RESUMO
BACKGROUND: Defecation delay (greater than or equal to 3 days post-surgery) is a common symptom in patients after lung tumor surgery. This study investigated the incidence and relevant risk factors of defecation delay in patients after lung tumor surgery. METHODS: Between October 2019 and March 2020, a prospective nested case-control study was conducted in 80 patients who received lung tumor surgery in the Department of Thoracic Surgery at the Sun Yat-sen University Cancer Center. According to the Rome III criteria for functional constipation and the accepted definitions in the literature, patients with defecation delay time greater than or equal to 3 days post-surgery were classified as the defecation delay group, and the remaining patients were considered the control group. A questionnaire survey was conducted to explore the trait of the stool, defecation time, postoperative activity, diet, and perioperative pain score. Statistical analyses were performed to compare the risk factors affecting defecation time in the two groups. RESULTS: Out of 80 patients, a total of 44 patients (44/80) experienced defecation delay after the operation. Univariate analysis showed that there were significant differences between the two groups in operation methods (P<0.029), postoperative stool trait (P<0.001), difficulty in defecation (P<0.01), and perioperative pain score (P=0.0178), suggesting that change of stool characteristics and pain were possible factors causing defecation delay. Multivariate analysis also revealed significant differences between the two groups in the postoperative pain score on the first day post-surgery (P=0.03). CONCLUSIONS: Defecation delay is a common symptom in patients after lung cancer surgery, and is related to operation method, pain score, and changes in stool characteristics. This study identified that minimally invasive surgery, postoperative pain relief treatment, and health education may play an important role in preventing delayed defecation.
RESUMO
The fractal characteristics of marine shale from the Middle-Upper Ordovician Wulalike Formation (O2w) in the southwest margin of the Ordos Basin are studied. Based on low-temperature nitrogen adsorption experiments, the FHH (Frenkel-Halsey-Hill) model was employed to investigate the relationship between the marine shale composition, such as TOC, mineral content and shale gas content, and pore structure parameters, such as BET specific surface area, average pore diameter, porosity and fractal dimension. The results show that the pore size distribution curve of shale slowly decreased after the pore size was greater than 50 nm, the pore size distribution showed multiple peaks, and the peak value was mainly in the range of 2-10 nm. Most pores are nanopores, although the pore type and shape are different. Two different fractal dimensions D1 and D2 are obtained from the two segments with relative pressures of 0-0.5 and 0.5-1.0, respectively: the D1 range is 2.77-2.82, and the D2 range is 2.63-2.66. As D1 is larger than D2, the pore structure of small pores is more uniform than that of large pores in the shale samples. The relationship between the fractal dimensions D1 and D2 and the total organic carbon (TOC) content is a convex curve. Fractal dimension D reaches its maximum when TOC is 0.53 wt.%. Fractal dimension D decreases with increasing specific surface area, porosity and average pore size. The fractal dimension has a different influence on the gas storage and migration in shale; the larger the fractal dimension is, the stronger the heterogeneity and the more complex the pore structure, and this outcome is conducive to the storage of gas in shale but not beneficial to the permeability and production of gas.
