Preparing the Bowel (Microbiome) for Surgery: Surgical Bioresilience.

The preparation of the bowel for radical surgery is a corner stone of elective colorectal practice. The evidence for this intervention is of variable quality and it is often contradictory, yet there is now a global move toward the adoption of oral antibiotic therapy for the reduction of perioperative infective complications, such as surgical site infections. The gut microbiome is a critical mediator of the systemic inflammatory response to surgical injury, wound healing, and perioperative gut function. The loss of critical microbial symbiotic functions caused by bowel preparation and surgery has an adverse impact on surgical outcomes, yet the mechanisms through which this occurs are poorly defined. In this review, the evidence for bowel preparation strategies is critically appraised in the context of the gut microbiome. The impact of antibiotic therapy on the surgical gut microbiome and the importance of the intestinal "resistome" to surgical recovery is described. Data to support the augmentation of the microbiome through diet, probiotic and symbiotic approaches, as well as fecal transplantation are also appraised. Finally, we propose a novel strategy of bowel preparation defined as " surgical bioresilience " and define areas or prioritization in this emerging field. This describes the optimization of surgical intestinal homeostasis and core surgical exposome-microbiome interactions that regulate the wound immune microenvironment, the systemic inflammatory response to surgical injury, and gut function across the perioperative time course.

Aortic Dimensions, Biophysical Properties, and Plasma Biomarkers in Children and Adults with Marfan or Loeys-Dietz Syndrome.

BACKGROUND: Aortic dilation, stiffening, and dissection are common and potentially lethal complications of Marfan syndrome (MFS) and Loeys-Dietz syndrome (LDS), which involve abnormal transforming growth factor beta (TGF-ß) signalling. The relation of aortic dimensions, stiffness, and biomarker levels is unknown. The objective of this study was to measure aortic dimensions, stiffness, TGF-ß and matrix metalloproteinase (MMP) levels, and endothelial function in patients with MFS, and to compare TGF-ß levels in patients with MFS receiving different therapeutic regimens. METHODS: This was a cohort study of 40 MFS and 4 LDS patients and 87 control participants. Aortic dimension and stiffness indexes, including pulse wave velocity (PWV), were measured using echocardiography and Doppler. Total and free TGF-ß and MMP blood levels were measured using Quantikine (R&D Systems, Inc, Minneapolis, MN) and Quanterix (Billerica, MA) kits. Endothelial function was measured using brachial artery flow-mediated dilation. RESULTS: PWV was increased in patients with MFS. There were increased MMP-2 levels in those with MFS but no increase in free or total TGF-ß or MMP-9 levels compared with control participants. There was no difference in TGF-ß levels between MFS patients receiving no medications, angiotensin receptor blockers, and ß-blockers. PWV correlated most strongly with age. Endothelial function showed premature gradual decline in patients with MFS. CONCLUSIONS: Despite the increased PWV, monitoring aortic stiffness or TGF-ß levels would not be helpful in patients with MFS. TGF-ß levels were not increased and the increased MMP-2 levels suggest consideration of a different therapeutic target.

CONTEXTE: La dilatation, la rigidification et la dissection de l'aorte sont des complications fréquentes et parfois mortelles du syndrome de Marfan (SM) et du syndrome de Loeys-Dietz (SLD), qui sont tous deux dûs à une anomalie de la voie de signalisation du facteur de croissance transformant bêta (TGF-ß). On ne connaît pas la relation entre les dimensions et la rigidité de l'aorte et la présence de biomarqueurs. Notre étude visait à mesurer les dimensions et la rigidité de l'aorte, les taux de TGF-ß et de métalloprotéases matricielles (MMP) et la fonction endothéliale chez des patients atteints du SM, et à les comparer aux taux de TGF-ß observés chez des patients également atteints de SM, mais recevant un autre traitement. MÉTHODOLOGIE: Il s'agissait d'une étude de cohorte menée auprès de 40 patients atteints du SM et de quatre patients atteints du SLD, ainsi que de 87 témoins. Les indices des dimensions et de la rigidité aortiques, y compris la vitesse d'onde de pouls (VOP), ont été mesurés par échocardiographie et par échographie Doppler. Les taux sanguins de TGF-ß et de MMP totaux et libres ont été mesurés à l'aide de trousses Quantikine (R&D Systems, Inc, Minneapolis, MN) et Quanterix (Billerica, MA). La fonction endothéliale a été mesurée par dilatation liée au flux dans l'artère brachiale. RÉSULTATS: La VOP était plus élevée chez les patients atteints du SM. On a aussi observé une hausse des taux de MMP-2 chez les patients atteints de SM, mais aucune augmentation des taux de TGF-ß ou de MMP-9 libres ou totaux comparativement aux témoins. Il n'y avait pas de différence entre les taux de TGF-ß chez les patients atteints de SM ne recevant aucun traitement, ceux qui prenaient un antagoniste des récepteurs de l'angiotensine et ceux qui prenaient un bêtabloquant. La VOP été plus fortement corrélée avec l'âge. La fonction endothéliale a affiché un déclin progressif prématuré chez les patients atteints du SM. CONCLUSIONS: Malgré l'augmentation de la VOP, il ne semble pas utile de surveiller la rigidité aortique ni les taux de TGF-ß en cas de SM. Les taux de TGF-ß n'étaient pas plus élevés chez les patients atteints du SM, et la hausse des taux de MMP-2 indique qu'il conviendrait de choisir une autre cible thérapeutique.

Role of Digital Resources in Minimally Invasive Colorectal Surgery Training.

Laparoscopic techniques have become the standard for many benign and malignant colorectal pathologies. Recently, the application of robotic-assisted technologies has been, and continues to be, explored. These new technologies require different skill sets and bring novel training challenges, and today's trainees must demonstrate competence in more techniques than ever. Compounding this is the reducing time spent operating in current training programs due to caps on working hours and service pressures. The need for adjunctive training strategies outside the operating room has prompted development of multimedia and digital resources to build the cognitive skills crucial in both nontechnical and technical aspects of surgery. Many are based on principles of cognitive task analysis, breaking down operations, and key decisions into nodal points to be mentally rehearsed. Resources built on this technique have shown improvements in both operative and nonoperative skills, suggesting these resources can advance trainees along the learning curve in minimally invasive surgical techniques. More work to fully elucidate the clinical benefits of such resources is required before their role as a substitute for lost operative training hours can be established. Despite this, alongside other developing technologies such as simulation, they are a promising addition to the armamentarium of the modern-day colorectal trainee.

Vestibular dysfunction in acute traumatic brain injury.

Traumatic brain injury (TBI) is the commonest cause of disability in under-40-year-olds. Vestibular features of dizziness (illusory self-motion) or imbalance which affects 50% of TBI patients at 5 years, increases unemployment threefold in TBI survivors. Unfortunately, vestibular diagnoses are cryptogenic in 25% of chronic TBI cases, impeding therapy. We hypothesized that chronic adaptive brain mechanisms uncouple vestibular symptoms from signs. This predicts a masking of vestibular diagnoses chronically but not acutely. Hence, defining the spectrum of vestibular diagnoses in acute TBI should clarify vestibular diagnoses in chronic TBI. There are, however, no relevant acute TBI data. Of 111 Major Trauma Ward adult admissions screened (median 38-years-old), 96 patients (87%) had subjective dizziness (illusory self-motion) and/or objective imbalance were referred to the senior author (BMS). Symptoms included: feeling unbalanced (58%), headache (50%) and dizziness (40%). In the 47 cases assessed by BMS, gait ataxia was the commonest sign (62%) with half of these cases denying imbalance when asked. Diagnoses included BPPV (38%), acute peripheral unilateral vestibular loss (19%), and migraine phenotype headache (34%), another potential source of vestibular symptoms. In acute TBI, vestibular signs are common, with gait ataxia being the most frequent one. However, patients underreport symptoms. The uncoupling of symptoms from signs likely arises from TBI affecting perceptual mechanisms. Hence, the cryptogenic nature of vestibular symptoms in TBI (acute or chronic) relates to a complex interaction between injury (to peripheral and central vestibular structures and perceptual mechanisms) and brain-adaptation, emphasizing the need for acute prospective, mechanistic studies.

Validation of the Baveno VI criteria to identify low risk cirrhotic patients not requiring endoscopic surveillance for varices.

BACKGROUND & AIMS: The Baveno VI guidelines propose that cirrhotic patients with a liver stiffness measurement (LSM) <20kPa and a platelet count >150,000/µl can avoid screening endoscopy as their combination is highly specific for excluding clinically significant varices. The aim of the study was to validate these criteria. METHODS: Transient elastography data was collected from two institutions from 2006-2015. Inclusion criteria were a LSM ⩾10kPa and an upper gastrointestinal endoscopy within 12months, with a diagnosis of compensated chronic liver disease. Exclusion criteria were porto-mesenteric-splenic vein thrombosis and non-cirrhotic portal hypertension. Varices were graded as low risk (grade <2) or high risk (grade ⩾2). RESULTS: The study included 310 patients (169 (55%) hepatitis C, and 275 (89%) Child-Pugh A). Varices were present in 23% cases, with 5% prevalence of high risk varices. Overall 102/310 (33%) met the Baveno VI criteria. Within this group 11% had varices and 2% had high risk varices, representing 2/15 (13%) of all high risk varices. The Baveno VI criteria gave a sensitivity 0.87, specificity 0.34, positive predictive value 0.06, negative predictive value 0.98, positive likelihood ratio 1.31 and negative likelihood ratio 0.39. The AUROC for LSM and platelet count combined was 0.746. CONCLUSIONS: The Baveno VI criteria performed well correctly identifying 98% of patients who could safely avoid endoscopy. LAY SUMMARY: This study examines the effectives of a recent set of guidelines published by the Baveno VI conference, which states that patients with chronic liver disease and a low liver stiffness (<20kPa) and high platelet count (>150) are at low risk of having varices and do not need a screening endoscopy. Varices are a complication of cirrhosis, confer a risk of serious bleeding, and can be diagnosed and treated by endoscopy. Our study reviewed the clinical records of patients who have had liver stiffness scans and endoscopy over a 9-year period at two hospitals. The results show that only about 2% of patients who meet the Baveno VI criteria will be miss-classified as not having varices.