The Utility of Neutrophil-to-Lymphocyte Ratio as a Severity Predictor of Acute Appendicitis, Length of Hospital Stay and Postoperative Complication Rates.

BACKGROUND: Numerous screening tools have been reported to aid in diagnosing appendicitis, but have poor severity prediction and lack accurate estimation of postoperative complications or total length of hospital stay (LOS). AIM: This study aims at evaluating the utility of neutrophil-to-lymphocyte (NLR) ratio in predicting the severity of appendicitis, LOS and 30-day complication rates. METHODS: Patients who underwent appendicectomy over a 4-year period were evaluated. Demographics, blood results, severity of appendicitis, LOS and 30-day complications were recorded. Recommended cut-off values of NLR and C-reactive protein (CRP) for severity of appendicitis were determined using receiver operating characteristic analysis. The Mann-Whitney test was performed to assess the correlations between LOS and 30-day complications with NLR. RESULTS: A total of 663 patients were included in the study of which 57.3% (n = 380) were male with mean patient age of 23.6 years, and 461 appendix specimens (69.6%) had simple inflammation on histological evaluation. A NLR of >6.35 or CRP of >55.6 were statistically associated with severe acute appendicitis, with a median of one extra hospital day admission (p < 0.0001). Mean NLR was statistically higher in patients with postoperative co(13.69 for severe vs. 7.29 for simple appendicitis group, p = 0.016). CONCLUSION: We advocate that NLR is a useful adjunct in predicting severity of appendicitis. It aids in delineating severe inflammation requiring surgery without substantial delay.

A novel dynamic integral sliding mode control for power electronic converters.

The key characteristics of the sliding mode control (SMC) are the ability to manage unmodeled dynamics with rapid response and the inherent robustness of parametric differences, making it an appropriate choice for the control of power electronic converters. However, its drawback of changing switching frequency causes critical electro-magnetic compatibility and switching power loss issues. This paper addresses the problem by proposing a dynamic integral sliding mode control for power converters having fixed switching frequency. A special hardware test rig is developed and tested under unregulated 12.5-22.5 V input and 30 V output. The experimental findings indicate excellent controller efficiency under wide range of loads and uncertain input voltage conditions. In addition, the findings indicate that the closed-loop system is robust to sudden differences in load conditions. This technique provides an improvement of 24.52% in the rise time, 20.10% in the settling time and 42.85% in robustness of the controller as compared to conventional controllers. Furthermore, the comparison with the existing fixed-frequency sliding mode control techniques is presented in a tabular form.