At-home determination of 24-h urine sodium excretion: Validation of chloride test strips and multiple spot samples

Comparison of test strip, conductivity, and novel smartphone digital image colorimetry methods for field assessment of soil chloride and salinity

Understanding the extent of salt-affected soils is important in agriculture for irrigation, crop selection and land management, and affordable smartphone-based techniques can broaden access to environmental analysis in resource-limited settings. A novel smartphone-based Digital Image Colorimetry (DImC) technique using colorimetric chloride test strips has been developed and compared to 3 other field techniques (direct soil conductivity (Csoil), soil extract solution conductivity (Cext), titration test strips (TS)) and 1 lab-based method (chloride analyser (CA)) for the assessment of soil salinity. A survey of soils from a coastal saltmarsh and neighbouring farmland was conducted in Southwest Scotland and a rapid sample preparation method suitable for in-field use was evaluated. Comparison of each method with the reference method (CA) using correlation plots, Bland-Altman plots, and concordance correlation coefficients, showed that the accuracy and precision of the methods decreased in the order Cext > DImC ≃ TS > Csoil. The novel DImC method had good accuracy, although the limit of detection (LOD = 20.30 mg L-1) and precision was poorer than Cext. The analysis of field-wet soils enabled a rapid estimate of soil Cl- in approximately 6 minutes and spatially interpolated maps of soil Cl- concentration, prepared using smartphone location data, identified areas of elevated soil salinity. Each field analysis method had specific benefits, and the low cost, portability and lack of specialist equipment required for the DImC method demonstrated suitability for use in agriculture, citizen science or conservation settings where resources may be limited. The example presented demonstrates how smartphones may be used to broaden access to environmental analysis techniques.

Sodium Intake Estimation in Hospital Patients Using AI-Based Imaging: Prospective Pilot Study

BACKGROUND

Measurement of sodium intake in hospitalized patients is critical for their care. In this study, artificial intelligence (AI)-based imaging was performed to determine sodium intake in these patients.

OBJECTIVE

The applicability of a diet management system was evaluated using AI-based imaging to assess the sodium content of diets prescribed for hospitalized patients.

METHODS

Based on the information on the already investigated nutrients and quantity of food, consumed sodium was analyzed through photographs obtained before and after a meal. We used a hybrid model that first leveraged the capabilities of the You Only Look Once, version 4 (YOLOv4) architecture for the detection of food and dish areas in images. Following this initial detection, 2 distinct approaches were adopted for further classification: a custom ResNet-101 model and a hyperspectral imaging-based technique. These methodologies focused on accurate classification and estimation of the food quantity and sodium amount, respectively. The 24-hour urine sodium (UNa) value was measured as a reference for evaluating the sodium intake.

RESULTS

Results were analyzed using complete data from 25 participants out of the total 54 enrolled individuals. The median sodium intake calculated by the AI algorithm (AI-Na) was determined to be 2022.7 mg per day/person (adjusted by administered fluids). A significant correlation was observed between AI-Na and 24-hour UNa, while there was a notable disparity between them. A regression analysis, considering patient characteristics (eg, gender, age, renal function, the use of diuretics, and administered fluids) yielded a formula accounting for the interaction between AI-Na and 24-hour UNa. Consequently, it was concluded that AI-Na holds clinical significance in estimating salt intake for hospitalized patients using images without the need for 24-hour UNa measurements. The degree of correlation between AI-Na and 24-hour UNa was found to vary depending on the use of diuretics.

CONCLUSIONS

This study highlights the potential of AI-based imaging for determining sodium intake in hospitalized patients.

Pain associated with intravascular instrumentation reduces orthostatic tolerance and predisposes to vasovagal reactions in healthy young adults without needle phobia: a randomised controlled study

PURPOSE

Vasovagal syncope (VVS), or fainting, is frequently triggered by pain, fear, or emotional distress, especially with blood-injection-injury stimuli. We aimed to examine the impact of intravenous (IV) instrumentation on orthostatic tolerance (OT; fainting susceptibility) in healthy young adults. We hypothesized that pain associated with IV procedures would reduce OT.

METHODS

In this randomised, double-blind, placebo-controlled, cross-over study, participants (N = 23; 14 women; age 24.2 ± 4.4 years) underwent head-up tilt with combined lower body negative pressure to presyncope on three separate days: (1) IV cannulation with local anaesthetic cream (EMLA) (IV + EMLA); (2) IV cannulation with placebo cream (IV + Placebo); (3) sham IV cannulation with local anaesthetic cream (Sham + EMLA). Participants rated pain associated with IV procedures on a 1-5 scale. Cardiovascular (finger plethysmography and electrocardiogram; Finometer Pro), and forearm vascular resistance (FVR; brachial Doppler) responses were recorded continuously and non-invasively.

RESULTS

Compared to Sham + EMLA (27.8 ± 2.4 min), OT was reduced in IV + Placebo (23.0 ± 2.8 min; p = 0.026), but not in IV + EMLA (26.2 ± 2.2 min; p = 0.185). Pain was increased in IV + Placebo (2.8 ± 0.2) compared to IV + EMLA (2.0 ± 2.2; p = 0.002) and Sham + EMLA (1.1 ± 0.1; p < 0.001). Orthostatic heart rate responses were lower in IV + Placebo (84.4 ± 3.1 bpm) than IV + EMLA (87.3 ± 3.1 bpm; p = 0.007) and Sham + EMLA (87.7 ± 3.1 bpm; p = 0.001). Maximal FVR responses were reduced in IV + Placebo (+ 140.7 ± 19.0%) compared to IV + EMLA (+ 221.2 ± 25.9%; p < 0.001) and Sham + EMLA (+ 190.6 ± 17.0%; p = 0.017).

CONCLUSIONS

Pain plays a key role in predisposing to VVS following venipuncture, and our data suggest this effect is mediated through reduced capacity to achieve maximal sympathetic activation during orthostatic stress. Topical anaesthetics, such as EMLA, may reduce the frequency and severity of VVS during procedures requiring needles and intravascular instrumentation.

Electrochemical Sensing of Urinary Chloride Ion Concentration for Near Real-Time Monitoring

Urinary chloride concentration is a valuable health metric that can aid in the early detection of serious conditions, such as acid base disorders, acute heart failure, and incidences of acute renal failure in the intensive care unit. Physiologically, urinary chloride levels frequently change and are difficult to measure, involving time-consuming and inconvenient lab testing. Thus, near real-time simple sensors are needed to quickly provide actionable data to inform diagnostic and treatment decisions that affect health outcomes. Here, we introduce a chronopotentiometric sensor that utilizes commercially available screen-printed electrodes to accurately quantify clinically relevant chloride concentrations (5-250 mM) in seconds, with no added reagents or electrode surface modification. Initially, the sensor's performance was optimized through the proper selection of current density at a specific chloride concentration, using electrical response data in conjunction with scanning electron microscopy. We developed a unique swept current density algorithm to resolve the entire clinically relevant chloride concentration range, and the chloride sensors can be reliably reused for chloride concentrations less than 50 mM. Lastly, we explored the impact of pH, temperature, conductivity, and additional ions (i.e., artificial urine) on the sensor signal, in order to determine sensor feasibility in complex biological samples. This study provides a path for further development of a portable, near real-time sensor for the quantification of urinary chloride.

Development of semi-quantitative urinary sodium test strip

Excessive salt consumption has been associated with greater risk of hypertension. Therefore, monitoring of dietary sodium consumption should be prioritized. As sodium is mainly excreted through urine, 24-hours urine sample can be used to estimate individual sodium intake. Thus, a simple and inexpensive semi-quantitative urinary sodium detection test strip was developed based on the enzymatic reaction between β-galactosidase and chlorophenol red-β-D-galactopyranoside. When tested, colour formation was distinguished at 0 M (chartreuse yellow), 0.05 M (sunflower), 0.1-0.15 M (mango tango), and 0.2-0.25 M (persimmon) sodium. Analysis from ImageJ showed a linear result (r² >0.9), low SD, and significant increase in magenta difference (p<0.01) between 0 M and 0.05-0.25 M sodium. Test strip can detect 0.03 M sodium at minimum but did not last for >2 days in adverse storage conditions (laboratory conditions, ∼80% relative humidity, 40°C, and direct light exposure) when stored in test strip bottles, and even shorter when exposed to the environment. The presence of urinary potassium, urea, and glucose did not affect test strip performance. Test strip produced comparable results to flame photometry with <15% variation when tested on overnight, random spot, and 24-hours urine samples. Overall, the developed test strip can be used to enzymatically semi-quantify 0.05-0.25 M sodium. Test strip was developed by using β-galactosidase and chlorophenol red-β-D-galactopyranoside for the enzymatic detection of urinary sodium. Test strip could perform urinary sodium monitoring by providing colour indicator based on the concentration of sodium tested in the urine sample at a quicker timing in comparison to current quantification methods. The developed test strip could be used by hypertensive and normotensive users conveniently and repeatably wherever and whenever possible without additional equipment. This article is protected by copyright. All rights reserved.

The effect of water temperature on orthostatic tolerance: a randomised crossover trial

Purpose

Bolus water drinking, at room temperature, has been shown to improve orthostatic tolerance (OT), probably via sympathetic activation; however, it is not clear whether the temperature of the water bolus modifies the effect on OT or the cardiovascular responses to orthostatic stress. The aim of this study was to assess whether differing water temperature of the water bolus would alter time to presyncope and/or cardiovascular parameters during incremental orthostatic stress.

Methods

Fourteen participants underwent three head-up tilt (HUT) tests with graded lower body negative pressure (LBNP) continued until presyncope. Fifteen minutes prior to each HUT, participants drank a 500 mL bolus of water which was randomised, in single-blind crossover fashion, to either room temperature water (20 °C) (ROOM), ice-cold water (0–3 °C) (COLD) or warm water (45 °C) (WARM). Cardiovascular parameters were monitored continuously.

Results

There was no significant difference in OT in the COLD (33 ± 3 min; p = 0.3321) and WARM (32 ± 3 min; p = 0.6764) conditions in comparison to the ROOM condition (31 ± 3 min). During the HUT tests, heart rate and cardiac output were significantly reduced (p < 0.0073), with significantly increased systolic blood pressure, stroke volume, cerebral blood flow velocity and total peripheral resistance (p < 0.0054), in the COLD compared to ROOM conditions.

Conclusions

In healthy controls, bolus cold water drinking results in favourable orthostatic cardiovascular responses during HUT/LBNP without significantly altering OT. Using a cold water bolus may result in additional benefits in patients with orthostatic intolerance above those conferred by bolus water at room temperature (by ameliorating orthostatic tachycardia and enhancing vascular resistance responses). Further research in patients with orthostatic intolerance is warranted.

Spot tests: past and present

Microchemistry, i.e., the chemistry performed at the scale of a microgram or less, has its roots in the late eighteenth and early nineteenth centuries. In the first half of the twentieth century a wide range of spot tests have been developed. For didactic reasons, they are still part of the curriculum of chemistry students. However, they are even highly important for applied analyses in conservation of cultural heritage, food science, forensic science, clinical and pharmacological sciences, geochemistry, and environmental sciences. Modern pregnancy tests, virus tests, etc. are the most recent examples of sophisticated spot tests. The present ChemTexts contribution aims to provide an overview of the past and present of this analytical methodology.

24-hour sodium and potassium excretion in the Americas: a systematic review and meta-analysis

Objective

To determine the 24-hour urinary sodium and potassium excretions in the Americas.

Methods

A systematic review and meta-analysis were performed seeking for studies conducted between 1990 and 2021 in adults living in any sovereign state of the Americas in Medline, Embase, Scopus, SciELO, and Lilacs. The search was first run on October 26^th, 2020 and was updated on December 15^th, 2021. Of 3 941 abstracts reviewed, 74 studies were included from 14 countries, 72 studies reporting urinary sodium (27 387 adults), and 42 studies reporting urinary potassium (19 610 adults) carried out between 1990 and 2020. Data were pooled using a random-effects meta-analysis model.

Results

Mean excretion was 157.29 mmol/24h (95% CI, 151.42-163.16) for sodium and 57.69 mmol/24h (95% CI, 53.35-62.03) for potassium. When only women were considered, mean excretion was 135.81 mmol/24h (95% CI, 130.37-141.25) for sodium and 51.73 mmol/24h (95% CI, 48.77-54.70) for potassium. In men, mean excretion was 169.39 mmol/24h (95% CI, 162.14-176.64) for sodium and 62.67 mmol/24h (95% CI, 55.41-69.93) for potassium. Mean sodium excretion was 150.09 mmol/24h (95% CI, 137.87-162.30) in the 1990s and 159.79 mmol/24h (95% CI, 151.63-167.95) in the 2010s. Mean potassium excretion was 58.64 mmol/24h (95% CI, 52.73-64.55) in the 1990s and 56.33 mmol/24/h (95% CI, 48.65-64.00) in the 2010s.

Conclusions

These findings suggest that sodium excretions are almost double the maximum level recommended by the World Health Organization and potassium excretions are 35% lower than the minimum requirement; therefore, major efforts to reduce sodium and to increase potassium intakes should be implemented.

Salt supplementation in the management of orthostatic intolerance: Vasovagal syncope and postural orthostatic tachycardia syndrome

Salt supplementation is a common non-pharmacological approach to the management of recurrent orthostatic syncope or presyncope, particularly for patients with vasovagal syncope (VVS) or postural orthostatic tachycardia syndrome (POTS), although there is limited consensus on the optimal dosage, formulation and duration of treatment. Accordingly, we reviewed the evidence for the use of salt supplementation to reduce susceptibility to syncope or presyncope in patients with VVS and POTS. We found that short-term (~3 months) salt supplementation improves susceptibility to VVS and associated symptoms, with little effect on supine blood pressure. In patients with VVS, salt supplementation is associated with increases in plasma volume, and an increase in the time taken to provoke a syncopal event during orthostatic tolerance testing, with smaller orthostatic heart rate increases, enhanced peripheral vascular responses to orthostatic stress, and improved cerebral autoregulation. Responses were most pronounced in those with a baseline sodium excretion <170 mmol/day. Salt supplementation also improved symptoms, plasma volume, and orthostatic responses in patients with POTS. Salt supplementation should be considered for individuals with recurrent and troublesome episodes of VVS or POTS without cardiovascular comorbidities, particularly if their typical urinary sodium excretion is low, and their supine blood pressure is not elevated. The efficacy of the response, in terms of the improvement in subjective and objective markers of orthostatic intolerance, and any potential deleterious effect on supine blood pressure, should be routinely monitored in individuals on high salt regimes.

Salt: The paradoxical philosopher's stone of autonomic medicine

Sodium chloride, or common table salt, for millennia has played a prominent role in human affairs. Salt is also a key molecule for regulating intravascular fluid volume in patients with orthostatic disorders. In this first article of a special issue of the journal focusing on salt and the autonomic nervous system, the historical and physiologic significance of salt is reviewed, highlighting its importance to society and to medicine. The relevance of salt both for civilization and for autonomic physiology penetrates into nearly every aspect of life and health. Replacing salt that has been depleted or administering salt to expand intravascular volume is considered standard treatment for patients with orthostatic hypotension and syndromes of orthostatic intolerance. The potential longterm effects of added salt, including effects unrelated to intravascular volume, have been insufficiently studied in patients with autonomic disorders. A salient concern is the potential increased risk of developing hypertension. Underappreciated aspects of salt include its ability to increase anxiety and through nonosmotic mechanisms to contribute to local tissue inflammation. Salt may be either salubrious or detrimental, or possibly both at the same time, depending on the clinical conditions. Reconciling these opposite effects in clinical practice requires weighing benefits against potential risks, assessing what is known alongside what is uncertain, and titrating treatment decisions to the particular needs of each individual patient.