Nutrient stimulation of mesenteric blood flow - implications for older critically ill patients

Meal timing and frequency implications in the development and prognosis of chronic kidney disease

Patients with chronic kidney disease (CKD) have a higher risk of death than the general population, the main cause being cardiovascular disease (CVD). Nutrition plays a key role in the prevention and treatment of CVD and kidney diseases. Currently, new evidence reinforces the importance of specific foods and general dietary patterns rather than isolated nutrients for cardiovascular risk. In addition, dietary patterns and healthy eating habits seem extremely relevant in decreasing risk factors. Epidemiologic and clinical intervention studies have suggested that late-night dinner and skipping breakfast are associated with an increased risk of obesity, insulin resistance, and CVD. In CKD, despite important changes in nutritional counseling in recent decades, less attention has been paid to meal timing and frequency. Therefore, the purpose of this review is to discuss the evidence of meal timing and frequency in CKD development and prognosis, presented under three main topics: risk of developing CKD, importance of dietary habits, and implications of fasting.

Outcomes associated with delayed enteral feeding after cardiac arrest treated with veno-arterial extracorporeal membrane oxygenation and targeted temperature management

INTRODUCTION

While early enteral nutrition is generally preferred in critically ill patients, the optimal timing of feeding among refractory cardiac arrest patients is unknown. We examined the association between timing of enteral nutrition and patient survival and safety outcomes in patients with refractory out-of-hospital cardiac arrest (OHCA) who were treated with extracorporeal cardiopulmonary resuscitation (ECPR).

METHODS

We performed a retrospective analysis of 142 consecutive patients presenting with OHCA due to ventricular fibrillation or ventricular tachycardia treated with ECPR and targeted temperature management (TTM). Neurologically favorable survival and clinical outcomes were compared between patients who received early enteral nutrition (<48 h after admission to the intensive care unit) and patients receiving delayed enteral nutrition (initiated >48 h after admission).

RESULTS

Enteral nutrition was initiated in 90/142 (63%) patients. Early enteral nutrition was provided in 34/90 (38%) while delayed nutrition occurred in 56/90 (62%). In adjusted analysis including patients who received nutrition, delayed enteral feeding was associated with increased odds of neurologically favorable survival (29 vs 54%, CI 1.04-7.25, p = 0.04). There were no significant differences in the incidence of pneumonia (18 vs 27%, p = 0.16), gastrointestinal bleeding (5.9 vs 3.6%, p = 0.42), intestinal ischemia (5.9 vs 5.4%, p = 0.90), ileus (12 vs 11%, p = 0.98), or need for tracheostomy (15 vs 20%, p = 0.81) between early and late feeding groups.

CONCLUSION

In patients with refractory OHCA treated with ECPR and TTM, delayed enteral nutrition was associated with improved neurologically favorable survival. Adverse events related to enteral feeding were not associated with timing of feeding initiation.

Application of Transmural Flow Across In Vitro Microvasculature Enables Direct Sampling of Interstitial Therapeutic Molecule Distribution

In vitro prediction of physiologically relevant transport of therapeutic molecules across the microcirculation represents an intriguing opportunity to predict efficacy in human populations. On-chip microvascular networks (MVNs) show physiologically relevant values of molecular permeability, yet like most systems, they lack an important contribution to transport: the ever-present fluid convection through the endothelium. Quantification of transport through the MVNs by current methods also requires confocal imaging and advanced analytical techniques, which can be a bottleneck in industry and academic laboratories. Here, it is shown that by recapitulating physiological transmural flow across the MVNs, the concentration of small and large molecule therapeutics can be directly sampled in the interstitial fluid and analyzed using standard analytical techniques. The magnitudes of transport measured in MVNs reveal trends with molecular size and type (protein versus nonprotein) that are expected in vivo, supporting the use of the MVNs platform as an in vitro tool to predict distribution of therapeutics in vivo.

APOE Genotype Influences Postprandial Blood Pressure after High Fat Feeding in Older Adults

OBJECTIVE

Postprandial hypotension (PPH) is a common phenomenon among older adults. The degree to which individuals experience PPH is related to cerebrovascular risk factors and the presence of neurodegenerative diseases such as Alzheimer's disease (AD). Carrier status of the E4 allele of the apolipoprotein E (APOE) gene is a risk factor for AD and influences a variety of responses to metabolic and dietary interventions. However, it is unknown whether APOE genotype influences the risk of PPH and whether type of meal can mediate that response.

DESIGN

Acute meal study with a crossover design.

PARTICIPANTS

32 cognitively healthy older adults with (n=18) and without (n=14) E4+ carrier status.

INTERVENTION

As a part of an ongoing meal study we examined the postprandial blood pressure response after ingestion of a high carbohydrate (HCM) and high fat meal (HFM).

MEASUREMENTS

Blood pressure measurements were taken at 7 time points and change scores, area under the curve (AUC) scores were calculated. Data were analyzed by repeated measures ANOVA as well as Pearson correlation.

RESULTS

Both meals produced a sustained drop in systolic (SBP) and diastolic (DBP) blood pressure, with 37.5% of participants meeting criteria for PPH. Participants carrying the E4+ risk gene experienced a larger decrease in SBP than E4- participants, and this was significantly different after the HFM (E4+ AUC = -30.8 ± 7.6, E4- AUC = -0.2 ± 8.7, p=0.015). Increasing age was associated with a larger drop in postprandial blood pressure but only for the E4+ group after the HFM (p=0.002).

CONCLUSIONS

These data suggest that E4+ individuals experience a greater postprandial blood pressure response particularly following high fat feeding, and this effect becomes more pronounced with age. The prevalence of PPH may play a role in the development of AD and may be mediated by diet.

Postprandial hypotension in older survivors of critical illness

PURPOSE

In older people postprandial hypotension occurs frequently; and is an independent risk factor for falls, cardiovascular events, stroke and death. The primary aim of this pilot study was to estimate the frequency of postprandial hypotension and evaluate the mechanisms underlying this condition in older survivors of an Intensive Care Unit (ICU).

MATERIALS AND METHODS

Thirty-five older (>65 years) survivors were studied 3 months after discharge. After an overnight fast, participants consumed a 300 mL drink containing 75 g glucose, labelled with 20 MBq 99mTc-calcium phytate. Patients had concurrent measurements of blood pressure, heart rate, blood glucose and gastric emptying following drink ingestion. Proportion of participants is presented as percent (95% CI) and continuous variables as mean (SD).

RESULTS

Postprandial hypotension was evident in 10 (29%; 95% CI 14-44), orthostatic hypotension in 2 (6%; 95% CI 0-13) and cardiovascular autonomic dysfunction in 2 (6%; 95% CI 0-13) participants. The maximal postprandial nadir for systolic blood pressure and diastolic blood pressures were -29 (14) mmHg and -18 (7) mmHg.

CONCLUSIONS

In this cohort of older survivors of ICU postprandial hypotension occurred frequently . This suggests that postprandial hypotension is an unrecognised issue in older ICU survivors.

The Relationship Between Intradialytic Nutrition and Gastrointestinal Symptoms Using a Modified Version of the Gastrointestinal Symptom Rating Scale

OBJECTIVE

Intradialytic nutrition has been shown to improve nutritional status in maintenance hemodialysis (HD) patients but remains controversial due in part to concerns over hemodynamic stability and gastrointestinal (GI) distress. There are limited data on the relationship between intradialytic nutrition and GI symptoms, possibly due to the lack of a validated tool. Therefore, we intended to validate a questionnaire to measure GI symptoms associated with a single HD treatment and determine the relationship between intradialytic nutrition and GI symptoms.

DESIGN

Cross-sectional study. Forty-eight maintenance HD patients.

MAIN OUTCOME MEASURE

GI symptoms and dietary intake during HD treatment.

RESULTS

In general, we found acceptable internal consistency (Cronbach's alpha >0.5, exception reflux domain) and repeatability in all 5 domains of a modified version of the Gastrointestinal Symptom Rating Scale. The prevalence of GI symptoms associated with a single HD treatment (generalized score greater than 1) was 54.2, 43.7, 6.2, 41.7, and 45.8% for the abdominal pain, indigestion, reflux, diarrhea, and constipation domains, respectively. More than two-thirds of patients chose to eat during treatment (168.6 ± 165.6 kcal) with the most commonly consumed items being candy, oral supplements, and cookies. There was no difference in GI symptoms among patients who did or did not eat (P > .05). However, the amount of total dietary fat and fiber consumed during treatment was associated with greater indigestion (P < .05) prior to accounting for outliers or multiple comparisons.

CONCLUSION

In this sample, the modified version of the Gastrointestinal Symptom Rating Scale was a generally valid tool for measuring GI symptoms associated with a single HD treatment. Patients who ate during treatment did not experience greater GI symptoms than those who did not; however, high amounts of fat and fiber may be associated with greater GI symptoms. Prospective trials should examine the relationship between GI symptoms and dietary intake during treatment in HD patients.