Estimation of Physiologic Ability and Surgical Stress scoring system for predicting complications following abdominal surgery: A metaanalysis spanning 2004 to 2022

BACKGROUND Postoperative complications remain a paramount concern for surgeons and healthcare practitioners.AIM To present a comprehensive analysis of the Estimation of Physiologic Ability and Surgical Stress(E-PASS)scoring system’s efficacy in predicting postoperative complications following abdominal surgery.METHODS A systematic search of published studies was conducted,yielding 17 studies with pertinent data.Parameters such as preoperative risk score(PRS),surgical stress score(SSS),comprehensive risk score(CRS),postoperative complications,post-operative mortality,and other clinical data were collected for meta-analysis.Forest plots were employed for continuous and binary variables,withχ2 tests assessing heterogeneity(P value).RESULTS Patients experiencing complications after abdominal surgery exhibited significantly higher E-PASS scores compared to those without complications[mean difference and 95%confidence interval(CI)of PRS:0.10(0.05-0.15);SSS:0.04(0.001-0.08);CRS:0.19(0.07-0.31)].Following the exclusion of low-quality studies,results remained valid with no discernible heterogeneity.Subgroup analysis indicated that variations in sample size and age may contribute to hetero-geneity in CRS analysis.Binary variable meta-analysis demonstrated a correlation between high CRS and increased postoperative complication rates[odds ratio(OR)(95%CI):3.01(1.83-4.95)],with a significant association observed between high CRS and postoperative mortality[OR(95%CI):15.49(3.75-64.01)].CONCLUSION In summary,postoperative complications in abdominal surgery,as assessed by the E-PASS scoring system,are consistently linked to elevated PRS,SSS,and CRS scores.High CRS scores emerge as risk factors for heightened morbidity and mortality.This study establishes the accuracy of the E-PASS scoring system in predicting postoperative morbidity and mortality in abdominal surgery,underscoring its potential for widespread adoption in effective risk assessment.

An investigation of machine learning techniques to estimate minimum horizontal stress magnitude from borehole breakout

Borehole breakout is a widely utilised phenomenon in horizontal stress orientation determination,and breakout geometrical parameters,such as width and depth,have been used to estimate both horizontal stress magnitudes.However,the accuracy of minimum horizontal stress estimation from borehole breakout remains relatively low in comparison to maximum horizontal stress estimation.This paper aims to compare and improve the minimum horizontal stress estimation via a number of machine learning(ML)regression techniques,including parametric and non-parametric models,which have rarely been explored.ML models were trained based on 79 laboratory data from published literature and validated against 23 field data.A systematic bias was observed in the prediction for the validation dataset whenever the horizontal stress value exceeded the maximum value in the training data.Nevertheless,the pattern was captured,and the removal of systematic bias showed that the artificial neural network is capable of predicting the minimum horizontal stress with an average error rate of 10.16%and a root mean square error of 3.87 MPa when compared to actual values obtained through conventional in-situ measurement techniques.This is a meaningful improvement considering the importance of in-situ stress knowledge for underground operations and the availability of borehole breakout data.

STRESS EFFECT DECAY ESTIMATES FOR ANISOTROPIC MATERIAL IN A SEMI-INFINITE STRIP

In this paper, Saint-Venant's principle for anisotropic material in an end-loaded. semi-infinite elastic strip is established. Energy method is used to establish the lower bounds of the decay estimate of stress effect. An explicit estimate formula in terms of the elastic constants of the anisotropic materials is presented. Finally, a numerical example for an end-loaded, off-axis, graphite-epoxy strip is given to illustrate the results.

Estimation of dynamic stress spectrum distribution in structural fatigue test

The determination of structural dynamic stress spectrum distribution is of great signifi- cance in the structural fatigue strength evaluation as well as reliability design. In previous empirical data processing methods, the data grouping and distribution fitting were excessively coarse and contained distinctive defects. This paper proposed an effective approach to statistically group actual measured dynamic stress data and validly extrapolate the combined distribution to fit the dynamic stress spectrum distribution. This approach has been verified its effectiveness through chi-square test, stress spectrum extrapolation and damage calculation in dynamic stress study.

Analytical investigations of in situ stress inversion from borehole breakout geometries

This study aims to investigate the feasibility of deriving in situ horizontal stresses from the breakout width and depth using the analytical method.Twenty-three breakout data with different borehole sizes were collected and three failure criteria were studied.Based on the Kirsch equations,relatively accurate major horizontal stress(sH)estimations from known minor horizontal stress(sh)were achieved with percentage errors ranging from 0.33%to 44.08%using the breakout width.The Mogi-Coulomb failure criterion(average error:13.1%)outperformed modified Wiebols-Cook(average error:19.09%)and modified Lade(average error:18.09%)failure criteria.However,none of the tested constitutive models could yield reasonable sh predictions from known sH using the same approach due to the analytical expression of the redistributed stress and the nature of the constitutive models.In consideration of this issue,the horizontal stress ratio(sH/sh)is suggested as an alternative input,which could estimate both sH and sh with the same level of accuracy.Moreover,the estimation accuracies for both large-scale and laboratory-scale breakouts are comparable,suggesting the applicability of this approach across different breakout sizes.For breakout depth,conformal mapping and complex variable method were used to calculate the stress concentration around the breakout tip,allowing the expression of redistributed stresses using binomials composed of sH and sh.Nevertheless,analysis of the breakout depth stabilisation mechanism indicates that additional parameters are required to utilise normalised breakout depth for stress estimation compared to breakout width.These parameters are challenging to obtain,especially under field conditions,meaning utilising normalised breakout depth analytically in practical applications faces significant challenges and remains infeasible at this stage.Nonetheless,the normalised breakout depth should still be considered a critical input for any empirical and statistical stress estimation method given its significant correlation with horizontal stresses.The outcome of this paper is expected to contribute valuable insights into the breakout stabilisation mechanisms and estimation of in situ stress magnitudes based on borehole breakout geometries.