The influence of fluid intake on stroke recurrence — A prospective study

Diagnosis and treatment of dehydration after stroke: A synthesis of existing evidence

Dehydration after stroke is associated with poor health outcomes, increased mortality, and poses a significant economic burden to health services. Yet research suggests that monitoring and assessment of hydration status is not routinely undertaken. In this commentary, we critically appraise a systematic review which aimed to synthesise the existing evidence regarding diagnosis and treatment of dehydration after stroke. The review discusses common measures of dehydration, describes studies evaluating rehydration treatments, and highlights the link between dehydration and poorer health outcomes in both human and animal studies. The reviewers suggest, future research should focus on determining a single, validated, objective measure to clinically diagnose dehydration in stroke patients. Research designs should include clearly defined patient characteristics, type and severity of stroke, and type and time point of dehydration measurement, to enable comparison between studies. Management of hydration status is a crucial element of acute stroke care which should be routinely practiced.

Validation of Total Water Intake from the Automated Self-Administered 24-h Recall, 4-d Food Records, and a Food Frequency Questionnaire Using Doubly Labeled Water

BACKGROUND

Although prior evidence indicates that water intake is important for health, the ability to accurately measure community-dwelling intake is limited. Only a few studies have evaluated self-reported water intake against an objective recovery biomarker.

OBJECTIVES

The aim was to compare preformed water intakes (all sources including food) by multiple Automated Self-Administered 24-h recalls (ASA24s), food frequency questionnaires (FFQs), and 4-d food records (4DFRs) against a recovery biomarker, doubly labeled water (DLW), to assess measurement error.

METHODS

Over 1 y, 1082 women and men (50%), aged 50 to 74 y, were asked to complete 6 ASA24s, 2 FFQs, 2 unweighted 4DFRs, and an administration of DLW (n = 686). Geometric means of water intake by self-report tools were compared with DLW. Attenuation factors and correlation coefficients between self-reported and the recovery biomarker (DLW) were estimated.

RESULTS

Mean water intakes by DLW were 2777 mL/d (interquartile range, 2350 to 3331) in women and 3243 mL/d (interquartile range, 2720 to 3838) in men. Compared with DLW, water intake was underestimated by 18% to 31% on ASA24s and 43% to 44% on 4DFRs. Estimated geometric means from FFQs differed from DLW by -1% to +13%. For a single ASA24, FFQ, and 4DFR, attenuation factors were 0.28, 0.27, and 0.32 and correlation coefficients were 0.46, 0.48, and 0.49, respectively. Repeated use of 6 ASA24s, 2 FFQs, and 2 4DFRs improved attenuation factors to 0.43, 0.32, and 0.39 and correlation coefficients to 0.58, 0.53, and 0.54, respectively.

CONCLUSIONS

FFQs may better estimate population means for usual water intake compared with ASA24 and 4DFR. Similar attenuation factors and correlation coefficients across all self-report tools indicate that researchers have 3 feasible options if the goal is understanding intake-disease relationships. The findings are useful for planning future nutrition studies that set policy priorities for populations and to understand the health impact of water. This trial was registered at clinicaltrials.gov as NCT03268577.

Benefits of water intake on kidney function in older adults: protocol for a randomized controlled trial

Objective: The goal of this study is to evaluate the benefits of an increase in water intake guided by a mathematical formula (per kg of body weight) on kidney function in older adults. Methods: Older adults (≥ 65 years old) cared for at the Internal Medicine Unit of a tertiary hospital will be randomized to receive or not guidance on water intake (30 mL/kg per day) after initial assessment of kidney function. After 14 days, participants will be reevaluated through clinical and laboratory examinations. Patients with uncompensated disease will be excluded. The main outcomes will be glomerular filtration rate and laboratory measures such as serum and urinary osmolality, sodium, urea, 24-h urine volume and serum creatinine, uric acid, and copeptin. The Mini Nutritional Assessment (MNA) questionnaire will be applied to participants at each visit. Categorical variables will be described as numbers of cases (%) and compared using the χ2 test whereas continuous variables will be analyzed with Student’s t-test in relation to baseline measures. The Generalized Estimating Equations (GEE) method will be performed to assess differences over time and between groups. This study was approved by the Institution’s Research Ethics Committee (grant number 16-0153) and is in accordance with the Declaration of Helsinki. Expected Results:By increasing water intake (ml/Kg) we expect to provide an improvement in kidney function in older population assessed by serum creatinine and cystatin-c applied to eGFR formulas. Relevance:Many conditions, both organic and behavioral, can contribute to chronic dehydration states in older adults. To mention, decreased ability to concentrate urine, reduced kidney mass, blood flow, and glomerular filtration rate (GFR) along with changes in sensitivity to hormones such as renin, vasopressin and natriuretic peptide can generate water imbalance, leading to dehydration. For being simple and inexpensive, this strategy may be broadly used and bring several health benefits to older adults.

Effects of Early Rehydration on Brain Perfusion and Infarct Core after Middle Cerebral Artery Occlusion in Rats

Imaging evidence for the effect of rehydration on cerebral perfusion and brain ischemia has never been proposed in the literature. This study aimed to test the hypothesis that early rehydration treatment can improve cerebral perfusion and decrease infarct volume, consequently reducing mortality of dehydrated stroke animals. Methods: Thirty dehydrated experimental rats were randomly assigned to either a rehydration or control group after middle cerebral artery occlusion (MCAO). Diffusion-weighted imaging and dynamic contrast enhancement perfusion imaging were performed at 30 min and 6 h after MCAO using a 9.4T MR imaging scanner to measure the infarct volume and brain perfusion. Results: The survival rates after the first MRI scan were 91.7% for the rehydration group and 58.3% for the control group (p = 0.059). The survival rates after the second MRI scan were 66.7% for the rehydration group, and 8.3% of the control group survived (p = 0.003). The infarct volume of the rehydration group was significantly smaller than control group at 30 min after MCAO (p = 0.007). The delay time and time to maximum were significantly shorter in the rehydration group at 30 min (p = 0.004 and 0.035, respectively). Conclusions: The findings suggest that early rehydration therapy can decrease the infarct volume, shorten the delay time of cerebral perfusion, and increase survival of dehydrated ischemic-stroke rats. This preliminary study provided imaging evidence that more intensive early hydration therapies and reperfusion strategies may be necessary for acute stroke patients with dehydrated status.

Primary 'dehydration' and acute stroke: a systematic research review

BACKGROUND AND PURPOSE

Hydration status at the time of stroke has been acknowledged as an important determinant in early stroke recovery. However, the diagnosis of dehydration, or more accurately, a volume-contracted state, at the time of stroke is challenging since there are currently no consensus diagnostic criteria. In this systematic review, we gather the available evidence about diagnosis and treatment of dehydration after stroke.

METHODS

Studies of hospitalized ischemic stroke patients that reported rates of dehydration from January 1997 to March 2017 were screened for inclusion via a systematic search of PubMed, CINAHL, Cochrane, and Scopus using keywords hydration, dehydration, hemodilution, viscosity, volume status, and thirst.

RESULTS

Twenty-five studies of 8699 acute stroke patients were included. Nineteen studies reported on the diagnostic approach to dehydration. Findings are synthesized into four main categories of available research including studies that specify: (1) biological mechanisms using animal models to investigate the relationship between dehydration and stroke; (2) measures of dehydration in the acute human stroke population; (3) rehydration therapies after stroke; and (4) outcomes after stroke in dehydrated patients.

CONCLUSIONS

We found considerable variation in terminology specific to hydration status, diagnostic approach to dehydration, and few prospective studies of treatment strategies with varying results. This review supports the need for consensus development of operational diagnostic criteria, standardization of language, and the opportunity for prospective study of rehydration strategies to impact outcome after stroke.

Total volume and composition of fluid intake and mortality in older women: a cohort study

OBJECTIVES

The health benefits of 'drinking at least 8 glasses of water a day" in healthy individuals are largely unproven. We aimed to examine the relationship between total fluid and the sources of fluid consumption, risk of rapid renal decline, cardiovascular disease (CVD) mortality and all-cause mortality in elderly women.

DESIGN, SETTING AND PARTICIPANTS

We conducted a longitudinal analysis of a population-based cohort study of 1055 women aged ≥70 years residing in Australia.

MAIN OUTCOME MEASURES

The associations between total daily fluid intake (defined as total volume of beverage excluding alcohol and milk) and the types of fluid (water, black tea, coffee, milk and other fluids) measured as cups per day and rapid renal decline, CVD and all-cause mortality were assessed using adjusted logistic and Cox regression analyses.

RESULTS

Over a follow-up period of 10 years, 70 (6.6%) experienced rapid renal decline and 362 (34.4%) died, of which 142 (13.5%) deaths were attributed to CVD. The median (IQR) intake of total fluid was 10.4 (8.5-12.5) cups per day, with water (median (IQR) 4 (2-6) cups per day) and black tea (median (IQR) 3 (1-4) cups per day) being the most frequent type of fluid consumed. Every cup per day higher intake of black tea was associated with adjusted HRs of 0.90 (95% CI 0.81 to 0.99) and 0.92 (95% CI 0.86 to 0.98) for CVD mortality and all-cause mortality, respectively. There were no associations between black tea intake and rapid renal decline, or between the quantity or type of other fluids, including water intake, and any clinical outcomes.

CONCLUSIONS

Habitual higher intake of black tea may potentially improve long-term health outcomes, independent of treating traditional CVD risk factors, but validation of our study findings is essential.

Elevated blood viscosity is associated with cerebral small vessel disease in patients with acute ischemic stroke

BACKGROUND

Increased level of blood viscosity, which is one of the major factors that determine blood rheology, has been reported as a risk factor or predictor for cerebrovascular events. We investigated how blood viscosity is associated with acute stroke and chronic radiological manifestations of cerebral small vessel disease, and how blood viscosity changes after stroke.

METHODS

We prospectively enrolled consecutive patients with acute ischemic stroke. Whole blood viscosities at a low or high shear rate were measured using a scanning capillary tube viscometer, and were referred to as diastolic blood viscosity (DBV) and systolic blood viscosity (SBV), respectively. Correlations between blood viscosity and acute stroke etiology or chronic radiological manifestations of cerebral small vessel disease were investigated. The temporal profiles of blood viscosity at the onset of stroke and follow-up at 1 and 5 weeks were investigated.

RESULTS

Of the 127 patients admitted with acute ischemic stroke, 63 patients were included in the final analyses. DBV at the onset of stroke was significantly higher in small artery occlusion (SAO) stroke than in other stroke subtypes (p = 0.037). DBV showed a significant positive correlation with the number of chronic lacunes (r = 0.274, p = 0.030). The temporal profiles of DBV in SAO stroke showed a transient decrease due to the hydration therapy after 1 week and recurrent elevation at 5 week follow-up (p = 0.009).

CONCLUSIONS

Our study suggests that elevated DBV may play a role in the development of acute and chronic manifestations of cerebral small vessel disease. The recurring elevation of DBV in SAO stroke indicates that sufficient hydration and additional therapeutic interventions targeting blood viscosity may be needed in patients with SAO stroke.

Assessment of hydration status in a large population

Both acute and chronic dehydration can have important implications for human behaviour and health. Young children, non-autonomous individuals and the elderly are at a greater risk of dehydration. Mild hypertonic dehydration could be related to less efficient cognitive and physical performance and has been reported to be associated with frequently occurring pathological conditions, especially nephrolithiasis. The assessment of hydration status in a large sample appears to be of interest for conducting epidemiological and large clinical studies aimed at improving preventive and curative care. Especially in large-population studies, methods that are used have to be accurate, cheap, quick and require no technical expertise. Body weight change is widely used to determine acute hydration changes, but seems to be insufficiently accurate in longitudinal studies. Bioimpedance analysis methods enable the assessment of total body water content, but their use is still under debate. Because plasma osmolality directly reflects intracellular osmolality, it constitutes a good marker to assess acute hydration changes, but not chronic hydration status because it changes constantly. Moreover, venepuncture is considered to be invasive and is not suitable for a large-sample study, especially in children. Urinary markers appear to be good alternatives for assessing hydration status in large populations. Collection of urine samples is non-invasive and cheap. High technical expertise is not required to perform urinary marker measurements and these measurements can be carried out quickly. Thus, methods based on urinary markers are very well suited for field studies. Urine colour is probably the least sensitive marker despite its high specificity. Urine osmolality and especially urine specific gravity could be easily used for determining hydration status in large-sample studies.

Association between water intake, chronic kidney disease, and cardiovascular disease: a cross-sectional analysis of NHANES data

BACKGROUND

Evidence from animal and human studies suggests a protective effect of higher water intake on kidney function and cardiovascular disease (CVD). Here the associations between water intake, chronic kidney disease (CKD) and CVD were examined in the general population.

METHODS

We conducted a cross-sectional analysis of the 2005-2006 National Health and Nutrition Examination Survey. Non-pregnant adults with an estimated glomerular filtration rate (eGFR) ≥30 ml/min/1.73 m(2) who were not taking diuretics were included. Total water intake from foods and beverages was categorized as low (<2.0 l/day), moderate (2.0-4.3 l/day) and high (>4.3 l/day). We examined associations between low total water intake and CKD (eGFR 30-60 ml/min/1.73 m(2)) and self-reported CVD.

RESULTS

Of 3,427 adults (mean age 46 (range 20-84); mean eGFR 95 ml/min/1.73 m(2) (range 30-161)), 13% had CKD and 18% had CVD. CKD was higher among those with the lowest (<2.0 l/day) vs. highest total water intake (>4.3 l/day) (adjusted odds ratio (OR) 2.52; 95% confidence interval (CI) 0.91-6.96). When stratified by intake of (1) plain water and (2) other beverages, CKD was associated with low intake of plain water: adjusted OR 2.36 (95% CI 1.10-5.06), but not other beverages: adjusted OR 0.87 (95% CI 0.30-2.50). There was no association between low water intake and CVD (adjusted OR 0.76; 95% CI 0.37-1.59).

CONCLUSIONS

Our results provide additional evidence suggesting a potentially protective effect of higher total water intake, particularly plain water, on the kidney.