INFLUENCE OF PULSATILE CATHETER PUMP SYNCHRONIZATION ON HAEMODYNAMIC VARIABLES: NUMERICAL SIMULATION

Severe cardiovascular diseases can be treated using left ventricular assist devices (LVAD). One of the possible LVADs is the Pulsatile Catheter (PUCA) pump that consists of a hydraulically or pneumatically driven membrane pump connected to a valved catheter. In this work a numerical model of the cardiocirculatory system and of the PUCA have been developed in order to study their interaction. In the numerical simulator a pathological condition of the left ventricle has been reproduced and successively the effects of the PUCA on the haemodynamic variables applied were studied. Different functioning modes were tested by changing the ratio between the pump frequency and the heart beat rate (HR) as 1:1, 1:2 or 1:3 and by introducing a delay time between the cardiac and the PUCA cycle. The performance of the pump was evaluated in terms of cardiac output, PUCA and coronary flows and it was studied for different HR values. Results show a good resemblance between the model and literature data and indicate that different synchronization and timing can influence the functioning of the pump. In particular, the frequency ratio and the time delay of the pump cycle can contribute to optimize the performance of the PUCA

Influence of Pulsatile Catheter Pump Synchronization on Haemodynamic Variables: Numerical Simulation.

Severe cardiovascular diseases can be treated using left ventricular assist devices (LVAD). One of the possible LVADs is the Pulsatile Catheter (PUCA) pump that consists of a hydraulically or pneumatically driven membrane pump connected to a valved catheter. In this work a numerical model of the cardiocirculatory system and of the PUCA have been developed in order to study their interaction. In the numerical simulator a pathological condition of the left ventricle has been reproduced and successively the effects of the PUCA on the haemodynamic variables applied were studied. Different functioning modes were tested by changing the ratio between the pump frequency and the heart beat rate (HR) as 1:1, 1:2 or 1:3 and by introducing a delay time between the cardiac and the PUCA cycle. The performance of the pump was evaluated in terms of cardiac output, PUCA and coronary flows and it was studied for different HR values. Results show a good resemblance between the model and literature data and indicate that different synchronization and timing can influence the functioning of the pump. In particular, the frequency ratio and the time delay of the pump cycle can contribute to optimize the performance of the PUCA

Textile sensors to measure sweat pH and sweat-rate during exercise

Sweat analysis can provide a valuable insight into a person’s well-being. Here we present wearable textile-based sensors that can provide real-time information regarding sweat activity. A pH sensitive dye incorporated into a fabric fluidic system is used to determine sweat pH. To detect the onset of sweat activity a sweat rate sensor is incorporated into a textile substrate. The sensors are integrated into a waistband and controlled by a central unit with wireless connectivity. The use of such sensors for sweat analysis may provide valuable physiological information for applications in sports performance and also in healthcare

A gel-free approach in vascular smooth muscle cell proteome: perspectives for a better insight into activation

<p>Abstract</p> <p>Background</p> <p>The use of chromatography coupled with mass spectrometry (MS) analysis is a powerful approach to identify proteins, owing to its capacity to fractionate molecules according to different chemical features. The first protein expression map of vascular smooth muscle cells (VSMC) was published in 2001 and since then other papers have been produced. The most detailed two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) map was presented by Mayr et al who identified 235 proteins, corresponding to the 154 most abundant unique proteins in mouse aortic VSMC. A chromatographic approach aimed at fractionating the VSMC proteome has never been used before.</p> <p>Results</p> <p>This paper describes a strategy for the study of the VSMC proteome. Our approach was based on pre-fractionation with ion exchange chromatography coupled with matrix assisted laser desorption-time of flight mass spectrometry analysis assisted by a liquid chromatography (LC-MALDI-TOF/TOF). Ion exchange chromatography resulted in a good strategy designed to simplify the complexity of the cellular extract and to identify a large number of proteins. Selectivity based on the ion-exchange chemical features was adequate if evaluated on the basis of protein pI. The LC-MALDI approach proved to be highly reproducible and sensitive since we were able to identify up to 815 proteins with a concentration dynamic range of 7 orders of magnitude.</p> <p>Conclusions</p> <p>In our opinion, the large number of identified proteins and the promising quantitative reproducibility made this approach a powerful method to analyze complex protein mixtures in a high throughput way and to obtain statistical data for the discovery of key factors involved in VSMC activation and to analyze a label-free differential protein expression.</p

Relationship between Pre-Implant Interleukin-6 Levels, Inflammatory Response, and Early Outcome in Patients Supported by Left Ventricular Assist Device: A Prospective Study

Purpose: The immune response is crucial in the development of multi-organ failure (MOF) and complications in end-stage heart failure patients supported by left ventricular assist device (LVAD). However, at pre-implant, the association between inflammatory state and post-LVAD outcome is not yet clarified. Aim of the study was to assess the relationship among preimplant levels of immune-related cytokines, postoperative inflammatory response and 3-month outcome in LVAD-patients. Methods: In 41 patients undergoing LVAD implantation, plasma levels of interleukin (IL)-6, IL-8, crucial for monocyte modulation, and urine neopterin/creatinine ratio (Neo/Cr), marker of monocyte activation, were assessed preoperatively, at 3 days, 1 and 4 weeks post-LVAD. MOF was evaluated by total sequential organ failure assessment (tSOFA) score. Intensive care unit (ICU)-death and/or post-LVAD tSOFA $11 was considered as main adverse outcome. Length of ICU-stay, 1 weektSOFA score, hospitalisation and 3-month survival were considered additional end-points. Results: During ICU-stay, 8 patients died of MOF, while 8 of the survivors experienced severe MOF with postoperative tSOFA score$11. Pre-implant level of IL-6 $ 8.3 pg/mL was identified as significant marker of discrimination between patients with or without adverse outcome (OR 6.642, 95% CI 1.201-36.509, p = 0.030). Patients were divided according to pre-implant IL-6 cutoff of 8.3 pg/ml in A [3.5 (1.2-6.1) pg/mL] and B [24.6 (16.4-38.0) pg/mL] groups. Among pre-implant variables, only white blood cells count was independently associated with pre-implant IL-6 levels higher than 8.3 pg/ml (OR 1.491, 95% CI 1.004-2.217, p = 0.048). The ICU-stay and hospitalisation resulted longer in B-group (p = 0.001 and p = 0.030, respectively). Postoperatively, 1 week-tSOFA score, IL-8 and Neo/Cr levels were higher in B-group. Conclusions: LVAD-candidates with elevated pre-implant levels of IL-6 are associated, after intervention, to higher release of monocyte activation related-markers, a clue for the development of MOF, longer clinical course and poor outcome

VAD in failing Fontan: simulation of ventricular, cavo-pulmonary and biventricular assistance in systolic/diastolic ventricular dysfunction and in pulmonary vascular resistance increase.

Aim: Due to the lack of donors, VADs could be an alternative to heart transplantation for Failing Fontan patients (PTs). Considering the complex physiopathology and the type of VAD connection, a numerical model (NM) could be useful to support clinical decisions. The aim of this work is to test a NM simulating the VADs effects on failing Fontan for systolic dysfunction (SD), diastolic dysfunction (DD) and pulmonary vascular resistance increase (PRI). Methods: Data of 10 Fontan PTs were used to simulate the PTs baseline using a dedicated NM. Then, for each PTs a SD, a DD and a PRI were simulated. Finally, for each PT and for each pathology, the VADs implantation was simulated. Results: NM can well reproduce PTs baseline. In the case of SD, LVAD increases the cardiac output (CO) (35%) and the arterial systemic pressure (ASP) (25%). With cavo-pulmonary assistance (RVAD) a decrease of inferior vena cava pressure (IVCP) (39%) was observed with 34% increase of CO. With the BIVAD an increase of ASP (29%) and CO (37%) was observed. In the case of DD, the LVAD increases CO (42%), the RVAD decreases the IVCP. In the case of PRI, the highest CO (50%) and ASP (28%) increase is obtained with an RVAD together with the highest decrease of IVCP (53%). Conclusions: The use of NM could be helpful in this innovative field to evaluate the VADs implantation effects on specific PT to support PT and VAD selection

Phenotype Changes of Circulating Monocytes in a Hypercholesterolemic Swine Model of Coronary Artery Disease

Objective: Inflammation and immunity activation play a key role in atherosclerosis (ATS) onset and progression. Aim of this study was to investigate the relationships between phenotype of circulating monocytes and coronary artery disease (CAD) development in a histologically well-characterized swine model of ATS. Methods: Blood samples were obtained from 6 animals at baseline and after 16 weeks high fat cholesterolenriched diet. Flow cytometry monocyte identification was performed (CD172a marker). Adhesion (CD18a, CD11a, CD11R3, CD49d, CD29), differentiation (CD14) and activation receptors (SLA-DR, CD16, CD163) were quantified as percentage of positivity (%) and Relative Fluorescence Intensity (RFI). Lipid parameters (LDL, oxLDL, HDL) and soluble endothelial ICAM-1 were measured and histologic quantitative assessment of coronary ATS was performed. Results: Flow cytometry analysis demonstrated a significant post-diet decrease of CD14 RFI and an increment of % SLA-DR. Pre-diet values of ICAM-1 and % SLA-DR correlated reciprocally (P=0.0191) and with several CAD severity indexes (P≤0.02). Positive correlations between RFI changes of CD29 (P=0.0213) and CD18a (P=0.0341) and morphometric indexes of coronary ATS were found. Post-diet RFI values of CD29, CD18a and CD16 were also closely related to morphometric parameters (P<0.03). A cumulative post-diet tendency to increase of CD14low/ CD163high monocyte fraction (45.07 ± 2.27 vs. 40.14 ± 3.16) and a tight correlation between changes of this monocyte subset and corresponding HDL variations (P=0.0100) were also observed. Conclusions: Blood monocyte orientation towards a macrophage-like phenotype, similar to a HDL-induced maturation, and a close association between markers changes and severity of diet induced coronary ATS could provide new insights into plaque growth and progression in CAD

Determination of sevoflurane and isopropyl alcohol in exhaled breath by thermal desorption gas chromatography-mass spectrometry for exposure assessment of hospital staff

Volatile anaesthetics and disinfection chemicals pose ubiquitous inhalation and dermal exposure risks in hospital and clinic environments. This work demonstrates specific non-invasive breath biomonitoring methodology for assessing staff exposures to sevoflurane (SEV) anaesthetic, documenting its metabolite hexafluoroisopropanol (HFIP) and measuring exposures to isopropanol (IPA) dermal disinfection fluid. Methods are based on breath sample collection in Nalophan bags, followed by an aliquot transfer to adsorption tube, and subsequent analysis by thermal desorption gas chromatography-mass spectrometry (TD-GC-MS). Ambient levels of IPA were also monitored. These methods could be generalized to other common volatile chemicals found in medical environments. Calibration curves were linear (r2=0.999) in the investigated ranges: 0.01-1000ppbv for SEV, 0.02-1700ppbv for IPA, and 0.001-0.1ppbv for HFIP. The instrumental detection limit was 10pptv for IPA and 5pptv for SEV, both estimated by extracted ion-TIC chromatograms, whereas the HFIP minimum detectable concentration was 0.5pptv as estimated in SIM acquisition mode. The methods were applied to hospital staff working in operating rooms and clinics for blood draws. SEV and HFIP were present in all subjects at concentrations in the range of 0.7-18, and 0.002-0.024ppbv for SEV and HFIP respectively. Correlation between IPA ambient air and breath concentration confirmed the inhalation pathway of exposure (r=0.95, p&lt;0.001) and breath-borne IPA was measured as high as 1500ppbv. The methodology is easy to implement and valuable for screening exposures to common hospital chemicals. Although the overall exposures documented were generally below levels of health concern in this limited study, outliers were observed that indicate potential for acute exposures

Comparison of sampling bags for the analysis of volatile organic compounds in breath

Nalophan, Tedlar and Cali-5-Bond polymeric bags were compared to determine the most suitable type for breath sampling and storage when volatile organic compounds are to be determined. Analyses were performed by thermal desorption gas chromatography mass spectrometry. For each bag, the release of contaminants and the chemical stability of a gaseous standard mixture containing eighteen organic compounds, as well as the CO2 partial pressure were assessed. The selected compounds were representative of breath constituents and belonged to different chemical classes (i.e. hydrocarbons, ketones, aldehydes, aromatics, sulfurs and esters). In the case of Nalophan, the influence of the surface-to-volume ratio, related to the bag's filling degree, on the chemical stability was also evaluated. Nalophan bags were found to be the most suitable in terms of contaminants released during storage (only 2-methyl-1,3-dioxalane), good sample stability (up to 24 h for both dry and humid samples), and very limited costs (about 1 for a 20 liter bag). The (film) surface-to-(sample) volume ratio was found to be an important factor affecting the stability of selected compounds, and therefore we recommended to fill the bag completely

Determination of volatile organic compounds in exhaled breath of heart failure patients by needle trap micro-extraction coupled with gas chromatography-tandem mass spectrometry

The analytical performances of needle trap micro-extraction (NTME) coupled with gas chromatography tandem mass spectrometry were evaluated by analyzing a mixture of twenty-two representative breath VOCs belonging to different chemical classes (i.e. hydrocarbons, ketones, aldehydes, aromatics and sulfurs). NTME is an emerging technique that guarantees detection limits in pptv range by pre-concentrating low volumes of sample, and it is particularly suitable for breath analysis. For most VOCs, detection limits between 20 and 500 pptv were obtained by pre-concentrating 25 mL of a humidified standard gas mixture at a flow rate of 15 mL/min. For all compounds, inter- and intra-day precisions were always below 15%, confirming the reliability of the method. The procedure was successfully applied to the analysis of exhaled breath samples collected from forty heart failure patients during their stay in the University Hospital of Pisa. The majority of patients (about 80%) showed a significant decrease of breath acetone levels (a factor of 3 or higher) at discharge compared to admission (acute phase) in correspondence to the improved clinical conditions during hospitalization, thus making this compound eligible as a biomarker of heart failure exacerbation