Search Results (10)

Background: The increased hospital morbidity and mortality associated with hyponatremia is well recognized in the critically ill pediatric population. Neonates and infants exposed to vasopressin following cardiopulmonary bypass (CPB) may be at increased risk for hyponatremia. We aimed to determine the associated effect and potential risk factors leading to hyponatremia and sodium variability in the immediate postoperative period in neonates and infants up to 90 days of age exposed to vasopressin following surgery for congenital heart disease. Methods: This was a retrospective review of 75 consecutive patients at a single tertiary cardiac intensive care unit (CICU) from 2018 to 2020. Using mixed-effects linear regression, we compared sodium trends and variability between the groups who did and did not receive vasopressin. Results: While sodium levels fell in both groups, beyond the first postoperative day, the group exposed to vasopressin had a significantly increased fall in sodium relative to the control (p < 0.001). Vasopressin exposure was associated with increased within-day sodium variability on postoperative days one and two (p < 0.05). Total incidents of moderate to severe hyponatremia (sodium < 130 mmol/L) were higher in the vasopressin group but did not reach statistical significance. Age, volume of modified ultrafiltration, and total diuretic dose were not risk factors for either effect in this study. Conclusions: While all patients in this study appeared to be at risk of postoperative hyponatremia, cumulative vasopressin dose appeared to increase the risk for absolute hyponatremia as well as greater sodium variability within the early postoperative period. Full article

Introduction: Patients on chronic hemodialysis (HD) have significantly higher mortality compared with the general population. Cardiovascular (CV) disease is the primary reason for death in these patients. Suboptimal extracellular fluid management increases the CV risk of HD patients. We aimed to study the effect of visit-to-visit ultrafiltration volume (UV) variability on CV events and mortality in chronic HD patients. Patients and Methods: In our study, 173 chronic HD patients were included (median age: 63 ± 13 years; 53% men). Ultrafiltration volume (UV) variability was analyzed retrospectively for 24 months. The standard deviation (SD) and coefficient of variation (CV) were calculated using the indices of UV variability. CV is the SD divided by the mean. The obtained parameters were SD and CV of the UV: UVSD and UVCV. UV data during the observation period were recorded and used to calculate UV variability. Routine transthoracal echocardiography was performed. Results: Patients were divided into groups based on the median of UVSD, low-UVSD (<568 mL) and high-UVSD (≥568 mL) group; and also based on the median of UVCV, low- (<0.29) and high-UVCV (≥0.29) group. All-cause mortality was significantly higher in the high compared to the low-UVSD (21/84 vs. 9/89; p < 0.001) group. Similarly, mortality was higher in the high-UVCV group compared to the low-UVCV group (18/78 vs. 12/95; p = 0.005) after 24 months. Major adverse CV event (MACE) rates were also significantly higher in the high- compared to the low-UVSD group (20/84 vs. 8/89; p < 0.001). Similarly, the MACE rate was significantly higher in the high-UVCV group compared to the low-UVCV group (15/78 vs. 13/95; p = 0.029) after 24 months. There was no significant difference between the groups in CV mortality. UVSD correlated with parathormone (PTH) level (r = 0.416; p = 0.015), and UVCV with total cholesterol (r = 0.419; p = 0.015). Left ventricular end-diastolic diameter (LVEDD) and end-systolic diameter (LVESD) were higher in the high-UVCV group compared to the low-UVCV group (49.95 vs. 52.08; p = 0.013 and 32.19 vs. 34.13; p = 0.034). Conclusions: According to our results, high UVSD and UVCD are associated with increased all-cause mortality and MACE rates but not CV mortality in chronic HD patients. Cardiovascular changes caused by increased UF volume variability during HD may contribute to higher CV morbidity and mortality in these patients. Full article

Background. Cardiovascular (CV) diseases are the most common causes of morbidity and mortality in hemodialysis (HD) patients. We studied the effect of high visit-to-visit ultrafiltration (UF) variability on CV abnormalities in HD patients. Methods. Twenty-nine consecutive patients (age: 65.6 ± 10.4 years) were recruited. Samples for routine lab tests were drawn pre-HD for syndecan-1 (SDC-1) and endothelin-1 (ET-1) measurements pre-, mid- and post-HD. Applanation tonometry was performed pre-, mid- and post-HD. Visit-to-visit ultrafiltration volume variability (UVSD) was calculated as the standard deviation of the UF volume/dialysis session in the preceding 12 months. Echocardiography was performed post-HD. Results. Patients were divided into two groups based on the median of UVSD (500 mL). The average UF volume/HD was not different between the groups. Blood pressure (BP) values were similar. Pre-HD cfPWV (10.75 m/s) was lower in the high UVSD group (14.1 m/s, p = 0.03). In the high UVSD group, post-HD cfPWV (13.9 m/s) was higher than the pre-HD cfPWV (p < 0.05). Pre-HD ET-1 was lower in the high UVSD group (8.6 ± 3.9 vs. 10.8 ± 2.7 pg/mL, p < 0.05). Left ventricular end-diastolic diameter (LVEDD) and left ventricular mass index (LVMI) were higher in the high UVSD group (55.7 ± 7.3 vs. 51.0 ± 5.4 mm and 449.9 ± 180.5 vs. 350.3 ± 85.9 g/m², p < 0.005, respectively). Left ventricular ejection fraction (LVEF) was lower in the high UVSD group (53.5 vs. 60, p < 0.05). Conclusions. High UVSD was associated with increased left ventricular hypertrophy and dysfunction and decreased LVEF compared to low visit-to-visit UV variability despite similar UF volumes temporarily compensated by more elastic arteries. The observed abnormalities may increase CV risk. Full article

This comprehensive study looks at how operational conditions affect the performance of a novel seven-channel titania ceramic ultrafiltration membrane for the treatment of produced water. A full factorial design experiment (2³) was conducted to study the effect of the cross-flow operating factors on the membrane permeate flux decline and the overall permeate volume. Eleven experimental runs were performed for three important process operating variables: transmembrane pressure (TMP), crossflow velocity (CFV), and filtration time (FT). Steady final membrane fluxes and permeate volumes were recorded for each experimental run. Under the optimized conditions (1.5 bar, 1 m/s, and 2 h), the membrane performance index demonstrated an oil rejection rate of 99%, a flux of 297 L/m²·h (LMH), a 38% overall initial flux decline, and a total permeate volume of 8.14 L. The regression models used for the steady-state membrane permeate flux decline and overall permeate volume led to the highest goodness of fit to the experimental data with a correlation coefficient of 0.999. A Multiple Linear Regression method and an Artificial Neural Network approach were also employed to model the experimental membrane permeate flux decline and analyze the impact of the operating conditions on membrane performance. The predictions of the Gaussian regression and the Levenberg–Marquardt backpropagation method were validated with a determination coefficient of 99% and a Mean Square Error of 0.07. Full article

Autologous platelet-rich plasma (PRP) preparations are prepared at the point of care. Centrifugation cellular density separation sequesters a fresh unit of blood into three main fractions: a platelet-poor plasma (PPP) fraction, a stratum rich in platelets (platelet concentrate), and variable leukocyte bioformulation and erythrocyte fractions. The employment of autologous platelet concentrates facilitates the biological potential to accelerate and support numerous cellular activities that can lead to tissue repair, tissue regeneration, wound healing, and, ultimately, functional and structural repair. Normally, after PRP preparation, the PPP fraction is discarded. One of the less well-known but equally important features of PPP is that particular growth factors (GFs) are not abundantly present in PRP, as they reside outside of the platelet alpha granules. Precisely, insulin-like growth factor-1 (IGF-1) and hepatocyte growth factor (HGF) are mainly present in the PPP fraction. In addition to their roles as angiogenesis activators, these plasma-based GFs are also known to inhibit inflammation and fibrosis, and they promote keratinocyte migration and support tissue repair and wound healing. Additionally, PPP is known for the presence of exosomes and other macrovesicles, exerting cell–cell communication and cell signaling. Newly developed ultrafiltration technologies incorporate PPP processing methods by eliminating, in a fast and efficient manner, plasma water, cytokines, molecules, and plasma proteins with a molecular mass (weight) less than the pore size of the fibers. Consequently, a viable and viscous protein concentrate of functional total proteins, like fibrinogen, albumin, and alpha-2-macroglobulin is created. Consolidating a small volume of high platelet concentrate with a small volume of highly concentrated protein-rich PPP creates a protein-rich, platelet-rich plasma (PR-PRP) biological preparation. After the activation of proteins, mainly fibrinogen, the PR-PRP matrix retains and facilitates interactions between invading resident cells, like macrophages, fibroblast, and mesenchymal stem cells (MSCs), as well as the embedded concentrated PRP cells and molecules. The administered PR-PRP biologic will ultimately undergo fibrinolysis, leading to a sustained release of concentrated cells and molecules that have been retained in the PR-PRP matrix until the matrix is dissolved. We will discuss the unique biological and tissue reparative and regenerative properties of the PR-PRP matrix. Full article

In this study, a lab scale direct membrane filtration (DMF) system using ultrafiltration membranes was operated to compare synthetic and real wastewater to evaluate their membrane fouling propensity and the partitioning of organics and nutrients during concentration. For fouling prevention, cyclic operation was used which consisted of 90 s of filtration followed by 15 s of relaxation and backwashing conducted every 15 min. The system was tested at a high initial flux of 80 LMH (L/m²·h), and the trials were run until a 90% volume reduction was achieved for each batch. Both the synthetic and real wastewater showed similar fouling propensities and organic and nutrient partitioning. The synthetic and real wastewater had an average flux of 46.3 LMH and 28.5 LMH and an average total chemical oxygen demand rejection of 90.3% and 83.1% after 30 h of operation, respectively. The recovery of organics was similar in both influents, resulting in 65.5% and 64.0% of the total chemical oxygen demand concentrations in the concentrate stream for synthetic and real wastewaters, respectively. The total phosphorous and nitrogen concentrations were also similar in terms of rejection rates resulting in 85% and 78% for the synthetic and 89% and 65% for the fresh WWs, respectively. The comparison revealed that synthetic wastewater, though not identical to real wastewater, can serve as a surrogate in DMF studies. This will help to remove one of the key sources of variability in current DMF studies and will allow for more rapid development of DMF technology. Full article

Textile wastewater is a challenging area for treatment by membrane separation technology due to its complex structure and the presence of reactive components. Therefore, most of the conventional technologies appear incapable of offering satisfactory treatment for the effluents. This paper studies the application of activated carbon, carbon nanotubes, and graphene oxide base polymeric nanofiltration membranes (NF) in the textile industry, which usually produces large volumes of wastewater containing complex contaminants from its daily operation. Hence, it is accepted that NF membranes offer solutions to the problem. The primary performances of NF membranes have been examined in terms of dye rejection, salt rejection, permeate flux, and COD rejection. Some of the NF membranes achieved maximum separation of dye and salts while some attained higher flux. This is due to the large variability of the parameters of textile wastewater and the NF membranes selected. However, for all these attempts, the general issue of (bio)fouling represents a key barrier to full-scale industrial implementation. The low fouling tendency of NF membranes has lately gained substantial attention since they are an exciting addition to conventional technologies (i.e., adsorption, biological degradation, coagulation, and ultrafiltration). Polymers membrane blended with oxidized activated carbon, carbon nanotubes, and graphene oxide increased hydrophilicity, textile dyes, slat rejection, BSA rejection, antibacterial activity, and water flux enhancement from 60% to 100%. We present some nanocomposite membrane developments and demonstrate how they can be used to reduce textile dyes. In addition, the process of membrane fouling and the various approaches for preventing and controlling fouling are discussed. Full article

Background: Ceftolozane-tazobactam is a new antibiotic against multidrug-resistant pathogens such as Pseudomonas aeruginosas. Ceftolozane-tazobactam dosage is still uncertain in children, especially in those with renal impairment or undergoing continuous renal replacement therapy (CRRT). Methods: Evaluation of different ceftolozane-tazobactam dosing regimens in three critically ill children. Ceftolozane pharmacokinetics (PK) were characterized by obtaining the patient’s specific parameters by Bayesian estimation based on a population PK model. The clearance (CL) in patient C undergoing CRRT was estimated using the prefilter, postfilter, and ultrafiltrate concentrations simultaneously. Variables such as blood, dialysate, replacement, and ultrafiltrate flow rates, and hematocrit were integrated in the model. All PK analyses were performed using NONMEM v.7.4. Results: Patient A (8 months of age, 8.7 kg) with normal renal function received 40 mg/kg every 6 h: renal clearance (CL_R) was 0.88 L/h; volume of distribution (Vd) Vd₁ = 3.45 L, Vd₂ = 0.942 L; terminal halflife (t_1/2,β) = 3.51 h, dosing interval area under the drug concentration vs. time curve at steady-state (AUC_τ,SS) 397.73 mg × h × L⁻¹. Patient B (19 months of age, 11 kg) with eGFR of 22 mL/min/1.73 m² received 36 mg/kg every 8 h: CL_R = 0.27 L/h; Vd₁ = 1.13 L; Vd₂ = 1.36; t_1/2,β = 6.62 h; AUC_SS 1481.48 mg × h × L⁻¹. Patient C (9 months of age, 5.8 kg), with severe renal impairment undergoing CRRT received 30 mg/kg every 8 h: renal replacement therapy clearance (CL_RRT) 0.39 L/h; Vd_{1 =} 0.74 L; Vd₂₌ 1.17; t _{1/2,β =} 3.51 h; AUC_τ,SS 448.72 mg × h × L⁻¹. No adverse effects attributable to antibiotic treatment were observed. Conclusions: Our results suggest that a dose of 35 mg/kg every 8 h can be appropriate in critically ill septic children with multi-drug resistance Pseudomonas aeruginosa infections. A lower dose of 10 mg/kg every 8 h could be considered for children with severe AKI. For patients with CRRT and a high effluent rate, a dose of 30 mg/kg every 8 h can be considered. Full article

Technical lignins, typically obtained from the biorefining of lignocellulosic raw materials, represent a highly abundant natural aromatic feedstock with high potential in a sustainable economy scenario, especially considering the huge primary production volumes and the inherently renewable nature of this resource. One of the main drawbacks in their full exploitation is their high variability and heterogeneity in terms of chemical composition and molecular weight distribution. Within this context, the availability of effective and robust fractionation processes represents a key requirement for the effective valorization of lignin. In the present work, a multistep fractionation of two different well known technical lignins obtained from two distinct delignification processes (soda vs. kraft pulping) was described. A comprehensive approach combining solvent extraction in organic or aqueous medium with membrane-assisted ultrafiltration was developed in order to maximize the process versatility. The obtained lignin fractions were thoroughly characterized in terms of their chemical, physical, thermal, and structural properties, highlighting the ability of the proposed approach to deliver consistent and reproducible fractions of well-controlled and predictable characteristics, irrespective of their biomass origin. The results of this study demonstrate the versatility and the reliability of this integrated multistep fractionation method, which can be easily adapted to different solvent media using the same ultrafiltration membrane set up, thereby enhancing the potential applicability of this approach in an industrial scale-up perspective for a large variety of starting raw lignins. Full article

This work presents the effects of variable wall permeability on two-dimensional flow and heat transfer in a leaky narrow channel containing water-based nanoparticles. The nanofluid is absorbed through the walls with an exponential rate. This situation arises in reverse osmosis, ultrafiltration, and transpiration cooling in industry. The mathematical model is developed by using the continuity, momentum, and energy equations. Using stream function, the transport equations are reduced and solved by using regular perturbation method. The expressions for stream function and temperature distribution are established, which helps in finding the components of velocity, wall shear stress, and heat transfer rate inside the channel. The results show that velocity components, temperature, wall shear stress, and rate of heat transfer are minimum at the entrance region due to the reabsorption of fluid containing nanoparticles. Additionally, with increasing volume fraction of nanoparticles, the rate of heat transfer enhances at all positions inside the channel. Titanium dioxide (TiO ${}_2$ ) nanoparticles show higher wall shear stress compared to copper and alumina. The streamlines confirms that all the fluid is reabsorbed before reaching the exit region of the channel for high reabsorption. Full article