Acute effects of intradialytic nutrition supplementation on hemodynamics, treatment efficiency, and gastrointestinal symptoms in maintenance hemodialysis patients
Poor nutritional status is common and among the strongest predictors of mortality in patients undergoing maintenance hemodialysis (HD) treatment. Reduced dietary intake, especially on days in which patients undergo treatment, is one factor that contributes to this poor nutritional status. Providing nutritional supplements or allowing patients to eat during HD treatment can help restore dietary intake, improve nutritional status, and significantly reduce mortality in malnourished patients. However, in the United States this practice is frequently restricted due to concerns about patient safety. To better understand practice patterns related to eating during HD treatment we conducted an international survey. We received 73 responses representing clinics in six continents. Among this cohort, 61 of 73 clinicians (85%) were at clinics that allowed patients to eat during treatment and 53 (73%) were at clinics that provided food during treatment. Interestingly, none of the nine clinics from North America provided food during treatment. In the second part of this survey, we asked the 61 clinicians who were at clinics which allowed patients to eat during treatment about their experience with the six most-cited reasons to restrict eating during treatment using a four point scale. Clinicians responded that they observed choking (98%), reduced Kt/V (98%), infection control issues (96%), spills or pests (83%), gastrointestinal issues (71%), and hypotension (62%) either “rarely” or “never.” The results of our survey suggested that gastrointestinal (GI) issues were amongst the conditions most frequently attributed to eating during HD treatment. However, there have been no studies directly examining the effects of providing nutrition on these symptoms. One reason for this lack of data may have been the absence of a validated tool to measure GI symptoms. Therefore, we developed and validated a questionnaire to measure GI symptoms associated with a single HD treatment. Following a brief face validation with renal dietitians, we recruited 50 maintenance HD patients and administered our survey following a mid-week HD treatment. During the same treatment we measured dietary intake by diet recall. Three weeks later we repeated this process. In general, we found good agreement between items in each domain and repeatability among individual domains. Prevalence of GI symptoms during treatment (77.1%) was much higher than previously reported and associated with the intake of fat (r=.318, p = 0.027) and fiber (.386, p = 0.007) during treatment. At the same time as our validation study, we also sought to determine the effect that liquid supplements had on the symptoms commonly associated with eating during treatment. We used a within-subjects design (n=8) to compare standard HD treatment (HD) to a standard HD treatment in which patients ingested 30 grams of whey protein starting 30 minutes into their treatment (HD + Protein). We found no interaction between groups in any hemodynamic variable (p>0.05). However, there was a main-effect of time for a reduction in SBP, decrease in heart rate, and a trend for a reduction in MAP. Furthermore, there was no difference in the reduction ratio of β2-microglobulin, reduction ratio of urea, GI symptoms, or symptomatic hypotension between the two treatments (p > 0.05 for all). These data suggest that 30 grams of whey protein by itself does not exacerbate symptoms during HD treatment. However, carbohydrates and lipids have been previously implicated as the primary cause of postprandial drops in blood pressure and GI symptoms during hemodynamic instability. Therefore, we applied the same within-subjects model to test for the effect of a renal specific mixed-macronutrient supplement. We baseline tested 11 HD patients to determine cardiovascular structure and function. Following baseline testing, we monitored a standard HD treatment (HD) and a standard HD treatment in which patients consumed a nutrition supplement (HD + ONS). HD + ONS resulted in a trend for an increase in blood glucose (p = 0.061) compared to HD. Despite this increase in glucose, a potentially vasoactive compound, we found no interactions among any hemodynamic variable (p>0.05 for all) in the HD + ONS compared to HD. While there were no interactions, postprandial beat-to-beat cardiac output and heart rate were elevated in the HD + ONS group compared to the HD group (p < 0.05) over the 150 minutes following supplementation. In spite of these hemodynamic alterations, we found no statistical difference between any measure of treatment efficiency or GI symptoms between HD and HD + ONS (p > 0.05 for all). When we compared the maximum change in BP following ONS with treatment characteristics, cardiovascular structure, and cardiovascular function, we found only baseline baroreceptor sensitivity was associated with the change in MAP (r=0.706, p=0.05). In conclusion, we tested the effects of two liquid nutritional supplements on three of the main reasons cited by clinicians to restrict intradialytic nutrition. We found no difference in blood pressure, treatment efficiency, or GI symptoms with either supplement. However, we did find an elevated cardiac output and heart rate following the consumption of a mixed-macronutrient supplement. Future work should continue to evaluate factors related to safety of intradialytic nutrition, especially the effect of different supplements on local postprandial hemodynamics, gut barrier function, and intestinal ischemia. However, our data do not support the frequent practice of restricting intradialytic nutrition.
University of Illinois - Urbana-Champaign
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