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In fiber-reinforced polymer (FRP) composite laminate structures operating under fluctuating stresses, interface delamination is seen as one of the significant damage mechanisms. The constant degradation of their relatively low interlaminar strength and stiffness are the primary reasons for delamination. This study develops an interlaminar fatigue damage model to quantify the mechanics of the damage process and address the reliability of composite structures. The model considers the failure process in two stages: (1) damage due to degradation of interlaminar elastic properties, and (2) damage due to dissipation of fracture energy through the damage evolution process. The model is examined for a case study of mode I fatigue loading of a carbon-fiber-reinforced polymer (CFRP) composite laminate. The results show that the interlaminar normal stress is confined to the crack front region, with tensile stress peaks at 70% of the interlaminar strength. Furthermore, a stable interface crack growth is predicted initially, followed by a sudden crack "jump" at 14,000 cycles. The simulation results are compared with the experimental data, with very good agreement, showing a successful validation of the fatigue model.
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Introduction The objective of our study was to compare the 30-day post-operative outcomes of laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB). Materials and Methods This randomized controlled study contained patients who underwent bariatric surgery from June 13, 2018 to October 12, 2019. A total of 116 patients having body mass index (BMI) > 35 kg/m2 (morbidly obese), age 18 to 65 years and with failure of conservative treatment were included. Group I patients underwent bariatric surgery using LRYGB technique while group II patients underwent bariatric surgery using the LSG technique. All patients were followed 30 days after surgery to determine early post-operative outcomes. Results The demographic profile, such as age and BMI, was similar between the groups. The mean operating time was 72 ±12 minutes in the LSG group and 156 ± 18 min in the LRYGB group (p-value 0.0001). Major complications were seen in five (8.62%) patients in LSG patients and in four (6.89%) patients in LRYGB group (p-value 0.12). Minor complications were seen in 21 (36.2%) patients in LSG group and in 19 (32.75%) patients in LRYGB group (p-value 0.15). The length of stay in the hospital in LSG group was 6.2±4.2 versus 9.4± 4.6 (p-value 0.0002). Conclusion Both LRYGB and LSG are effective and safe bariatric procedures with a similar incidence of major complications. However, LSG is associated with shorter operative time and hospital stay. Long-term follow-up studies are required to compare the effectiveness of these procedures.
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BACKGROUND: Inadvertent coughing and desaturation are the most commonly faced and feared respiratory complications in post-anaesthesia period. The study was done to compare the efficacy of intravenous lignocaine versus sevoflurane in prevention of coughing and desaturation at extubation in children less than 6 years of age. METHODS: This Randomized Control Trial was carried out from May 2013 to May 2016, at Combined Military Hospital Nowshera after obtaining approval from the hospital ethics committee (IREC-0003/5/13/Aneas). Children aged three months to six years undergoing surgical procedures requiring the placement of definitive airway were randomly assigned into two groups. Patients were anaesthetized by standardized balanced anaesthesia technique. In Group A (n=355), three minutes prior to extubation lignocaine 2% was used intravenously. In Group B (n=355), isoflurane was switched off, breathing circuit changed and sevoflurane started at minimum alveolar concentration (MAC 3-4%) for 3 minutes prior to extubation. Assessment for extubation was clinical. Oxygen saturation and severity of coughing were noted for 5 consecutive minutes, after extubation. RESULTS: In group-A, 156 patients were less than 2 years of age while in group-B, 135 patients were less than 2 years old. In group-A, 199 and in group-B, 220 children were 2-6 years of age respectively. Post stratification the p-value for weight was 0.17 (p-value >0.05) and t-statistic was 1.36. Post stratification p-value for gender was 0.12 (p-value>0.05) and chi square statistic was 2.49. Group A had more eventful extubation with 270 cases of cough (76%) as compared to group-B where it was noted in 199 cases (56%). Similarly, desaturation was observed in 85 cases in group-A (24%) as compared to 28 cases (8%) in group-B. The difference between the groups was statistically significant. CONCLUSIONS: Sevoflurane based anaesthetic vapours mixture causes statistical significant prevention from events like coughing episodes and desaturation in post-extubation in children less than six years of age undergoing elective surgery.
