Prediction of plasma sodium changes in the acutely ill patients: the potential role of tissue sodium content.

BACKGROUND Rapid correction of dysnatremias can result in neurological complications. Therefore, various formulas are available to predict changes in plasma sodium concentration ([Na+]) after treatment, but these have been shown to be inaccurate. This could be explained by sodium acumulation in skin and muscle tissue, which is not explicitly considered in these formulas. We assessed the association between clinical and biochemical factors related to tissue sodium accumulation and the discrepancy between predicted and measured plasma [Na+]. METHODS We used data from an intensive care unit (ICU) cohort with complete data on sodium, potassium, and water balance. The predicted plasma [Na+] was calculated using the Barsoum-Levine (BL) and the Nguyen-Kurtz (NK) formula. We calculated the discrepancy between predicted and measured plasma sodium and fitted a linear mixed-effect model to investigate its association with factors related to tissue sodium accumulation. RESULTS We included 594 ICU days of sixty-three patients in our analysis. The mean plasma [Na+] at baseline was 147±6 mmol/L. The median (IQR) discrepancy between predicted and measured plasma [Na+] was 3.14 mmol/L (1.48, 5.55) and 3.53 mmol/L (1.81, 6.44) for the BL and NK formulas, respectively. For both formulas, estimated total body water (p=0.027), initial plasma [Na+] (p<0.001) and plasma [Na+] change (p<0.001) were associated with the discrepancy between predicted and measured plasma [Na+]. CONCLUSION In this ICU cohort, initial plasma [Na+], total body water, and plasma [Na+] changes, all factors that are related to tissue sodium accumulation, were associated with the inaccurateness of plasma [Na+] prediction

Pathophysiology, risk, diagnosis, and management of venous thrombosis in space: where are we now?

The recent incidental discovery of an asymptomatic venous thrombosis (VT) in the internal jugular vein of an astronaut on the International Space Station prompted a necessary, immediate response from the space medicine community. The European Space Agency formed a topical team to review the pathophysiology, risk and clinical presentation of venous thrombosis and the evaluation of its prevention, diagnosis, mitigation, and management strategies in spaceflight. In this article, we discuss the findings of the ESA VT Topical Team over its 2-year term, report the key gaps as we see them in the above areas which are hindering understanding VT in space. We provide research recommendations in a stepwise manner that build upon existing resources, and highlight the initial steps required to enable further evaluation of this newly identified pertinent medical risk

Pathophysiology, risk, diagnosis, and management of venous thrombosis in space: where are we now?

The recent incidental discovery of an asymptomatic venous thrombosis (VT) in the internal jugular vein of an astronaut on the International Space Station prompted a necessary, immediate response from the space medicine community. The European Space Agency formed a topical team to review the pathophysiology, risk and clinical presentation of venous thrombosis and the evaluation of its prevention, diagnosis, mitigation, and management strategies in spaceflight. In this article, we discuss the findings of the ESA VT Topical Team over its 2-year term, report the key gaps as we see them in the above areas which are hindering understanding VT in space. We provide research recommendations in a stepwise manner that build upon existing resources, and highlight the initial steps required to enable further evaluation of this newly identified pertinent medical risk

Role of salt intake in prevention of cardiovascular disease: controversies and challenges.

Strong evidence indicates that reduction of salt intake lowers blood pressure and reduces the risk of cardiovascular disease (CVD). The WHO has set a global target of reducing the population salt intake from the current level of approximately 10 g daily to 85 categories of food; many other developed countries are following the UK's lead. In developing countries where most of the salt is added by consumers, public health campaigns have a major role. Every country should adopt a coherent, workable strategy. Even a modest reduction in salt intake across the whole population can lead to a major improvement in public health and cost savings

Estimation of sodium and potassium intake: Current limitations and future perspectives

Globally, average dietary sodium intake is double the recommended amount, whereas potassium is often consumed in suboptimal amounts. High sodium diets are associated with increased cardiovascular and renal disease risk, while potassium may have protective properties. Consequently, patients at risk of cardiovascular and renal disease are urged to follow these recommendations, but dietary adherence is often low due to high sodium and low potassium content in processed foods. Adequate monitoring of intake is essential to guide dietary advice in clinical practice and can be used to investigate the relationship between intake and health outcomes. Daily sodium and potassium intake is often estimated with 24-h sodium and potassium excretion, but long-term balance studies demonstrate that this method lacks accuracy on an individual level. Dietary assessment tools and spot urine collections also exhibit poor performance when estimating individual sodium and potassium intake. Collection of multiple consecutive 24-h urines increases accuracy, but also patient burden. In this narrative review, we discuss current approaches to estimating dietary sodium and potassium intake. Additionally, we explore alternative methods that may improve test accuracy without increasing burden

Enhanced interstitial fluid drainage in the hippocampus of spontaneously hypertensive rats

Hypertension is associated with cognitive decline and various forms of dementia, including Alzheimer's disease. In animal models of hypertension, many of Alzheimer's disease characteristics are recapitulated, including brain atrophy, cognitive decline, amyloid beta accumulation and blood brain barrier dysfunction. Removal of amyloid beta and other waste products depends in part on clearance via the brain interstitial fluid (ISF). Here we studied the impact of hypertension on ISF drainage, using spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). At 8 months, high (500 kD) and low (3 kD) fluorescent molecular weight tracers released passively into the hippocampus showed a drastically enhanced spreading in SHR. Tracer spreading was inhomogeneous, with accumulation at ISF-CSF borders, around arteries, and towards the stratum lacunosum moleculare. These locations stained positively for the astrocyte marker GFAP, and aquaporin 4. Despite enhanced dispersion, clearance of tracers was not affected in SHR. In conclusion, these data indicate enhanced bulk flow of ISF in the hippocampus of hypertensive rats. ISF drains along astrocytes towards the cerebrospinal fluid compartment, which leads to sieving of high molecular weight solutes. Sieving may lead to a local increase in the concentration of waste products and potentially promotes the aggregation of amyloid beta

The kidney, volume homeostasis and osmoregulation in space: current perspective and knowledge gaps

Although we have sent humans into space for more than 50 years crucial questions regarding kidney physiology, volume regulation and osmoregulation remain unanswered. The complex interactions between the renin-angiotensin-aldosterone system, the sympathetic nervous system, osmoregulatory responses, glomerular function, tubular function, and environmental factors such as sodium and water intake, motion sickness and ambient temperature make it difficult to establish the exact effect of microgravity and the subsequent fluid shifts and muscle mass loss on these parameters. Unfortunately, not all responses to actual microgravity can be reproduced with head-down tilt bed rest studies, which complicates research on Earth. Better understanding of the effects of microgravity on kidney function, volume regulation and osmoregulation are needed with the advent of long-term deep space missions and planetary surface explorations during which orthostatic intolerance complaints or kidney stone formation can be life-threatening for astronauts. Galactic cosmic radiation may be a new threat to kidney function. In this review, we summarise and highlight the current understandings of the effects of microgravity on kidney function, volume regulation and osmoregulation and discuss knowledge gaps that future studies should address