The effect of intraoperative goal-directed fluid therapy in patients under anesthesia for gastrointestinal surgery

BACKGROUND Intraoperative fluid management is an important aspect of anesthesia mana-gement in gastrointestinal surgery.Intraoperative goal-directed fluid therapy(GDFT)is a method for optimizing a patient's physiological state by monitoring and regulating fluid input in real-time.AIM To evaluate the efficacy of intraoperative GDFT in patients under anesthesia for gastrointestinal surgery.METHODS This study utilized a retrospective comparative study design and included 60 patients who underwent gastrointestinal surgery at a hospital.The experimental group(GDFT group)and the control group,each comprising 30 patients,received intraoperative GDFT and traditional fluid management strategies,respectively.The effect of GDFT was evaluated by comparing postoperative recovery,com-plication rates,hospitalization time,and other indicators between the two patient groups.RESULTS Intraoperative blood loss in the experimental and control groups was 296.64±46.71 mL and 470.05±73.26 mL(P<0.001),and urine volume was 415.13±96.72 mL and 239.15±94.69 mL(P<0.001),respectively.The postoperative recovery time was 5.44±1.1 days for the experimental group compared to 7.59±1.45 days(P<0.001)for the control group.Hospitalization time for the experimental group was 10.87±2.36 days vs 13.65±3 days for the control group(P<0.001).The visual analogue scale scores of the experimental and control groups at 24 h and 48 h INTRODUCTION Gastrointestinal surgery is one of the most common procedures in the field of general surgery[1],involving the stomach,intestines,liver,pancreas,spleen,and other internal abdominal organs[2,3].With advancements in surgical technology and anesthesia methods,the safety and success rates of surgery have significantly improved[4,5].However,intraop-erative fluid management remains a critical challenge[6].Traditional fluid management strategies often rely on experience and basic physiological parameters,which may lead to excessive or insufficient fluid input,thereby affecting postoperative recovery and complication rates.Intraoperative goal-directed fluid therapy(GDFT)is an emerging fluid management strategy that dynamically adjusts fluid input volume by monitoring the patient's hemodynamic parameters in real-time to optimize the patient's physiological state[7,8].GDFT has shown superiority in many surgical fields;however,its application in gastrointestinal surgery requires further research and verification[9,10].The application of intraoperative GDFT in clinical settings has gradually increased in recent years[11,12].Studies have demonstrated that GDFT can optimize tissue perfusion and oxygenation by precisely controlling fluid input and reducing the occurrence of postoperative complications[13,14].For example,in cardiac and major vascular surgeries,GDFT significantly reduced the incidence of postoperative acute kidney injury and cardiovascular events[15,16].Similarly,in abdominal surgery,GDFT effectively reduced postoperative infections and expedited recovery[17].However,studies on the utilization of GDFT in gastrointestinal surgery are relatively limited and they are confounded by contradictory findings[18].Traditional fluid management strategies typically rely on estimating fluid input volume based on the patient's weight,preoperative status,and basic physiological parameters[19].However,this method lacks real-time dynamic adjustment,which may result in either insufficient or excessive fluid input,consequently affecting postoperative recovery.Insufficient fluid input can lead to hypovolemia and inadequate tissue perfusion,whereas excessive fluid input can cause tissue edema and postoperative complications,such as pulmonary edema and heart failure.GDFT involves dynamically adjusting fluid input volume by monitoring the patient's hemodynamic parameters in real-time,such as cardiac output,pulse pressure variability,and central venous pressure.Commonly used monitoring equipment include esophageal Doppler and pulse wave profile analyzers[20].These devices provide real-time hemo-dynamic data to assist anesthesiologists in tailoring fluid therapy to a patient's specific condition.Firstly,the patient's volume responsiveness is assessed by preloading fluid;secondly,fluid input volume is dynamically adjusted based on real-time monitoring data;finally,vasoactive and inotropic drugs are administered in combination to further optimize the patient’s hemodynamic status.Through personalized fluid management,GDFT can more accurately maintain intraop-erative hemodynamic stability and reduce complications[21].Gastrointestinal surgery involves procedures on multiple organs,often requiring prolonged operative times and extensive tissue trauma,which presents challenges for intraop-erative fluid management.Surgical procedures can lead to significant bleeding and fluid loss,requiring prompt and effective fluid replenishment.In addition,the slow recovery of gastrointestinal function after surgery and susceptibility to complications such as intestinal obstruction and delayed gastric emptying elevate the necessity for postoperative fluid management.

Intraoperative Blood Pressure Lability Acts as a Key Mediator in the Impacts of Goal-Directed Fluid Therapy on Postoperative Complications in Patients Undergoing Major Spine Surgery

Objective Although goal-directed fluid therapy(GDFT)has been proven to be effective in reducing the incidence of postoperative complications,the underlying mechanisms remain unknown.The aim of this study was to examine the mediating role of intraoperative hemodynamic lability in the association between GDFT and the incidence of postoperative complications.We further tested the role of this mediation effect using mean arterial pressure,a hemodynamic indicator.Methods This secondary analysis used the dataset of a completed nonrandomized controlled study to investigate the effect of GDFT on the incidence of postoperative complications in patients undergoing posterior spine arthrodesis.We used a simple mediation model to test whether there was a mediation effect of average real variability between the association of GDFT and postoperative complications.We conducted mediation analysis using the mediation package in R(version 3.1.2),based on 5,000 bootstrapped samples,adjusting for covariates.Results Among the 300 patients in the study,40%(120/300)developed postoperative complications within 30 days.GDFT was associated with fewer 30-day postoperative complications after adjustment for confounders(odds ratio:0.460,95%CI:0.278,0.761;P=0.003).The total effect of GDFT on postoperative complications was-0.18(95%CI:-0.28,-0.07;P<0.01).The average causal mediation effect was-0.08(95%CI:-0.15,-0.04;P<0.01).The average direct effect was-0.09(95%CI:-0.20,0.03;P=0.17).The proportion mediated was 49.9%(95%CI:18.3%,140.0%).Conclusions The intraoperative blood pressure lability mediates the relationship between GDFT and the incidence of postoperative complications.Future research is needed to clarify whether actively reducing intraoperative blood pressure lability can prevent postoperative complications.

Goal-directed fluid therapy in gastrointestinal cancer surgery:A prospective randomized study

Objective:To investigate the effects of perioperative goal-directed fluid therapy(GDFT)on intraoperative fluid balance,postoperative morbidity,and mortality.Methods:This is a prospective randomized study,and 90 patients who underwent elective open gastrointestinal cancer surgery between April 2017 and May 2018 were included.Patients were randomized into 2 groups that received liberal fluid therapy(the LFT group,n=45)and goal-directed fluid therapy(the GDFT group,n=45).Patients’Colorectal Physiologic and Operative Severity Score for the enUmeration of Mortality and Morbidity(CR-POSSUM)physiological score,Charlson Comorbidity Index(CCI),perioperative vasopressor and inotrope use,postoperative AKIN classification,postoperative intensive care unit(ICU)hospitalization,hospital stay,and 30-day mortality were recorded.Results:The volume of crystalloid used perioperatively and the total volume of fluid were significantly lower in the GDFT group compared to the LFT group(P<0.05).CR-POSSUM physiological score and CCI were significantly higher in the GDFT group(P<0.05).Although perioperative vasopressor and inotrope use was significantly higher in the GDFT group(P<0.05),postoperative acute kidney injury development was not affected.Postoperative mortality was determined to be similar in both groups(P>0.05).Conclusion:Although GDFT was demonstrated to be a good alternative method to LFT in open gastrointestinal cancer surgery,and it can prevent perioperative fluid overload,and the postoperative results are comparable in the two groups.

Effect of Goal-Directed Fluid Therapy on Lung Function, Cognitive Function and Inflammatory Response in Patients Undergoing Radical Esophageal Cancer Surgery under One-Lung Ventilation

Objective: To explore the effects of goal-directed fluid therapy (GDFT) on lung function, cognitive function and inflammatory response in patients undergoing radical esophageal cancer surgery under one-lung ventilation. Methods: Sixty-seven patients undergoing radical esophageal cancer surgery were divided into GDFT group (GDFT therapy) and control group (conventional liquid therapy). The changes in patients’ pulmonary function, cognitive function and inflammatory response were evaluated. Results: Both alveolar-arterial oxygen partial pressure difference [P(A-a)O2] and respiratory index (RI) increased at one-lung ventilation for 30 minutes (T2) and decreased at one-lung ventilation for 60 minutes (T3), and after surgery (T4) in the two groups, and the GDFT group was lower than the control group (P < 0.05);theoxygenation index (OI) of the two groups decreased at T2, T3, and T4 compared with that at T1 (before one-lung ventilation), and the GDFT group was higher than the control group (P < 0.05). At T4 and T5, the tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), central nervous system specific protein (S100β), and neuron specific enolase (NSE) in the GDFT group were lower compared to the control group (P < 0.05), while interleukin-10 (IL-10) was higher compared to the control group (P < 0.05);the incidence of perioperative neurocognitive disorder (PND) in the GDFT group was lower than that in the control group (P < 0.05). Conclusion: GDFT can help prevent lung injury during radical esophageal cancer surgery under one-lung ventilation, reduce the body’s inflammatory response, and reduce the incidence of perioperative cognitive disorder to a certain extent.

Research of goal-directed fluid therapy on laparoscopic liver resection

Objective To explore the application effect of goal-directed fluid therapy(GDFT)on laparoscopic liver resection.Methods From July 2023 to December 2023,48 patients who underwent laparoscopic liver resection were randomly divided into the GDFT group and the CLCVP(controlled low central venous pressure)group.The patients in the GDFT group were guided by stroke volume variability(SVV)during surgery,while those in the CLCVP group were guided by a controlled low central venous pressure technique during fluid replacement surgery.Intraoperative bleeding volume,fluid replacement volume,urine output,liver blood flow obstruction time,postoperative exhaust time,length of hospital stays,and incidence of complications were recorded and compared between the two groups of patients.Results There was a difference between the two groups in terms of crystal fluid,colloid fluid,total fluid volume,and urine volume(P>0.05).However,the bleeding volume in the GDFT group(515.61±246.71)mL was lower than that in the CLCVP group(389.37±187.35)mL(P<0.05);and the blockade time of liver blood flow in the GDFT group(46.33±7.26)min was shorter than that of the CLCVP group(41.84±6.24)min(P<0.05);the postoperative exhaust time of patients in the GDFT group(4.86±1.24)d was shorter than that of patients in the CLCVP group(6.42±1.05)d(P<0.05);the hospitalization days of patients in the GDFT group(9.21±2.15)d were fewer than those in the CLCVP group(11.04±4.29)d(P<0.05).There were no statistically significant differences in the incidence of postoperative complications between the two groups of patients(P>0.05).Conclusion GDFT guided by SVV can stabilize intraoperative hemodynamics in patients undergoing laparoscopic liver resection,reduce intraoperative bleeding,and reduce liver blood flow blockage time.It is safer and more reliable than traditional fluid therapy.

Goal-directed therapy in intraoperative fluid and hemodynamic management

Intraoperative fluid management is pivotal to the outcome and success of surgery, especially in high-risk proce- dures. Empirical formula and invasive static monitoring have been traditionally used to guide intraoperative fluid management and assess volume status. With the awareness of the potential complications of invasive procedures and the poor reliability of these methods as indicators of volume status, we present a case scenario of a patient who underwent major abdominal surgery as an example to discuss how the use of minimally invasive dynamic monitoring may guide intraoperative fluid therapy.

Goal-directed Fluid Therapy May Improve Hemodynamic Stability of Parturient with Hypertensive Disorders of Pregnancy Under Combined Spinal Epidural Anesthesia for Cesarean Delivery and the Well-being of Newborns

Background： Hypotension induced by combined spinal epidural anesthesia in parturient with hypertensive disorders of pregnancy （HDP） can easily compromise blood supply to vital organs including uteroplacental perfusion and result in fetal distress. The aim of this study was to investigate whether the goal-directed fluid therapy （GDFT） with LiDCOrapid system can improve well-being of both HDP parturient and their babies. Methods： Fifty-two stable HDP parturient scheduled for elective cesarean delivery were recruited. After loading with 10 ml/kg lactated Ringer＇s solution （LR）, parturient were randomized to the GDFT and control group. In the GDFT group, individualized fluid therapy was guided by increase in stroke volume （ASV） provided via LiDCO rapid system. The control group received the routine fluid therapy. The primary endpoints included maternal hypotension and the doses of vasopressors administered prior to fetal delivery. The secondary endpoints included umbilical blood gas abnormalities and neonatal adverse events. Results： The severity of HDP was similar between two groups. The total LR infusion （P 〈 0.01） and urine output （P 〈 0.05） were higher in the GDFT group than in the control group. Following twice fluid challenge tests, the systolic blood pressure, mean blood pressure, cardiac output and SV in the GDFT group were significantly higher, and the heart rate was lower than in the control group. The incidence of maternal hypotension and doses of phenylephrine used prior to fetal delivery were significantly higher in the control group than in the GDFT group （P 〈 0.01）. There were no differences in the Apgar scores between two groups. In the control group, the mean values of pH in umbilical artery/vein were remarkably decreased （P 〈 0.05）, and the incidences of neonatal hypercapnia and hypoxemia were statistically increased （P 〈 0.05） than in the GDFT group. Conclusions： Dynamic responsiveness guided fluid therapy with the LiDCOrapid system may provide potential benefits to stable HDP parturient and their babies.

Effect of goal-directed fluid therapy based on both stroke volume variation and delta stroke volume on the incidence of composite postoperative complications among individuals undergoing meningioma resection

To the Editor:In neurosurgery,intraoperative fluid administration is essential in maintaining appropriate systemic and cerebral perfusion pressure,oxygenation,and metabolism.Meningioma resection can involve massive intraoperative blood loss due to an abundant blood supply in structures.Moreover,the routine use of mannitol during meningioma resection may affect hemodynamic stability.Fluid overload is correlated to neurological,pulmonary,or gastrointestinal(GI)edema,which has unfavorable outcomes.[1]Thus,neurosurgeries,particularly meningioma resection,require individualized fluid therapy to achieve a balance between inadequate fluid and fluid overload.

Effects of fluid therapy combined with a preoperative glucose load regimen on postoperative recovery in patients with rectal cancer

BACKGROUND Patients with rectal cancer undergoing radical resection often have poor post-operative recovery due to preoperative fasting and water deprivation and the removal of diseased tissue,and have a high risk of complications.Therefore,it is of great significance to apply appropriate rehydration regimens to patients un-dergoing radical resection of rectal cancer during the perioperative period to improve the postoperative outcomes of patients.AIM To analyze the effects of goal-directed fluid therapy(GDFT)with a preoperative glucose load regimen on postoperative recovery and complications in patients undergoing radical resection for rectal cancer.METHODS Patients with rectal cancer who underwent radical resection(n=184)between January 2021 and December 2023 at our hospital were randomly divided into either a control group or an observation group(n=92 in each group).Both groups received a preoperative glucose load regimen,and routine fluid replacement and GDFT were additionally implements in the control and observation groups,res-pectively.The operative conditions,blood levels of lactic acid and inflammatory markers,postoperative recovery,cognitive status,hemodynamic indicators,brain oxygen metabolism,and complication rates were compared between the groups.RESULTS The colloidal fluid dosage,total infusion,and urine volume,as well as time to first exhaust,time to food intake,and postoperative length of hospital stay,were lower in the observation group(P<0.05).No significant differences were observed between the two groups in terms of operation time,bleeding volume,crystalloid liquid consumption,time to tracheal extubation,complication rate,heart rate,or mean arterial pressure(P>0.05).Compared with the control group,in the ob-servation group the lactic acid level was lower immediately after the surgery(P<0.05);the Mini-Mental State Examination score was higher on postoperative day 3(P<0.05);the pulse pressure variability(PPV)was lower at 30 min after pneumoperitoneum(P<0.05),though the differences in the PPV of the two groups was not significant at the remaining time points(P>0.05);tumor necrosis factor-αand interleukin-6 levels were lower on postoperative day 3(P<0.05);and the left and right regional cerebral oxygen saturation was higher immediately after the surgery and 30 min after pneumoperitoneum(P<0.05).CONCLUSION GDFT combined with the preoperative glucose load regimen is a safe and effective treatment strategy for im-proving postoperative recovery and risk of complications in patients with rectal cancer undergoing radical re-section.

Intraoperative Goal-Directed Therapies in Femoral and Pelvic Osteotomies in Children and In-Hospital Postoperative Outcomes

Background: Femoral and pelvic osteotomies are potential hemorrhagic interventions where transfusion requirements can be necessary. Objective: We undertook a secondary analysis of patients who underwent femoral and pelvic osteotomy in the initial cohort. The objective of this secondary analysis was to describe intraoperative and postoperative outcomes and to describe intraoperative management in these patients in terms of blood product management and fluid and hemodynamic therapy with the aim of implementing optimization management protocols for postoperative outcome improvement. Methods: A secondary analysis of patients who underwent femoral and pelvic osteotomy surgery was included in the initial retrospective study. Results: There were eighteen patients with a mean age of 104 ± 47.1 months. Four (22.2%) patients had intraoperative and/or postoperative complications. One patient (5.6%) had an intraoperative hemorrhagic shock, two patients (11.1%) had postoperative neurologic failure, and one patient (5.6%) had postoperative wound sepsis. The transfusion rate was 50% in nine patients. Conclusion: Femoral and pelvic osteotomies are interventions where blood, transfusion and fluid requirements can be increased;thus, this implies the necessity of a global patient blood management protocol with point-of-care tests and fluid- and hemodynamic-guided protocols with validated tools in children for intraoperative and postoperative outcome optimization.

Scoliosis in Children: Impact of Goal-Directed Therapies on Intraoperative and Postoperative Outcomes

Background: Scoliosis is among interventions with high postoperative complication rates due to the characteristics of the surgery, where blood loss, transfusion and fluid requirements can be increased. A monocentric retrospective observational study was undertaken earlier to determine predictors of intraoperative and postoperative outcomes in surgical patients. In this initial cohort, there were patients who underwent scoliosis surgery, and a secondary analysis to describe outcomes in these patients was realized and presented here. Objective: To describe intraoperative and postoperative outcomes in patients under 18 years old in scoliosis surgery included in the initial study and to propose improvement and implementation measures. Methods: A secondary analysis of patients undergoing scoliosis surgery from 1 January 2014 to 17 May 2017 was undertaken in our institution—Necker Enfants Malades university hospital. The study was approved by the Ethics Committee. Results: There were 116 patients with a mean age of 147.5 ± 40.2 months. Twenty-eight patients (24.1%) presented intraoperative and/or postoperative complications. The most common intraoperative complication was hemorrhagic shock in 3 patients (2.6%). The most common postoperative organ failure was neurologic in seven patients (6%), respiratory in 3 patients (2.6%), cardio-circulatory in 2 patients (1.7%) and renal failure in 1 patient (0.9%). The most common postoperative infection was surgical wound sepsis in 8 patients (6.9%), urinary sepsis in 3 patients (2.6%), and abdominal sepsis and septicemia in 2 patients (1.7%). 12 patients (10.3%) had reoperations. Fifty-six patients (48.3%) had intraoperative transfusion. There was no in-hospital mortality. Conclusion: The portion of patients with intraoperative and or postoperative complications was 24.1%, integrating goal-directed therapies in this surgical setting could improve postoperative outcomes.

Simplified Intraoperative Goal-Directed Therapy Using the FloTrac/Vigileo System: An Analysis of Its Usefulness and Safety

Purpose: We investigated whether the simplified intraoperative Goal-Directed Therapy (GDT) could improve the factors affecting medical costs, and contribute in standardizing intraoperative fluid management. Methods: The enrolled patients underwent esophagectomy, pancreatoduodenectomy, or aortic stent grafting in 2012, and between March 2013 and October 2014. We conducted a comparison study on the effects of GDT, between the before-GDT historical control group (n = 100) and GDT group (n = 100). The hemodynamic indices used for control group patients were conventional: Blood pressure, heart rate, and urine output. For GDT group, additionally, we used stroke volume variation (SVV) and stroke volume index (SVI). The primary outcomes were the length of intensive care unit (ICU) stay and hospital stay (LOS). Regression analysis was used to identify factors affecting LOS. The secondary outcomes were the albumin use, the fluid amount administered, and the variation in the fluid administration rate. Results: The control and GDT groups comprised 96 and 99 patients, respectively. The patient characteristics were similar. The length of ICU stay was significantly shorter (2.1 ± 2.1 days vs. 2.8 ± 1.9 days, P = 0.0009) and LOS was shorter but without statistical significance (24.5 ± 17.7 days vs. 27.7 ± 20.1 days, P = 0.21) in the GDT group than in the control group. The fluid amount administered and the presence/ absence of albumin use were factors affecting LOS. The variation of the fluid administration rate was significantly lower in the GDT group. Conclusion: The simplified GDT may contribute to the improvement of medical economics and standardize the fluid management.

Extension of Goal-Directed Behavior Model for Post-Pandemic Korean Travel Intentions to Alternative Local Destinations: Perceived Risk and Knowledge

Since the outbreak of COVID-19,tourists have been increasingly concerned over various risks of international travel,while knowledge of the pandemic appears to vary significantly.In addition,as travel restrictions continue to impact adversely on international tourism,tourism efforts should be placed more on the domestic markets.Via structural equation modeling,this study unearthed different risk factors impacting Korean travelers’choices of alternative local destinations in the post-pandemic era.In addition,this study extended the goal-directed behavior framework with the acquisition of perceived risk and knowledge of COVID-19,which was proven to hold a sig-nificantly superior explanatory power of tourists’decisions of local alternatives over foreign countries during the COVID-19 pandemic.Furthermore,desire was found to play an imminent mediating role in the conceptual mod-el,maximizing the impact of perceived risk on travel intentions.Henceforth,this research offers meaningful the-oretical implication as thefirst empirical study to deepen the goal-directed behaviour framework with perceived risk and knowledge in the context of post-COVID-19 era.It also serves as insightful knowledge for Korean tour-ism authorities and practitioners to understand local tourists’decision-making processes and tailor effective recovery strategy for domestic tourism.

Effect of fracture fluid flowback on shale microfractures using CT scanning

The field data of shale fracturing demonstrate that the flowback performance of fracturing fluid is different from that of conventional reservoirs,where the flowback rate of shale fracturing fluid is lower than that of conventional reservoirs.At the early stage of flowback,there is no single-phase flow of the liquid phase in shale,but rather a gas-water two-phase flow,such that the single-phase flow model for tight oil and gas reservoirs is not applicable.In this study,pores and microfractures are extracted based on the experimental results of computed tomography(CT)scanning,and a spatial model of microfractures is established.Then,the influence of rough microfracture surfaces on the flow is corrected using the modified cubic law,which was modified by introducing the average deviation of the microfracture height as a roughness factor to consider the influence of microfracture surface roughness.The flow in the fracture network is simulated using the modified cubic law and the lattice Boltzmann method(LBM).The results obtained demonstrate that most of the fracturing fluid is retained in the shale microfractures,which explains the low fracturing fluid flowback rate in shale hydraulic fracturing.

Synthetic polymers:A review of applications in drilling fluids

With the growth of deep drilling and the complexity of the well profile,the requirements for a more complete and efficient exploitation of productive formations increase,which increases the risk of various complications.Currently,reagents based on modified natural polymers(which are naturally occurring compounds)and synthetic polymers(SPs)which are polymeric compounds created industrially,are widely used to prevent emerging complications in the drilling process.However,compared to modified natural polymers,SPs form a family of high-molecular-weight compounds that are fully synthesized by undergoing chemical polymerization reactions.SPs provide substantial flexibility in their design.Moreover,their size and chemical composition can be adjusted to provide properties for nearly all the functional objectives of drilling fluids.They can be classified based on chemical ingredients,type of reaction,and their responses to heating.However,some of SPs,due to their structural characteristics,have a high cost,a poor temperature and salt resistance in drilling fluids,and degradation begins when the temperature reaches 130℃.These drawbacks prevent SP use in some medium and deep wells.Thus,this review addresses the historical development,the characteristics,manufacturing methods,classification,and the applications of SPs in drilling fluids.The contributions of SPs as additives to drilling fluids to enhance rheology,filtrate generation,carrying of cuttings,fluid lubricity,and clay/shale stability are explained in detail.The mechanisms,impacts,and advances achieved when SPs are added to drilling fluids are also described.The typical challenges encountered by SPs when deployed in drilling fluids and their advantages and drawbacks are also discussed.Economic issues also impact the applications of SPs in drilling fluids.Consequently,the cost of the most relevant SPs,and the monomers used in their synthesis,are assessed.Environmental impacts of SPs when deployed in drilling fluids,and their manufacturing processes are identified,together with advances in SP-treatment methods aimed at reducing those impacts.Recommendations for required future research addressing SP property and performance gaps are provided.

Step-over of strike-slip faults and overpressure fluid favor occurrence of foreshocks:Insights from the 1975 Haicheng fore-main-aftershock sequence,China

This study analyzed and summarized in detail the spatial and temporal distributions of earthquakes,tidal responses,focal mechanisms,and stress field characteristics for the M 7.3 Haicheng earthquake sequence in February 1975.The foreshocks are related to the main fault and the conjugate faults surrounding the extension step-over in the middle.The initiation timing of the foreshock clusters and the original time of the mainshock were clearly modulated by the Earth's tidal force and coincided with the peak of dilational volumetric tidal strain.As a plausible and testable hypothesis,we proposed a fluid-driven foreshock model,by which all observed seismicity features can be more reasonably interpreted with respect to the results of existing models.Together with some other known examples,the widely existing step-over along strike-slip faults and associated conjugate faults,especially for extensional ones in the presence of deep fluids,favor the occurrence of short-term foreshocks.Although clustered seismicity with characteristics similar to those of the studied case is not a sufficient and necessary condition for large earthquakes to occur under similar tectonic conditions,it undoubtedly has a warning significance for the criticality of the main fault.Subsequent testing would require quantification of true/false positives/negatives.

Reservoir quality evaluation of the Narimba Formation in Bass Basin,Australia:Implications from petrophysical analysis,sedimentological features,capillary pressure and wetting fluid saturation

The evaluation of reservoir quality was accomplished on the Late Paleocene to Early Eocene Narimba Formation in Bass Basin,Australia.This study involved combination methods such as petrophysical analysis,petrography and sedimentological studies,reservoir quality and fluid flow units from derivative parameters,and capillary pressure and wetting fluid saturation relationship.Textural and diagenetic features are affecting the reservoir quality.Cementation,compaction,and presence of clay minerals such as kaolinite are found to reduce the quality while dissolution and secondary porosity are noticed to improve it.It is believed that the Narimba Formation is a potential reservoir with a wide range of porosity and permeability.Porosity ranges from 3.1%to 25.4%with a mean of 15.84%,while permeability ranges between 0.01 mD and 510 mD,with a mean of 31.05 mD.Based on the heterogenous lithology,the formation has been categorized into five groups based on permeability variations.Group I showed an excellent to good quality reservoir with coarse grains.The impacts of both textural and diagenetic features improve the reservoir and producing higher reservoir quality index(RQI)and flow zone indicators(FZI)as well as mostly mega pores.The non-wetting fluid migration has the higher possibility to flow in the formation while displacement pressure recorded as zero.Group II showed a fair quality reservoir with lower petrophysical properties in macro pores.The irreducible water saturation is increasing while the textural and digenetic properties are still enhancing the reservoir quality.Group III reflects lower quality reservoir with mostly macro pores and higher displacement pressure.It may indicate smaller grain size and increasing amount of cement and clay minerals.Group IV,and V are interpreted as a poor-quality reservoir that has lower RQI and FZI.The textural and digenetic features are negatively affecting the reservoir and are leading to smaller pore size and pore throat radii(r35)values to be within the range of macro,meso-,micro-,and nano pores.The capillary displacement pressure curves of the three groups show increases reaching the maximum value of 400 psia in group V.Agreement with the classification of permeability,r35 values,and pore type can be used in identifying the quality of reservoir.

Effect of bubble morphology and behavior on power consumption in non-Newtonian fluids’aeration process

Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate of impeller, ventilation, rheological properties and bubble morphology in the reactor. In this perspective, through optimal computational fluid dynamics models and experiments, the relationship between power consumption, volumetric mass transfer rate(kLa) and initial bubble size(d0) was constructed to establish an efficient operation mode for the aeration process of non-Newtonian fluids. It was found that reducing the d0could significantly increase the oxygen mass transfer rate, resulting in an obvious decrease in the ventilation volume and impeller speed. When d0was regulated within 2-5 mm,an optimal kLa could be achieved, and 21% of power consumption could be saved, compared to the case of bubbles with a diameter of 10 mm.

Use of Early Goal-Directed Therapy in the Emergency Department before and after the Sepsis Trilogy

The management of sepsis evolved recently with the publication of three large trials (referred to as the sepsis trilogy) investigating the efficacy of early goal-directed therapy (EGDT). Our goal was to determine if the publication of these trials has influenced the use of EGDT when caring for patients with severe sepsis and septic shock in the emergency department (ED). In February 2014, we surveyed a sample of board-certified emergency medicine physicians regarding their use of EGDT in the ED. A follow-up survey was sent after the publication of the sepsis trilogy. Data was analyzed using 95% confidence intervals to determine if there was a change in the use of EGDT following the publication of the above trials. Subgroup analyses were also performed with regard to academic affiliation and emergency department volume. Surveys were sent to 308 and 350 physicians in the pre-and post-publication periods, respectively. Overall, ED use of EGDT did not change with publication of the sepsis trilogy, 48.7% (CI 39.3% - 58.2%) before and 50.5% (CI 40.6% - 60.3%) after. Subgroup analysis revealed that academic-affiliated EDs significantly decreased EGDT use following the sepsis trilogy while nonacademic departments significantly increased EGDT use. Use of EGDT was significantly greater in community departments versus academic departments following the publication of the sepsis trilogy. There was no change overall in the use of EGDT protocols when caring for patients with severe sepsis and septic shock, but subgroup analyses revealed that academic departments decreased their use of EGDT while community departments increased use of EGDT. This may be due to varying rates of uptake of the medical literature between academic and community healthcare systems.

Microscopic characteristics of tight sandstone reservoirs and their effects on the imbibition efficiency of fracturing fluids:A case study of the Linxing area,Ordos Basin

The Linxing area within the Ordos Basin exhibits pronounced reservoir heterogeneity and intricate micro-pore structures,rendering it susceptible to water-blocking damage during imbibition extraction.This study delved into the traits of tight sandstone reservoirs in the 8th member of the Shihezi Formation(also referred to as the He 8 Member)in the study area,as well as their effects on fracturing fluid imbibition.Utilizing experimental techniques such as nuclear magnetic resonance(NMR),high-pressure mercury intrusion(HPMI),and gas adsorption,this study elucidated the reservoir characteristics and examined the factors affecting the imbibition through imbibition experiments.The findings reveal that:①The reservoir,with average porosity of 8.40%and average permeability of 0.642×10^(-3)μm^(2),consists principally of quartz,feldspar,and lithic fragments,with feldspathic litharenite serving as the primary rock type and illite as the chief clay mineral;②Nano-scale micro-pores and throats dominate the reservoir,with dissolution pores and intercrystalline pores serving as predominant pore types,exhibiting relatively high pore connectivity;③Imbibition efficiency is influenced by petrophysical properties,clay mineral content,and microscopic pore structure.Due to the heterogeneity of the tight sandstone reservoir,microscopic factors have a more significant impact on the imbibition efficiency of fracturing fluids;④A comparative analysis shows that average pore size correlates most strongly with imbibition efficiency,followed by petrophysical properties and clay mineral content.In contrast,the pore type has minimal impact.Micropores are vital in the imbibition process,while meso-pores and macro-pores offer primary spaces for imbibition.This study offers theoretical insights and guidance for enhancing the post-fracturing production of tight sandstone reservoirs by examining the effects of these factors on the imbibition efficiency of fracturing fluids in tight sandstones.