs(λ) bias into derived products is broadly confirmed on regional and global scales using Argo floats and data from the cloud-aerosol lidar with orthogonal polarization instrument aboard the cloud-aerosol lidar and infrared pathfinder satellite. The artifactual seasonality in ocean color is prominent in areas of low biomass (i.e., subtropical gyres) and is not easily discerned in areas of high biomass. While we have eliminated several candidates that could cause the biases in Rrs(λ), there are still outstanding questions regarding potential contributions from atmospheric corrections. Specifically, we provide evidence that the aquatic bidirectional reflectance distribution function may in part cause the observed seasonal bias, but this does not preclude an additional effect of the aerosol estimation. Our investigation highlights the contributions that atmospheric correction schemes can make in introducing biases in Rrs(λ), and we recommend more simulations to discern these influence Rrs(λ) biases. Community efforts are needed to find the root cause of the seasonal bias because all past, present, and future data are, or will be, affected until a solution is implemented.