Explore the vast range of titles available.

Background and Aims: Dynamic parameters such as the respiratory variation in aortic flow peak velocity (ΔVpeak) and inferior vena cava distensibility index (dIVC) are accurate indices of fluid responsiveness in adults. Little is known about their utility in children. We studied the ability of these indices to predict fluid responsiveness in anaesthetised and mechanically ventilated children. Methods: This prospective study was conducted in 42 children aged between one to 14 years scheduled for elective surgery under general endotracheal anaesthesia. Mechanical ventilation was initiated with a tidal volume of 10 ml/kg. ΔVpeak, dIVC and stroke volume index (SVI) were measured before and after volume expansion (VE) with 10 ml/kg of crystalloid using transthoracic echocardiography. Patients were considered to be responders (R) and non-responders (NR) when SVI increased to either ≥15% or <15% after VE. ΔVpeak and dIVC were analysed between R and NR. Results: The best cut-off value for ΔVpeak as defined by the receiver operator characteristics (ROC) curve analysis was 12.2%, for which sensitivity, specificity, positive predictive value and negative predictive value were 100%, 94%, 96% and 100%, respectively, the area under the curve was 0.975. The best cut-off value for dIVC as defined by the ROC curve analysis was 23.5%, for which sensitivity, specificity, positive predictive value and negative predictive value were 91%, 89%, 91% and 89%, respectively, the area under the curve was 0.95. Conclusion: ΔVpeak and dIVC are reliable indices of fluid responsiveness in children.

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-Δ) 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-ΔSV and PLR-Δ cardiac output (PLR-ΔCO) for predicting fluid responsiveness were higher in the GEF ≥20% group than in the GEF <20% group (ΔSV: 12% vs. 8%; ΔCO: 7% vs. 6%), with increased sensitivity (ΔSV: 92% vs. 92%; ΔCO: 81% vs. 80%) and specificity (ΔSV: 86% vs. 70%; ΔCO: 86% vs. 77%), respectively. PLR-Δ 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.

ABSTRACT Introduction: External volume expansion (EVE) is one method, which has been utilised for increasing the survival of adipose tissue grafts. EVE releases positive pressure from the graft and also induces intense levels of edema that decreases diffusion of metabolites essential for graft survival initially. The ideal timing of external volume expansion in relation to the injection of the fat to facilitate survival is not yet clear. Aims and Objectives: This study was undertaken to evaluate and compare the efficacy of external volume expansion applied at variable time points in relation to the injection of the fat. Materials and Methods: Athymic mouse was the animal model and human lipo-aspirate mixed with PRP was used as graft. An indigenous dome shaped silicone device was fabricated to deliver a negative pressure of -30 mm of Hg. The EVE was applied at variable time intervals. At the end of 4 weeks visual, histological and radiological features of the injected fat were compared. The adipose tissue was stained with human vimentin to ascertain the origin of the retained fat. Results: All the grafts, which had EVE, had significantly better volume retention and vascularity. The groups which underwent a delayed EVE or prior expansion followed by concomitant graft injection and expansion showed the most optimal vascularity and graft retention. Conclusions: A delayed EVE or prior expansion followed by concomitant graft injection and expansion may be the most ideal combinations to optimize graft take. However, on account of the relatively small sample size, there was a limitation in drawing statistically significant conclusions for certain variables.

Significant efforts are being made across academia and industry to better characterize lithium ion battery cells as reliance on the technology for applications ranging from green energy storage to electric mobility increases. The measurement of short-term and long-term volume expansion in lithium-ion battery cells is relevant for several reasons. For instance, expansion provides information about the quality and homogeneity of battery cells during charge and discharge cycles. Expansion also provides information about aging over the cell’s lifetime. Expansion measurements are useful for the evaluation of new materials and the improvement of end-of-line quality tests during cell production. These measurements may also indicate the safety of battery cells by aiding in predicting the state of charge and the state of health over the lifetime of the cell. Expansion measurements can also assess inhomogeneities on the electrodes, in addition to defects such as gas accumulation and lithium plating. In this review, we first establish the mechanisms through which reversible and irreversible volume expansion occur. We then explore the current state-of-the-art for both contact and noncontact measurements of volume expansion. This review compiles the existing literature on four approaches to contact measurement and eight noncontact measurement approaches. Finally, we discuss the different considerations when selecting an appropriate measurement technique.

Background Acute kidney injury (AKI) in the intensive care unit is associated with significant mortality and morbidity. Objectives To determine and update previous recommendations for the prevention of AKI, specifically the role of fluids, diuretics, inotropes, vasopressors/vasodilators, hormonal and nutritional interventions, sedatives, statins, remote ischaemic preconditioning and care bundles. Method A systematic search of the literature was performed for studies published between 1966 and March 2017 using these potential protective strategies in adult patients at risk of AKI. The following clinical conditions were considered: major surgery, critical illness, sepsis, shock, exposure to potentially nephrotoxic drugs and radiocontrast. Clinical endpoints included incidence or grade of AKI, the need for renal replacement therapy and mortality. Studies were graded according to the international GRADE system. Results We formulated 12 recommendations, 13 suggestions and seven best practice statements. The few strong recommendations with high-level evidence are mostly against the intervention in question (starches, low-dose dopamine, statins in cardiac surgery). Strong recommendations with lower-level evidence include controlled fluid resuscitation with crystalloids, avoiding fluid overload, titration of norepinephrine to a target MAP of 65–70 mmHg (unless chronic hypertension) and not using diuretics or levosimendan for kidney protection solely. Conclusion The results of recent randomised controlled trials have allowed the formulation of new recommendations and/or increase the strength of previous recommendations. On the other hand, in many domains the available evidence remains insufficient, resulting from the limited quality of the clinical trials and the poor reporting of kidney outcomes.

Purpose We performed a systematic review and meta-analysis of studies investigating the passive leg raising (PLR)-induced changes in cardiac output (CO) and in arterial pulse pressure (PP) as predictors of fluid responsiveness in adults. Methods MEDLINE, EMBASE and Cochrane Database were screened for relevant original and review articles. The meta-analysis determined the pooled area under the ROC curve, the sensitivity, specificity and threshold for the PLR test when assessed with CO and PP. Results Twenty-one studies (991 adult patients, 995 fluid challenges) were included. CO was measured by echocardiography in six studies, calibrated pulse contour analysis in six studies, bioreactance in four studies, oesophageal Doppler in three studies, transpulmonary thermodilution or pulmonary artery catheter in one study and suprasternal Doppler in one study. The pooled correlation between the PLR-induced and the fluid-induced changes in CO was 0.76 (0.73–0.80). For the PLR-induced changes in CO, the pooled sensitivity was 0.85 (0.81–0.88) and the pooled specificity was 0.91 (0.88–0.93). The area under the ROC curve was 0.95 ± 0.01. The best threshold was a PLR-induced increase in CO ≥10 ± 2 %. For the PLR-induced changes in PP (8 studies, 432 fluid challenges), the pooled sensitivity was 0.56 (0.49–0.53), the pooled specificity was 0.83 (0.77–0.88) and the pooled area under the ROC curve was 0.77 ± 0.05. Sensitivity and subgroup analysis were consistent with the primary analysis. Conclusions PLR-induced changes in CO very reliably predict the response of CO to volume expansion in adults with acute circulatory failure. When PLR effects are assessed by changes in PP, the specificity of the PLR test remains acceptable but its sensitivity is poor.

Background A passive leg raising (PLR) test is positive if the cardiac index (CI) increased by > 10%, but it requires a direct measurement of CI. On the oxygen saturation plethysmographic signal, the perfusion index (PI) is the ratio between the pulsatile and the non-pulsatile portions. We hypothesised that the changes in PI could predict a positive PLR test and thus preload responsiveness in a totally non-invasive way. Methods In patients with acute circulatory failure, we measured PI (Radical-7) and CI (PiCCO2) before and during a PLR test and, if decided, before and after volume expansion (500-mL saline). Results Three patients were excluded because the plethysmography signal was absent and 3 other ones because it was unstable. Eventually, 72 patients were analysed. In 34 patients with a positive PLR test (increase in CI ≥ 10%), CI and PI increased during PLR by 21 ± 10% and 54 ± 53%, respectively. In the 38 patients with a negative PLR test, PI did not significantly change during PLR. In 26 patients in whom volume expansion was performed, CI and PI increased by 28 ± 14% and 53 ± 63%, respectively. The correlation between the PI and CI changes for all interventions was significant ( r  = 0.64, p  < 0.001). During the PLR test, if PI increased by > 9%, a positive response of CI (≥ 10%) was diagnosed with a sensitivity of 91 (76–98%) and a specificity of 79 (63–90%) (area under the receiver operating characteristics curve 0.89 (0.80–0.95), p  < 0.0001). Conclusion An increase in PI during PLR by 9% accurately detects a positive response of the PLR test. Trial registration ID RCB 2016-A00959-42. Registered 27 June 2016.

During septic shock, fluid therapy is aimed at increasing cardiac output and improving tissue oxygenation, but it poses two problems: it has inconsistent and transient efficacy, and it has many well-documented deleterious effects. We suggest that there is a place for its personalization according to the patient characteristics and the clinical situation, at all stages of circulatory failure. Regarding the choice of fluid for volume expansion, isotonic saline induces hyperchloremic acidosis, but only for very large volumes administered. We suggest that balanced solutions should be reserved for patients who have already received large volumes and in whom the chloremia is rising. The initial volume expansion, intended to compensate for the constant hypovolaemia in the initial phase of septic shock, cannot be adapted to the patient’s weight only, as suggested by the Surviving Sepsis Campaign, but should also consider potential absolute hypovolemia induced by fluid losses. After the initial fluid infusion, preload responsiveness may rapidly disappear, and it should be assessed. The choice between tests used for this purpose depends on the presence or absence of mechanical ventilation, the monitoring in place and the risk of fluid accumulation. In non-intubated patients, the passive leg raising test and the mini-fluid challenge are suitable. In patients without cardiac output monitoring, tests like the tidal volume challenge, the passive leg raising test and the mini-fluid challenge can be used as they can be performed by measuring changes in pulse pressure variation, assessed through an arterial line. The mini-fluid challenge should not be repeated in patients who already received large volumes of fluids. The variables to assess fluid accumulation depend on the clinical condition. In acute respiratory distress syndrome, pulmonary arterial occlusion pressure, extravascular lung water and pulmonary vascular permeability index assess the risk of worsening alveolar oedema better than arterial oxygenation. In case of abdominal problems, the intra-abdominal pressure should be taken into account. Finally, fluid depletion in the de-escalation phase is considered in patients with significant fluid accumulation. Fluid removal can be guided by preload responsiveness testing, since haemodynamic deterioration is likely to occur in patients with a preload dependent state.

Background Plasma volume expansion is an important physiologic change across gestation. High or low expansion has been related to adverse pregnancy outcomes, yet there is a limited understanding of normal/healthy plasma volume expansion. We aimed to evaluate the pattern of plasma volume expansion across healthy pregnancies from longitudinal studies. Methods We conducted a systematic review and meta-analysis to identify original studies that measured plasma volume in singleton pregnancies of healthy women. Specifically, we included studies that measured plasma volume at least two times across gestation and one time before or after pregnancy in the same women. PubMed, Web of Science, Cochrane, CINAHL, and clinicaltrials.gov databases were searched from the beginning of each database to February 2019. We combined data across studies using a random effects model. Results Ten observational studies with a total of 347 pregnancies were eligible. Plasma volume increased by 6% (95% CI 3–9) in the first trimester compared to the nonpregnant state. In the second trimester, plasma volume was increased by 18% (95% CI 12–24) in gestational weeks 14–20 and 29% (95% CI 21–36) in weeks 21–27 above the nonpregnant state. In the third trimester, plasma volume was increased by 42% (95% CI 38–46) in weeks 28–34 and 48% (95% CI 44–51) in weeks 35–38. The highest rate of increase occurred in the first half of the second trimester. Included studies were rated from moderate to high quality; 7 out of 10 studies were conducted over 30 years ago. Conclusions In healthy pregnancies, plasma volume begins to expand in the first trimester, has the steepest rate of increase in the second trimester, and peaks late in the third trimester. The patterns observed from these studies may not reflect the current population, partly due to the changes in BMI over the last several decades. Additional longitudinal studies are needed to better characterize the range of normal plasma volume expansion across maternal characteristics.

Currently, silicon is considered among the foremost promising anode materials, due to its high capacity, abundant reserves, environmental friendliness, and low working potential. However, the huge volume changes in silicon anode materials can pulverize the material particles and result in the shedding of active materials and the continual rupturing of the solid electrolyte interface film, leading to a short cycle life and rapid capacity decay. Therefore, the practical application of silicon anode materials is hindered. However, carbon recombination may remedy this defect. In silicon/carbon composite anode materials, silicon provides ultra-high capacity, and carbon is used as a buffer, to relieve the volume expansion of silicon; thus, increasing the use of silicon-based anode materials. To ensure the future utilization of silicon as an anode material in lithium-ion batteries, this review considers the dampening effect on the volume expansion of silicon particles by the formation of carbon layers, cavities, and chemical bonds. Silicon-carbon composites are classified herein as coated core-shell structure, hollow core-shell structure, porous structure, and embedded structure. The above structures can adequately accommodate the Si volume expansion, buffer the mechanical stress, and ameliorate the interface/surface stability, with the potential for performance enhancement. Finally, a perspective on future studies on Si−C anodes is suggested. In the future, the rational design of high-capacity Si−C anodes for better lithium-ion batteries will narrow the gap between theoretical research and practical applications.