OC-065 PEEKABOO WITH MESHES AND MACHINES: DEEP LEARNING TO IDENTIFY TACKS AND MESHES ON CT SCANS

Aim

To identify the presence of tacks and meshes in CT scans of patients who have previously undergone hernia repairs

Materials & Methods

We annotated data from >100 anonymised Hernia CT scans of patients who had undergone previous ventral hernia repairs and used machine learning(ML)/ deep learning(DL) techniques to identify the presence of meshes and tacks.Annotation of CT scans was performed using computer vision tools. A combination of image processing, feature extraction and artificial intelligence(AI) techniques were used to create models that could identify tacks and meshes on CT scans.

Results

We were able to identify the presence of meshes and tacks with >55% accuracy. The AI model under construction is continuing to improve performance.

Conclusions

Identification of the mesh is a challenge for surgeons and radiologists alike. The presence of machine learning techniques has revolutionised radiology and made the identification of obscure structures possible. Meshes present a unique challenge as they constitute a foreign tissue which integrates into native tissue. We believe that identification of hernia meshes and tacks can help surgeons identify the right planes for planning re-surgeries while operating in patients with previous hernia repairs or while tackling recurrences.

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.

Plantar pressure distribution profile of type 2 diabetes mellitus with diabetic foot syndrome: A hospital-based observational study

INTRODUCTION: The prevalence of diabetic foot syndrome is increasing in the Indian population. It is a triad of neurological, vascular, and biomechanical changes due to long term diabetes mellitus (DM). Altered plantar pressure distribution is a risk factor for developing diabetic foot ulcers. The purpose of this study is to evaluate the altered plantar pressure distribution in diabetic peripheral neuropathy individuals with peripheral vascular disease in comparison with diabetic peripheral neuropathy and non-diabetic neuropathy. Therefore, the objective of the study is to evaluate the plantar pressure distribution and parameters in type 2 DM (T2DM) with diabetic foot syndrome.METHODS: In this study, 60 participants with T2DM were recruited in either one of the three groups: 20 Diabetic non-neuropathy (DNN), 20 Diabetic peripheral neuropathy (DPN), and 20 Diabetic peripheral neuropathy with the peripheral arterial disease (DNPAD). Then we compared the plantar pressure parameters like maximum plantar pressure, pressure-time integral, fore foot-hind foot ratio, and total contact area were measured using a WinTrack plantar pressure system.RESULTS: The diabetic peripheral neuropathy with peripheral vascular disease group shown a significant difference in all the  plantar pressure parameters measured in comparison with the diabetic peripheral neuropathy group. There was increased Maximum plantar pressure, pressure-time integral and forefoot hindfoot ratio, and reduced total contact area of the foot (p < 0.05).CONCLUSION: For patients, with combined peripheral neuropathy and peripheral vascular disease have increased plantar pressure distribution, are at higher risks of developing neuro-ischemic foot, which further leads to diabetic foot ulcers.

Signs and landmarks in eTEP Rives-Stoppa repair of ventral hernias

BACKGROUND

After years of playing second-fiddle to laparoscopic underlay repairs, the retro-muscular Rives-Stoppa repair is rapidly gaining popularity thanks to the endoscopic eTEP approach. It extends all the advantages of a retro-muscular mesh placement-increased tolerance for infection, mechanical robustness, reduced need for mesh fixation-in an ergonomically acceptable system.

METHODS

The eTEP technique described by Belyansky's group requires a "crossover" from one retro-rectus space to the other. The aim of the crossover is to safely amalgamate the retro-rectus spaces for placement of a large extra-peritoneal prosthesis. By salvaging peritoneum in the midline and operating in the extra-peritoneal plane, one can avoid large defects in the posterior rectus sheath (PRS)-peritoneum complex which need closure. Correct identification of anatomical landmarks is imperative to safely perform the surgery.

RESULTS

The "lamppost sign" signals the lateral limit of retro-rectus dissection, preventing iatrogenic injury to the neurovascular bundles and linea semilunaris. After crossover has been safely achieved, the medial edges of the divided posterior rectus sheaths are found connected to each other by a strip of pre-peritoneal fat and peritoneum in the midline. These structures, along with the neck of hernia constitute the "volcano sign". For inferior defects, the vas deferens, the inferior epigastric and gonadal vessels form a triradiate conformation termed the "Mercedes-Benz sign".

CONCLUSION

These signs serve as tools to identify the composition of the surgical field, avoiding iatrogenic injury to the linea alba and linea semilunaris, while reducing the time taken for posterior closure.

An early experience with transversus abdominis release for complex ventral hernias: a retrospective review of 100 cases

BACKGROUND

Transversus abdominis release (TAR) is a relatively recent surgical technique for ventral hernia repair which allows placement of a large prosthesis in the retro-muscular plane with considerable myofascial medialization. A retrospective review of 100 cases who underwent TAR for complex ventral hernias was performed to evaluate the safety and efficacy of TAR in a series of large ventral hernias.

METHODS

Between March 2016 and May 2019, 100 consecutive patients who underwent open TAR were identified from our prospectively maintained database. A retrospective review was performed to analyze patient demographics, peri-operative events, adverse outcomes and recurrence.

RESULTS

12 primary and 88 incisional hernia cases underwent TAR with prosthetic mesh repair during the study period. Mean age was 52.5 years, mean BMI was 30.87 kgs/m², mean ASA class 1.95. In our series, 41% were diabetic, 11% had COPD. All patients underwent preoperative CT scans. The mean defect was 140.18 cm². Average mesh area was 1344 cm². Average blood loss was 245 mL. Defects were bridged in 19% cases despite bilateral component separation. Readmission rate at 1 month was 3%, for wound complications. We recorded 9 surgical site infections, 17 surgical site occurrences, 10 of which needed procedural interventions. We recorded no recurrences at a mean follow-up duration of 20.2 months.

CONCLUSIONS

Our early results with TAR are encouraging. We have demonstrated that the repair allows anatomical reconstruction with a large sublay mesh while inflicting minimal morbidity. TAR can be a valuable tool in complex ventral hernia repair.

Assessment of fidelity and utility of the whole-genome amplification for the clinical tests offered in a histocompatibility and immunogenetics laboratory

Increasing emphasis on the use of molecular tests in a histocompatibility and immunogenetics laboratory (HIL) poses a potential problem of lack of sufficient DNA to perform multiple genetic analyses. In this study, we report the feasibility, fidelity and utility of multiple displacement amplification (MDA) method to perform whole-genome amplification (WGA) to generate DNA specimens that can be analyzed by multiple molecular techniques and can be used for different clinical tests offered by an HIL. The MDA-generated DNA when compared with the native DNA showed 100% congruency in genotyping of 37 genes/loci using multiple downstream molecular techniques: sequence-based typing and sequence-specific primer-based typing for 5 human leukocyte antigen (HLA) class I and II genes (HLA-A, B, C, DRB1 and DQB1), luminex-based sequence-specific oligonucleotide (SSO) genotyping for a panel of 16 killer immunoglobulin-like receptor (KIR) genes and automated fragment size analysis for a panel of 15 short tandem repeat (STR) loci and amelogenin gene. For post-allogeneic hematopoietic cell transplantation (HCT) chimerism analysis, MDA-generated DNA appeared useful for enriching pre-transplant DNA but not for enriching post-transplant chimeric DNA. Overall, our results show that MDA-based WGA could generate DNA of high yield and fidelity that can be used for various clinical tests and research purposes.