Erratum to:“An Approximate Method for Calculating the Fluid Force and Response of A Circular Cylinder at Lock-in” [China Ocean Engineering,22(3),2008,371-384]

Because of my carelessness,Eq.（1）in the paper "An approximate method for calculating the fluid force and response of a circular cylinder at lock-in"(China Ocean Engineering,22（3）,2008,pp.373)should be f’-1.0/U’-5.0=f’;-1.0/5.75f’;-5.0,not f’=U’/5.75. My apology is hereby given.

The Co-seismic Response of Underground Fluid in Yunnan to the Nepal MS8.1 Earthquake

In this paper,statistics are taken on the co-seismic response of underground fluid in Yunnan to the Nepal M_S8. 1 earthquake,and the co-seismic response characteristics of the water level and water temperature are analyzed and summarized with the digital data. The results show that the Nepal M_S8. 1 earthquake had greater impact on the Yunnan region,and the macro and micro dynamics of fluids showed significant co-seismic response. The earthquake recording capacity of water level and temperature measurement is significantly higher than that of water radon and water quality to this large earthquake; the maximum amplitude and duration of co-seismic response of water level and water temperature vary greatly in different wells. The changing forms are dominated by fluctuation and step rise in water level,and a rising or falling restoration in water temperature. From the records of the main shock and the maximum strong aftershock,we can see that the greater magnitude of earthquake,the higher ratio of the occurrence of co-seismic response,and in the same well,the larger the response amplitude,as well as the longer the duration. The amplitude and duration of co-seismic response recorded by different instruments in a same well are different. Water temperature co-seismic response almost occurred in wells with water level response,indicating that the well water level and water temperature are closely related in co-seismic response,and the well water temperature seismic response was caused mainly by well water level seismic response.

Passive leg raising as an indicator of fluid responsiveness in patients with severe sepsis

In the management of critically ill patients, the assessment of volume responsiveness and the decision to administer a fluid bolus constitute a common dilemma for physicians. Static indices of cardiac preload are poor predictors of volume responsiveness. Passive leg raising （PLR） mimics an endogenous volume expansion （VE） that can be used to predict fluid responsiveness. This study was to assess the changes in stroke volume index （SVI） induced by PLR as an indicator of fluid responsiveness in mechanically ventilated patients with severe sepsis. This was a prospective study. Thirty-two mechanically ventilated patients with severe sepsis were admitted for VE in ICU of the First Affiliated Hospital, Zhejiang University School of Medicine and Ningbo Medical Treatment Center Lihuili Hospital from May 2010 to December 2011. Patients with non-sinus rhythm or arrhythmia, parturients, and amputation of the lower limbs were excluded. Measurements of SVI were obtained in a semi-recumbent position （baseline） and during PLR by the technique of pulse indicator continuous cardiac output （PiCCO） system prior to VE. Measurements were repeated after VE （500 mL 6% hydroxyethyl starch infusion within 30 minutes） to classify patients as either volume responders or non-responders based on their changes in stroke volume index （ASVI） over 15%. Heart rate （HR）, systolic artery blood pressure （ABPs）, diastolic artery blood pressure （ABPd）, mean arterial blood pressure （ABPm）, mean central venous pressure （CVPm） and cardiac index （CI） were compared between the two groups. The changes ofABPs, ABPm, CVPm, and SVI after PLR and VE were compared with the indices at the baseline. The ROC curve was drawn to evaluate the value of ASVI and the change of CVPm （ACVPm） in predicting volume responsiveness. SPSS 17.0 software was used for statistical analysis. Among the 32 patients, 22 were responders and 10 were non-responders. After PLR among the responders, some hemodynamic variables （including ABPs, ABPd, ABPm and CVPm） were significantly elevated （101.2±17.6 vs. 118.6±23.7, P=0.03; 52.8±10.7 vs. 64.8±10.7, P=0.006; 68.3±11.7 vs. 81.9±14.4, P=0.008; 6.8±3.2 vs. 11.9±4.0, P=0.001）. After PLR, the area under curve （AUC） and the ROC curve of ASVI and ACVPm for predicting the responsiveness after VE were 0.882±0.061 （95%CI 0.759-1.000） and 0.805±0.079 （95%CI 0.650-0.959） when the cut-off levels of ASVI and ACVPm were 8.8% and 12.7%, the sensitivities were 72.7% and 72.7%, and the specificities were 80% and 80%. Changes in ASVI and ACVPm induced by PLR are accurate indices for predicting fluid responsiveness in mechanically ventilated patients with severe sepsis.

A novel triple responsive smart fluid for tight oil fracturing-oil expulsion integration

The traditional multi-process to enhance tight oil recovery based on fracturing and huff-n-puff has obvious deficiencies,such as low recovery efficiency,rapid production decline,high cost,and complexity,etc.Therefore,a new technology,the so-called fracturing-oil expulsion integration,which does not need flowback after fracturing while making full use of the fracturing energy and gel breaking fluids,are needed to enable efficient exploitation of tight oil.A novel triple-responsive smart fluid based on“pseudo-Gemini”zwitterionic viscoelastic surfactant(VES)consisting of N-erucylamidopropyl-N,N-dimethyl-3-ammonio-2-hydroxy-1-propane-sulfonate(EHSB),N,N,N′,N′-tetramethyl-1,3-propanediamine(TMEDA)and sodium p-toluenesulfonate(NaPts),is developed.Then,the rheology of smart fluid is systematically studied at varying conditions(CO_(2),temperature and pressure).Moreover,the mechanism of triple-response is discussed in detail.Finally,a series of fracturing and spontaneous imbibition performances are systematically investigated.The smart fluid shows excellent CO_(2)-,thermal-,and pressure-triple responsive behavior.It can meet the technical requirement of tight oil fracturing construction at 140°C in the presence of 3.5 MPa CO_(2).The gel breaking fluid shows excellent spontaneous imbibition oil expulsion(∼40%),salt resistance(1.2×104 mg/L Na+),temperature resistance(140°C)and aging stability(30 days).

Meta-Analysis of Invasive versus Non-Invasive Techniques to Predict Fluid Responsiveness by Passive Leg Raising in the Critically Ill

Objective: To analyze the accuracy and specificity of recent studies to compare the ability of predicting fluid responsiveness with Passive Leg Raising (PLR) by using invasive or non-invasive techniques during passive leg raising. Data Sources: MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews were systematically searched. Study Selection: Clinical trials that reported the sensitivity, specificity and area under the receiver operating characteristic curve (AUC) between the responder and non-responder induced by passive leg raising and Volume Expansion (VE) in critical ill patients were selected. 246 studies were screened, 14 studies were included for data extraction, which met our inclusion criteria. Data Extraction: Data were abstracted on study characteristics, patient population, type and amount of VE, time of VE, definition of responders, position, techniques used for measuring hemodynamic change, number and percentage of responders, the correlation coefficient, sensitivity, specificity, best threshold and area under the ROC curve (AUC). Meta-analytic techniques were used to summarize the data. Data Synthesis: A total of 524 critical ill patients from 14 studies were analyzed. Data are reported as point estimate (95% confidence intervals). The pooled sensitivity and specificity of invasive techniques were 80% (73% - 85%) and 89% (84% - 93%) respectively with the area under the sROC of 0.94. While, the pooled sensitivity and specificity of non-invasive techniques were 88% (84% - 92%) and 91% (86% - 94%) respectively with the area under the sROC of 0.95. The pooled DOR of invasive techniques was 32.2 (13.6 - 76.8), which was much lower than that of non-invasive techniques with the value of 64.3 (33.9 - 121.7). Conclusions: The hemodynamic indexes changes induced by PLR could reliably predict fluid responsiveness. Non-invasive hemodynamic techniques with their accuracy and safety can benefit the daily work in ICUs. Because the number of patients included in the present trials was small, further studies should be undertaken to confirm these findings.

Diagnostic Accuracy of Transthoracic Echocardiography to Predict Fluid Responsiveness by Passive Leg Raising in the Critically Ill: A Meta-Analysis

Background: Hemodynamic instability is common in critical patients and not all patients respond to fluid challenge, so we need accurate and rapid hemodynamic techniques to help the clinicians to guide fluid treatment. Numerous hemodynamic techniques have been used to predict fluid responsiveness till now. Transthoracic echocardiography (TTE) appears to have the ability to predict fluid responsiveness, but there is no consensus on whether it can be used by passive leg raising (PLR). Methods: We performed a literature search using MEDLINE (source PubMed, from 1947), EMBASE (from 1974) and the Cochrane Database of Systematic Reviews for prospective studies with no restrictions. Pooled effect estimates were obtained by using random-effects meta-analysis. Results: 7 prospective studies involving 261 patients and 285 boluses were identified. The pooled sensitivity and specificity of TTE are 86% (79% - 91%) and 90% (83% - 94%), respectively. The summary receiver operating characteristic (sROC) curve shows an optimum joint sensitivity and specificity of 0.88, with area under the sROC curve (AUC) of 0.94. The result of diagnostic odds ratio (DOR) is 50.62 (95% confidence interval [CI]: 23.70 - 108.12). The results of positive likelihood ratio (+LR) and negative likelihood ratio (?LR) are 7.07 (95% CI: 4.39 - 11.38) and 0.19 (95% CI: 0.13 - 0.28), which indicated strong diagnostic evidence. Conclusions: TTE is a repeatable and reliable noninvasive tool to predict fluid responsiveness in the critically ill during PLR with good test performance. This meta-analysis brings evidence to employ well-trained clinician-echocardiographers to assess patients’ volume statue via TTE to benefit daily work in intensive care units (ICUs).

A Study to Observe Pulse Pressure Variation after Induction with Propofol for General Anesthesia

Background and Aims: Pulse pressure variation (PPV) is a reliable and predictive dynamic parameter presently being utilized for fluid responsiveness. In the operating room, fluid administration based on PPV monitoring helps the physician in deciding whether to volume resuscitate or use interventions in patients undergoing surgery. Propofol is an intravenous induction agent which lowers blood pressure. There are multiple causes such as depression in cardiac output, and peripheral vasodilatation for hypotension. We undertook this study to observe the utility of PPV as a guide to fluid therapy after propofol induction. Primary outcome of our study was to monitor PPV as a marker of fluid responsiveness for the hypotension caused by propofol induction. Secondary outcome included the correlation of PPV with other hemodynamic parameters like heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP);after induction with propofol at regular interval of time. Methods: A total number of 90 patients were recruited. Either of the radial artery was then cannulated under local anaesthesia with 20G VygonLeadercath arterial cannula and invasive monitoring transduced. A baseline recording of heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and PPV was then recorded. Patients were then induced with predetermined doses of propofol (2 mg/kg) and recordings of HR, SBP, DBP, and PPV were taken at 5, 10 and 15 minutes. Results: Intraoperatively, PPV was significantly higher at 5 minutes and significantly lower at 15 minutes after induction. It was observed that there were no statistically significant correlations between PPV and SBP or DBP. PPV was strongly and directly associated with HR. Conclusion: We were able to establish that PPV predicts fluid responsiveness in hypotension caused by propofol induction;and can be used to administer fluid therapy in managing such hypotension. However, PPV was not directly correlated with hypotension subsequent to propofol administration.

Hemodynamic monitoring and management of patients undergoing high-risk surgery:a survey among Chinese anesthesiologists

Hemodynamic monitoring and optimization improve postoperative outcome during high-risk surgery.However,hemodynamic management practices among Chinese anesthesiologists are largely unknown.This study sought to evaluate the current intraoperative hemodynamic management practices for high-risk surgery patients in China.From September 2010 to November 2011,we surveyed anesthesiologists working in the operating rooms of 265 hospitals representing 28 Chinese provinces.All questionnaires were distributed to department chairs of anesthesiology or practicing anesthesiologists.Once completed,the 29-item questionnaires were collected and analyzed.Two hundred and 10 questionnaires from 265 hospitals in China were collected.We found that 91.4%of anesthesiologists monitored invasive arterial pressure,82.9%monitored central venous pressure（CVP）,13.3%monitored cardiac output（CO）,10.5%monitored mixed venous saturation,and less than 2%monitored pulse pressure variation（PPV） or systolic pressure variation（SPV） during high-risk surgery.The majority（88%） of anesthesiologists relied on clinical experience as an indicator for volume expansion and more than 80%relied on blood pressure,CVP and urine output.Anesthesiologists in China do not own enough attention on hemodynamic parameters such as PPV,SPV and CO during fluid management in high-risk surgical patients.The lack of CO monitoring may be attributed largely to the limited access to technologies,the cost of the devices and the lack of education on how to use them.There is a need for improving access to these technologies as well as an opportunity to create guidelines and education for hemodynamic optimization in China.

Veno-Venous Extra-Corporeal Membrane Oxygenation (ECMO) in a Child with Hemoptysis and Fontan Circulation

Background: Extracorporeal membrane oxygenation is a rescue life support technique used in life threatening conditions of refractory respiratory and/or cardiac distress. Indication for extracorporeal life support in children depends on age and varies from pulmonary to cardiac pathologies. In some cases, it may be used as a bridge to a therapeutic procedure. We described here the management of respiratory failure due to hemoptysis in a child with a Fontan circulation and veno-venous extracorporeal membrane oxygenation which served as a bridge to angio-embolization. Hemoptysis can be a life threatening condition which can lead to hypovolemic shock and impaired alveolar gas exchange. The latter can result in respiratory failure and consequent asphyxia. When hemoptysis occurs in a patient with a univentricular heart and a Fontan circulation, management of this clinical situation can be challenging due to the particular physiology of the latter. Total cavopulmonary connection is a palliative surgical repair which constitutes Fontan circulation as a definitive treatment in patients with a univentricular heart. Methods: Case report description of a 16 year-old boy with a univentricular heart and a Fontan circulation who presented hemoptysis managed with a veno-venous extracorporeal membrane oxygenation (ECMO) as a bridge to angio-embolization. Results: Hemoptysis due to diffuse intra-alveolar hemorrhage from collateral circulation was successfully treated in this young patient with pulmonary vascular embolization. This allowed to wean the patient from extra-corporeal membrane oxygenation. Conclusion: Veno-venous ECMO can be life-saving as a bridge to angio-embolization for severe hemoptysis in patients with Fontan circulation. The reported case allows to underline that our multidisciplinary approach in this complex pediatric patient surely participated to improve outcome.

Effect of Systolic Cardiac Function on Passive Leg Raising for Predicting Fluid Responsiveness： A Prospective Observational Study

Background：Passive leg raising （PLR） represents a ＂self-volume expansion （VE）＂ that could predict fluid responsiveness,but the influence of systolic cardiac function on PLR has seldom been reported.This study aimed to investigate whether systolic cardiac function,estimated by the global ejection fraction （GEF） from transpulmonary-thermodilution,could influence the diagnostic value of PLR.Methods：This prospective,observational study was carried out in the surgical Intensive Care Unit of the First Affiliated Hospital of Sun Yat-sen University from December 2013 to July 2015.Seventy-eight mechanically ventilated patients considered for VE were prospectively included and divided into a low-GEF （〈20%） and a near-normal-GEF （〉20%） group.Within each group,baseline hemodynamics,after PLR and after VE （250 ml 5% albumin over 30 min）,were recorded.PLR-induced hemodynamic changes （PLR-△） were calculated.Fluid responders were defined by a 15% increase of stroke volume （SV） after VE.Results：Twenty-five out of 38 patients were responders in the GEF 〈20% group,compared to 26 out of 40 patients in the GEF 〉20% group.The thresholds of PLR-△SV and PLR-△ cardiac output （PLR-△CO） for predicting fluid responsiveness were higher in the GEF 〉20% group than in the GEF 〈20% group （△SV：12% vs.8%;△CO：7% vs.6%）,with increased sensitivity （△SV：92% vs.92%;△CO：81% vs.80%） and specificity （△SV：86% vs.70%;△CO：86% vs.77%）,respectively PLR-△ heart rate could predict fluid responsiveness in the GEF 〉20% group with a threshold value of-5% （sensitivity 65%,specificity 93%） but could not in the GEF 〈20% group.The pressure index changes were poor predictors.Conclusions：In the critically ill patients on mechanical ventilation,the diagnostic value of PLR for predicting fluid responsiveness depends on cardiac systolic function.Thus,cardiac systolic function must be considered when using PLR.Trial Registration：Chinese Clinical Trial Register,ChiCTR-OCH-13004027;http：//www.chictr.org.cn/showproj.aspx？proj=5540.

Mandatory criteria for the application of variability-based parameters of fluid responsiveness: a prospective study in different groups of ICU patients

Background and objective： Stroke volume variation（SVV） has high sensitivity and specificity in predicting fluid responsiveness. However, sinus rhythm（SR） and controlled mechanical ventilation（CV） are mandatory for their application. Several studies suggest a limited applicability of SVV in intensive care unit（ICU） patients. We hypothesized that the applicability of SVV might be different over time and within certain subgroups of ICU patients. Therefore, we analysed the prevalence of SR and CV in ICU patients during the first 24 h of Pi CCO-monitoring（primary endpoint） and during the total ICU stay. We also investigated the applicability of SVV in the subgroups of patients with sepsis, cirrhosis, and acute pancreatitis. Methods： The prevalence of SR and CV was documented immediately before 1241 thermodilution measurements in 88 patients. Results： In all measurements, SVV was applicable in about 24%. However, the applicability of SVV was time-dependent： the prevalence of both SR and CV was higher during the first 24 h compared to measurements thereafter（36.1% vs. 21.9%; P0.001）. Within different subgroups, the applicability during the first 24 h of monitoring ranged between 0% in acute pancreatitis, 25.5% in liver failure, and 48.9% in patients without pancreatitis, liver failure, pneumonia or sepsis. Conclusions： The applicability of SVV in a predominantly medical ICU is only about 25%–35%. The prevalence of both mandatory criteria decreases over time during the ICU stay. Furthermore, the applicability is particularly low in patients with acute pancreatitis and liver failure.

Passive Leg Raising in Intensive Care Medicine

Fluid challenge is a common diagnostic method to help the physician detennine fluid responsiveness, which is an important component of fluid management in critically ill patients）H Raising legs of a patient induces the transfer of a variable amount of blood （approximately 200-300 ml） contained in the venous reservoir from the limb to central venous compartment. According to Franck-Starling curve, this transient increase of preload might lead to an increase in cardiac output （CO） in thture responders resulting from their preload-reserve status. Many clinical studies have validated passive leg raising （PLR）, and the advantage of PLR is attractive in Intensive Care Unit （ICU）. Recently, PER has been suggested as a simple and potential method to predict fluid responsiveness, which is similar to an ＂auto-fluid challenge＂ without a drop of fluid. However, one study revealed poor application of PLR in the real world, We acknowledged that the lack of education on PLR would result in the current practice. On the other hand, the application of PLR might be not simple in clinical practice, and the holy grail of fluid responsiveness still needs to be discovered. The standard of PLR has not been established, and some questions of PLR merit discussion.