Elderly female patients in continuing care: why are they hyperosmolar?

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.

The Role of Nuclear Factor of Activated T Cells 5 in Hyperosmotic Stress-Exposed Human Lens Epithelial Cells

We investigated the role of nuclear factor of activated T cells 5 (NFAT5) under hyperosmotic conditions in human lens epithelial cells (HLECs). Hyperosmotic stress decreased the viability of human lens epithelial B-3 cells and significantly increased NFAT5 expression. Hyperosmotic stress-induced cell death occurred to a greater extent in NFAT5-knockout (KO) cells than in NFAT5 wild-type (NFAT5 WT) cells. Bcl-2 and Bcl-xl expression was down-regulated in NFAT5 WT cells and NFAT5 KO cells under hyperosmotic stress. Pre-treatment with a necroptosis inhibitor (necrostatin-1) significantly blocked hyperosmotic stress-induced death of NFAT5 KO cells, but not of NFAT5 WT cells. The phosphorylation levels of receptor-interacting protein kinase 1 (RIP1) and RIP3, which indicate the occurrence of necroptosis, were up-regulated in NFAT5 KO cells, suggesting that death of these cells is predominantly related to the necroptosis pathway. This finding is the first to report that necroptosis occurs when lens epithelial cells are exposed to hyperosmolar conditions, and that NFAT5 is involved in this process.

Influence of age and sex on signal intensities of the posterior lobe of the pituitary gland on T1-weighted images from 3 T MRI

PURPOSE

To elucidate the influence of age and sex on the signal intensity (SI) of the posterior lobe of the pituitary gland (PPG) on T1-weighted images (T1WI) from 3 T MRI.

MATERIALS AND METHODS

Sagittal T1WI acquired from three-dimensional fast spoiled gradient recalled acquisition in the steady state in 1,634 subjects without conditions affecting antidiuretic hormone were evaluated retrospectively. The presence or absence of a bright signal in the PPG was assessed qualitatively. The SI ratio of the PPG to the pons (SIR) was obtained from quantitative measurements. We statistically analyzed these data, creating 14 subject groups categorized according to age and sex, and applied a Poisson generalized linear model to the SIR data.

RESULTS

The characteristic bright signal was absent in 47 subjects (2.8 %), with no significant difference in incidence among the groups. The SIR was inversely related to age in both males (r > 0.7) and females (r > 0.9), and was significantly higher in females in the third to the eighth decades (p < 0.05). Analysis of the whole SIR dataset using a generalized linear model showed that the estimated SIR decreased by 1.7 % per decade and is higher in females.

CONCLUSION

Age and sex influence the SI of the PPG on T1WI. These findings may aid the recognition of PPG signal abnormalities on T1WI.

[Risk factors contributing to insufficient water intake in elderly living in nursing homes and long-term care units: a review of the literature]

Elderly living in nursing homes and long-term care units are well-known to be vulnerable to dehydration. Insufficient water intake contributes to suboptimal hydration status and leads to decreased quality of life and global health status. Based on published studies, 32 to 96% of nursing home residents had insufficient water intake and more than 50% drank less than 1.5L per day. Risk factors contributing to decreased water intake in nursing home residents can be divided into two categories, depending whether they apply to the individuals per se (individual factors) or their social and institutional environment (environmental factors). Water intake is associated with meals and medication administration frequency. Diminished thirst sensation, intentional fluid restriction, dysphagia and functional dependency are individual factors recognized as most contributing to decreased water intake. Lack of familial support and insufficient staff are also important since they can contribute to decreased patients' assistance. Dietitians can play a fundamental role in preventing suboptimal hydration status by identifying risk factors that are known to compromise individual's water intake and by implementing corrective measures.

Is the prevalence of dehydration among community-dwelling older adults really low? Informing current debate over the fluid recommendation for adults aged 70+years

Objective

The fluid recommendation for adults aged 70+ years has been criticised on the basis of a low prevalence of dehydration in community-dwelling older adults. This study explores whether the low prevalence might reflect limitations of individual dehydration indices.

Design

Cross-sectional data on plasma sodium, blood urea nitrogen (BUN), creatinine, glucose and potassium were used to classify 1737 participants of the 1992 Established Populations for Epidemiologic Studies of the Elderly (EPESE) (70+ years) according to multiple dehydration indices. Associations between dehydration indices, health and functional status were evaluated.

Results

Depending on the indicator used, the prevalence of dehydration ranged from 0.5% for hypotonic hypovolaemia only (plasma tonicity <285 mOsm l−1 with orthostatic hypotension) to 60% with dehydration defined as either plasma sodium ≥145 mEq l−1, BUN/creatinine ratio ≥20, tonicity ≥295 mOsm l−1, or hypotonic hypovolaemia. Elevated tonicity and BUN/creatinine ratio were respectively associated with chronic disease and functional impairment.

Conclusions

The true prevalence of dehydration among community-dwelling adults may be low or high, depending on the indicator(s) used to define dehydration. Before we can pinpoint a generalisable prevalence of dehydration for community-dwelling seniors and draw conclusions about fluid recommendations, validation studies of dehydration indices and longitudinal studies of dehydration, health and functional status are needed.

Dehydration: biological considerations, age-related changes, and risk factors in older adults

Maintenance of water balance is essential to normal physiologic function and vigorous aging. Older adults, however, frequently experience alterations in fluid homeostasis, which result in dehydration. This article describes the physiology of water balance, age-related changes that influence fluid regulation, and associated risk factors for dehydration in older adults. Fluid hygiene is an important health promotion activity for this age group, but when efforts to prevent imbalance are unsuccessful, early identification and intervention to correct problems should be done to minimize adverse consequences. Although much is known about fluid homeostasis, dehydration, and contributory factors in the aging process, water disorders remain prevalent in this group. A great deal of work is still needed to determine "best practices" and creative clinical interventions to support adequate fluid intake behaviors. Both quality management programs and research studies provide avenues for systematic evaluation.

Response to dehydration in elderly patients in long-term care

Elderly patients in long-term care have a high plasma osmolality (pOSM) and associated increased mortality. In these patients, we examined pOSM, thirst (visual analogue scale, VAS) and arginine vasopressin (AVP) response to 16-hour dehydration and 2-hour rehydration. Twelve patients were randomly divided into two groups (A & B). Group A had their fluid balance monitored for two weeks, group B did not. Single measurements of VAS, pOSM and AVP were conducted on days 0, 7 and 13. Dehydration tests were conducted in both groups at the start of the study (DAY 1), and at the end of the two-week period (DAY 14). There were no significant differences between group A and B, so the results are presented for the two groups combined. There was a significant increase in both pOSM and VAS during dehydration, and a significant fall in both variables during rehydration [F (9,99) = 18.69, p < 0.001, and F(9,99) = 11.25, p < 0.001, respectively]. Plasma AVP did not change significantly during either dehydration or rehydration [F (9,99) = 0.59, p = 0.8]. There were no significant differences in response for any of the three variables between DAY 1 and DAY 14. We conclude that elderly patients in long-term care exhibit changes in thirst and osmolality during dehydration and rehydration, and that these responses are reproducible. The lack of a significant AVP response requires further investigation.

Indices of dehydration among frail nursing home patients: highly variable but stable over time

OBJECTIVE

To determine changes in standard laboratory measures of dehydration among residents of a nursing home care unit (NHCU) over a 6-month period.

DESIGN

A prospective cohort analytic study.

SETTING

A 130-bed NHCU in a Department of Veterans Affairs Hospital.

PATIENTS

Fifteen infirm but stable male residents (mean age 77 years; range (R) 62-93) on one ward of the NHCU.

MAIN OUTCOME MEASURES

We studied prospectively for 6 months the serum osmolality (osm), serum sodium (Na), blood urea nitrogen/creatinine (BUN/Cr) ratios and weight (wt) for 15 patients of the NHCU. None of the patients was acutely ill during the study period or exhibited clinical signs of dehydration.

RESULTS

Mean serum osm at baseline: 291.6 mOsm/kg (R 278 to 300); 3 months: 291.5 mOsm/kg (R 276 to 301); 6 months: 291.3 mOsm/kg (R 283-300) were all similar. Forty percent (6/15) of patients had at least one high normal/elevated reading (> or = 295 mOsm/kg) during the study. Three patients (20%) had readings of > or = 300 mOsm/kg, but none of these patients had either concurrent increased serum Na (> or = 146 mmole/L) or BUN/Cr ratios (> or = 25). Mean serum Na at baseline: 143.0 mmole/L (R 139-148); 3 months: 142.1 mmole/L (R 138-149); 6 months: 142.9 mmole/L (R 137-150) were all similar. Sixty percent (9/15) of the patients maintained normal (nl) serum Na levels throughout the study. The relationship between the change in serum Na and serum osm levels from baseline to 6 months was not significant (r = 0.242). BUN/Cr ratios ranged from 12-34 over the study period with 3 of 15 patients (20%) demonstrating elevated ratios consistently throughout the study without clinical evidence of dehydration. Only two patients had both high nl/elevated serum osm and elevated serum Na, although both had nl BUN/Cr ratios. Neither of these patients was thought by staff to be clinically dehydrated. Analysis of variance (ANOVA) indicated none of the laboratory measures changed significantly over time (serum osm: F(2,28) < 1; Na: F(2,28) < 1; BUN/Cr: F(2,28) < 1). There was no significant change in weight between the baseline and six month readings.

CONCLUSIONS

These data suggest that in the presence of clinical stability, long-term care residents may have a serum osm in the high normal/elevated range without overt clinical evidence of dehydration, an accompanying elevated Na, or BUN/Cr ratio. This may indicate a different central osm setting for these residents as the serum osm appeared to be stable for each resident over time. These data also suggest that measures of serum osm, Na, and BUN/Cr in the long-term care setting may accurately predict future laboratory values in an individual patient if baseline values are drawn when the patient is not acutely ill.

Arginine vasopressin and osmolality in the elderly

OBJECTIVES

To evaluate the influence of age on plasma arginine vasopressin (AVP) concentrations and the relationship between plasma AVP and serum osmolality in younger and older subjects, and in the elderly, to assess the effect of gender on plasma AVP concentration and to determine the impact of prostaglandin blockade on renal responsiveness to AVP.

DESIGN

Cross-sectional study; randomized, double-blind, crossover, placebo-controlled study.

SETTING

The Renal Laboratory, Royal North Shore Hospital (younger adults) and Clinical Room, St Vincents Hospital (elderly subjects).

PARTICIPANTS

45 younger adults (35 +/- 9 years), and 41 elderly subjects (29 males, 12 females; 78 +/- 3 years). All subjects were healthy and non-institutionalized. The elderly subjects were screened to exclude significant pathology (clinical assessment, multiple investigations).

INTERVENTION

Blood samples were drawn from all younger and elderly subjects. The elderly subjects were randomly allocated indomethacin or placebo for 1 month. Following a 1 to 2-week washout, the alternative was administered for a further 1 month.

MAIN OUTCOME MEASURES

Plasma AVP and serum osmolality and plasma AVP, serum, and urine osmolality at baseline were measured on indomethacin and placebo.

RESULTS

In the elderly subjects, baseline plasma AVP concentration was significantly higher than in the younger subjects studied (4.7 +/- 0.7 vs 2.1 +/- 0.2 pg/mL respectively; P = 0.0003). Plasma AVP was strongly correlated with serum osmolality in the younger subjects (r = 0.76, P = 0.0001) but not in the elderly cohort (r = -0.18, P = 0.26). No difference was found between the sexes in plasma AVP (P = 0.89), and indomethacin treatment did not alter the plasma AVP/urine osmolality ratio (P = 0.85) in the elderly subjects. In addition, changes in plasma AVP with indomethacin therapy did not correlate with changes in serum osmolality (r = 0.16, P = 0.09).

CONCLUSIONS

Aging is accompanied by an increase in plasma AVP concentrations. In healthy, elderly subjects, plasma AVP is not dependent on serum osmolality and is not influenced by gender. Indomethacin has no effect on the renal responsiveness to plasma AVP.