Hydration is a process involving the balance between water intake and output. Although the body derives water from food and metabolic processes, over half of fluid intake occurs through drinking water and other beverages (Davidhizar, Dunn, & Hart, 2004; Sawka, Cheuvront, & Carter, 2005). Davidhizar et al. (2004) report that fluid requirements are variable and are dependent upon a variety of factors, including acute illness and age. Under normal conditions, healthy elderly consume sufficient quantities of fluids to meet their needs (Bossingham, Carnell, & Campbell, 2005; Kant, Graubard, & Atchison, 2009). However, during acute illness, they are more susceptible to fluid imbalance due to decreased thirst perception (Kenney & Chiu, 2000; Phillips, Rolls, Ledingham, & Morton, 1984; Sheehy, Perry, & Cromwell, 1999). Furthermore, Kedlaya and Brandstater (2002) report that insufficient oral fluid intake is associated with medical conditions such as acute stroke. This is concerning since dehydration has been linked to venous thromboembolism after acute stroke (Kelly et al., 2004) and is a strong predictor of hospital re-admission (Kind, Smith, Frytak, & Finch, 2007). Despite the effect acute illness has on fluid balance in the older adult, reports of dehydration in the stroke population are largely attributed to dysphagia (Kedlaya & Brandstater, 2002).
Dysphagia, or difficulty swallowing, is a common morbidity following acute stroke, with the incidence ranging from 25% to 81% depending on the method of assessment, time post onset and lesion location (Martino et al., 2005). Thickened liquids are often recommended for patients diagnosed with aspiration of thin liquids. Low, Wyles, Wilkinson and Sainsbury (2001) reported that thickened liquids were recommended for 59% of dysphagic patients following instrumental examination. Some patients are able to reduce aspiration of thin liquids by using various compensatory strategies (e.g., chin tuck) (Rasley et al., 1993). However, many patients post stroke are not able to effectively use these strategies due to coexisting language and/or cognitive impairments. When compensatory strategies are either ineffective or difficult to implement, dysphagic patients are able to continue oral fluid intake via thickened liquids (Garcia, Chambers, & Molander, 2005). Despite this benefit, thickened liquids are implicated as a risk factor associated with dehydration (Finestone, Foley, Woodbury, & Greene-Finestone, 2001; Whelan, 2001).
Finestone et al. (2001) and Whelan (2001) documented substandard oral fluid intake in patients post stroke restricted to thickened liquids. These same authors reported that mean fluid intake did not meet estimated fluid requirements based on a standard of 30 mL/kg. Whelan (2001) reported participants consumed an average of 455 mL/day, whereas the Finestone et al. (2001) participants consumed an average of 755 mL/day. Patient dissatisfaction with thickened liquids is reported to be a principal cause contributing to poor fluid intake (Pelletier, Caslpo, VanLieshout, & Goff, 2003). Matta, Chambers, Garcia and Helverson (2006) found that the main flavor of beverages was altered regardless of what brand of thickener was used or the type of beverage thickened; providing support of anecdotal accounts of poor taste. Since substandard fluid intake has been largely attributed to patients’ dislike of thickened liquids, it is reasonable to postulate that patients post stroke receiving thin liquids might consume sufficient amounts of fluids. Prior studies have investigated adequacy of fluid intake for non-oral dysphagic patients who are on enteral feedings (Finestone et al., 2001; Leibovitz, Baumoehl, Yaina, Platinovitz, & Segal, 2007); however, there are limited data on oral fluid intake of patients post stroke receiving thin liquids. Because the elderly population is subject to fluid imbalance during illness and the incidence of acute stroke in this population is high (Saposnik et al., 2009), understanding trends in fluid intake is important.
The aim of this study was threefold: (1) To determine if elderly patients hospitalized for acute stroke met a minimum standard of fluid intake (1500 mL/day) for three consecutive days, (2) To determine whether a difference exists between elderly post stroke patients receiving thin liquids and elderly post stroke patients receiving thickened liquids, and (3) To compare fluid intake patterns between patients hospitalized post stroke and their healthy community dwelling peers.
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Fluid intake was recorded in units of milliliters for a period of 72 consecutive hours for 10 community dwelling healthy elderly (CDE), 10 patients post stroke receiving thin liquids (STL) and 10 patients post stroke receiving thickened liquids (STH). Full factorial two-way ANOVA using reciprocal data was conducted, with Tukey's HSD used for post hoc analysis. The main effect for group (CDE, STL and STH) was strongly significant (F (2) = 17.715, p < .001). Post hoc analysis of group differences for mean fluid intake, including calculation of effect size, revealed that the CDE group drank significantly more fluids (M ± SD; 1961 ± 529 mL/day) than the STL group (1237 ± 442 mL/day; p = .004, d = 1.3) and STH group (947 ± 144 mL/day; p = .001, d = 1.9). A significant difference in mean fluid intake was found between the STL group versus the STH group (p = .04, d = .6). The CDE group consumed 724 mL more on average than the STL group and 1024 mL more on average than the STH group.
The data were analyzed according to time periods when fluids were consumed. Time periods were clustered into two main categories: fluids consumed during meals (breakfast, lunch, and dinner) and between meals (morning, afternoon, and evening). The number of drinking bouts and mean fluid intake for the different time periods of the three groups are found in Figures 1–3. In general, mean intake was greater during meals versus between meals for all three groups, however, the difference was relatively small (CDE: ≤132 mL, STL: ≤161 mL, and STH: ≤137 mL). The CDE group had greater number of drinking bouts between meals than either hospitalized groups.
Mean fluid intake of the CDE exceeded a minimum standard of fluid intake of 1500 mL/day, whereas the STL and STH groups did not. Eighty percent of the CDE exceeded this standard, with only two participants falling below this standard by 280 mL or less. Of the hospitalized groups, only one participant in the STL group exceeded this standard, consuming an average of 2415 mL/day. The remainder of the STL group did not meet the minimum standard (range of 158 to 637 mL below standard). All patients receiving thickened liquids fell short of 1500 mL (range of 317 to 806 mL below the minimum standard).
A total of 98 unannounced observations of the patients hospitalized post stroke were made. Observations took place during peak activity hours (between 7:30 am and 6:00 pm). Table 1 contains summary data regarding the availability of drinks. The STL group had beverages present in their room more frequently and the beverages were more accessible than the STH group. For the STH group, liquid consistency was subjectively assessed during the observation by the principal investigator. Thickened beverages matched the recommended consistency only 54% of the time. In instances when there was a discrepancy between the recommended and actual consistency, 53% were judged to be too thick.
Table 1. Percentage of Unannounced Observations with Positive Findings
|Observation||Thin Liquid Group (%)||Thickened Liquid Group (%)|
|Drink or water pitcher present in room||91||75|
|Drink or water pitcher in close proximity of patient||88||56|
|Drink containers opened||63||72|
|If patient on thickened liquids, consistency of drink present matches recommended consistency||N/A||54|
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Findings from the current study support existing evidence that patients post stroke receiving thickened liquids consume insufficient amounts of fluids. However, findings revealed that insufficient fluid intake is also a concern for patients post stroke receiving thin liquids. The STH (post stroke thickened liquids) group demonstrated a mean fluid intake of 947 ± 144 mL/day. Although participants in the present study consumed more fluid than the participants in the studies conducted by Finestone et al. (2001) and Whelan (2001), mean fluid intake still did not meet a standard of 1500 mL/day. Poor palatability and patient dissatisfaction have been cited as factors contributing to substandard fluid intake (Finestone et al., 2001; Whelan, 2001). Dissatisfaction could result from a variety of factors, including suppressed or altered taste and a grainy texture (Matta et al., 2006). Furthermore, studies have reported wide variability in degree of viscosity over time (Dewar & Joyce, 2006), beverage type and temperature (Adeleye & Rachal, 2007) even when prepared according to manufacturer's specifications. In this study, the consistency of thickened beverages did not match the recommended consistency in over half of our observations, with a majority of the liquids subjectively judged as being too thick. This can have a detrimental effect on satisfaction and subsequent intake of thickened liquids; however, other factors need to be considered.
Unannounced observations revealed interesting patterns regarding accessibility of fluids for the patients who were hospitalized post stroke. The STL (post stroke thin liquids) participants were observed to have beverages in their room (between meals) more frequently (91%). Thickened beverages were present during 75% of the observations but were within reach of the participant only 54% of the time. In contrast, the STL participants were able to access their beverages 88% of the time observed. Despite a greater opportunity to consume fluids, the STL participants still did not meet a minimum standard of fluid intake of 1500 mL/day.
Mean fluid intake of STL group was 1237 ± 442 mL/day. Although a significant difference was found between the two groups, the actual difference was only 290 mL. This equates to approximately 9 ounces of fluid, or slightly more than one cup per day. In contrast, the CDE group consumed significantly more fluids than both the hospitalized groups, drinking 24 fluid ounces more than STL group and 34 fluid ounces more than STH group. The CDE group exceeded the fluid intake standard used in this study, which supports evidence from prior studies that healthy elderly consume sufficient amount of fluids (Bossingham et al., 2005; Kant et al., 2009). The large disparity in oral fluid intake between the CDE group and the hospitalized groups could be explained by the frequency in which patients are drinking (or number of drinking bouts between meals).
The STL group had more opportunity for fluid consumption between meals; however, the number of drinking bouts between meals was similar for the two hospitalized groups (mean of six for the STL group and five for the STH group). This is in contrast to a mean of 11 drinking bouts between meals for the CDE group. The number of drinking bouts is reported to correlate strongly with fluid intake, with greater number of ingestion sessions resulting in more fluid intake (Gasper, 1999; Simmons, Alessi, & Schnelle, 2001). Holmes (2006) speculates that hospitalization often deters older individuals from their daily routines; including the timing and selection of meals and beverages. Rather than retrieving a beverage when desired, patients typically rely on others to provide them with beverages. In addition, the beverages offered may not satisfy individual preferences. One participant reported that she did not like coffee, which happened to be the only beverage on her tray. It is also possible that patients receiving thickened liquids experience a more restricted beverage selection. On one occasion, a family member was observed thickening a beverage brought from home. The participant reportedly did not like the selection of thickened beverages offered on the menu but liked this particular beverage. We did not investigate the relationship between beverage preference and fluid intake; however, Simmons et al. (2001) found that compliance with beverage preference, in conjunction with more frequent offerings resulted in significantly more fluid intake.
The limitations of the study are recognized. Every effort was made to control for errors in measurement and recording of fluid intake. However, in studies investigating fluid intake, the potential for inaccurate measurement and recording of fluids consumed are commonly considered potential sources of error (Finestone et al., 2001; Whelan, 2001). Staff education and follow-up regarding the procedures of the study were completed daily in an effort to minimize the potential for such errors. Second, the sample size was small. Regardless, the disparity in average fluid intake between the CDE group and the hospitalized groups was large. Lastly, we did not identify the severity of dysphagia for our hospitalized participants. Study participants were identified as either receiving thickened liquids due to dysphagia or receiving thin liquids. The ability to tolerate thin liquids does not imply the absence of dysphagia. Dysphagic individuals who are able to safely consume thin liquids may use compensatory strategies that facilitates safety while drinking, but impedes adequate volume of intake (e.g., instructed to sip slowly).
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In the current study, patients who were hospitalized post stroke did not meet a minimum standard of fluid intake, regardless of liquid viscosity. Poor fluid intake in patients receiving thickened liquids was expected, but it was not expected for patients receiving thin liquids. Dysphagia is linked with substandard fluid intake post stroke; however, the relationship between functional impairments in communication, cognition, and/or self feeding post stroke and substandard fluid intake is less clear. Deficits in one or more of these domains may explain the substandard fluid intake reported in the current study. In addition, non-stroke related factors including the type and frequency of beverages offered as well as providing the correct consistency of thickened liquids to dysphagic patients could impact adequate fluid intake. Future studies are needed to determine if service delivery practices (e.g., greater beverage selection) improve fluid intake in patients hospitalized post stroke.
Key Practice Points
- Insufficient oral fluid intake in the stroke population has been linked to venous thromboembolism, and is a strong predictor of hospital readmission.
- Thickened liquids are often recommended for dysphagic patients diagnosed with aspiration of thin liquids since compensatory strategies are often difficult to implement due to co-existing language or cognitive impairments.
- Dehydration in the stroke population is largely attributed to thickened liquids; however patients receiving thin liquids did not meet a minimum standard of fluid intake.
- Multiple factors contribute to insufficient fluid intake in hospitalized patients post-stroke regardless of liquid viscosity; including number of drinking episodes and beverage preference.
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