Non-Invasive Estimation of Plasma Sodium Concentration During Hemodialysis via Capacitively-Coupled Electrical Impedance Spectroscopy

This paper presents a compact, low-cost, and noninvasive system for real-time estimation of plasma sodium concentration ([Na]Pl) during a hemodialysis (HD) session with state-of-the-art accuracy. It is based on electrical impedance spectroscopy (EIS) performed with a capacitively-coupled impedance sensing cell and a high-frequency measurement device, both custom-built. The EIS data are processed to infer the resistance of the liquid inside the cell, which is used together with an optical hemoglobin sensor to estimate the [Na]Pl. Validation of the EIS was performed by estimating the conductivity of bloodmimicking fluid (BMF). The complete method was validated using whole bovine blood, comparing the results to those obtained with standard instruments. The system was able to estimate the [Na]Pl with sufficient accuracy (RMS error of 3.0 mol/m3 with respect to reference data) to provide clinically useful information. The proof-of-concept hardware can be converted to a cheap and compact circuit board for integration into an HD machine

In vitro determination of hemoglobin A1c for diabetes diagnosis and management: technology update

It is fascinating to consider the analytical improvements that have occurred since glycated hemoglobin was first used in routine clinical laboratories for diabetes monitoring around 1977; at that time methods displayed poor precision, there were no calibrators or material with assayed values for quality control purposes. This review outlines the major improvements in hemoglobin A1c (HbA1c) measurement that have occurred since its introduction, and reflects on the increased importance of this hemoglobin fraction in the monitoring of glycemic control. The use of HbA1c as a diagnostic tool is discussed in addition to its use in monitoring the patient with diabetes; the biochemistry of HbA1c formation is described, and how these changes to the hemoglobin molecule have been used to develop methods to measure this fraction. Standardization of HbA1c is described in detail; the development of the IFCC Reference Measurement Procedure for HbA1c has enabled global standardization to be achieved which has allowed global targets to be set for glycemic control and diagnosis. The importance of factors that may interfere in the measurement of HbA1c are highlighted

A wearable mechatronic device for extracorporeal blood ultrafiltration

The interest in the design of portable and wearable medical devices is related to both the relevant clinical and social benefits for patients and the potential economic savings for national health services. Biomedical technologies are improving at a very fast rate and represent an extraordinary means to develop innovative portable and wearable devices which can help people live in a prosperous way, in particular reducing sorrow in case of disease. This leads to a widespread effort to develop devices which can execute at home therapies that are usually performed in hospitals. This thesis presents a new wearable and portable device for extracorporeal blood ultrafiltration, named WUF (Wearable UltraFiltration device), able to remove excess fluids from fluid overload patients with chronic kidney disease and/or congestive heart failure. The design requirements that a modern wearable device for extracorporeal ultrafiltration must meet have been identified thanks to a thorough literature review on previous similar proposals followed by an extensive risk analysis. The design of the WUF prototype has faced several difficulties, ranging from the identification or conceivement of safe and reliable components to the design of a compact and neat layout. For most components it was possible to identify commercial (off-the-shelf) products meeting the requirements, nonetheless for some others, specific investigations, studies and developments were needed and led to the design of customized solutions or the formulation of original approaches. The design of an effective, efficient, safe and reliable control architecture, based on two microcontrollers and one microcomputer, the implementation of the control logic and of a graphical user interface have been carried out too being essential features of such a mechatronic device. A backpack/trolley design has been chosen as the layout for the device, since such a solution guarantees the best tradeoff between miniaturization and ergonomics. The design introduces an original positioning of the vast majority of components in three independent planar panels: one for disposable components, one for non-disposable devices and one for electronic boards and controllers. This arrangement of components can drastically simplify and speed up the in-hospital operations needed before and after a therapy with the WUF

Supra-physiological doses of testosterone affect membrane oxidation of human neutrophils monitored by the fluorescent probe C11-BODIPY581/591

The purpose of this study was to determine the effects of supra-physiological doses of testosterone (TES) on membrane oxidation of activated human neutrophils in vitro using an innovative and sensitive technique: the real-time detection with the fluorescence probe C11-BODIPY581/591. Methodological controls were performed with the lipid-soluble and powerful antioxidant astaxanthin at different neutrophil density cultures. Neutrophils from nine healthy young men (23.4 ± 2.5 years, 174.4 ± 7.0 cm height, and 78.3 ± 7.0 kg weight) were isolated and treated with 0.1 or 10 μM TES for 24 h and subsequently labeled with the free radical-sensitive probe C11-BODIPY581/591 for monitoring membrane oxidation after neutrophil activation with phorbol-12-myristate-13-acetate (PMA). First-order exponential decay kinetic indicated that both 0.1 and 10 μM TES severely increased baseline membrane oxidation in non-activated human neutrophils (compared to control). However, similar kinetics of membrane oxidation were observed in control and 0.1 μM TES-treated neutrophils after PMA activation, whereas chemical activation did not alter the baseline higher rates of membrane oxidation in 10 μM TES-treated neutrophils. The data presented here support the hypothesis that TES exerts distinct effects on the membrane oxidation of human neutrophils, depending on its dose (here, 102 to 104-fold higher than physiological levels in men) and on PMA activation of the oxidative burst. Furthermore, this paper also presents an innovative application of the free radical-sensitive probe C11-BODIPY581/591 for monitoring (auto-induced) membrane oxidation as an important parameter of viability and, thus, responsiveness of immune cells in inflammatory processes

Supra-physiological doses of testosterone affect membrane oxidation of human neutrophils monitored by the fluorescent probe C11-BODIPY581/591

The purpose of this study was to determine the effects of supra-physiological doses of testosterone (TES) on membrane oxidation of activated human neutrophils in vitro using an innovative and sensitive technique: the real-time detection with the fluorescence probe C11-BODIPY581/591. Methodological controls were performed with the lipid-soluble and powerful antioxidant astaxanthin at different neutrophil density cultures. Neutrophils from nine healthy young men (23.4 ± 2.5 years, 174.4 ± 7.0 cm height, and 78.3 ± 7.0 kg weight) were isolated and treated with 0.1 or 10 μM TES for 24 h and subsequently labeled with the free radical-sensitive probe C11-BODIPY581/591 for monitoring membrane oxidation after neutrophil activation with phorbol-12-myristate-13-acetate (PMA). First-order exponential decay kinetic indicated that both 0.1 and 10 μM TES severely increased baseline membrane oxidation in non-activated human neutrophils (compared to control). However, similar kinetics of membrane oxidation were observed in control and 0.1 μM TES-treated neutrophils after PMA activation, whereas chemical activation did not alter the baseline higher rates of membrane oxidation in 10 μM TES-treated neutrophils. The data presented here support the hypothesis that TES exerts distinct effects on the membrane oxidation of human neutrophils, depending on its dose (here, 102 to 104-fold higher than physiological levels in men) and on PMA activation of the oxidative burst. Furthermore, this paper also presents an innovative application of the free radical-sensitive probe C11-BODIPY581/591 for monitoring (auto-induced) membrane oxidation as an important parameter of viability and, thus, responsiveness of immune cells in inflammatory processes

Infections Related to the Use of Medical Devices and Changes in the Oropharyngeal Flora

Background: Humans exist in mutualistic balance with a large range of microbiota. Illness and hospitalization can disturb this balance and contribute to hospital-acquired infections (HAIs), which occur most often in critically ill patients. The use of medical devices such as central venous catheters (CVCs) and endotracheal tubes (ETTs) is essential in the care of critically ill patients. At the same time, they increase the risk of HAI by forcing or disrupting the normal barriers in the human body. All such devices eventually become colonized with microbes (usually normal flora), that form biofilms on the surface of the foreign material and subsequently lead to infection. The three types of devices related to the majority of HAIs in the intensive care unit are ETTs, urinary catheters, and CVCs.Aim: The present research was conducted to study: (i) changes in oropharyngeal microbial flora during hospitalization; (ii) compare biofilm formation on widely used ETTs with different surface properties and to explore factors potentially predictive of biofilm formation; (iii) the incidence of catheter-related infections and the impact of implementing a simple hygiene insertion bundle; (iiii) compare the blood compatibility of widely used CVCs.Paper I: In a clinical observational study, oropharyngeal cultures were collected from 487 individuals: 77 controls, 193 ward patients, and 217 critically ill patients. The results indicated that occurrence of an abnormal oropharyngeal flora is an early and frequent event in hospitalized patients, particularly the critically ill. Also, colonization with gut flora in the oropharynx was common in critically ill patients. Treatment with proton pump inhibitors was associated with colonization of gut flora in the oropharynx. The result of paper I reinforces the hypothesis that proton pump inhibitor use increases the risk of pneumonia by changing the oral flora, harboring gut bacteria which then may be micro aspirated into the lungs.Paper II: In a clinical observational study, biofilm formation on three widely used ETTs was compared in critically ill patients. Biofilm formation on the tubes was found to be an early and frequent event, and high-grade biofilm formation on the ETTs was associated with development of VAP. Compared to uncoated polyvinyl chloride (PVC) ETTs, silicone-coated and noble-metal-coated PVC ETTs were independently associated with reduced high-grade biofilm formation. Methods aimed at the continuous monitoring of biofilm formation are warranted. Routines for biofilm removal need further study.Paper III: This retrospective study compared the incidence of catheter-related infections and catheter-related bloodstream infections during a 2-year period starting 1 year before and ending 1 year after the implementation of a simple hygiene insertion bundle. A total of 1,722 catheter insertions were included. The incidence of catheter-related infections and catheter-related bloodstream infections in this Scandinavian cohort was low. Thus, it seems that the implementation of a simple hygiene insertion bundle was effective in reducing catheter-related infections. The use of multiple-lumen catheters was associated with increased risk of catheter-related infections.Paper IV: In an experimental study, the blood compatibility of three coated and three uncoated CVC materials was evaluated in a modified Chandler loop model imitating the flow of blood in a vein. When in contact with blood, all the tested catheters had some impact on blood cells, contact coagulation, the complement system, or inflammatory markers, although the effects varied significantly. A polyurethane catheter coated with chlorohexidine and silver sulfadiazine showed the most unfavorable blood compatibility profile. A silicone dialysis catheter exhibited the greatest variation in the blood compatibility tests. Poor blood compatibility could cause inflammation and facilitate the development of catheter-related thrombosis in patients receiving these central venous catheters, but clinical significance has to be studied further