BackgroundThere is currently conflicting evidence surrounding the effects of obesity on postoperative outcomes. Previous studies have found obesity to be associated with adverse events, but others have found no association. The aim of this study was to determine whether increasing body mass index (BMI) is an independent risk factor for development of major postoperative complications.MethodsThis was a multicentre prospective cohort study across the UK and Republic of Ireland. Consecutive patients undergoing elective or emergency gastrointestinal surgery over a 4‐month interval (October–December 2014) were eligible for inclusion. The primary outcome was the 30‐day major complication rate (Clavien–Dindo grade III–V). BMI was grouped according to the World Health Organization classification. Multilevel logistic regression models were used to adjust for patient, operative and hospital‐level effects, creating odds ratios (ORs) and 95 per cent confidence intervals (c.i.).ResultsOf 7965 patients, 2545 (32·0 per cent) were of normal weight, 2673 (33·6 per cent) were overweight and 2747 (34·5 per cent) were obese. Overall, 4925 (61·8 per cent) underwent elective and 3038 (38·1 per cent) emergency operations. The 30‐day major complication rate was 11·4 per cent (908 of 7965). In adjusted models, a significant interaction was found between BMI and diagnosis, with an association seen between BMI and major complications for patients with malignancy (overweight: OR 1·59, 95 per cent c.i. 1·12 to 2·29, P = 0·008; obese: OR 1·91, 1·31 to 2·83, P = 0·002; compared with normal weight) but not benign disease (overweight: OR 0·89, 0·71 to 1·12, P = 0·329; obese: OR 0·84, 0·66 to 1·06, P = 0·147).ConclusionOverweight and obese patients undergoing surgery for gastrointestinal malignancy are at increased risk of major postoperative complications compared with those of normal weight.

Background This study aimed to determine the impact of pulmonary complications on death after surgery both before and during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Methods This was a patient-level, comparative analysis of two, international prospective cohort studies: one before the pandemic (January–October 2019) and the second during the SARS-CoV-2 pandemic (local emergence of COVID-19 up to 19 April 2020). Both included patients undergoing elective resection of an intra-abdominal cancer with curative intent across five surgical oncology disciplines. Patient selection and rates of 30-day postoperative pulmonary complications were compared. The primary outcome was 30-day postoperative mortality. Mediation analysis using a natural-effects model was used to estimate the proportion of deaths during the pandemic attributable to SARS-CoV-2 infection. Results This study included 7402 patients from 50 countries; 3031 (40.9 per cent) underwent surgery before and 4371 (59.1 per cent) during the pandemic. Overall, 4.3 per cent (187 of 4371) developed postoperative SARS-CoV-2 in the pandemic cohort. The pulmonary complication rate was similar (7.1 per cent (216 of 3031) versus 6.3 per cent (274 of 4371); P = 0.158) but the mortality rate was significantly higher (0.7 per cent (20 of 3031) versus 2.0 per cent (87 of 4371); P < 0.001) among patients who had surgery during the pandemic. The adjusted odds of death were higher during than before the pandemic (odds ratio (OR) 2.72, 95 per cent c.i. 1.58 to 4.67; P < 0.001). In mediation analysis, 54.8 per cent of excess postoperative deaths during the pandemic were estimated to be attributable to SARS-CoV-2 (OR 1.73, 1.40 to 2.13; P < 0.001). Conclusion Although providers may have selected patients with a lower risk profile for surgery during the pandemic, this did not mitigate the likelihood of death through SARS-CoV-2 infection. Care providers must act urgently to protect surgical patients from SARS-CoV-2 infection.

When monitoring separation events in microfluidic devices, one frequently needs to detect small amounts of analyte in picolitre sized volumes with a time response of milliseconds. Fluorescence detection is typically the method of choice due to its very high sensitivity and fast response. However, since many analytes are not naturally fluorescent, labelling protocols may have to be introduced and thereby increase the complexity of the analysis. Here, we present an alternative method that is based on optical absorption, or more specifically on the ring-down time of an optical signal in a cavity or loop made of waveguide material. This optical decay constant changes as small liquid samples containing absorbing species are introduced into a fiber-optic loop. It is demonstrated that one can obtain the optical decay constant using a continuous wave laser beam that is intensity modulated and then coupled into an optical fiber loop. The inherent exponential decay in the fiber loop introduces a phase shift of the light emitted from the loop with respect to the pumping beam. By measuring this phase shift, one can readily determine the concentration of the analyte introduced between the two fiber ends and a model is established to describe the relationship. It is demonstrated that this technique, dubbed "phase-shift fiber-loop ring-down spectroscopy" (PS-FLRDS), is well suited as an absorption detector for any flow system in which the optical absorption path is limited by the instrument architecture.

Background: Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery. Methods: This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and intercentre variation in critical care admission after emergency laparotomy. Results: Of 4529 patients included, 37.8% (n¼1713) underwent planned critical care admissions from theatre. Some 3.1% (n¼86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n¼133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51e19.97) than planned admissions (OR: 2.32, 95% CI: 1.43e3.85). Some 26.7% of patients (n¼1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8e51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n¼10/145) of centres outside the 95% CI. Conclusions: After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

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This study examines the persuasion process involved in social media marketing (SMM), particularly in the higher education sector. Based on the theoretical foundations of the information adoption model, a conceptual model of elaboration of SMM communication is developed and tested. The self-administered survey conducted among a sample of international student travellers in New Zealand examines the influence of argument quality, source credibility, audience involvement and audience engagement on their attitude formation and decision-making. The study particularly examines the mediating effects of audience involvement and engagement in SMM communication. Results based on structural equation modelling suggest that social media content quality is a significant predictor of online users’ transportation, identification and parasocial interaction effects. Despite there being additional evidence to support the arguments over social media, source credibility is found to be a strong influencer of international student traveller’s cognitive, emotional and behavioural engagement dimensions. Further, it is evident from the study that there is a strong correlation between cognitive engagement and attitude formation in SMM. Implications for tourism marketers in terms of SMM strategies are discussed.

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