Required Fluid Volume Research Articles

Analysis of Fluid Replacement in Two Fluidic Chambers for Oblique-Incidence Reflectivity Difference (OI-RD) Biosensor.

Optical biosensors have a significant impact on various aspects of our lives. In many applications of optical biosensors, fluidic chambers play a crucial role in facilitating controlled fluid delivery. It is essential to achieve complete liquid replacement in order to obtain accurate and reliable results. However, the configurations of fluidic chambers vary across different optical biosensors, resulting in diverse fluidic volumes and flow rates, and there are no standardized guidelines for liquid replacement. In this paper, we utilize COMSOL Multiphysics, a finite element analysis software, to investigate the optimal fluid volume required for two types of fluidic chambers in the context of the oblique-incidence reflectivity difference (OI-RD) biosensor. We found that the depth of the fluidic chamber is the most crucial factor influencing the required liquid volume, with the volume being a quadratic function of the depth. Additionally, the required fluid volume is also influenced by the positions on the substrate surface bearing samples, while the flow rate has no impact on the fluid volume.

Using a Fluid Resuscitation Algorithm to Reduce the Incidence of Abdominal Compartment Syndrome in the Burn Intensive Care Unit.

Patients with large burns must be carefully resuscitated to balance adequate tissue perfusion with the risk of end-organ damage. One devastating complication of overresuscitation is abdominal compartment syndrome. Reducing the volume of fluids given during resuscitation may reduce the incidence of abdominal compartment syndrome and improve outcomes. To determine whether decreasing fluid resuscitation volume in a burn center reduced the incidence of abdominal compartment syndrome. This retrospective cohort study involved all patients with severe burns (total body surface area ≥20%) who were admitted to a burn intensive care unit over 4 years (n = 166). Primary outcomes were required fluid volume, whether differences in the patient characteristics measured affected outcomes, rate of abdominal compartment syndrome, and incidence of abdominal hypertension. After the first 2 years, the Parkland fluid resuscitation algorithm was modified to decrease the volume goal, and patients were assessed for the incidence of abdominal compartment syndrome and related complications such as kidney failure, abdominal hypertension, and ventilator days. A total of 16% of patients resuscitated using the Parkland equation experienced abdominal compartment syndrome compared with 10% of patients resuscitated using the modified algorithm, a difference of 6 percentage points (P = .39). Average volume administered was 11.8 L using the Parkland formula and 9.4 L using the modified algorithm (P = .03). Despite a significant decrease in the amount of fluid administered, no significant difference was found in incidence of abdominal compartment syndrome or urine output. Matched prospective studies are needed to improve resuscitation care for patients with large burns.

Integrated Path Tracking Controller of Underground Articulated Vehicle Based on Nonlinear Model Predictive Control

This paper proposes an integrated path tracking controller for articulated vehicles. A nonlinear model-predictive control (NMPC)-based reference state tracker is designed as an upper-level controller to solve the vehicle’s longitudinal velocity and steering rate. A terminal cost is introduced into the NMPC to improve the controller’s stability. A lower-level controller is developed to translate upper-level solutions into vehicle actuators’ signals, including steering and driving controllers. The steering controller translates the steering rate into the linear velocity of the cylinder to calculate the required fluid volume and ultimately into the rotation speed of the steering motor. The neural network method is applied in the driving controller to ensure accuracy under different loadings. In order to investigate the effects of the path tracking controller, an articulated dump truck is adapted for the field tests by adding the steering-by-wire system and driving-by-wire system, respectively. Experimental verifications of the lower-level controller are performed. The results show that the controller can accurately satisfy the demand. Finally, the tracking performance of the integrated path tracking controller is analyzed experimentally under different reference velocities. The results indicate that tracking accuracy can be guaranteed.

Физиологические основы целенаправленной инфузионной терапии в кардиохирургии (обзор)

Goal-directed fluid therapy is a paradigm in perioperative medicine, which includes haemodynamic monitoring and individualized haemodynamic management in high-risk patients by means of fluid therapy. This approach has certain benefits compared with the traditional model of fluid therapy during the perioperative period of cardiac surgery. The required fluid volume can be hard to determine. Traditionally, fluid therapy was guided by static preload parameters, such as central venous pressure and pulmonary artery occlusion pressure, which failed to provide adequate precision. In opposition to static parameters, a number of dynamic indices and tests were developed to assess fluid responsiveness. The cornerstone of dynamic indices are cyclic preload changes due to intrathoracic pressure variations during mechanical ventilation. Dynamic tests are circulatory stress tests involving preload changes. The most frequently used tests are passive leg raise, fluid challenge test, and some others. However, in spite of their satisfactory predictive value, dynamic indices and tests have certain limitations, which must be taken into consideration. For instance, mechanical ventilation, sinus rhythm, intact thorax, and normal respiratory mechanics are obligatory conditions for applying dynamic indices. Thus, using dynamic indices can be difficult in cardiac surgery, making the search for new methods to overcome their limitations highly important.

Association between enterocyte injury and fluid balance in patients with septic shock: a post hoc exploratory analysis of a prospective observational study

BackgroundThe required fluid volume differs among patients with septic shock. Enterocyte injury caused by shock may increase the need for fluid by triggering a systematic inflammatory response or an ischemia-reperfusion injury in the presence of intestinal ischemia/necrosis. This study aimed to evaluate the association between enterocyte injury and positive fluid balance in patients with septic shock.MethodsThis study was a post hoc exploratory analysis of a prospective observational study that assessed the association between serum intestinal fatty acid-binding protein, a biomarker of enterocyte injury, and mortality in patients with septic shock. Intestinal fatty acid-binding protein levels were recorded on intensive care unit admission, and fluid balance was monitored from intensive care unit admission to Day 7. The association between intestinal fatty acid-binding protein levels at admission and the infusion balance during the early period after intensive care unit admission was evaluated. Multiple linear regression analysis, with adjustments for severity score and renal function, was performed.ResultsOverall, data of 57 patients were analyzed. Logarithmically transformed intestinal fatty acid-binding protein levels were significantly associated with cumulative fluid balance per body weight at 24 and 72 h post-intensive care unit admission both before (Pearson’s r = 0.490 [95% confidence interval: 0.263–0.666]; P < 0.001 and r = 0.479 [95% confidence interval: 0.240–0.664]; P < 0.001, respectively) and after (estimate, 14.4 [95% confidence interval: 4.1–24.7]; P = 0.007 and estimate, 26.9 [95% confidence interval: 11.0–42.7]; P = 0.001, respectively) adjusting for severity score and renal function.ConclusionsEnterocyte injury was significantly associated with cumulative fluid balance at 24 and 72 h post-intensive care unit admission. Enterocyte injury in patients with septic shock may be related to excessive fluid accumulation during the early period after intensive care unit admission.

Novel 1\u2009L polyethylene glycol-based bowel preparation (NER1006): proof of concept assessment versus standard 2\u2009L polyethylene glycol with ascorbate \u2013 a randomized, parallel group, phase 2, colonoscopist-blinded trial

BackgroundColonoscopy requires colon cleansing. For this, many polyethylene glycol (PEG)-based preparations still require a high preparation-volume intake. Using an increased osmotic load with ascorbate (Asc), five new low-volume PEG-based bowel preparations (LVPEG) were tested for clinical proof of concept.MethodsThis two-part, open-label study examined preparation-volumes of 1–1.25 L and total required fluid volumes of 2–3 L. Part 1, in healthy volunteers, used mean cumulative 24-h stool weight (target > 2750 g) to identify a lead candidate. Part 2 was endoscopist-blinded: patients undergoing screening colonoscopy were randomized before treatment with the selected lead, one of two variants of it, or the control 2 L PEG + Asc. Two primary endpoints were used for proof of concept demonstration: mean 24-h stool weight and bowel cleansing success (Harefield Cleansing Scale).ResultsA total of 120 subjects (30 per group) were enrolled/randomized 1:1:1:1 (max 40:60 gender ratio) per completed Part. In Part 1, LVPEG-3 achieved the largest mean stool weight (3399 g: P < 0.0001 vs target) and was selected for Part 2. In Part 2, stool weights exceeded the target, notably for LVPEG-4 (3215 g: P < 0.001), which achieved 100% cleansing success after a total required fluid intake of 2 L. The control achieved 90% cleansing success. Adverse events were few, gastrointestinal in nature and similar between groups.ConclusionsLVPEG-4 achieved a clinically useful combination of cleansing, safety/tolerability and low consumption volume: 1 L preparation + 1 L required additional fluid. Named NER1006, LVPEG-4 demonstrated clinical proof of concept and warrants further investigation.Trial registrationOctober 2012.Identifier: NCT01714466. EudraCT: 2012–003052-37The trial was prospectively registered.

Study on the methods and effect of creating artificial ascites in thermal ablation of liver or kidney tumors under ultrasonic guidance

Objective To evaluate the effect of artificial ascites under ultrasonic guidance in the thermal ablation of liver or kidney tumors, so as to provide basis for successfully creating artificial ascites, increasing the complete ablation rate of the tumors and reducing the damage of important organs. Methods Seven hundred and thirty-six patients with artificial ascites were performed under ultrasonic guidance during the thermal ablation of liver or kidney tumors and six hundred and seventy-nine patients were successfully performed. The success rate of creating artificial ascites at different sites, time requirement, the effect of ascites, puncture times were analyzed, while curative effect and complications were evaluated and summarized. Results The success rate of creating artificial ascites was 92.3%; the average time of creating artificial ascites was(9.1±1.3)minutes; the average puncture times was(1.1±0.2)times; complete ablation was 98.7%; the complication of ascites creation was 0.44%, minor complications after ablation was 6.20%, severe complications was 0.59%. The required fluid volume and success rates for the creation of artificial ascites in different sites were different. The volume of fluid needed was relatively high in the liver-gastric space, and the success rate was relatively low; the success rate of liver septum and liver-kidney crypts was the highest. Heat injury complications of the important organs such as gastrointestinal tract, esophagus, diaphragm near the liver or kidney tumors were 0. Conclusions The establishment of artificial ascites improves the local curative effect and reduces the complication of tumors ablation in difficult locations. The methods and effect of artificial ascites in different parts of liver or kidney are different. Key words: Ultrasonic guidance; Liver tumors; Kidney tumors; Thermal ablation; Artificial ascites

Colloids versus crystalloids for fluid resuscitation in critically ill people.

Colloids versus crystalloids for fluid resuscitation in critically ill people.

Application value of limited liquid resuscitation combined with continuous renal replacement therapy in treatment of severe acute pancreatitis companied with abdominal compartment syndrome

Objective To investigate the application value of limited liquid resuscitation combined with continuous renal replacement therapy (CRRT) in treatment of severe acute pancreatitis (SAP) companied with abdominal compartment syndrome (ACS). Methods The retrospective cohort study was adopted. The clinical data of 67 patients with SAP companied with ACS who were admitted to the Fuling Center Hospital of Chongqing from January 2005 to December 2014 were collected. Among 67 patients, 33 receiving conventional liquid resuscitation between January 2005 and December 2010 were allocated into the control group and 34 receiving limited liquid resuscitation combined with CRRT between January 2011 and December 2014 were allocated into the observation group. Observation indicators included: (1) required fluid volume and time of negative fluid balance in the 2 groups; (2) changes of pathological and physiological indicators after treatment in the 2 groups; (3) outcomes and prognosis of patients in the 2 groups. Measurement data with normal distribution were represented as ±s and comparison between groups was analyzed using t test. Count data were analyzed using the chi-square test. Repeated measurement data were analyzed by repeated measures ANOVA. Results (1) Required fluid volume and time of negative fluid balance in the 2 groups: required fluid volumes at 6, 24, 48 and 72 hours after resuscitation were (2 449±339)mL, (4 820±757)mL, (9 428±1 272)mL, (13 127±1 565)mL in the control group and (2 360±314)mL, (4 582±530)mL, (8 564±970)mL, (11 470±1 253)mL in the observation group, respectively, with a statistically significant difference in required fluid volume between the 2 groups (F=13.035, P 0.05), and there were significant differences in changing trends of CRP, IAP and oxygenation index between the 2 groups (F=4.009, 15.276, 14.959, P 0.05). (3) Outcomes and prognosis of patients in the 2 groups: numbers of patients with surgery, local complications and infection and duration of hospital stay were 11, 16, 14, (46±17)days in the control group and 4, 6, 6, (36±14)days in the observation group, respectively, with statistically significant differences between the 2 groups (χ2=4.484, 7.221, 4.910, t=2.433, P 0.05). Conclusion Limited liquid resuscitation combined with CRRT can effectively control IAP of patients with SAP companied with ACS and improve oxygenation index, meanwhile, it can also reduce number of patients with surgery, infection and local complications and duration of hospital stay. Key words: Severe acute pancreatitis; Abdominal compartment syndrome; Limited liquid resuscitation; Continuous renal replacement therapy

Effects of fluid resuscitation with synthetic colloids or crystalloids alone on shock reversal, fluid balance, and patient outcomes in patients with severe sepsis

To assess shock reversal and required fluid volumes in patients with septic shock. Prospective before and after study comparing three different treatment periods. Fifty-bed single-center surgical intensive care unit. Consecutive patients with severe sepsis. Fluid therapy directed at preset hemodynamic goals with hydroxyethyl starch (predominantly 6% hydroxyethyl starch 130/0.4) in the first period, 4% gelatin in the second period, and only crystalloids in the third period. Main outcome was time to shock reversal (serum lactate <2.2 mmol/L and discontinuation of vasopressor use). Hemodynamic goals were mean arterial pressure >70 mm Hg; ScvO2 <70%; central venous pressure >8 mm Hg. Safety outcomes were acute kidney injury defined by Risk, Injury, Failure, Loss, and End-stage kidney disease criteria and new need for renal replacement therapy. Hemodynamic measures, serum lactate, and creatinine were comparable at baseline in all study periods (hydroxyethyl starch n = 360, gelatin n = 352, only crystalloids n = 334). Severity scores, hospital length of stay, and intensive care unit or hospital mortality did not differ significantly among groups. All groups showed similar time to shock reversal. More fluid was needed over the first 4 days in the crystalloid group (fluid ratios 1.4:1 [crystalloids to hydroxyethyl starch] and 1.1:1 [crystalloids to gelatin]). After day 5, fluid balance was more negative in the crystalloid group. Hydroxyethyl starch and gelatin were independent risk factors for acute kidney injury (odds ratio, 95% confidence interval 2.55, 1.76-3.69 and 1.85, 1.31-2.62, respectively). Patients receiving synthetic colloids received significantly more allogeneic blood products. Shock reversal was achieved equally fast with synthetic colloids or crystalloids. Use of colloids resulted in only marginally lower required volumes of resuscitation fluid. Both low molecular weight hydroxyethyl starch and gelatin may impair renal function.

Review of a Fluid Resuscitation Protocol

Recent reviews of burn resuscitation have included the suggestion that "fluid creep" may be influenced by practitioner error. Our center uses a nursing-driven resuscitation protocol that permits titration of fluid based on hourly urine output, including the addition of colloid when patients fail to respond appropriately. The purpose of this study was to examine protocol compliance. We reviewed 140 patients (26 children) with burns of ≥20% TBSA who received protocol-directed resuscitation from 2005 to 2010. We compared each patient's actual hourly fluid infusion with that predicted by the protocol. Sixty-seven patients (48%) completed resuscitation using crystalloid alone, whereas 73 patients required colloid supplementation. Groups did not differ in age, gender, weight, or time from injury to admission. Patients requiring colloid had larger median total burns (33.0 vs 23.5% TBSA) and full-thickness burns (15.5 vs 4.5% TBSA) and more inhalation injuries (60.3 vs 28.4%; P < .001) than those who resuscitated with crystalloid alone. Because we included basic maintenance fluids in their regimen, patients had median predicted requirements of 5.4 ml/kg/%TBSA. Crystalloid-only patients required fluid volumes close to Parkland predictions (4.7 ml/kg/%TBSA), whereas patients who received colloid required more fluid than the predicted volume (7.5 ml/kg/%TBSA). However, the hourly difference between the predicted and received fluids was a median of only 1.0% (interquartile range: -6.1 to 11.1%) and did not differ between groups. Pediatric patients had greater calculated differences than adults. Crystalloid patients exhibited higher urine outputs than colloid patients until colloid was started, suggesting that early over-resuscitation did not contribute to fluid creep. Adherence to our protocol for burn shock resuscitation was excellent overall. Fluid creep exhibited by more seriously injured patients was not due to nurses' failure to follow the protocol. This review has illuminated some opportunities for practice improvement, possibly using a computerized decision support system.

Burn resuscitation with two doses of 4 mL/kg hypertonic saline dextran provides sustained fluid sparing: a 48-hour prospective study in conscious sheep.

The large fluid volumes usually required for burn resuscitation can be suppressed for 8 to 12 hours by intravenous infusion of 4 mL x kg(-1) hypertonic saline dextran (HSD) 1 hour after burn. We hypothesized that a double (8 mL x kg(-1)) dose of HSD or two repeated doses of 4 mL x kg(-1) could enhance or prolong the volume sparing. We produced a full-thickness flame burn covering 40% of the body surface on 18 anesthetized sheep. One hour after the burn, the animals were awake and resuscitated with either (1) lactated Ringer's solution (LR) only, (2) 8 mL x kg(-1) HSD followed by LR, or (3) 4 mL x kg(-1) HSD followed by LR, with a second dose of 4 mL x kg(-1) HSD administered when net fluid accumulation increased to 20 mL x kg(-1). For all regimens, infusion rates were adjusted to produce a urine output of 1 to 2 mL x kg(-1) x h(-1). Animals resuscitated with only LR required fluid volumes identical to that predicted by the Parkland formula for the first 12 hours. Infusion of 8 mL x kg(-1) HSD initially created a net fluid loss (urine output > infused volume), followed by a rebound fluid requirement eventually equaling that of animals treated with LR only. Animals treated with two separate doses of 4 mL x kg(-1) HSD generally did not experience a net fluid loss or a rebound fluid requirement. Also in the HSD x 2 group, peak and net fluid accumulation was less than that of the other two groups from 18 hours through 48 hours, although the difference was not significant. An initial 4 mL x kg(-1) dose of HSD reduces fluid requirements early after burn, and a second dose administered after an appropriate interval may prolong volume sparing through 48 hours. An 8 mL x kg(-1) continuously infused initial dose was without prolonged fluid sparing effect. The volume-sparing effect of HSD is thus dependent on all of the following: dose, dosing interval, and infusion rate.

Prevention of urinary calculi after paralytic poliomyelitis.

Urinary calculi after poliomyelitis are largely confined to long-term respirator patients. Prophylaxis of calculi can be effective if begun early in the paralyzing and immobilizing diseases. Proper positioning is required to prevent stasis of crystalline material in the genitourinary tract. Calcium intake of 500 to 700 mg. daily was achieved by limiting milk and milk products to the equivalent of one and one-half glasses. Having patients produce 1,500 to 2,000 ml, of urine daily is the hardest task in the prophylactic program. Placing fluid reservoirs, connected to self-service drinking tubes, next to each patient aided in attaining a high fluid intake. The medical problem of renal stones was discussed frequently in lay language with the patients as a group. Once the problem was understood by some of the patients, one or more usually prompted the rest to work toward the required fluid volumes. A program of prophylaxis of urinary calculi appears to be widely applicable.