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.

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.

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-β) signalling. The relation of aortic dimensions, stiffness, and biomarker levels is unknown. The objective of this study was to measure aortic dimensions, stiffness, TGF-β and matrix metalloproteinase (MMP) levels, and endothelial function in patients with MFS, and to compare TGF-β 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-β 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-β or MMP-9 levels compared with control participants. There was no difference in TGF-β levels between MFS patients receiving no medications, angiotensin receptor blockers, and β-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-β levels would not be helpful in patients with MFS. TGF-β levels were not increased and the increased MMP-2 levels suggest consideration of a different therapeutic target.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Association between preadmission frailty and care level at discharge in older adults undergoing emergency laparotomy

Background

Older adults undergoing emergency abdominal surgery have significantly poorer outcomes than younger adults. For those who survive, the level of care required on discharge from hospital is unknown and such information could guide decision-making. The ELF (Emergency Laparotomy and Frailty) study aimed to determine whether preoperative frailty in older adults was associated with increased dependence at the time of discharge.

Methods

The ELF study was a UK-wide multicentre prospective cohort study of older patients (65 years or more) undergoing emergency laparotomy during March and June 2017. The objective was to establish whether preoperative frailty was associated with increased care level at discharge compared with preoperative care level. The analysis used a multilevel logistic regression adjusted for preadmission frailty, patient age, sex and care level.

Results

A total of 934 patients were included from 49 hospitals. Mean(s.d.) age was 76·2(6·8) years, with 57·6 per cent women; 20·2 per cent were frail. Some 37·4 per cent of older adults had an increased care level at discharge. Increasing frailty was associated with increased discharge care level, with greater predictive power than age. The adjusted odds ratio for an increase in care level was 4·48 (95 per cent c.i. 2·03 to 9·91) for apparently vulnerable patients (Clinical Frailty Score (CFS) 4), 5·94 (2·54 to 13·90) for those mildly frail (CFS 5) and 7·88 (2·97 to 20·79) for those moderately or severely frail (CFS 6 or 7), compared with patients who were fit.

Conclusion

Over 37 per cent of older adults undergoing emergency laparotomy required increased care at discharge. Frailty scoring was a significant predictor, and should be integrated into all acute surgical units to aid shared decision-making and discharge planning.

TP1-9 Vestibular dysfunction in acute traumatic brain injury

Objectives

Vestibular dysfunction following traumatic brain injury (TBI) is a major cause of morbidity and unemployment and has impact on the patient’s ability to rehabilitate. Chronically, up to a quarter of TBI cases have cryptogenic dizziness and imbalance, possibly due to chronic brain adaptation that masks the diagnosis. Establishing the spectrum of vestibular diagnoses in acute TBI – when they may be more obvious – may aid diagnosis in chronic TBI cases.

Design

Prospective audit of referrals to specialist neuro-otology team.

Subjects

Consecutive Major Trauma Ward TBI in-patients admitted between June 2014 and May 2015.

Methods

All cases were screened by the therapists for vestibular symptoms and/or signs and referred for specialist neuro-otology review.

Results

Of 111 patients screened, 96 had features of vestibular dysfunction. Of 96 cases, SYMPTOMS (i.e. subjective report) included: – imbalance (58.3%) – headache (50%) -dizziness (40%) Of 96 cases, SIGNS (i.e. examination) included: – gait ataxia (75.5%) – broken smooth pursuit (61.2%) – positive Hallpike (51%) – positive head impulse test (18%). The data indicate that BPPV affects 49% and headache with migraine-like features affect 40.8%. Acute peripheral unilateral vestibular loss affects 18% TBI cases.

Conclusions

Vestibular dysfunction in TBI is common, typically involving peripheral and central structures, often in the same case, and requires specialist neuro-otological management.

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.