Evolution of groundwater system in the Pearl River Delta and its adjacent shelf since the late Pleistocene.

Our extensive field studies demonstrate that saline groundwater inland and freshened groundwater offshore coexist in the same aquifer system in the Pearl River delta and its adjacent shelf. This counterintuitive phenomenon challenges the commonly held assumption that onshore groundwater is typically fresh, while offshore groundwater is saline. To address this knowledge gap, we conduct a series of sophisticated paleo-hydrogeological models to explore the formation mechanism and evolution process of the groundwater system in the inland-shelf systems. Our findings indicate that shelf freshened groundwater has formed during the lowstands since late Pleistocene, while onshore saline groundwater is generated by paleo-seawater intrusion during the Holocene transgression. This reveals that terrestrial and offshore groundwater systems have undergone alternating changes on a geological timescale. The groundwater system exhibits hysteresis responding to paleoclimate changes, with a lag of 7 to 8 thousand years, suggesting that paleoclimatic forcings exert a significantly residual influence on the present-day groundwater system.

Effect of intravenous lidocaine on outcomes in patients receiving propofol for gastrointestinal endoscopic procedures: an updated systematic review and meta-analysis.

BACKGROUND: Gastrointestinal endoscopic procedures (GEPs) are frequently employed for the diagnosis and treatment of various gastrointestinal ailments. While propofol sedation is widely used during these procedures, there is a concern regarding its potential negative effects. Intravenous (IV) lidocaine has been suggested as an add-on to propofol sedation for GEPs, but current evidence on its efficiency and safety is limited. This systematic review and meta-analysis aimed to assess the impact of IV lidocaine on outcomes in patients receiving propofol during GEPs. METHODS: Electronic databases were screened for randomized controlled trials (RCTs), published up to 31 March 2023, investigating the effectiveness of intravenous lidocaine addition to propofol sedation during GEPs. RESULTS: A total of 12 RCTs involving 712 patients that received IV lidocaine and propofol for GEF and 719 patients that received propofol were analyzed. Adding IV lidocaine to propofol sedation led to significant reduction in pain after the procedure (standardized mean difference (SMD) = - 0.91, 95% confidence interval [CI]; - 1.51 to - 0.32), decreased propofol usage (SMD = - 0.89; 95% CI, - 1.31 to - 0.48), lower recovery time (SMD = - 0.95 min; 95% CI, - 1.48 to - 0.43), and decreased pain score (SMD = - 0.91; 95% CI, - 1.51 to - 0.32). The overall rate of adverse events was markedly less in the lidocaine group than in the control group (RR = 0.74; 95% CI, 0.56 to 0.99). CONCLUSION: Our results show that IV lidocaine improves patient outcomes by reducing post-procedural pain, decreasing propofol usage, shortening recovery time, and lowering pain scores. This study provides compelling evidence supporting the use of intravenous lidocaine as an adjunct to propofol sedation for gastrointestinal endoscopic procedures. However, further research is necessary to optimize the use of lidocaine and fully understand its long-term effects.

Influence of goal-directed fluid therapy guided by the Vigileo-FloTracTM system on intestinal mucosal barrier function in elderly patients with colorectal cancer.

Introduction: Colorectal cancer is a clinically common malignancy arising in the digestive tract. Aim: To evaluate the influence of goal-directed fluid therapy (GDFT) guided by the Vigileo-FloTracTM system on intestinal mucosal barrier function in elderly patients with colorectal cancer. Material and methods: A prospective study was conducted on 106 elderly patients with colorectal cancer. They were divided into control and research groups (n = 53) using a random number table, and subjected to conventional fluid therapy and Vigileo-FloTracTM system-guided GDFT, respectively. Their intraoperative indicators, postoperative indicators, and changes of haemodynamics, oxygen metabolism, intestinal mucosal barrier function at different time points, and incidence rates of complications were compared. Results: Compared with the control group, the intraoperative urine volume, colloid fluid volume, crystalloid fluid volume, and total infusion volume were lower, and the first postoperative exhaust time, first postoperative feeding time, and hospital stay were shorter in the research group (p < 0.05). At T1 and T2, mean artery pressure, heart rate, central venous pressure, oxygen consumption, oxygen delivery, and oxygen extraction ratio in the research group were lower than in the control group, but all of them first rose and then fell in the 2 groups (p < 0.05). On the 3rd day after surgery, the levels of serum endothelin, diamine oxidase and D-lactate declined in both groups, and the decline was more obvious in the research group (p < 0.05). Conclusions: GDFT guided by the Vigileo-FloTracTM system is beneficial to the prognosis of patients by effectively decreasing fluid infusion.