Fluid Control with Hydrophobic Pillars in Paper-Based Microfluidics

Paper-based microfluidics has been widely used in chemical and medical analysis applications. In the conventional paper-based microfluidic approach, fluid is propagating inside the porous structure, and the flow direction of the fluid propagation is usually controlled with the pre-defined hydrophobic barrier (e.g. wax). However, the fluid propagation velocity inside the paper-based microfluidic devices largely depends on the material properties of paper and fluid, the relative control method is rarely reported. In this study, a fluid propagation velocity control method is proposed for paper-based microfluidics: hydrophobic pillar arrays with different configurations were deposited in the microchannels in paper-based microfluidics for flow speed control, result indicates the deposited hydrophobic pillar arrays can effectively slow down the fluid propagation at different levels and can be used to passively control the fluid propagation inside microchannels for paper-based microfluidics. For the demonstration of the proposed fluid control methods, a paper-based microfluidic device for nitrite test in water was also fabricated. The proposed fluid control method for paper-based microfluidics may have significant importance for applications that involve sequenced reactions and more actuate fluid manipulation.

Effects of the Combination of Auricular Acupressure and a Fluid-Restriction Adherence Program on Salivary Flow Rate, Xerostomia, Fluid Control, Interdialytic Weight Gain, and Diet-Related Quality of Life in Patients Undergoing Hemodialysis

Adherence to fluid-restriction is a clinical priority in nephrology care. This study examines the effects of a combination of auricular acupressure (AA) and a fluid-restriction adherence program on the salivary flow rate, xerostomia, fluid control, interdialytic weight gain (IDWG), and diet-related quality of life (DQOL) among hemodialysis patients in South Korea. Using a quasi-experimental design, 84 hemodialysis patients were assigned to the experimental group (AA + fluid-restriction adherence program; n = 29), the comparison group (fluid-restriction adherence program; n = 27), and the control group (usual care; n = 28). The program lasted 6 weeks, and data were collected at baseline, immediately after the intervention, and 4 months post-intervention. There was a significant interaction between group and time for salivary flow rate, fluid control, IDWG, and DQOL (all p < 0.005). Compared with the control group, the experimental group had a significantly improved salivary flow rate, fluid control, IDWG, and DQOL at weeks 6 and 22, whereas the comparison group had improved fluid control and DQOL at week 6. The combination of AA and a fluid-restriction adherence program could be provided to hemodialysis patients as cost-effective, safe, and complementary interventions to promote sustainable patient adherence to fluid-restriction.

The Role of Peritoneal Dialysis in the Treatment of Acute Kidney Injury in Patients With Acute-on-Chronic Liver Failure: A Prospective Brazilian Study

This study aimed to explore the role of peritoneal dialysis (PD) in acute-on-chronic liver disease (ACLD) in relation to metabolic and fluid control and outcome. Fifty-three patients were treated by PD (prescribed Kt/V = 0.40/session), with a flexible catheter, tidal modality, using a cycler and lactate as a buffer. The mean age was 64.8 ± 13.4 years, model of end stage liver disease (MELD) was 31 ± 6, 58.5% were in the intensive care unit, 58.5% needed intravenous inotropic agents including terlipressin, 69.5% were on mechanical ventilation, alcoholic liver disease was the main cause of cirrhosis and the main dialysis indications were uremia and hypervolemia. Blood urea and creatinine levels stabilized after four sessions at around 50 and 2.5 mg/dL, respectively. Negative fluid balance (FB) and ultrafiltration (UF) increased progressively and stabilized around 3.0 L and −2.7 L/day, respectively. Weekly-delivered Kt/V was 2.7 ± 0.37, and 71.7% of patients died. Five factors met the criteria for inclusion in the multivariable analysis. Logistic regression identified as risk factors associated with Acute Kidney Injury (AKI) in ACLD patients: MELD (OR = 1.14, CI 95% = 1.09–2.16, p = 0.001), nephrotoxic AKI (OR = 0.79, CI 95% = 0.61–0.93, p = 0.02), mechanical ventilation (OR = 1.49, CI 95% = 1.14–2.97, p &lt; 0.001), and positive fluid balance (FB) after two PD sessions (OR = 1.08, CI 95% = 1.03–1.91, p = 0.007). These factors were significantly associated with death. In conclusion, our study suggests that careful prescription may contribute to providing adequate treatment for most Acute-on-Chronic Liver Failure (ACLF) patients without contraindications for PD use, allowing adequate metabolic and fluid control, with no increase in the number of infectious or mechanical complications. MELD, mechanical complications and FB were factors associated with mortality, while nephrotoxic AKI was a protective factor. Further studies are needed to better investigate the role of PD in ACLF patients with AKI.

Using airflow-driven, evaporative gradients to improve sensitivity and fluid control in colorimetric paper-based assays

An airflow based, evaporative enrichment method for use in microfluidic paper-based assays. The method is used for fluid control in a multistep assay and as a technique to improve sensitivity in colorimetric detection assays.