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Lupine Publishers | Continuous or Intermittent? Which Regimen of Enteral Nutrition is Better for Acute Stroke Patients? a Systematic Review and Meta-Analysis

 Lupine Publishers| Journal of Neurology and Brain Disorders

 

Abstract

Background and purpose: Enteral nutrition via nasogastric tube in acute stroke patients with dysphagia is an important determinant of patient outcomes. It is unclear whether intermittent or continuous feeding is more efficacious. The aim of this review is to examine the current evidence comparing the effectiveness of intermittent versus continuous feeding in stroke patients in terms of nutritional status, gastrointestinal intolerance and other complications.

Methods: A systematic review of randomized controlled studies comparing intermittent with continuous nasogastric feeding in acute stroke patients was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Metaanalyses) guidance using predefined search terms. The search was conducted in MEDLINE and EMBASE up to 1st March 2019. Two independent reviewers assessed study quality using the Joanna Briggs Institute Critical Appraisal Tool. Meta-analyses were conducted, where appropriate, using a random-effects model to pool risk ratio with corresponding 95% CI.

Results: Three studies including a total of 184 patients were identified. All three were medium to low quality. The definition of intermittent enteral nutrition within each study varied considerably in terms of volume, rate and mode of delivery. Achievement of nutritional targets was the same for both feeding patterns in the one study it was reported. Only aspiration pneumonia and diarrhea were measured by all three studies. There was no significant difference in the incidence of aspiration pneumonia (RR 0.91, 95% CI 0.53-1.57, p=0.74, I2=50%) and diarrhea (RR 1.74, 95% CI 0.70-4.30, p=0.23, I2=42%) between the two patterns of feeding. Other outcomes including, vomiting, gastric retention, mortality, pre-albumin and nasogastric tube complications showed no significant differences.

Conclusion: There is very little and low-quality evidence to inform patterns of enteral feeding after stroke. The available evidence shows no significant difference in nutritional achievement and complications between intermittent and continuous nasogastric tube feeding in acute stroke patients.

Keywords: Stroke; Enteral; Nutrition; Nasogastric; Dysphagia

Background

Dysphagia occurs in up to 50% of patients following a stroke [1- 4] and increases the risk of pneumonia almost ten-fold [5]. Strokerelated pneumonia is associated with longer length of hospital stay, worse levels of disability and increased mortality [6-9]. In most dysphagic patients, adaptation of the consistency of diet and fluids is sufficient to ensure that the swallow is safe. However, in a small proportion insertion of a Nasogastric Tube (NGT) is required to ensure safe and adequate nutrition. Despite this, more than twothirds of NGT-fed stroke patients still develop pneumonia [10] Gastric dysmotility is a well-documented phenomenon that occurs in critically ill patients, including acute stroke patients, whereby incomplete gastric emptying results in stasis, heightening the risk of reflux and aspiration of gastric contents [10-13]. NGT bolus feeding was first described by Morrison et al. [14] in 1895 for children with Diphtheria, who received 6-ounce bolus feeds 3 times a day via NGT. However, it wasn’t until 1910s when Morgan et al. [15] and Jones et al. [16] began administering their enteral feeds “drop by drop” rather than as a bolus. Contemporaneously, the regimen most frequently used in most patients requiring enteral feeding is continuous (i.e. low volume pumped feed lasting 16-24 hours without interruption). However, recent attention has been afforded to examining whether a discontinuous feeding strategy - often described as either intermittent or bolus (i.e. high volume of feed administered over a short period multiple times a day) - could reduce patients’ risk of pneumonia and achieve better nutrition and digestive tolerance.

Intermittent feeding reflects normal human feeding patterns more closely than continuous feeding. A period of fasting interrupted by the ingestion of a discrete meal causes gastric distension and subsequent stimulation of gut motility, secretion of digestive enzymes and metabolic responses to nutrient loading [17- 18]. This physiological gastrointestinal response to intermittent feeding has been demonstrated in healthy adults, neonates and intensive care populations [17-20]. While there are good theoretical reasons to assume that intermittent feeding is more physiological, most stroke patients in the UK receive nasogastric feeding continuously, as there are concerns that intermittent feeding may be less well tolerated. Guidance and practice relating to enteral feeding after stroke differs between countries; with the American Heart Association [21] and the Royal College of Physicians [22] not addressing the issue, Australian Guidelines allowing for both options [23] and intermittent feeding described as “traditional” in China [24]. The aim of this systematic review is to determine whether there are differences in the achievement of adequate nutrition, gastrointestinal tolerance, and metabolic stability between intermittent and continuous nasogastric feeding.

Methods

This systematic review and meta-analysis were prepared according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines [25].

Criteria for Considering Studies for this Review

The inclusion criteria for this review were:
a. Population: Acute stroke patients aged 18 or more with a nasogastric tube receiving enteral nutrition
b. Intervention: Intermittent enteral nutrition: by bolus, gravity systems or infusion pump several times a day with a rest between feeds
c. Control: Continuous enteral nutrition: with gravity systems or infusion pumps, without interruption for a minimum period of 12 hours/day
d. Outcomes: Nutritional status, aspiration pneumonia, diarrhea, vomiting, gastric distension, gastric retention, hyperglycemia, pre-albumin, mortality, length of stay, and NGT complications
e. Study Design: Randomized controlled trials or pseudo-randomised controlled trials (a study without true randomisation) that compared continuous and intermittent enteral feeding methods.

Search Strategy

A literature search was performed using MEDLINE (1966 – 1^st March 2019) and EMBASE (1974– 1st March 2019). Studies were searched for using the terms enteral, nutrition, nasogastric, gastrointestinal, feeding as Medical Subject Heading (MeSH) and free text terms. These were combined with the set operator “AND” with following terms: intermittent, continuous as both MeSH and free text terms. Publications were restricted to those studying adult populations, defined as greater than 18 years old, with a documented diagnosis of stroke according to accepted international criteria [26]. This search strategy is described in Appendix 1. The reference lists of all eligible studies that were identified were also comprehensively searched for studies not identified using the initial search strategy. This search was performed independently by two reviewers.

Selection of studies

Two reviewers (GDP and ET) assessed the studies independently for inclusion using the title and abstract. In cases where relevance could not be determined solely from the abstract, the full text was consulted. Any disagreements were resolved by consensus with a third reviewer (CR).

Data extraction and management

Data extraction was done manually by two reviewers (GDP and ET). Differences were discussed and adjudicated in faceto- face meetings. Foreign language papers were translated, and descriptions of each study were derived. This included authors, year of publication, type of participant, location, study design, sample size, age and gender of participants, exclusion criteria, when feeding was started, monitoring period, nasogastric tube size, type of feed and definitions of each intervention. In addition, data was extracted for definition and results of each outcome from all studies.

Assessment of risk of bias in included studies

Methodological quality of the studies was assessed using the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (MAStARI) Critical Appraisal tool for experimental studies [27].

Data synthesis

The studies presented in this review all fitted the conceptual definitions of intermittent and continuous enteral nutrition, as outlined in the inclusion criteria. However, there were differences in the volume, rate and temperature of nutrient delivered. In addition, two of the studies did not use true randomisation. Taking into consideration these limitations, a meta-analysis has been carried out with the outcome’s diarrhea and aspiration pneumonia, as these were the outcomes assessed by all studies. Narrative synthesis was used where outcomes did not allow meta-analysis. The meta-analysis was performed using Review Manager (RevMan) Version 5.3. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014. Data was extracted from all three studies for the outcome’s diarrhea and aspiration pneumonia. We calculated risk ratios (RR) and 95% CIs using the Mantel–Haenszel model. Statistical heterogeneity among trials was assessed by the I2 test, with I2 >50 representing possible substantial heterogeneity. The meta-analysis was performed with a random‐effects model irrespective of the level of heterogeneity as the included trials varied considerably in a number of methodological features.

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