Ultrasound measurements on the inferior vena cava by renal nursing staff for assessment and management of intravascular volume status in haemodialysis patients

Title: Ultrasound measurements on the inferior vena cava (IVC-US) by renal nursing staff for assessment and management of intravascular volume status in haemodialysis patients. Aims: The primary aim of this thesis was to provide evidence that renal nurses could safely and efficiently perform IVC-US on haemodialysis patients to obtain objective assessment of intravascular volume status and potentially reduce adverse events and morbidity. The secondary aims for this study were: (1) conduct a systematic literature review to identify evidence if renal nurses have previously used this method for intravascular volume assessment; (2) teach a renal nurse through a staged educational programme, guided by a medically trained ultrasonographer, a sonologist, to gain competency in ultrasound image acquisition and interpretation of the scans; (3) measure the prevalence of any form of intradialytic hypotension in a satellite haemodialysis clinic over a three-month period and (4) attain concurrent IVC-US and bioimpedance spectroscopy measurements on 30 patients during their haemodialysis treatment and to compare these findings with their intravascular volume status using the traditional clinical nursing assessment method. Materials and Methods: To achieve this primary aim, this thesis was separated into multiple phases. First, a systematic literature review of medical and nursing databases was performed to summarise the use of IVC-US in haemodialysis patients by renal nurses. The second phase involved a retrospective data analysis, where the prevalence rate of nurse-documented fluid related intradialytic hypotensive events was measured and a Generalised Estimating Equation (GEE) model was used to predict the likelihood of any form of intradialytic hypotension or postdialytic overhydration. In the next phase a four-step educational programme was developed in collaboration with an expert sonologist, guiding the renal nurse through the process of skill acquisition and accurate fluid assessment based on nurse-performed IVC-US scans. Following this phase, and after receiving theoretical training and performing 100 proctored scans, the renal nurse then performed 60 IVC-US scans independently, which were subsequently assessed by two sonologists, resulting in a cross-sectional interrater study, confirming competency. The final phase of the thesis consisted of a simulative pilot study, where 30 haemodialysis patients were assessed during three intradialytic moments of a single session on their intravascular volume status with IVC-US. Results: The systematic literature review revealed that there is a paucity of knowledge regarding renal nurses and IVC-US. The 3-month data analysis has shown that intradialytic hypotension (IDH) was still the most common adverse intradialytic event with 13.1% of all treatments affected. The renal nurse mastered the educational programme and was deemed competent by the experts. Finally, the simulative pilot study revealed that if IVC-US had been performed and indicated intravascular hypovolemia, patients had a 14-fold chance to experience subsequent IDH events. An algorithm using IVC-US combined with bioimpedance spectroscopy (BIS) and mean arterial pressure (MAP) revealed a sensitivity of 95% and a specificity of 100% for the prevention of IDH. Conclusions: This thesis demonstrates the obvious need for more objective and reliable fluid assessment methods in the haemodialysis population to improve clinical outcomes. Most importantly, it has been shown that renal nurses can master the skill to perform IVC-US and that IVC-US is a useful and reliable method of fluid assessment. Performing IVC-US is a transferrable skill and has potential to be preventative for intradialytic hypotension if added to the clinical fluid assessment routine by renal nurses. It has potential to change clinical practice and policy in future, but further research studies are needed to provide evidence for this

Residual renal function – How fast does the residual urine output function decline in the first year of haemodialysis? – A scoping review

Background: Haemodialysis is the most common treatment method in Australia for individuals requiring renal replacement therapy. Although it is known that the residual renal function in these patients has many advantages for their overall health outcomes and that the residual urine volume production is also declining over time, it is unknown how fast this functional decline occurs when patients are embarking on their first year on haemodialysis. Aim: This scoping review sought to determine if the functional decline in renal residual function in the first year of haemodialysis has been previously investigated, documented or quantified. Method: The scoping review was performed using variety of nursing and medical databases comprising MEDLINE, Embase, Web of Science and CINAHL Plus with Full Text. Results: The decline of renal residual function in patients on Peritoneal dialysis over the first year of treatment has previously been described, but not in detail for patients receiving haemodialysis. There is a paucity of knowledge how fast residual urine production can decline in patients receiving haemodialysis during their first year of treatment. A PRISMA checklist has been used to validate the results of this scoping review. Conclusions: The extended preservation of renal residual function in patients on haemodialysis is crucial for their survival and may have a positive impact on their quality of life. An observational study is needed to examine how fast the functional decrease of the residual urine production function within patients receiving haemodialysis generally occurs. This information could prove to be useful in the context of treatment goals and could inform clinical practice

Some stars fade quietly: Varied Supernova explosion outcomes and their effects on the multi-phase interstellar medium

We present results from galaxy evolution simulations with a mutiphase Interstellar medium (ISM), a mass resolution of $4$ M$_{\odot}$ and a spatial resolution of 0.5 pc. These simulations include a stellar feedback model that includes the resolved feedback from individual massive stars and accounts for heating from the far UV-field, non-equilibrium cooling and chemistry and photoionization. In the default setting, individual supernova (SN) remnants are realized as thermal injections of $10^{51}$ erg; this is our reference simulation WLM-fid. Among the remaining seven simulations, there are two runs where we vary this number by fixing the energy at $10^{50}$ erg and $10^{52}$ erg (WLM-1e50 and WLM-1e52, respectively). We carry out three variations with variable SN-energy based on the data of Sukhbold et al. (2016) (WLM-variable, WLM-variable-lin, and WLM-variable-stoch). We run two simulations where only 10 or 60 percent of stars explode as SNe with $10^{51}$ erg, while the remaining stars do not explode (WLM-60prob and WLM-10prob). We find that the variation in the SN-energy, based on the tables of Sukhbold et al. (2016), has only minor effects: the star formation rate changes by roughly a factor of two compared to the fiducial run, and the strength of the galactic outflows in mass and energy only decreases by roughly 30 percent, with typical values of $\eta_m \sim 0.1$ and $\eta_e \sim 0.05$ (measured at a height of 3 kpc after the hot wind is fully decoupled from the galactic ISM). In contrast, the increase and decrease in the canonical SN-energy has a clear impact on the phase structure, with loading factors that are at least 10 times lower/higher and a clear change in the phase structure. We conclude that these slight modulations are driven not by the minor change in SN-energy but rather by the stochasticity of whether or not an event occurs when variable SN-energies are applied.Comment: 21 Pages, 9 Figures, 2 Tables, comments welcome! Submitted to Ap

Can a renal nurse assess fluid status using ultrasound on the inferior vena cava? A cross-sectional interrater study: Ultrasound on the inferior vena cava

Introduction: Ultrasound of the inferior vena cava (IVC-US) has been used to estimate intravascular volume status and fluid removal during a hemodialysis session. Usually, renal nurses rely on other, imprecise methods to determine ultrafiltration. To date, no study has examined whether renal nurses can reliably perform ultrasound for volume assessment and for potential prevention of intradialytic hypotension. This pilot study aimed to determine if a renal nurse could master the skill of performing and correctly interpreting Point of Care Ultrasound on patients receiving hemodialysis. Methods: After receiving theoretical training and performing 100 training scans, a renal nurse performed 60 ultrasound scans on 10 patients. These were categorized by the nurse into hypovolemic, euvolemic, or hypervolemic through measurement of the maximal diameter and degree of collapse of the IVC. Scans were subsequently assessed for adequacy and quality by two sonologists, who were blinded to each other\u27s and the nurse\u27s results. Findings: The interrater reliability of 60 scans was good, with intraclass correlation 0.79 (95% confidence interval (CI) =0.63–0.87) and with a good interrater agreement for the following estimation of intravascular volume (Cohen\u27s weighted Kappa κw = 0.62), when comparing the nurse to an expert sonographer. Discussion: A renal nurse can reliably perform ultrasound of the IVC in hemodialysis patients, obtaining high quality scans for volume assessment of hemodialysis patients. This novel approach could be more routinely applied by other renal nurses to obtain objective measures of patient volume status in the dialysis setting

Magnetic buoyancy in simulated galactic discs with a realistic circum galactic medium

We present simulations of isolated disc galaxies in a realistic environment performed with the Tree-SPMHD-Code Gadget-3. Our simulations include a spherical circum-galactic medium (CGM) surrounding the galactic disc, motivated by observations and the results of cosmological simulations. We present three galactic models with different halo masses between 10e10 Msol and 10e12 Msol, and for each we use two different approaches to seed the magnetic field, as well as a control simulation without a magnetic field. We find that the amplification of the magnetic field in the centre of the disc leads to a biconical magnetic outflow of gas that magnetizes the CGM. This biconical magnetic outflow reduces the star formation rate (SFR) of the galaxy by roughly 40 percent compared to the simulations without magnetic fields. As the key aspect of our simulations, we find that small scale turbulent motion of the gas in the disc leads to the amplification of the magnetic field up to tens of 10e-6 G, as long as the magnetic field strength is low. For stronger magnetic fields turbulent motion does not lead to significant amplification but is replaced by an alpha-omega dynamo. The occurance of a small scale turbulent dynamo becomes apparent through the magnetic power spectrum and analysis of the field lines' curvature. In accordance with recent observations we find an anti-correlation between the spiral structure in the gas density and in the magnetic field due to a diffusion term added to the induction equation.Comment: 22 pages, 16 figures, submitted to MNRA

“Machine-Dependent”: The lived experiences of patients receiving hemodialysis in Pakistan

This study aimed to explore the lived experiences of patients receiving maintenance hemodialysis in Pakistan. Purposive sampling was used to recruit 24 patients and six healthcare professionals, each participated in a semi-structured interview. Interpretive Phenomenological Analysis was used to analyze interviews’ data. Two superordinate themes, “The experience of hemodialysis” and “The conceptualizations of hemodialysis” as well as six sub-themes were identified. The experience of hemodialysis was related to, the implications of HD procedure on everyday life, social, cognitive, emotional, financial, and occupational influences. While all participants recognized the importance of hemodialysis for their survival, their conceptualizations of the treatment varied. Despite facing multiple challenges, optimism and independence were observed among participants. Stigma related to hemodialysis, and role adaptation, which appear unique to the Pakistani context, highlight a need for tailored interventions designed to enhance and maintain the mental health of patients receiving hemodialysis in Pakistan

A formation mechanism for "Wrong Way" Radio Relics

Radio Relics are typically found to be arc-like regions of synchrotron emission in the outskirts of merging clusters. They typically show synchrotron spectra that steepen towards the cluster center, indicating that they are caused by relativistic electrons being accelerated at outwards traveling merger shocks. A number of radio relics break with this ideal picture and show morphologies that are bent the opposite way and spectral index distributions which do not follow expectations from the ideal picture. We propose that these "Wrong Way" Relics can form when an outwards travelling shock wave is bent inwards by an in-falling galaxy cluster or group. We test this in an ultra-high resolution zoom-in simulation of a massive galaxy cluster with an on-the-fly spectral Cosmic Ray model. This allows us to study not only the synchrotron emission at colliding shocks, but also their synchrotron spectra to adress the open question of relics with strongly varying spectral indices over the relic surface.Comment: 10 pages, 4 figures, submitted to ApJ. Comments welcome! arXiv admin note: text overlap with arXiv:2308.0044

CRESCENDO: An on-the-fly Fokker-Planck Solver for Spectral Cosmic Rays in Cosmological Simulations

Non-thermal emission from relativistic Cosmic Ray (CR) electrons gives insight into the strength and morphology of intra-cluster magnetic fields, as well as providing powerful tracers of structure formation shocks. Emission caused by CR protons on the other hand still challenges current observations and is therefore testing models of proton acceleration at intra-cluster shocks. Large-scale simulations including the effects of CRs have been difficult to achieve and have been mainly reduced to simulating an overall energy budget, or tracing CR populations in post-processing of simulation output and has often been done for either protons or electrons. We introduce CRESCENDO: Cosmic Ray Evolution with SpeCtral Electrons aND prOtons, an efficient on-the-fly Fokker-Planck solver to evolve distributions of CR protons and electrons within every resolution element of our simulation. The solver accounts for CR (re-)acceleration at intra-cluster shocks, based on results of recent PIC simulations, adiabatic changes and radiative losses of electrons. We show its performance in test cases as well as idealized galaxy cluster (GC) simulations. We apply the model to an idealized GC merger following best-fit parameters for CIZA J2242.4+5301-1 and study CR injection, radio relic morphology, spectral steepening and synchrotron emission.Comment: 25 pages (21 main paper + 4 appendix), 17 figures. Submitted to MNRA