Diagnostic accuracy of calculated serum osmolarity to predict dehydration in older people: adding value to pathology laboratory reports

Prevalence and risk factors associated with dehydration of patients with dysphagia in eastern China: A cross-sectional study

AIMS

Dehydration is one of the common complications of dysphagia and poses significant risks including hospitalization and mortality, but the relationship between dysphagia and dehydration has received little attention. This study aims to determine the prevalence and risk factors for dehydration of patients with dysphagia in eastern China, and to provide reference for early identification and prevention of dehydration.

METHODS

A descriptive, cross-sectional design was conducted. Three hundred and thirty-seven (n = 337) patients with dysphagia participated in the study between August and December 2022. Information relating to participants' demographic variables, nutrition, cognition, functional, hydration status and fluid intake was collected. Univariate analysis was used to examine related impact factors, and then binary logistic regression analysis was conducted to determine reliable impact factors.

RESULTS

Among 337 patients with dysphagia, the average age was 63.47 ± 16.96, most participants were male (72.1%) and married (91.7%). The prevalence of dehydration was calculated to be 43.9%, the mean plasma osmolality score was 293.53 mmol/L. Diseases with the highest prevalence were stroke (78.3%), followed by hypertension (63.5%). The risk for dehydration increased with older age, usage of more medicines such as diuretics and beta-blockers, worse functional status and lower fluid intake.

CONCLUSION

This study found a high percentage of dehydration in patients with dysphagia. Findings can provide a basis for targeted nursing interventions for clinical prevention and treatment of dehydration.

Methods of determining optimal cut-point of diagnostic biomarkers with application of clinical data in ROC analysis: an update review

INTRODUCTION

An important application of ROC analysis is the determination of the optimal cut-point for biomarkers in diagnostic studies. This comprehensive review provides a framework of cut-point election for biomarkers in diagnostic medicine.

METHODS

Several methods were proposed for the selection of optional cut-points. The validity and precision of the proposed methods were discussed and the clinical application of the methods was illustrated with a practical example of clinical diagnostic data of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and malondialdehyde (MDA) for prediction of inflammatory bowel disease (IBD) patients using the NCSS software.

RESULTS

Our results in the clinical data suggested that for CRP and MDA, the calculated cut-points of the Youden index, Euclidean index, Product and Union index methods were consistent in predicting IBD patients, while for ESR, only the Euclidean and Product methods yielded similar estimates. However, the diagnostic odds ratio (DOR) method provided more extreme values for the optimal cut-point for all biomarkers analyzed.

CONCLUSION

Overall, the four methods including the Youden index, Euclidean index, Product, and IU can produce quite similar optimal cut-points for binormal pairs with the same variance. The cut-point determined with the Youden index may not agree with the other three methods in the case of skewed distributions while DOR does not produce valid informative cut-points. Therefore, more extensive Monte Carlo simulation studies are needed to investigate the conditions of test result distributions that may lead to inconsistent findings in clinical diagnostics.

Hydration Status Assessment in Older Patients

BACKGROUND

Hydration disturbances are common in old age: the reported prevalence of dehydration in elderly patients ranges from 19% to 89%, depending on the definition and the population in question. However, the clinical assessment of patients' hydration status is difficult. In this review, we discuss the diagnostic value of currently used methods that may or may not be suitable for assessing older patients' hydration status.

METHODS

We conducted a selective literature search for relevant studies concerning patients aged 65 and above. Of the 355 articles retrieved by the initial search, a multistep selection process yielded 30 that were suitable for inclusion in this review.

RESULTS

107 different methods for the diagnostic assessment of dehydration in older persons were evaluated on the basis of the reviewed publications. High diagnostic value, especially for the determination of hyperosmolar dehydration, was found for serum osmolality, serum sodium concentration, inferior vena cava ultrasonography, a history (from the patient or another informant) of not drinking between meals, and axillary dryness. On the other hand, a variety of clinical signs such as a positive skin turgor test, sunken eyes, dry mouth, tachycardia, orthostatic dysregulation, and dark urine were found to be of inadequate diagnostic value.

CONCLUSION

Only five of the 107 methods considered appear to be suitable for determining that a patient is dehydrated. Thus, the available scientific evidence indicates that all clinicians should critically reconsider their own techniques for assessing hydration status in elderly patients. To optimize the clinical assessment of patients' hydration status, there seems to be a need for the rejection of unsuitable methods in favor of either newly developed criteria or of a combination of the best criteria already in use.

Low-intake dehydration and nutrition impact symptoms in older medical patients - A retrospective study

BACKGROUND AND AIMS

Malnutrition and low-intake dehydration both increase complications and mortality in hospitalized older medical patients. Nutrition Impact Symptoms (NIS) are barriers for obtaining an adequate nutritional intake and possibly adequate fluid. Therefore, we aimed to assess the prevalence of low-intake dehydration and specific NIS, and the relation between low-intake dehydration and specific NIS.

METHODS

A retrospective cohort study among older patients (≥65 years) from the Medical Department at Herlev-Gentofte Hospital and referred to a clinical dietitian. Data about sex, age, BMI, prevalence of nutritional risk (NRS-2002), low-intake dehydration (calculated osmolarity >295 mmol/L), and NIS (the EATEN-questionnaire, comprising 16 NIS-questions and whether these were respectively present and limiting nutritional intake) were collected from the hospital records.

RESULTS

We included 99 patients (61% women), mean age 81 years (±7.9), median BMI 21.8 kg/m2 (IQR:19.5-25.4). Nutritional risk was found in 74%, and low-intake dehydration in 40% of the included patients. The three most frequent NIS-present were: Early satiety (84%), no appetite (82%), and tiredness (72%). The three most frequent NIS-limiting intake were: No appetite (73%), early satiety (69%), and dry mouth (42%). We found low-intake dehydration to be related to a lower prevalence of the following NIS-present; dry mouth (58% vs.80%, p = 0.0210), and breathlessness (24% vs.49%, p = 0.0179). Among the NIS-limiting intake a lower prevalence of other pains was related to low-intake dehydration (7% vs.29%, p = 0.0233).

CONCLUSION

NIS and low-intake dehydration are highly prevalent in older patients. There is limited association between low-intake dehydration and specific NIS.

The association between malnutrition and dehydration in older adults admitted to a geriatric unit: An observational study

BACKGROUND AND AIM

There is an overlap between the risk factors causing low intake of water and low intake of nutrients, respectively. This study aims to explore the agreement between the assessment of malnutrition and the outcome of low-intake dehydration in a population of older hospitalized patients.

METHODS

Patients ≥65 years old and hospitalized at the geriatric hospital ward were screened for eligibility within 96 h of admission. Dehydration was assessed with the calculated serum osmolarity ≥295 mmol/L (1.86 × (Na+ + K+) + 1.15 × glucose + urea + 14), and (risk of) malnutrition was assessed with NRS-2002 ≥ 3 points, MNA-SF ≤ 7 points, MNA-LF < 17, MUST ≥ 2 points, and GLIM after screening with NRS-2002 and MNA-LF. Follow-up data regarding exercise rehabilitation, readmissions, and mortality was collected 30 days after discharge. Statistics used were the Chi-squared test, Fishers-exact test, and Wilcoxon signed rank test.

RESULTS

A total of 114 patients (57% females) were included. Median age 85.5 (IQR 80; 89.25) years. A total of 49 (43%) were dehydrated. Fewer females were dehydrated (F: 42.9% vs. M: 67.7%, p = 0.013). The patients with osmolarity ≥295 mmol/L had a higher median weight (68.3 (IQR 58.5; 78.4) vs. 62 (IQR 51.8; 72.1), p = 0.021) and mid-up-arm circumference (27 (IQR 26; 30) vs. 25.5 (IQR 22.9; 28.3), p = 0.004). No significant difference was found in the prevalence of malnutrition between those with or without dehydration (NRS-2002; 70% vs. 81%, p = 0.174; MNA-SF: 23.1 vs. 23.2%, p = 1.0; MNA-LF: 37.1 vs. 30.2%, p = 0.644; MUST: 24.5 vs. 33.8%, p = 0.308; GLIM after screening with NRS-2002: 84.4 vs. 74.5%, p = 0.405, GLIM after screening with MNA-LF: 74.1 vs. 75.6%, p = 0.438). Kappa values varied around 0 and reflected low agreement. There were no differences in the follow-up data, between those who were normohydrated and those who were dehydrated.

CONCLUSION

We found low agreement between the assessment of malnutrition and low-intake dehydration in a population of older hospitalized patients. All geriatric patients should therefore be assessed for both conditions.

Influence of Impaired Hydration Status on Postoperative in-Hospital Death in Patients with Acute Type A Aortic Dissection

Background

The hydration state of the body is getting more and more attention from researchers. The purpose of this study is to investigate the relationship between impaired hydration status and postoperative hospitalization death in patients with A AAD.

Methods

From January 2019 to October 2021, the clinical data of 299 patients undergoing A AAD surgery were retrospectively analyzed. Patients were divided into normal hydration group, imminent dehydration group and current dehydration group according to the dehydration standard at admission. Univariate and multivariate logistic regression analysis were used to determine the independent risk factors for in-hospital death of patients with A AAD.

Results

Postoperative in-hospital death in A AAD patients was significantly more common in the imminent and current dehydration groups (>295mmol/L) (26.7% vs 11.9%; P=0.001). The length of ICU stay was significantly longer in the impending and current dehydration groups (P<0.05). After controlling for other factors by multivariate logistic regression analysis, the results showed that the group of impending and current dehydration (>295) (OR=3.61, 95% confidence interval [CI]: 1.61-8.06; P=0.002), CRRT (OR=10.55, 95%[CI]: 3.59-31.01; P<0.001), lactic acid (OR=1.25, 95%[CI]: 1.13-1.38; P<0.001), CAD (OR=5.27, 95%[CI]: 1.12-24.80; P=0.035) was an independent risk factor for in-hospital death in A AAD patients. Albumin (OR=0.92, 95%[CI]: 0.85-0.99; P=0.040) is a protective factor.

Conclusion

The presence of high serum osmotic pressure on admission of A AAD patients can independently predict postoperative death, and the impaired body hydration status should be paid attention to.

Low-intake dehydration prevalence in non-hospitalised older adults: Systematic review and meta-analysis

BACKGROUND & AIMS

Low-intake dehydration amongst older people, caused by insufficient fluid intake, is associated with mortality, multiple long-term health conditions and hospitalisation. The prevalence of low-intake dehydration in older adults, and which groups are most at-risk, is unclear. We conducted a high-quality systematic review and meta-analysis, implementing an innovative methodology, to establish the prevalence of low-intake dehydration in older people (PROSPERO registration: CRD42021241252).

METHOD

We systematically searched Medline (Ovid), Cochrane CENTRAL, Embase (Ovid), CINAHL and Proquest from inception until April 2023 and Nutrition and Food Sciences until March 2021. We included studies that assessed hydration status for non-hospitalised participants aged ≥65 years, by directly-measured serum/plasma osmolality, calculated serum/plasma osmolarity and/or 24-h oral fluid intake. Inclusion, data extraction and risk of bias assessment was carried out independently in duplicate.

RESULTS

From 11,077 titles and abstracts, we included 61 (22,398 participants), including 44 in quality-effects meta-analysis. Meta-analysis suggested that 24% (95% CI: 0.07, 0.46) of older people were dehydrated (assessed using directly-measured osmolality >300 mOsm/kg, the most reliable measure). Subgroup analyses indicated that both long-term care residents (34%, 95% CI: 0.09, 0.61) and community-dwelling older adults (19%, 95% CI: 0.00, 0.48) were highly likely to be dehydrated. Those with more pre-existing illnesses (37%, 95% CI: 0.14, 0.62) had higher low-intake dehydration prevalence than others (15%, 95% CI: 0.00, 0.43), and there was a non-significant suggestion that those with renal impairment (42%, 95% CI: 0.23, 0.61) were more likely to be dehydrated than others (23%, 95% CI: 0.03, 0.47), but there were no clear differences in prevalence by age, sex, functional, cognitive or diabetic status. GRADE quality of evidence was low as to the exact prevalence due to high levels of heterogeneity between studies.

CONCLUSION

Quality-effects meta-analysis estimated that a quarter of non-hospitalised older people were dehydrated. Widely varying prevalence rates in individual studies, from both long-term care and community groups, highlight that dehydration is preventable amongst older people.

IMPLICATIONS

One in every 4 older adults has low-intake dehydration. As dehydration is serious and prevalent, research is needed to better understand drinking behaviour and assess effectiveness of drinking interventions for older people.

Hydration Status in Older Adults: Current Knowledge and Future Challenges

Adequate hydration is essential for the maintenance of health and physiological functions in humans. However, many older adults do not maintain adequate hydration, which is under-recognized and poorly managed. Older adults are more vulnerable to dehydration, especially those living with multiple chronic diseases. Dehydration is associated with adverse health outcomes in older adults, and acts as an independent factor of the hospital length of stay, readmission, intensive care, in-hospital mortality, and poor prognosis. Dehydration is a prevalent health problem in older adults, accounting for substantial economic and social burden. This review attempts to provide current knowledge of hydration including patterns of body water turnover, the complex mechanisms behind water homeostasis, the effects of dehydration on the health of the body, and practical guidance for low-intake dehydration in older adults.

Water intake, hydration status and 2-year changes in cognitive performance: a prospective cohort study

BACKGROUND

Water intake and hydration status have been suggested to impact cognition; however, longitudinal evidence is limited and often inconsistent. This study aimed to longitudinally assess the association between hydration status and water intake based on current recommendations, with changes in cognition in an older Spanish population at high cardiovascular disease risk.

METHODS

A prospective analysis was conducted of a cohort of 1957 adults (aged 55-75) with overweight/obesity (BMI between ≥ 27 and < 40 kg/m²) and metabolic syndrome from the PREDIMED-Plus study. Participants had completed bloodwork and validated, semiquantitative beverage and food frequency questionnaires at baseline, as well as an extensive neuropsychological battery of 8 validated tests at baseline and 2 years of follow-up. Hydration status was determined by serum osmolarity calculation and categorized as < 295 mmol/L (hydrated), 295-299.9 mmol/L (impending dehydration), and ≥ 300 mmol/L (dehydrated). Water intake was assessed as total drinking water intake and total water intake from food and beverages and according to EFSA recommendations. Global cognitive function was determined as a composite z-score summarizing individual participant results from all neuropsychological tests. Multivariable linear regression models were fitted to assess the associations between baseline hydration status and fluid intake, continuously and categorically, with 2-year changes in cognitive performance.

RESULTS

The mean baseline daily total water intake was 2871 ± 676 mL/day (2889 ± 677 mL/day in men; 2854 ± 674 mL/day in women), and 80.2% of participants met the ESFA reference values for an adequate intake. Serum osmolarity (mean 298 ± 24 mmol/L, range 263 to 347 mmol/L) indicated that 56% of participants were physiologically dehydrated. Lower physiological hydration status (i.e., greater serum osmolarity) was associated with a greater decline in global cognitive function z-score over a 2-year period (β: - 0.010; 95% CI - 0.017 to - 0.004, p-value = 0.002). No significant associations were observed between water intake from beverages and/or foods with 2-year changes in global cognitive function.

CONCLUSIONS

Reduced physiological hydration status was associated with greater reductions in global cognitive function over a 2-year period in older adults with metabolic syndrome and overweight or obesity. Future research assessing the impact of hydration on cognitive performance over a longer duration is needed.

TRIAL REGISTRATION

International Standard Randomized Controlled Trial Registry, ISRCTN89898870. Retrospectively registered on 24 July 2014.

Preoperative dehydration identified by serum calculated osmolarity is associated with severe frailty in patients with hip fracture

BACKGROUND & AIMS

Preoperative dehydration is a well-known predictor of in-hospital complications and poor functional outcomes in older patients with hip fractures. In an orthopedic and geriatric cooperative setting, we aimed to investigate whether preoperative dehydration was associated with frailty, prolonged hospital stays and short-term mortality in older patients with hip fractures.

METHODS

This retrospective cohort study was conducted in a Danish university hospital. The study population consisted of patients 65+ years surgically treated for hip fracture. Dehydration was defined as serum calculated osmolarity above 295 mmol/L. Outcomes were frailty at discharge measured by the Multidimensional Prognostic Index, hospital stay of 7 days or more and 90-day mortality.

RESULTS

In total, 214 patients were consecutively included in the study from March 11, 2018, to August 31, 2020. The mean age was 81.2 (SD: 7.6) and 69% of the patients were women. The prevalence of preoperative dehydration was 40%. It was associated with severe frailty (Odds Ratio (OR): 2.08 [95% confidence interval (CI): 1.11-3.90]; p = 0.02) and prolonged hospital stay (OR: 2.28 [95% CI: 1.29-4.04]; p = 0.02). Seven percent died when dehydrated compared to 5% in the non-dehydrated (p = 0.91).

CONCLUSION

Prevalence of preoperative dehydration is high among older patients with hip fractures and is associated with severe frailty and length of hospital stay. Systematic screening for dehydration on admission is advisable and may contribute to more adequate fluid management in the perioperative phase.

Lower hydration status increased diabetic retinopathy among middle-aged adults and older adults: Results from NHANES 2005-2008

Background

Diabetic retinopathy (DR) is a common complication of diabetic patients. Retinal physiological function is affected by hydration status. We aimed to explore the association between hydration status and DR.

Methods

National Health and Nutrition Examination Survey (NHANES) 2005-2008 was used to perform this cross-sectional study. Serum osmolality was used to assess hydration status for all participants and calculated osmolality was evaluated for only older people. DR and its severity were evaluated and graded into mild non-proliferative retinopathy, moderate/severe non-proliferative retinopathy, and proliferative diabetic retinopathy by the Early Treatment for Diabetic Retinopathy Study protocol and NHANES Digital Grading Protocol. Fully adjusted multivariable logistic regression models were used by SAS OnDemand for Academics.

Results

Among the 5,220 United States adults aged 40 or older, compared with the lowest osmolality group, participants with the highest quartile of serum osmolarity had higher odds of DR (OR: 1.371, 95% CI: 1.001-1.876). For participants with DR, the adjusted OR (95 % CI) of moderate/severe non-proliferative retinopathy and proliferative diabetic retinopathy in the higher serum osmolarity group was 2.119 (1.200-3.741) and 7.001 (3.175-15.438), respectively. Furthermore, in older people, higher calculated osmolarity was significantly associated with increased occurrence of DR (OR: 2.039, 95% CI: 1.305-3.186).

Conclusions

Adults with lower hydration status had higher risk of DR, moderate/severe non-proliferative retinopathy, and proliferative diabetic retinopathy. Dehydration in older adults, classified by calculated osmolality, is associated with a higher rate of DR. There was consistent trend in the results between the two methods.

Postoperative Dehydration Is Associated with Frailty and Decreased Survival in Older Patients with Hip Fracture

BACKGROUND

Hyperosmolar dehydration (HD) is a risk factor for severe complications in hip fracture in older patients. However, evidence for recommending screening of dehydration is insufficient and its relation with frailty and mortality is unclear. We tested the hypothesis that postoperative HD is associated with frailty and increased mortality.

METHODS

We recruited 625 older (>65 years) patients surgically treated for hip fracture and co-managed by an orthogeriatric team over one year in 2017. Pre- and postoperative HD (serum osmolarity > 300 mmol/L) was diagnosed. Frailty and associated mortality risk were assessed by the Multidimensional Prognostic Index (MPI).

RESULTS

The prevalence of preoperative HD was 20.4%. Compared with no-HD, MPI was similar in HD patients despite higher (p < 0.05) prevalence of polypharmacy, arterial hypertension, diabetes, chronic kidney disease and heart failure. After surgery the incidence of HD decreased to 16.5%, but increased (p = 0.003) in the MPI high-risk subgroup. Postoperative HD was associated with more complications and was an independent determinant of adjusted hospital length of stay (LOS) and of 60- to 365-days mortality.

CONCLUSIONS

Older frail patients with hip fracture are prone to developing postoperative HD, which independently predicts prolonged hospital LOS and mortality. Systematically screening older patients for frailty and dehydration is advisable to customize hydration management in high-risk individuals.

Predictors of short- and long-term mortality among acutely admitted older patients: role of inflammation and frailty

BACKGROUND

Frailty, demographic and clinical variables linked to incident diseases (e.g., dehydration, inflammation) contribute to poor outcomes in older patients acutely hospitalized. Their predictivity on short-, intermediate- and long-term mortality in a comprehensive model has been scarcely investigated.

AIMS

To test the performance of a predictive tool considering frailty and inflammation as well as age, sex and impaired hydration status on 1-year mortality in acutely admitted older patients.

METHODS

Retrospective observational study including 529 medical patients (age 84.6 ± 7.3 years). At hospital admission, frailty was assessed by the Multidimensional Prognostic Index (MPI). The Glasgow Prognostic Score (GPS) was used to grade systemic inflammation. Serum osmolarity was calculated to assess hydration.

RESULTS

After adjusting for age, sex, GPS and osmolarity, the severe-risk MPI was a strong predictor for 1-year mortality (OR 4.133; 95% CI 2.273-7.516; p < 0.001). Age > 85 years, male sex, GPS-2 and serum osmolarity > 300 mOsm/L were independent predictors of mortality in the same multivariable model. The MPI alone showed a moderate discrimination power (AUC 0.678; 95% CI 0.628-0.729; p < 0.001) on 1-year mortality, which increased by 12.5% after the addition of the above predictors in the fully adjusted regression model (AUC 0.763; 95% CI 0.719-0.807; p < 0.001). The severe-risk MPI adjusted for the same factors was also an independent predictor of mortality after 60 and 180 days since hospital admission.

DISCUSSION

Inflammation and impaired hydration are potentially modifiable risk factors for severe outcomes in older acutely hospitalized patients. A model combining GPS, age, gender, and plasma osmolarity improved the accuracy of MPI at admission in predicting long-term mortality.

Interventions to Improve Hydration in Older Adults: A Systematic Review and Meta-Analysis

Dehydration is common in the elderly, especially when hospitalised. This study investigated the impact of interventions to improve hydration in acutely unwell or institutionalised older adults for hydration and hydration linked events (constipation, falls, urinary tract infections) as well as patient satisfaction. Four databases were searched from inception to 13 May 2020 for studies of interventions to improve hydration. Nineteen studies (978 participants) were included and two studies (165 participants) were meta-analysed. Behavioural interventions were associated with a significant improvement in hydration. Environmental, multifaceted and nutritional interventions had mixed success. Meta-analysis indicated that groups receiving interventions to improve hydration consumed 300.93 mL more fluid per day than those in the usual care groups (95% CI: 289.27 mL, 312.59 mL; I² = 0%, p < 0.00001). Overall, there is limited evidence describing interventions to improve hydration in acutely unwell or institutionalised older adults. Behavioural interventions appear promising. High-quality studies using validated rather than subjective methods of assessing hydration are needed to determine effective interventions.

Impaired hydration status in acutely admitted older patients: prevalence and impact on mortality

BACKGROUND

impaired hydration is common in the older people, however studies of its effects on outcome in the acute setting are limited.

OBJECTIVES

to assess (i) the prevalence of impaired hydration, (ii) its relationship with laboratory markers of altered hydration and with (iii) short- and long-term mortality.

DESIGN

retrospective cohort study.

SETTING

University Hospital-Internal Medicine Department.

SUBJECTS

a total of 5,113 older patients consecutively acutely admitted from October 2015 to July 2016.

METHODS

according to calculated serum osmolarity at admission hydration status was stratified in: low osmolarity (<275 mmol/L), euhydration (275-295 mmol/L), impending (296-300 mmol/L) and current dehydration (>300 mmol/L). Relationships with serum sodium, potassium, glucose, urea, estimated glomerular filtration rate (eGFR), haematocrit, urea/creatinine ratio (Urea/Cr) and urine specific gravity (USG) were determined. Charlson Comorbidity Index, Modified Early Warning Score, Glasgow Prognostic Score, Norton score and Nutritional Risk Screening-2002 were calculated.

RESULTS

current and impending dehydration, euhydration and low-osmolarity were detected in 51.7, 17.1, 28.5 and 2.7% of the patients, respectively. Osmolarity correlated with urea (r = 0.846). Associations with serum sodium, creatinine, eGFR and urea/Cr were low but significant, being negligible that with USG and haematocrit. Serum sodium and urea increased in the transition from low- to high-osmolarity (P < 0.001 in all pairwise comparisons). In multivariate modelling current dehydration, functional dependence, clinical instability and high nutritional risk were associated (P < 0.001) with reduced short- and long-term survival.

CONCLUSIONS

impaired hydration is common in older people acutely admitted to medical care and is associated with poor outcome. Early assessment of calculated serum osmolarity is mandatory to target dehydration and hypoosmolar disorders.

The Effect of Medium-Term Sauna-Based Heat Acclimation (MPHA) on Thermophysiological and Plasma Volume Responses to Exercise Performed under Temperate Conditions in Elite Cross-Country Skiers

The influence of a series of ten sauna baths (MPHA) on thermophysiological and selected hematological responses in 14 elite cross-country skiers to a submaximal endurance exercise test performed under thermoneutral environmental conditions was studied. Thermal and physiological variables were measured before and after the exercise test, whereas selected hematological indices were studied before, immediately after, and during recovery after a run, before (T1) and after sauna baths (T2). MPHA did not influence the baseline internal, body, and skin temperatures. There was a decrease in the resting heart rate (HR: p = 0.001) and physiological strain (PSI: p = 0.052) after MPHA and a significant effect of MPHA on systolic blood pressure (p = 0.03), hematological indices, and an exercise effect but no combined effect of treatments and exercise on the tested variables. A positive correlation was reported between PSI and total protein (%ΔTP) in T2 and a negative between plasma volume (%ΔPV) and mean red cellular volume (%ΔMCV) in T1 and T2 in response to exercise and a positive one during recovery. This may suggest that MPHA has a weak influence on body temperatures but causes a moderate decrease in PSI and modifications of plasma volume restoration in response to exercise under temperate conditions in elite athletes.

Accuracy of the calculated serum osmolarity to screen for hyperosmolar dehydration in older hospitalised medical patients

BACKGROUND AND AIMS

Simple hyperosmolar dehydration, also termed water-loss dehydration (HD), is common in older hospitalised patients, thus increasing the risk of morbidity and mortality. Directly measured serum osmolality is the reference standard to determine HD; however, it is not a routine test due to its complexity and cost. Thus, a simple valid objective diagnostic tool to detect HD is needed. Consequently, we aimed to validate the agreement between measured s-osmolality (mOsm/kg) and calculated s-osmolarity (mOsm/L).

METHODS

Patients aged >65 were included from the emergency medical department at Herlev Hospital, Copenhagen, Denmark. Exclusion criteria were: eGFR< 30 mmol/L, severe heart failure, decompensated cirrhosis, alcohol intake or initiated rehydration treatment. We obtained data for measured s-osmolality as well as calculated osmolarity, using the by ESPEN recommended equation [1.86x (Na⁺ + K⁺)+1.15 ∗glucose + urea+14]. To determine accuracy, we used cut-off values of >295 mOsm/L versus >300 mOsm/kg.

RESULTS

A total of 90 patients (female 53%), age median 78 yrs (72-86 yrs) were included. According to the measured mOsm/kg, impending HD was evident in 32% (n = 10), of these 11% (n = 10) had current HD. There was a significant association between calculated mOsm/L and measured Osm/kg (r² = 0.7513, p < 0.0001). A sensitivity of 90% (95% CL: 56%-100%), a specificity of 68% (95% CL: 56%-78%), Positive predictive value (PPV) of 26% (95% CL: 12%-43%), and Negative predictive value (NPV) of 98% (95% CL: 90%-100%) were observed. Notably, only 20% (n = 2) of the patients who were dehydrated according to the measured Osm/kg were correctly clinically diagnosed with dehydration.

CONCLUSIONS

The equation recommended by ESPEN to calculate osmolarity was found to be an accurate objective diagnostic tool to assess HD in older hospitalised medical patients. The method is markedly superior to the current clinical practice.

Tear Osmolarity in the Diagnosis of Systemic Dehydration and Dry Eye Disease

Systemic dehydration due to inadequate water intake or excessive water loss, is common in the elderly and results in a high morbidity and significant mortality. Diagnosis is often overlooked and there is a need for a simple, bedside diagnostic test in at-risk populations. Body hydration is highly regulated with plasma osmolality (pOsm) being tightly controlled over a wide range of physiological conditions. By contrast, normal tear osmolarity (tOsm) is more variable since the tear film is exposed to evaporation from the open eye. While plasma hyperosmolality is a diagnostic feature of systemic dehydration, tear hyperosmolality, with other clinical features, is diagnostic of dry eye. Studies in young adults subjected to exercise and water-deprivation, have shown that tOsm may provide an index of pOsm, with the inference that it may provide a simple measure to diagnose systemic dehydration. However, since the prevalence of both dry eye and systemic dehydration increases with age, the finding of a raised tOsm in the elderly could imply the presence of either condition. This diagnostic difficulty can be overcome by measuring tear osmolality after a period of evaporative suppression (e.g., a 45 min period of lid closure) which drives tOsm osmolality down to a basal level, close to that of the pOsm. The arguments supporting the use of this basal tear osmolarity (BTO) in the diagnosis of systemic dehydration are reviewed here. Further studies are needed to confirm that the BTO can act as a surrogate for pOsm in both normally hydrated subjects and in patients with systemic dehydration and to determine the minimum period of lid closure required for a simple, "point-of-care" test.

A novel clinical nomogram for the evaluation of disorders of plasma osmolality

Disorders of water and sodium homeostasis in the human body—or dysnatraemias—are frequently encountered in clinical practice, but their analysis is often complex and their management is often troublesome. For many clinicians, it remains challenging to correctly interpret all relevant biochemical parameters involved in the analysis of dysnatraemia, especially when a rapid ‘bedside’ evaluation is required to initiate treatment. By mathematically deriving the relationship between plasma osmolality and urine osmolality under physiological circumstances, we were able to propose a novel and clinically useful nomogram for the rapid evaluation of disorders of plasma osmolality. We believe that the presented osmolality nomogram could be a transparent and clinically useful tool for the quick evaluation of disorders of the water and sodium balance in patients.

Factors associated with low-intake dehydration among older inpatients: A pilot study

OBJECTIVES

To assess fluid intake among older inpatients and factors associated with low-intake dehydration.

METHODS

Daily fluid intake and access were assessed within the 24-hour period, and blood was drawn to measure serum osmolality.

RESULTS

Of 89 patients, 16% and 27% had serum osmolality ≥ 300 (dehydrated) and 295-299 mOsm/kg (impending dehydration), respectively. Median (IQR) total fluid intake was 1.7 (1.6, 1.9) L/day. Fluid intake from beverages (P = .06) and water (P = .02) was higher in hydrated than impending/dehydrated patients. Of all fluid sources, only water intake was associated with hydration status (P = .02). The adjusted odds of serum osmolality ≥ 295 were increased for patients in the first (<0.3 L, P = .007) and second (0.3-0.8 L, P = .04) tertiles of water intake than those in the third tertile (≥0.8 L). Bladder control difficulty was associated with lower water intake (P = .03).

CONCLUSION

Monitoring water intake and assisting patients with bladder control difficulty may be key strategies to maintain hydration.

Fluid Intake Recommendation Considering the Physiological Adaptations of Adults Over 65 Years: A Critical Review

The aim of this critical review was to clarify recommended fluid intake for older people. A literature search of published articles and guidelines on fluid intake recommendations until April 2020 was carried out using PUBMED, Scopus, Cochrane, and Google Scholar. In this review, we focused on people over 65 years old at different care levels. The results show that the mean fluid intake ranges between 311 and 2390 mL/day. However, it is difficult to know whether this corresponds to the real pattern of fluid intake, due to the variability of data collection methods. With respect to the recommendations, most international organizations do not take into consideration the physiology of ageing or the health problems associated with an older population. In conclusions, we recommend to follow the guideline of the European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Food Safety Authority (EFSA). ESPEN is the only guideline which takes into account age. It is also based on EFSA recommendations. This authority takes into consideration all fluids consumed (ranging from food to fluids). If it is known that around 20% of all fluids consumed come from food, the result would effectively be that the EFSA recommends the same as the ESPEN guidelines: 1.6 L/day for females and 2.0 L/day for males. The findings could help raise the awareness of professionals in the sector with respect to the required fluid intake of the elderly and, in this way, contribute to avoiding the consequences of dehydration.

Critical evaluation of equations for serum osmolality: Proposals for effective clinical utility

BACKGROUND

Many studies have assessed the predictive accuracy of serum osmolality equations. Different approaches for selecting a usable equation were compared using thirty published equations and patient data from a regional hospital laboratory.

METHODS

Laboratory records were extracted with same-sample results for measured serum osmolality, sodium, potassium, urea and glucose analysed in a regional hospital laboratory between 1/1/2017-31/12/2018. Differences were analysed using Passing-Bablok and difference (Bland-Altman) analysis. Three approaches were compared: the shotgun approach, adjusting for bias, and deriving a novel equation using multivariate analysis. The criteria for success included bias ≤0.7%, a 230 - 400 mOsm/kg range, and osmolal gap (OG) 95% reference limits within ±10 mOsm/kg.

RESULTS

The majority of equations produced proportionally negative-biased results. The shotgun approach identified two equations (EQ19, EQ6) with bias ≤0.7% but unworkable OG reference limits. The bias adjustment approach produced several equations with bias ≤ 0.7% and OG reference limits within or equivalent to ±10 mOsm/kg. A novel equation generated by us (1.89Na⁺ + 1.71 K⁺ + 1.08 Urea + 1.08 Glucose + 13.7) improved with the adjustment of bias and was not superior to the adjusted published equations.

CONCLUSION

Few published equations are immediately usable. Adjustment of bias derives several usable equations of which the best had OG ranges <20 mOsm/kg. We conclude that adjustment of bias can generate equations of equal or superior performance to that of novel equations.

Increased rates of hypernatraemia during modest heatwaves in temperate climates

BACKGROUND

Hypernatraemia is associated with morbidity and mortality, particularly in the older person. Last summer, Ireland experienced prolonged periods of excessive heat. The Irish meteorological service defines a heatwave as temperatures exceeding 25°C for five consecutive days.

AIM

This study sought to compare the frequency of hypernatraemia (sodium (Na+) >145 mmol/l) observed during a modest heatwave with that during average ambient temperature in the temperate Irish climate.

DESIGN

Retrospective cross-sectional analysis with nested case-control study.

METHODS

The 10-day period from 24 June to 3 July in 2017 and 2018 were chosen as the control and heatwave periods, respectively. Patients aged >65 with at least one Na+ value recorded on the laboratory information system were included. Local meteorological data, age, gender and Na+ levels were evaluated.

RESULTS

Maximum air temperatures were significantly higher during the heatwave period (mean 27°C vs. 16.8°C, P < 0.0001). Hypernatraemia was present in 3.6% (66/1840) of samples collected during the heatwave compared to 1.4% (23/1593) in the control period. The mean age of affected patients was similar in both groups, 75 years ±7 (P = 1.000). Almost half of participants (49.5%) were male. The frequency of hypernatraemia observed was not influenced by gender, P = 0.33. The median sodium concentrations were similar in both groups, P = 1.00.

CONCLUSION

Hypernatraemia was 2.5 times more frequent in samples drawn during the heatwave compared to the control period. In this study, neither age nor gender impacted the profile of patients diagnosed with hypernatraemia. A modest rise in temperatures increases hypernatraemia rates in temperate climates.

Underhydration Is Associated with Obesity, Chronic Diseases, and Death Within 3 to 6 Years in the U.S. Population Aged 51-70 Years

Nationally representative data from the National Health and Nutrition Examination Survey (NHANES) indicate that over 65% of adults aged 51–70 years in the U.S. do not meet hydration criteria. They have hyponatremia (serum sodium < 135 mmol/L) and/or underhydration (serum sodium >145 mmol/L, spot urine volume <50 mL, and/or spot urine osmolality ≥500 mmol/kg). To explore potential public health implications of not meeting hydration criteria, data from the NHANES 2009–2012 and National Center for Health Statistics Linked Mortality Files for fasting adults aged 51–70 years (sample n = 1200) were used to determine if hyponatremia and/or underhydration were cross-sectionally associated with chronic health conditions and/or longitudinally associated with chronic disease mortality. Underhydration accounted for 97% of the population group not meeting hydration criteria. In weighted multivariable adjusted Poisson models, underhydration was significantly associated with increased prevalence of obesity, high waist circumference, insulin resistance, diabetes, low HDL, hypertension, and metabolic syndrome. Over 3–6 years of follow-up, 33 chronic disease deaths occurred in the sample, representing an estimated 1,084,144 deaths in the U.S. Alongside chronic health conditions, underhydration was a risk factor for an estimated 863,305 deaths. Independent of the chronic health conditions evaluated, underhydration was a risk factor for 128,107 deaths. In weighted multivariable Cox models, underhydration was associated with 4.21 times greater chronic disease mortality (95% CI: 1.29–13.78, p = 0.019). Zero chronic disease deaths were observed for people who met the hydration criteria and did not already have a chronic condition in 2009–2012. Further work should consider effects of underhydration on population health.

What Serum Sodium Concentration Is Suggestive for Underhydration in Geriatric Patients?

Dehydration is a concern among aging populations and can result in hospitalization and other adverse outcomes. There is a need to establish simple measures that can help in detecting low-intake dehydration (underhydration) in geriatric patients. The predictive performance of sodium, urea, glucose, and potassium to discriminate between patients with and without underhydration was evaluated using receiver-operating characteristic (ROC) curve analysis of data collected during the cross-sectional study of patients admitted to the geriatric ward. A total of 358 participants, for whom osmolarity could be calculated with the Khajuria and Krahn equation, were recruited to the study. Impending underhydration (osmolarity > 295 mmol/L) was diagnosed in 58.4% of cases. Serum sodium, urea, fasting glucose, and potassium (individual components of the equation) were significantly higher in dehydrated participants. The largest ROC area of 0.88 was obtained for sodium, and the value 140 mMol/L was found as the best cut-off value, with the highest sensitivity (0.80; 95% CI: 0.74–0.86) and specificity (0.83; 95% CI: 0.75–0.88) for prediction of underhydration. The ROC areas of urea, glucose, and potassium were significantly lower. Serum sodium equal to 140 mmol/L or higher appeared to be suggestive of impending underhydration in geriatric patients. This could be considered as the first-step screening procedure for detecting underhydration in older adults in general practice, especially when limited resources restrict the possibility of more in-depth biochemical assessments.

Impending Low Intake Dehydration at Admission to A Geriatric Ward- Prevalence and Correlates in a Cross-Sectional Study

Dehydration risk increases with frailty and functional dependency, but a limited number of studies have evaluated this association in hospitalized geriatric patients. This cross-sectional study aimed to assess the prevalence and determinants of dehydration in patients admitted to the geriatric ward. Dehydration was diagnosed when calculated osmolarity was above 295 mMol/L. Logistic regression analyses (direct and stepwise backward) were used to assess determinants of impending dehydration. 358 of 416 hospitalized patients (86.1%) were included: 274 (76.5%) women, and 309 (86.4%) 75+ year-old. Dehydration was diagnosed in 209 (58.4%) cases. Significantly higher odds for impending dehydration were observed only for chronic kidney disease with trends for diabetes and procognitive medication when controlling for several health, biochemical, and nutritional parameters and medications. After adjusting for “dementia” the negative effect of “taking procognitive medications” became a significant one. Chronic kidney disease, diabetes, taking procognitive medications and hypertension were the main variables for the outcome prediction according to the stepwise backward regression analysis. This may indicate an additional benefit of reducing the risk of dehydration when using procognitive drugs in older patients with dementia.

The role of perfusion index and plethysmography variability index for predicting dehydration severity in patients with acute gastroenteritis

Background:

Acute gastroenteritis is a clinical syndrome that may cause severe dehydration in affected individuals and a reason of mortality and morbidity in all age groups. Measurement of perfusion index and plethysmography variability index may provide emergency physicians valuable information about hemodynamics of the patient.

Objectives:

Our study aimed to investigate the role of perfusion index and plethysmography variability index measurement at admission for estimating dehydration severity and determiningthe possible change in those parameters after fluid replacement among patients presenting to emergency department with acute gastroenteritis.

Methods:

This was a prospective cross-sectional study. Patients diagnosed with acute gastroenteritis at the emergency department were consecutively enrolled. The two groups were defined according to the severity of dehydration: mild and moderate/severe dehydration groups. The values of perfusion index and plethysmography variability index of all patients were measured.

Results:

A total of 180 patients were included in the study. As compared with the mild dehydration group, moderate/severe dehydration group had a significantly lower perfusion index value and significantly higher plethysmography variability index value on admission (p < 0.001 for both comparisons). Among moderate/severe dehydration patients, perfusion index value significantly increased and plethysmography variability index significantly decreased after treatment (p < 0.001). There was a significant positive correlation between osmolarity and plethysmography variability index (r = 0.298; p = 0.007) and a significant negative correlation between osmolality and perfusion index (r = −0.259; p = 0.019) in the patients with moderate/severe dehydration.

Conclusion:

The study show that perfusion index and plethysmography variability index may be useful for determining the severity of dehydration in acute gastroenteritis and may be use for assessing the response to fluid replacement especially in patients with severe dehydration at emergency department.

Colon cancer cells cultured under hyperosmotic conditions as in vitro model to investigate dehydration effects on cancer drug susceptibility

BACKGROUND

In most clinical studies older people are underrepresented compared to the demographic reality. However, risk for some severe diseases like cancer typically increase with age. Most insight into cancer treatment comes from mixed-age patient cohorts, leading to a lack of detailed understanding of cancer drug effects in the elderly population. There is growing evidence that cancer drug effects can be influenced by dehydration conditions often found in older people. Colon cancer remains the second leading cause of death by cancer in Europe. Inter- and intra-heterogeneity of tumors contribute to why some individuals do not respond to specific cancer therapies or may often suffer a relapse.

OBJECTIVE

Our study applies an in vitro drug test system for simulating treatment with cytostatics of colorectal cancer in elderly patients with dehydration condition.

METHODS

Two well-known colon cancer cell lines, Caco-2 and RKO, harboring defined cancer-related mutations, were step-wisely adapted from routine culture medium to a severe hyperosmotic condition (397 mOmol/kg) by adding sodium chloride to the medium. We investigated the effects of these cell culture conditions, which should mimic cellular dehydration in elderly people, on the growth characteristics of the cells. Therefore, cell proliferation was investigated by measuring population doubling times. Furthermore, we investigated how the metabolic activity of the cells was influenced by treatment with different concentrations of cyclophosphamide (CPA) under normal and hyperosmotic conditions.

RESULTS

We found that Caco-2 and RKO cell lines have an identical cell doubling time of 23 hours in normosmotic medium. However, hyperosmotic medium lifted the doubling time of Caco-2 cells to 31 hours while that of RKO cells did not change. Despite reduced cell proliferation rates, hyperosmotic medium sensitized Caco-2 cells to treatment with 10 mM CPA for 48 hours as measured by metabolic activity assays on ATP levels.

CONCLUSIONS

The two investigated colon cancer cells lines reacted differently to hyperosmotic conditions. Only the growth of Caco-2 cells was reduced by increased osmolality. Despite this reduced growth their sensitivity to an alkylating cytostatic agent was even slightly increased. We are now in line to examine these effects in more detail and with more tumor cell lines.

Impact of 3-day high and low dietary sodium intake on sodium status in response to exertional-heat stress: a double-blind randomized control trial

PURPOSE

To determine the impact of altering dietary sodium intake for 3 days preceding exercise on sweat sodium concentration [Na⁺], and cardiovascular and thermoregulatory variables.

METHODS

Fifteen male endurance athletes (runners n = 8, cyclists n = 7) consumed a low (LNa, 15 mg kg^-1 day^-1) or high (HNa, 100 mg kg^-1 day^-1) sodium diet, or their usual free-living diet [UDiet, 46 (37-56) mg kg^-1 day^-1] for 3 days in a double-blind, randomized cross-over design, collecting excreted urine (UNa) and refraining from exercise. On day 4, they completed 2 h running at 55% [Formula: see text]O_2max or cycling at 55% maximum aerobic power in T_amb 35 °C. Pre- and post-exercise blood samples were collected, and sweat from five sites using absorbent patches along the exercise protocol.

RESULTS

UNa on days 2-3 pre-exercise [mean (95% CI) LNa 16 (12-19) mg kg^-1 day^-1, UDiet 46 (37-56) mg kg^-1 day^-1, HNa 79 (72-85) mg kg^-1 day^-1; p < 0.001] and pre-exercise aldosterone [LNa 240 (193-286) mg kg^-1 day^-1, UDiet 170 (116-224) mg kg^-1 day^-1, HNa 141 (111-171) mg kg^-1 day^-1; p = 0.001] reflected sodium intake as expected. Pre-exercise total body water was greater following HNa compared to LNa (p < 0.05), but not UDiet. Estimated whole-body sweat [Na⁺] following UDiet was 10-11% higher than LNa and 10-12% lower than HNa (p < 0.001), and correlated with pre-exercise aldosterone (1st h r =  - 0.568, 2nd h r =  - 0.675; p < 0.01). Rectal temperature rose more quickly in LNa vs HNa (40-70 min; p < 0.05), but was similar at the conclusion of exercise, and no significant differences in heart rate or perceived exertion were observed.

CONCLUSIONS

Three day altered sodium intake influenced urinary sodium excretion and sweat [Na⁺], and the rise in rectal temperature, but had no effect on perceived exertion during moderate-intensity exercise in hot ambient conditions.

Applications of Manganese-Enhanced Magnetic Resonance Imaging in Ophthalmology and Visual Neuroscience

Understanding the mechanisms of vision in health and disease requires knowledge of the anatomy and physiology of the eye and the neural pathways relevant to visual perception. As such, development of imaging techniques for the visual system is crucial for unveiling the neural basis of visual function or impairment. Magnetic resonance imaging (MRI) offers non-invasive probing of the structure and function of the neural circuits without depth limitation, and can help identify abnormalities in brain tissues in vivo. Among the advanced MRI techniques, manganese-enhanced MRI (MEMRI) involves the use of active manganese contrast agents that positively enhance brain tissue signals in T1-weighted imaging with respect to the levels of connectivity and activity. Depending on the routes of administration, accumulation of manganese ions in the eye and the visual pathways can be attributed to systemic distribution or their local transport across axons in an anterograde fashion, entering the neurons through voltage-gated calcium channels. The use of the paramagnetic manganese contrast in MRI has a wide range of applications in the visual system from imaging neurodevelopment to assessing and monitoring neurodegeneration, neuroplasticity, neuroprotection, and neuroregeneration. In this review, we present four major domains of scientific inquiry where MEMRI can be put to imperative use — deciphering neuroarchitecture, tracing neuronal tracts, detecting neuronal activity, and identifying or differentiating glial activity. We deliberate upon each category studies that have successfully employed MEMRI to examine the visual system, including the delivery protocols, spatiotemporal characteristics, and biophysical interpretation. Based on this literature, we have identified some critical challenges in the field in terms of toxicity, and sensitivity and specificity of manganese enhancement. We also discuss the pitfalls and alternatives of MEMRI which will provide new avenues to explore in the future.

A multidisciplinary consensus on dehydration: definitions, diagnostic methods and clinical implications

Background: Dehydration appears prevalent, costly and associated with adverse outcomes. We sought to generate consensus on such key issues and elucidate need for further scientific enquiry. Materials and methods: A modified Delphi process combined expert opinion and evidence appraisal. Twelve relevant experts addressed dehydration's definition, objective markers and impact on physiology and outcome. Results: Fifteen consensus statements and seven research recommendations were generated. Key findings, evidenced in detail, were that there is no universally accepted definition for dehydration; hydration assessment is complex and requires combining physiological and laboratory variables; "dehydration" and "hypovolaemia" are incorrectly used interchangeably; abnormal hydration status includes relative and/or absolute abnormalities in body water and serum/plasma osmolality (pOsm); raised pOsm usually indicates dehydration; direct measurement of pOsm is the gold standard for determining dehydration; pOsm >300 and ≤280 mOsm/kg classifies a person as hyper or hypo-osmolar; outside extremes, signs of adult dehydration are subtle and unreliable; dehydration is common in hospitals and care homes and associated with poorer outcomes. Discussion: Dehydration poses risk to public health. Dehydration is under-recognized and poorly managed in hospital and community-based care. Further research is required to improve assessment and management of dehydration and the authors have made recommendations to focus academic endeavours. Key messages Dehydration assessment is a major clinical challenge due to a complex, varying pathophysiology, non-specific clinical presentations and the lack of international consensus on definition and diagnosis. Plasma osmolality represents a valuable, objective surrogate marker of hypertonic dehydration which is underutilized in clinical practice. Dehydration is prevalent within the healthcare setting and in the community, and appears associated with increased morbidity and mortality.

Hydration Status of Assisted Living Memory Care Residents

Water intake and hydration status of assisted living memory care (ALMC) residents were evaluated. Thirty-two residents (eight men; mean age 86.5 years; Global Deterioration Scale [GDS] 3 to 7) from four ALMC units participated. Ingested food and fluid amount, type, and time, and ingestion behaviors were observed from 7:00 a.m. to 7:00 p.m. Related factors were obtained from chart review/participant survey. Mean fluid intake was 1,160.16 mL; mean water intake from food and fluid was 56.55% (SD = 23.4%) of recommended water intake (RWI). Only one participant met 100% RWI. Using osmolality laboratory results (available for 21 participants), five participants were hydrated, whereas eight (38.1%) participants were in impending dehydration and dehydration categories, respectively. Fluid intake, GDS, and level of assistance during meals predicted RWI. Water intake of ALMC residents is inadequate, placing them at risk for dehydration, and justifies development and implementation of care standards for increasing water intake. [Journal of Gerontological Nursing, 45(4), 21-29.].

Signs and Symptoms of Low-Intake Dehydration Do Not Work in Older Care Home Residents-DRIE Diagnostic Accuracy Study

OBJECTIVES

To assess the diagnostic accuracy of commonly used signs and symptoms of low-intake dehydration in older care home residents.

DESIGN

Prospective diagnostic accuracy study.

SETTING

56 care homes offering residential, nursing, and/or dementia care to older adults in Norfolk and Suffolk, United Kingdom.

PARTICIPANTS

188 consecutively recruited care home residents aged ≥65 years, without cardiac or renal failure and not receiving palliative care. Overall, 66% were female, the mean age was 85.7 years (standard deviation 7.8), and the median Mini-Mental State Examination MMSE score was 23 (interquartile range 18-26).

INDEX TESTS

Over 2 hours, participants underwent double-blind assessment of 49 signs and symptoms of dehydration and measurement of serum osmolality from a venous blood sample. Signs and symptoms included skin turgor; mouth, skin, and axillary dryness; capillary refill; sunken eyes; blood pressure on resting and after standing; body temperature; pulse rate; and self-reported feelings of thirst and well-being.

REFERENCE STANDARD

Serum osmolality, with current dehydration defined as >300 mOsm/kg, and impending dehydration ≥295 mOsm/kg.

OUTCOME MEASURES

For dichotomous tests, we aimed for sensitivity and specificity >70%, and for continuous tests, an area under the curve in receiver operating characteristic plots of >0.7.

RESULTS

Although 20% of residents had current low-intake dehydration and a further 28% impending dehydration, none of the commonly used clinical signs and symptoms usefully discriminated between participants with or without low-intake dehydration at either cut-off.

CONCLUSIONS/IMPLICATIONS

This study consolidates evidence that commonly used signs and symptoms of dehydration lack even basic levels of diagnostic accuracy in older adults, implying that many who are dehydrated are not being identified, thus compromising their health and well-being. We suggest that these tests be withdrawn from practice and replaced with a 2-stage screening process that includes serum osmolarity, calculated from sodium, potassium, urea, and glucose levels (assessed routinely using the Khajuria and Krahn equation), followed by serum osmolality measurement for those identified as high risk (calculated serum osmolarity >295 mmol/L).

Protective measures of patients with cardiovascular diseases from exposure to heat waves: medicated and non-medicated

In conditions of climate warming with an increase in heat waves associated with an increase in cardiovascular morbidity and mortality, the particular interest is the effect of cardiovascular drugs on adaptation to high temperatures. The review reflects the results of European and domestic studies on the safety of therapy during long and short heat waves. Recommendations for the correction of therapy during this period are given. Self-control of blood pressure (SCAD) is a mandatory component of the therapy of arterial hypertension during heat waves. With the development of clinically significant hypotension, a reduction in the dose of antihypertensive drugs is necessary. It is recommended to start with a dose reduction and/or withdrawal of diuretics and nitrates. Not recommended the complete abolition of antihypertensive therapy because of the risk of hypertensive crises, characteristic of abnormal heat, as well as due to the increase in blood pressure when the weather changes and the temperature drops. With increasing blood pressure during heat waves, it is recommended to give preference to calcium channel antagonists, angiotensin converting enzyme inhibitors (ACE inhibitors) and selective beta-blockers. It is necessary to inform patients about the additional protective effect of statins in order to increase adherence to therapy. Patients taking diuretics require individual daily monitoring of fluid intake and body weight. An overview of recommendations on sanogenic behavior during heat waves is given. Details are considered rules for the use of air conditioning, methods of diagnosis of dehydration and drinking mode Keywords: heat waves, cardiovascular complications, preventive measures.

Detection of Glycemia and Osmolarity Changes Using Eye Examinations

Background: Glycated hemoglobin (HbA1c) is an index of the average blood glucose level over the preceding 2-3 months. In experimental studies, the lens responded to changes in osmolarity by forming vacuoles. By observing the vacuoles of the lens during eye examination, can we detect changes in osmolarity and glycemia over the last 6 months through HbA1c levels? Methods: In total, 400 patients (mean age, 67.7 ± 9.8 years), including those with diabetes mellitus, hypertension, and heart failure, were included in the study. The control group contained 70 patients matched in terms of age and sex and who had no prior disease (mean age, 67.8 ± 9.4 years). Monthly Na, glucose, and blood urea nitrogen values were used to calculate changes in osmolarity over 6 months. HbA1c values were also recorded. Biomicroscopy was used to evaluate lens vacuolation; all vacuoles were digitally photographed and converted to ImageJ format. Results: The sensitivity and specificity of using large vacuoles to detect HbA1c ≥10% were 88.0% (95% confidence interval [CI]: 68.8-97.4) and 82.6% (95% CI: 74.1-89.2), respectively. The sensitivity and specificity of detecting a 10 mOsm/kg change in osmolarity were 61% (95% CI: 48.9-72.4) and 94.5% (95% CI: 91.5-96.7), respectively. Conclusions: Lens vacuoles, which can be observed with a simple and quick examination, can be used to detect HbA1c levels and osmolarity changes over the last 6 months. Because of their relationship to the severity of retinopathy, vacuoles can also be used as a weak control indicator.

Prediction of neurologic deterioration based on support vector machine algorithms and serum osmolarity equations

OBJECTIVE

Dehydration on admission is correlated with neurological deterioration (ND). The primary objective of our study was to use support vector machine (SVM) algorithms to identify an ND prognostic model, based on dehydration equations.

METHODS

This study included a total of 382 patients hospitalized with acute ischemic stroke. The following parameters were recorded: age, sex, laboratory values (serum sodium, potassium, chlorinum, glucose, and urea), and vascular risk factor data. Receiver operating characteristic (ROC) curve analysis was used to evaluate the discriminative performance of the BUN/Cr ratio as well as each of 38 equations for predicting ND. We used the Boruta algorithm for feature selection. After optimizing the SVM kernel parameters, we built an SVM model to predict ND and used the test set to obtain predictive values for assessing model accuracy.

RESULTS

In total, 102 of 382 patients (26.7%) with acute ischemic stroke developed ND. In all patients, the BUN/Cr ratio and each of 38 equations were significant predictors of ND. Equation 20 [1.86 × Na+ + glucose + urea + 9] yielded the maximum area under the ROC curve, and faired best in terms of prognostic performance (a cutoff value of 284.49 mM yielded a sensitivity of 94.12% and specificity of 61.43%). Equation 32 predicted ND poststroke across population groups, and worked well in older as well as young adults; (a cutoff value of 297.08 mM yielded a sensitivity of 93.14% and specificity of 60.00%). Feature selection by the Boruta algorithm was used to decrease the number of variables from 18 to 5 in the condition. The specificity of test samples for the SVM prediction model increased from 44.1% to 89.4%, and the AUC increased from 0.700 to 0.927.

CONCLUSIONS

SVM algorithms can be used to establish a prediction model for dehydration-associated ND, with good classification results.

ESPEN guideline on clinical nutrition and hydration in geriatrics

BACKGROUND

Malnutrition and dehydration are widespread in older people, and obesity is an increasing problem. In clinical practice, it is often unclear which strategies are suitable and effective in counteracting these key health threats.

AIM

To provide evidence-based recommendations for clinical nutrition and hydration in older persons in order to prevent and/or treat malnutrition and dehydration. Further, to address whether weight-reducing interventions are appropriate for overweight or obese older persons.

METHODS

This guideline was developed according to the standard operating procedure for ESPEN guidelines and consensus papers. A systematic literature search for systematic reviews and primary studies was performed based on 33 clinical questions in PICO format. Existing evidence was graded according to the SIGN grading system. Recommendations were developed and agreed in a multistage consensus process.

RESULTS

We provide eighty-two evidence-based recommendations for nutritional care in older persons, covering four main topics: Basic questions and general principles, recommendations for older persons with malnutrition or at risk of malnutrition, recommendations for older patients with specific diseases, and recommendations to prevent, identify and treat dehydration. Overall, we recommend that all older persons shall routinely be screened for malnutrition in order to identify an existing risk early. Oral nutrition can be supported by nursing interventions, education, nutritional counseling, food modification and oral nutritional supplements. Enteral nutrition should be initiated if oral, and parenteral if enteral nutrition is insufficient or impossible and the general prognosis is altogether favorable. Dietary restrictions should generally be avoided, and weight-reducing diets shall only be considered in obese older persons with weight-related health problems and combined with physical exercise. All older persons should be considered to be at risk of low-intake dehydration and encouraged to consume adequate amounts of drinks. Generally, interventions shall be individualized, comprehensive and part of a multimodal and multidisciplinary team approach.

CONCLUSION

A range of effective interventions is available to support adequate nutrition and hydration in older persons in order to maintain or improve nutritional status and improve clinical course and quality of life. These interventions should be implemented in clinical practice and routinely used.

Basal Tear Osmolarity as a metric to estimate body hydration and dry eye severity

The osmolarities of various bodily fluids, including tears, saliva and urine, have been used as indices of plasma osmolality, a measure of body hydration, while tear osmolarity is used routinely in dry eye diagnosis, the degree of tear hyperosmolarity providing an index of disease severity. Systemic dehydration, due to inadequate water intake or excessive water loss is common in the elderly population, has a high morbidity and may cause loss of life. Its diagnosis is often overlooked and there is a need to develop a simple, bedside test to detect dehydration in this population. We hypothesize that, in the absence of tear evaporation and with continued secretion, mixing and drainage of tears, tear osmolarity falls to a basal level that is closer to that of the plasma than that of a tear sample taken in open eye conditions. We term this value the Basal Tear Osmolarity (BTO) and propose that it may be measured in tear samples immediately after a period of evaporative suppression. This value will be particular to an individual and since plasma osmolarity is controlled within narrow limits, it is predicted that it will be stable and have a small variance. It is proposed that the BTO, measured immediately after a defined period of eye closure, can provide a new metric in the diagnosis of systemic dehydration and a yardstick against which to gauge the severity of dry eye disease.

The sensitivity of the human thirst response to changes in plasma osmolality: a systematic review

BACKGROUND

Dehydration is highly prevalent and is associated with adverse cardiovascular and renal events. Clinical assessment of dehydration lacks sensitivity. Perhaps a patient's thirst can provide an accurate guide to fluid therapy. This systematic review examines the sensitivity of thirst in responding to changes in plasma osmolality in participants of any age with no condition directly effecting their sense of thirst.

METHODS

Medline and EMBASE were searched up to June 2017. Inclusion criteria were all studies reporting the plasma osmolality threshold for the sensation of thirst.

RESULTS

A total of 12 trials were included that assessed thirst intensity on a visual analogue scale, as a function of plasma osmolality (pOsm), and employed linear regression to define the thirst threshold. This included 167 participants, both healthy controls and those with a range of pathologies, with a mean age of 41 (20-78) years.The value ±95% CI for the pOsm threshold for thirst sensation was found to be 285.23 ± 1.29 mOsm/kg. Above this threshold, thirst intensity as a function of pOsm had a mean ± SEM slope of 0.54 ± 0.07 cm/mOsm/kg. The mean ± 95% CI vasopressin release threshold was very similar to that of thirst, being 284.3 ± 0.71 mOsm/kg.Heterogeneity across studies can be accounted for by subtle variation in experimental protocol and data handling.

CONCLUSION

The thresholds for thirst activation and vasopressin release lie in the middle of the normal range of plasma osmolality. Thirst increases linearly as pOsm rises. Thus, osmotically balanced fluid administered as per a patient's sensation of thirst should result in a plasma osmolality within the normal range. This work received no funding.

Copeptin Blood Content as a Diagnostic Marker of Chronic Kidney Disease

Plasma content of copeptin increases with the advancement of chronic kidney disease (CKD). The purpose of this study was to evaluate copeptin content as a potential marker of CKD, as a single pathology or with coexisting heart failure. Seventy-six patients were divided into the following groups: Group 1 (control), without CKD and heart failure; Group 2, CKD stage 3a; Group 3, CKD stage 3b; Group 4, CKD stage 4; Group 5, CKD stage 5; and Group 6, CKD stage 3b and heart failure. For all patients, plasma concentrations of copeptin, creatinine, urea, cystatin C, sodium, C-reactive protein (CRP), N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and blood pH were assessed. We found that plasma content of creatinine, urea, CRP, cystatin, NT-proBNP, and copeptin increased with CKD progression. Heart failure in CKD patients was not the cause of an appreciable increase of copeptin level. Copeptin/creatinine, copeptin/cystatin C ratios, and especially copeptin/eGFR ratio enhanced copeptin prognostic sensitivity concerning renal failure in CKD, compared with copeptin alone. The copeptin×NT-proBNP ratio decreased along CKD progression, reaching a nadir in the accompanying heart failure. In contradistinction, copeptin×NT-proBNP/creatinine ratio increased along CKD progression, reaching a peak in the accompanying heart failure. We conclude that copeptin is an important marker in CKD, but not so concerning heart failure in the disease. A decrease in copeptin×NT-proBNP and an increase in copeptin×NT-proBNP/creatinine ratio are useful markers of cardiac function decline in CKD.

A Profile of Renal Function in Northern Cameroonians with Essential Hypertension

BACKGROUND/AIM

The two-way cause and effect relationship existing between high blood pressure and kidney dysfunction is currently a well-documented phenomenon with patients in either category being almost equally predisposed to the other pathology. Our goal was to assess the renal function capacity of hypertensive patients in our setting.

METHODS

This cross-sectional descriptive study involved the determination of blood pressure levels and the collection of blood and urine samples for the measurement of renal function markers. Hypertensive patients who came for medical follow-up constituted the study participants, and were enrolled consecutively into the study from February to May 2015. Data analysis was performed using the SPSS 20.0 software, and significant differences were determined at p < 0.05.

RESULTS

The prevalence of elevated creatinine and urea levels were 35 and 27%. Eighty percent of the participants had a decreased glomerular filtration rate (≤90 mL/min/1.73 m3), with at least 36% recording less than 60 mL/min/1.73 m3. Proteinuria and glucosuria were recorded in 15% and 8% of the participants, respectively. The mean diastolic pressure was observed to be significantly higher in participants with proteinuria (p = 0.016), and participants' weight directly correlated with systolic blood pressure (p = 0.015). Furthermore, the mean estimated glomerular filtration rate was relatively lower in participants >60 years compared to those <60 years (p < 0.001).

CONCLUSION

Renal function is often perturbed in hypertensive patients, and good blood pressure control may reduce the progression of renal impairment. Thus, a systematic evaluation of renal function in addition to blood pressure control in hypertensive patients is indispensable towards effectively reducing the occurrence of renal events and preventing end-stage renal disease.

Estimating basal tear osmolarity in normal and dry eye subjects

PURPOSE

Tear osmolarity (tOsm) is used as a measure of severity in dry eye disease (DED) and has been proposed as an index of body hydration. In DED the level of tear hyperosmolarity is compared with that of a control population. It is proposed here that a better index of body hydration and a more valid reference point in DED can be acquired by measuring the tOsm after a period of evaporative suppression.

METHOD

8 normal and DED subjects were recruited, their tOsm measured in uncontrolled environmental 'clinic conditions'. Then in experiment 1 they entered a controlled environment chamber and had tOsm measured after 45 minutes of eye closure and then, with the eyes open, at 15 minute intervals for a further 45 minutes, at a relative humidity (RH) of 45%. Alternatively, in experiment 2, they had tOsm measured every 15 minutes for 45 minutes during exposure to 70% RH, as a separate measure to suppress evaporation.

RESULTS

A significant decrease in tOsm occurred in both normal and DED subjects after lid closure in experiment 1 (normal RE p=0.015; normal LE p=0.006; DED RE p=0.0002; DED LE p=0.01). The tOsm also fell slightly after exposure to 70% RH in experiment 2 significant in the LE of normal group only (normal LE p=0.045).

CONCLUSIONS

Suppression of tear evaporation resulted in a fall in tOsm, close to that of plasma osmolarity (285-295mOsm/L). It is proposed that this new measure, termed Basal Tear Osmolarity (BTO), could provide a valuable index of plasma osmolarity and hence of body hydration and in DED, a personal baseline against which to gauge the severity of tear hyperosmolarity.