Use of residual volume as a marker for enteral feeding intolerance: prospective blinded comparison with physical examination and radiographic findings

Gastric Cross-Sectional Area to Predict Gastric Intolerance in Critically Ill Patients: The Sono-ICU Prospective Observational Bicenter Study

To evaluate the correlation between gastric cross-sectional area (GCSA) and the occurrence of gastric intolerance in critically ill patients within 24 hours of the measurement.

DESIGN

Two-center prospective observational study.

SETTING

Two academic ICUs in France between June 2020 and August 2021.

PATIENTS

All surgical intubated ICU patients greater than or equal to 18 years old receiving enteral feeding for greater than 12 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Forty-four patients were included, 11 (25%) of whom presented digestive intolerance. Primary outcome was assessment of the association between GCSA and the occurrence of gastric intolerance within 24 hours of the measurement. GCSA value was significantly higher in patients with upper digestive intolerance compared to those without (553 mm² [interquartile range (IQR), 500-649 mm²] vs 970 mm² [IQR, 777-1,047]; p < 0.001, respectively). The optimal threshold for predicting upper digestive intolerance was 720 mm² (area under the receiver operating characteristic curve 0.86; positive predictive value 62.5%; negative predictive value 96.4%; sensibility 0.91; and specificity 0.81). Multivariate analysis (weighted by propensity score), including known risk factors, showed that GCSA above the 720 mm² threshold was independently associated with the occurrence of upper digestive intolerance (odds ratio, 1.85; 1.37-2.49; p < 0.0002). Measurement quality was "good" (i.e., liver, aorta, superior mesenteric vein, and pancreas were all visualized) in 81% of cases.

CONCLUSIONS

Measurement of GCSA by ultrasound would allow prediction of gastric intolerance in critically ill patients. This should be confirmed by a prospective score validation and interventional trials.

The correlation between gastric residual volumes and markers of gastric emptying: a post-hoc analysis of a randomized clinical trial

BACKGROUND

The correlation between gastric residual volumes (GRV) and markers of gastric emptying (GE) in critically ill patients is unclear. This is especially true for ICU surgical patients as they are underrepresented in previous studies.

METHODS

We conducted a post-hoc analysis of a multicenter trial that investigated the effectiveness of a promotility drug in increasing enteral nutrition intake. Pharmacokinetic markers of GE [3-O-methylglucose (3-OMG) and acetaminophen] were correlated with GRV measurements. High-GRV was defined as one episode of >400 mL or two consecutive episodes of >250 mL, and delayed GE was defined as <20^th percentile of the pharmacokinetic GE marker that had the strongest correlation with GE.

RESULTS

Out of 77 patients, 8 (10.4%) had high-GRV, and 15 (19.5%) had delayed GE. 3-OMG concentration at 60 mins had the strongest correlation with GRV (Rho: - 0.631), and high-GRV had low sensitivity (46.7%) but high specificity (98.4%) in discriminating delayed GE. The positive (87.5%) and negative (88.4%) predictive values were similar. There was a small sample of surgical patients (n = 14, 18.2%), and they had a significantly higher incidence of high-GRV (29% vs 6%, P: 0.032) and a trend towards delayed GE (36% vs 16%, p: 0.132) when compared to medical patients.

CONCLUSION

GRV reflects GE, and high-GRV is an acceptable surrogate marker of delayed GE. Based on our preliminary observation, surgical patients may have a higher risk of high-GRV and delayed GE. In summary, GRV should be monitored to determine if complex investigations or therapeutic interventions are warranted. This article is protected by copyright. All rights reserved.

Premedication with reformulated simethicone and sodium bicarbonate improves mucosal visibility during upper gastrointestinal endoscopy: a double-blind, multicenter, randomized controlled trial

Background

The reformulated simethicone emulsion from Berlin Chemical AG might develop white flocculate precipitate covering the gastric mucosa when used before esophagogastroduodenoscopy (EGD). We aim to investigate whether combining the reformulated simethicone emulsion with 5% sodium bicarbonate solution could prevent the development of white precipitate and improve visibility during EGD.

Methods

Our clinical study involved 523 patients. They were randomly assigned to two groups. In Group A, patients received a warm solution containing 30 ml 5% sodium bicarbonate solution and 15 ml reformulated simethicone emulsion. In Group B, patients received 45 ml 40 °C lukewarm water. Visibility scores were recorded and analyzed. Flushes, volume of flush water, overall time taken for EGD and complications during or after the procedure were also recorded.

Results

We found that no white precipitate was observed during EGD in Group A. Moreover, visibility scores in Group A were significantly lower (P < 0.01). Patients in Group A had fewer flushes (P < 0.01) and smaller volume of flush water (P < 0.01). In addition, the overall time taken for the EGD procedure was significantly shorter in Group A (P < 0.01). The percentage of patients who had no adverse response was significantly higher in Group A than in Group B (P < 0.01).

Conclusions

Premedication with a mixed solution of 15 ml reformulated simethicone emulsion and 30 ml 5% sodium bicarbonate solution can prevent the development of white precipitate, substantially enhancing mucosal visibility safely.

Trial registration: The registered name of the trial is “Efficacy of using premedication with reformulated simethicone emulsion during upper gastrointestinal endoscopy examination”. Its Current Controlled Trials number is ChiCTR1900021689. Its date of registration is 11 September 2019. Retrospectively registered, http://www.medresman.org.cn/uc/sindex.aspx.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-021-01623-w.

Prospective evaluation of a novel enteral feeding guideline based on individual gastric emptying times: an improvement project in a pediatric intensive care unit

BACKGROUND

On a 20-bed, mixed cardiac and general, UK pediatric intensive care unit (PICU), we aimed to determine if a physiologically based enteral feeding guideline for critically ill children, using feed frequency tailored to individual gastric emptying times, resulted in earlier establishment of full feeds (when 100% of fluid allowance (FA) available to be given as intravenous maintenance fluid or feed, defined as free FA [FFA], is given as enteral nutrition [EN]) and an increase in FFA given as EN.

METHODS

Four prospective audits (totaling 331 patients and 19,771 hours) were conducted at 1 year before guideline introduction and 1, 5, and 10 years after. Patient feeding data were collected from admission until day 4 or discharge, including reasons why feed was withheld.

RESULTS

The median time from admission to establishing full feeds decreased from 18 to 10 hours preguideline and postguideline and was sustained over 10 years. After adjustment for 5 confounders, this represented a reduction in the geometric mean time to full feeds of 30% (2009), 29% (2013), and 48% (2019) compared with 2007 (all P < .01). Nil-per-oral (NPO) hours were categorized as due to modifiable and nonmodifiable factors. Preguideline and postguideline NPO hours from modifiable factors decreased from 21 (2007) to 10 (2009) per 100 audit hours, which was sustained across 10 years (all P < .01). Conversely, NPO hours from nonmodifiable factors ranged from 27 to 36 per 100 audit hours throughout the audits, with no consistent trend over time. Similar inconsistency was shown in the proportion of FFA given as EN: 48% (2007), 71% (2009), 51% (2013), and 64% (2019). Continuous nasogastric and hourly bolus feeds decreased over time; they comprised 66% of feeds in 2007 but only 4%-11% in subsequent periods, being replaced with more 2-6 hour bolus, on-demand, or continuous nasojejunal feeds.

CONCLUSION

The guideline was associated with sustained reduction in the time to establishing full feeds and NPO hours due to modifiable factors and more or no less FFA being given as EN.

Are Classic Bedside Exam Findings Required to Initiate Enteral Nutrition in Critically Ill Patients: Emphasis on Bowel Sounds and Abdominal Distension

The general physical examination of a patient is an axiom of critical care medicine, but evidence to support this practice remains sparse. Given the lack of evidence for a comprehensive physical examination of the entire patient on admission to the intensive care unit, which most clinicians consider an essential part of care, should clinicians continue the practice of a specialized gastrointestinal system physical examination when commencing enteral nutrition in critically ill patients? In this review of literature related to gastrointestinal system examination in critically ill patients, the focus is on gastrointestinal sounds and abdominal distension. There is a summary of what these physical features represent, an evaluation of the evidence regarding use of these physical features in patients after abdominal surgery, exploration of the rationale for and against using the physical findings in routine practice, and detail regarding what is known about each feature in critically ill patients. Based on the available evidence, it is recommended that an isolated symptom, sign, or bedside test does not provide meaningful information. However, it is submitted that a comprehensive physical assessment of the gastrointestinal system still has a role when initiating or administering enteral nutrition: specifically, when multiple features are present, clinicians should consider further investigation or intervention.

Gastrointestinal Dysfunction and Feeding Intolerance in Critical Illness: Do We Need an Objective Scoring System?

PURPOSE OF REVIEW

Efforts to provide early enteral nutrition in critical illness are thwarted by gastrointestinal dysfunction and feeding intolerance. While many of the signs and symptoms of this dysfunction reflect gastroparesis and intestinal dysmotility, other symptoms which may or may not be related are often included such as diarrhea, bleeding, and intra-abdominal hypertension. This paper discusses the need to monitor tolerance of nutritional therapy in the critical care setting and reviews the results of those clinical trials which have helped establish objective measures, define feeding intolerance, and provide a tool to guide continued delivery of the enteral regimen.

RECENT FINDINGS

While definitions vary, the presence of gastrointestinal dysfunction and feeding intolerance correlates with adverse clinical outcomes, including prolonged duration of mechanical ventilation, greater length of stay in the intensive care unit, and increased mortality. Despite their prognostic value, it is not clear to what extent these scoring systems should direct nutritional therapy. The clinician should be astute in the careful selection of monitors, in identifying and addressing signs and symptoms of intolerance, and by responding appropriately with feeding strategies that are effective and safe. Early enteral feeding in critical illness has been shown to be optimized by following protocols which allow monitoring patient tolerance while providing individualized care.

Measuring gastric residual volumes in critically ill burn patients - A systematic review

PURPOSE

Measuring gastric residual volumes (GRV) is common in intensive care units (ICU) in patients receiving enteral nutrition (EN) and are a common source of feeding interruptions. Interruptions in EN yield adverse outcomes and are an area of improvement in burn care. The objectives of this study are to summarize the literature's ICU GRV practices and offer practical suggestions to GRV management in the burn patient.

METHODS

PubMed, SCOPUS, and OvidSP Medline were systematically reviewed using the keywords: burns; thermal injury; gastric residual volume; enteral feeding; tube feeding; enteral nutrition; gastric intolerance; ICU; critical illness. Reviews, case reports, and consensus and opinion papers were excluded.

RESULTS

26 articles were identified. Six burn-specific studies were identified. GRV practices vary widely and are a common cause of EN interruption. Elevated GRVs do not equate to gastrointestinal intolerance and do not always reflect aspiration risk.

CONCLUSIONS

We advocate a GRV threshold of 500mL should be used to optimize the benefits of EN in burn ICUs. A single incident of elevated GRVs should not mandate immediate EN rate reduction or cessation but should prompt a thoughtful examination of secondary causes of gastrointestinal intolerance. Randomized controlled trials are needed to define the ideal GRV threshold and re-evaluate its role in burn care.

Effects of a Gastric Feeding Protocol on Efficiency of Enteral Nutrition in Critically Ill Infants and Children

Objective: Enteral nutrition (EN) has well-established benefits in critically ill children. Optimally, full nutritional support should be achieved expeditiously. The authors hypothesized that a protocolized continuous gastric EN (GEN) approach would decrease time to goal feeding rate and calories (TTG). Design: 96 patients were enrolled, divided equally into control (pre) and treatment (post) groups. Patients were monitored every 4 hours for 5 signs of feeding intolerance. Significance was defined as P < .05. Setting: 23-bed multidisciplinary pediatric intensive care unit (PICU). Subjects: PICU patients <18 years of age in whom GEN was to be started were eligible. Exclusion criteria included patients receiving total parental nutrition, <24 hours postoperative, had transpyloric feeding, had previous fundoplication, had preexisting gastrointestinal disease or chronic regimen. Interventions: The authors instituted a protocolized, weight-based approach to GEN and collected outcomes and tolerance data on both the control and treatment groups. Measurements and Main Results: There was no difference in TTG between the control and treatment groups. However, for patients less than 10 kg (74/96 patients), TTG was 15 hours faster in the treatment group compared with the control (56.85 ± 22.71, 70.44 ± 32.45 hours, respectively). Conclusions: The authors investigated the value of a GEN protocol in improving efficiency to goal nutrition in critically ill children. While no difference was found overall, in the subgroup analysis (77%) a significant improvement in TTG was found in infants <10 kg. Further investigation is needed to define impact on patient outcomes, such as length of stay, weight gain, and ICU morbidities.

Gastric Residual Volume: Rethinking the Threshold

There are many challenges related to enteral feedings of the mechanically ventilated patient. Among the most often debated issues is the threshold for gastric residual volume before further feeding. This brief article considers the factors to be considered and reviews current thinking on the topic.

Enhancing Interpretation of Gastric Residual Volume by Refractometry

The traditional practice of gastric residual volumes (GRVs) is flawed in its design and conception, is poorly standardized in its technique, is an inaccurate measure of gastric emptying, and serves as an insensitive marker for regurgitation and aspiration. The refractive index of a solution (like an enteral formula) is a physical property of that solution, which is remarkably constant and reproducible under varying conditions of concentration, pH, and temperature. Refractometry may be performed quickly and easily at the bedside, requires only a small representative sample of aspirated solution, and provides valuable measurements that can be used to calculate both the true total volume of contents and the specific volume of formula remaining in the stomach. Refractometry complements the use of GRVs as a monitor for patients receiving enteral feeding and should improve the accuracy with which patients at risk for aspiration may be identified.

Gastric Feeding as an Extension of an Established Enteral Nutrition Protocol

BACKGROUND

Indiscriminate gastric feeding in ICU patients imposes unacceptable risks of aspiration. Believing that a subset of ICU patients can be fed safely via the stomach, we have developed a protocol to identify appropriate patients and guide the bedside clinician in how to safely and effectively feed via the stomach.

METHODS

A literature search was done to identify appropriate medical literature. High grade evidence along with local expert opinions were used to develop a protocol. This protocol has been refined and implemented.

RESULTS

Based on perceived risk of aspiration, patients are assigned enteral access (ie, stomach vs. distal post-pyloric). Enteral formula is selected based on patient characteristics. It is then advanced by a standard protocol with specific precautions while monitoring for symptoms of intolerance. Management of intolerance is dictated by the type and severity of intolerance.

CONCLUSION

We have implemented a gastric feeding into a subset of our ICU patients. Gastric feeding requires certain precautions but appears to be safe. With more experience and better understanding of the pathogenesis gastroparesis, we believe that most ICU patients should be able to safely feed into the stomach. This is logistically easier than post-pyloric feeding and offers physiologic advantages.

Monitoring Enteral Nutrition Support Tolerance in Infants and Children

Enteral nutrition support is used extensively in the care of infants and children, both for acute and chronic conditions. Monitoring a child's tolerance of enteral feedings is an ongoing challenge. Monitoring routines vary significantly between institutions, practitioners, and patient settings, and a number of definitions are used for "intolerance." Some guidelines have scientific basis and others are passed along in a more anecdotal fashion. This review describes commonly used monitors for tolerance to enteral nutrition for infants and children and discusses pertinent data relevant to practice.

Aspiration and the Risk of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is a major concern in the intensive care unit. It is estimated that the risk of developing VAP may be as high as 1% per ventilated day, and the attributable mortality approaches 50% in some series. A growing body of evidence implicates the role of microaspiration of contaminated oropharyngeal and perhaps gastroesophageal secretions into the airways as an integral step in the pathogenesis of VAP. In patients who have been intubated and mechanically ventilated for >72 hours, the majority of VAP is caused by enteric gram-negative organisms, presumably of gastrointestinal origin. As a result, strategies designed to minimize the risk of these contaminated secretions into the normally sterile airways are of paramount importance in terms of VAP prevention. This review highlights the important etiological role of the gut in the development of VAP and also discusses the evidence behind interventions that may modulate the risk of both aspiration and subsequent VAP.

Gastric Residual Volume (GRV) and Gastric Contents Measurement by Refractometry

BACKGROUND

Traditional use of gastric residual volumes (GRVs), obtained by aspiration from a nasogastric tube, is inaccurate and cannot differentiate components of the gastric contents (gastric secretion vs delivered formula). The use of refractometry and 3 mathematical equations has been proposed as a method to calculate the formula concentration, GRV, and formula volume. In this paper, we have validated these mathematical equations so that they can be implemented in clinical practice.

METHODS

Each of 16 patients receiving a nasogastric tube had 50 mL of water followed by 100 mL of dietary formula (Osmolite HN, Abbott Laboratories, Columbus, OH) infused into the stomach. After mixing, gastric content was aspirated for the first Brix value (BV) measurement by refractometry. Then, 50 mL of water was infused into the stomach and a second BV was measured. The procedure of infusion of dietary formula (100 mL) and then water (50 mL) was repeated and followed by subsequent BV measurement. The same procedure was performed in an in vitro experiment. Formula concentration, GRV, and formula volume were calculated from the derived mathematical equations.

RESULTS

The formula concentrations, GRVs, and formula volumes calculated by using refractometry and the mathematical equations were close to the true values obtained from both in vivo and in vitro validation experiments.

CONCLUSIONS

Using this method, measurement of the BV of gastric contents is simple, reproducible, and inexpensive. Refractometry and the derived mathematical equations may be used to measure formula concentration, GRV, and formula volume, and also to serve as a tool for monitoring the gastric contents of patients receiving nasogastric feeding.

Effect of Feeding-Tube Properties on Residual Volume Measurements in Tube-Fed Patients

BACKGROUND

The effect of feeding tube size and port configuration on the ability to measure gastric residual volume (GRV) is poorly understood. In addition, there is confusion about the need to measure GRVs during feedings into the small bowel. This study sought to (1) compare the volume of gastric contents obtained from small-diameter feeding tubes and large-diameter sump tubes concurrently positioned in the stomach and (2) describe the distribution of GRVs during small-bowel feedings.

METHODS

For the first objective, GRV measurements were made from 10-Fr tubes (n = 645) and 14-Fr or 18-Fr sump tubes (n = 645) concurrently present in 62 critically ill patients. Sixty-milliliter syringes were used to measure GRVs from the 10-Fr tubes; the fluid was returned to the stomach and measurements were repeated from the large-diameter sump tubes. To address the second research objective, 890 GRV measurements were made from 14-Fr or 18-Fr gastric sump tubes (not connected to suction) in 75 critically ill patients who were receiving small-bowel feedings.

RESULTS

When GRVs were >50 mL, a linear regression equation indicated that volumes obtained from the large-diameter sump tubes were about 1.5 times greater than those obtained from the small-diameter tubes concurrently present in the stomach, p < .001. Gastric volumes > or =100 mL were found in 11.6% of the 890 measurements made in patients receiving small-bowel feedings; volumes > or =150 mL were found in 5.4% of the measurements.

CONCLUSIONS

The findings suggest that GRVs obtained from large-diameter sump tubes are about 1.5 times greater than those obtained from 10-Fr tubes. Large GRVs occur in at least 5% of patients receiving postpyloric feedings.

A Double-Blind Randomized Clinical Trial Comparing the Effect of Neostigmine and Metoclopramide on Gastric Residual Volume of Mechanically Ventilated ICU Patients

BACKGROUND

In critically ill patients, enteral feeding through the nasogastric tube is the method of choice for nutritional support. Gastrointestinal feeding intolerance and disturbed gastric emptying are common challenges in these patients. The aim of this study was to compare the effect of Neostigmine and Metoclopramide on gastric residual volume (GRV) in mechanically ventilated ICU patients.

METHODS

In a double blind, randomized clinical trial, a total of 60 mechanically ventilated ICU patients with GRV >120 mL (3 hours after the last gavage), were randomly assigned into two groups A and B. At baseline and 6 hours later, patients in group A and B received intravenous infusion of neostigmine in a dose of 2.5 mg and metoclopramide in a dose of 10 mg in 100 ml of normal saline, within 30 minutes. Patients' gastric residual volumes were evaluated before the beginning of the intervention, and 3, 6, 9 and 12 hours after the intervention.

RESULTS

After adjusting of other variables (Sex, BMI and ICU stay period) generalized estimating equation (GEE) model revealed that neostigmine treatment increased odds of GRV improvement compare to metoclopramide group (Estimate 1.291, OR= 0.3.64, 95% CI 1.07-12.34). However there is a statistically significant time trend (within-subject differences or time effect) regardless of treatment groups (P<0.001). The median time from intervention to GRV improvement was 6 hours (95% CI 3.75-8.25) and 9 hours (95% CI 7.38-10.17) in neostigmine and metoclopramide groups, respectively. This difference was statistically significant (P<0.05).

CONCLUSION

It seems that neostigmine is more effective than metoclopramide in reducing GRV and improving gastric emptying in mechanically ventilated ICU patients without significant complication and this protocol may be effective on the tolerance of enteral feeding in ICU patients. Further well-designed randomized clinical trials are needed.

Gastric Dysmotility in Critically Ill Children: Pathophysiology, Diagnosis, and Management

OBJECTIVE

We aimed to review gastric dysmotility in critically ill children: 1) its pathophysiology, with a focus on critical care diseases and therapies that affect gastric motility, 2) diagnostic methodologies, and 3) current and future potential therapies.

DATA SOURCES

Eligible studies were identified from PubMed and MEDLINE.

STUDY SELECTION

Literature search included the following key terms: "gastric emptying," "gastric motility/dysmotility," "gastrointestinal motility/dysmotility," "nutrition intolerance," and "gastric residual volume."

DATA EXTRACTION

Studies since 1995 were extracted and reviewed for inclusion by the authors related to the physiology, pathophysiology, diagnostic methodologies, and available therapies for gastric emptying.

DATA SYNTHESIS

Delayed gastric emptying, a common presentation of gastric dysmotility, is present in up to 50% of critically ill children. It is associated with the potential for aspiration, ventilator-associated pneumonia, and inadequate delivery of enteral nutrition and may affect the efficacy of enteral medications, all of which may be result in poor patient outcomes. Gastric motility is affected by critical illness and its associated therapies. Currently available diagnostic tools to identify gastric emptying at the bedside have not been systematically studied and applied in this cohort. Gastric residual volume measurement, used as an indirect marker of delayed gastric emptying in PICUs around the world, may be inaccurate.

CONCLUSIONS

Gastric dysmotility is common in critically ill children and impacts patient safety and outcomes. However, it is poorly understood, inadequately defined, and current therapies are limited and based on scant evidence. Understanding gastric motility and developing accurate bedside measures and novel therapies for gastric emptying are highly desirable and need to be further investigated.

Enteral nutrition intolerance in critically ill septic burn patients

The purpose of this study was to investigate the frequency of enteral feeding intolerance in critically ill septic burn patients, the effect of enteral feeding intolerance on the efficacy of feeding, the correlation between the infection marker (procalcitonin [PCT]) and the nutrition status marker (prealbumin) and the impact of feeding intolerance on the outcome of septic burn patients. From January 2009 to December 2012 the data of all burn patients with the diagnosis of sepsis who were placed on enteral nutrition were analyzed. Septic patients were divided into two groups: group A, septic patients who developed feeding intolerance; group B, septic patients who did not develop feeding intolerance. Demographic and clinical characteristics of patients were analyzed and compared. The diagnosis of sepsis was applied to 29% of all patients. Of these patients 35% developed intolerance to enteral feeding throughout the septic period. A statistically significant increase in mean PCT level and a decrease in prealbumin level was observed during the sepsis period. Group A patients had statistically significant lower mean caloric intake, higher PCT:prealbumin ratio, higher pneumonia incidence, higher Sequential Organ Failure Assessment Maximum Score, a longer duration of mechanical ventilation, and a higher mortality rate in comparison with the septic patients without gastric feeding intolerance. The authors concluded that a high percentage of septic burn patients developed enteral feeding intolerance. Enteral feeding intolerance seems to have a negative impact on the patients' nutritional status, morbidity, and mortality.

Gastric residual volume in critically ill patients: a dead marker or still alive?

Early enteral nutrition (EN) is consistently recommended as first-line nutrition therapy in critically ill patients since it favorably alters outcome, providing both nutrition and nonnutrition benefits. However, critically ill patients receiving mechanical ventilation are at risk for regurgitation, pulmonary aspiration, and eventually ventilator-associated pneumonia (VAP). EN may increase these risks when gastrointestinal (GI) dysfunction is present. Gastric residual volume (GRV) is considered a surrogate parameter of GI dysfunction during the progression of enteral feeding in the early phase of critical illness and beyond. By monitoring GRV, clinicians may detect patients with delayed gastric emptying earlier and intervene with strategies that minimize or prevent VAP as one of the major risks of EN. The value of periodic GRV measurements with regard to risk reduction of VAP incidence has frequently been questioned in the past years. Increasing the GRV threshold before interrupting gastric feeding results in marginal increases in EN delivery. More recently, a large randomized clinical trial revealed that abandoning GRV monitoring did not negatively affect clinical outcomes (including VAP) in mechanically ventilated patients. The results have revived the discussion on the role of GRV monitoring in critically ill, mechanically ventilated patients receiving early EN. This review summarizes the most recent clinical evidence on the use of GRV monitoring in critically ill patients. Based on the clinical evidence, it discusses the pros and cons and further addresses whether GRV is a dead marker or still alive for the nutrition management of critically ill patients.

Definition, prevalence, and outcome of feeding intolerance in intensive care: a systematic review and meta-analysis

Clinicians and researchers frequently use the phrase 'feeding intolerance' (FI) as a descriptive term in enterally fed critically ill patients. We aimed to: (1) determine what is the most accepted definition of FI; (2) estimate the prevalence of FI; and (3) evaluate whether FI is associated with important outcomes. Systematic searches of peer-reviewed publications using PubMed, MEDLINE, and Web of Science were performed with studies reporting FI extracted. We identified 72 studies defining FI. In 33 studies, the definition was based on large gastric residual volumes (GRVs) together with other gastrointestinal symptoms, while 30 studies relied solely on large GRVs, six studies used inadequate delivery of enteral nutrition (EN) as a threshold, and three studies gastrointestinal symptoms without reference to GRV. The median volume used to define a 'large' GRV was 250 ml (ranges from 75 to 500 ml). The pooled proportion (n = 31 studies) of FI was 38.3% (95% CI 30.7-46.2). Five studies reported outcomes, all of them observed adverse outcome in FI patients. In three studies, respectively, FI was associated with increased mortality and ICU length-of-stay. In summary, FI is inconsistently defined but appears to occur frequently. There are preliminary data indicating that FI is associated with adverse outcomes. A standard definition of FI is required to determine the accuracy of these preliminary data.

Nutrition algorithms and bedside nutrient delivery practices in pediatric intensive care units: an international multicenter cohort study

BACKGROUND

Enteral nutrition (EN) delivery is associated with improved outcomes in critically ill patients. We aimed to describe EN practices, including details of algorithms and individual bedside practices, in pediatric intensive care units (PICUs).

METHODS

Available EN algorithm details from 31 international PICUs were obtained. Daily nutrient intake data from 524 mechanically ventilated patients, 1 month to 18 years old, were prospectively documented, including EN delivery, adjunct therapies, and energy prescription. Practices associated with higher percentage adequacy of EN delivery were determined by regression analysis.

RESULTS

Nine EN algorithms were available. All algorithms defined advancement and EN intolerance; 7 of 9 defined intolerance by gastric residual volume; 3 of 9 recommended nutrition screening and fasting guidelines. Few elements were in agreement with the American Society for Parenteral and Enteral Nutrition and the European Society of Paediatric Gastroenterology, Hepatology, and Nutrition guidelines. Of the 341 patients who received EN exclusively 32.9% received ≥66.6% of prescribed energy on day 7. Percentage adequacy of EN delivered was inversely associated with days to EN initiation (-8.92; P < .001) and hours per EN interruption (-1.65; P = .001) and was not associated with the use of algorithms, promotility agents, or postpyloric feeding.

CONCLUSIONS

A minority of PICUs employ EN algorithms; recommendations were variable and not in agreement with national guidelines. Optimal EN delivery was achieved in less than one-third of our cohort. EN adjunct therapies were not associated with increased EN delivery. Studies aimed at promoting early EN and decreasing interruptions may optimize energy delivery in the PICU.

Gastric emptying measurement of liquid nutrients using the (13)C-octanoate breath test in critically ill patients: a comparison with scintigraphy

PURPOSE

Scintigraphy is considered the most accurate technique for the measurement of gastric emptying (GE) but, for patients in the intensive care unit, it is technically demanding, involves radiation and can interfere with care. The (13)C-octanoate breath test ((13)C-OBT) is a simple, non-invasive technique that does not involve radiation exposure.

AIM

To evaluate the performance of the (13)C-OBT in the assessment of GE in critically ill patients.

METHODS

The GE was assessed in 33 mechanically ventilated patients (23 M; 54.3 ± 3.0 yrs; APACHE II: 22.0 ± 1.1). Following test meal administration (100 ml Ensure(®)), concurrent scintigraphic measurement and breath samples ((13)C-OBT) were collected over 4 h. Scintigraphic meal retention was determined and the gastric emptying coefficient (GEC) and half emptying time [t50(BT)] were calculated for the (13)C-OBT. Delayed GE was defined as meal retention >13 % at 180 min.

RESULTS

Delayed GE was identified in 27/33 patients. Meal retention correlated modestly with t50(BT) (r = 0.55-0.66; P < 0.001) and well with GEC (r = -0.63 to -0.74; P < 0.0001). The strength of agreement between the two techniques was highest between GEC and retention at 120 min. The best cut-off GEC for defining delayed GE was 3.25 (AUC = 0.75; 95 % CI = 0.52-0.99; P = 0.05), with 89 % sensitivity and 67 % specificity to detect delayed GE. The GE was delayed in all (23/23) patients with feed intolerance (GRV > 250 ml) on scintigraphy and 91 % (21/23) patients on (13)C-OBT.

CONCLUSION

In critical illness, there was a correlation between (13)C-OBT and gastric scintigraphy, with GEC performing as a better and more sensitive marker of detecting delayed GE than t50. However the relatively wide 95 % confidence intervals suggest that (13)C-OBT is more suitable as a technique to assess GE in a group setting for research studies rather than for individual patients in clinical practice.

Use of gastric residual volume to guide enteral nutrition in critically ill patients: a brief systematic review of clinical studies

OBJECTIVE

In critically ill patients, the optimal procedure to monitor upper gastrointestinal function is controversial. Several authors have proposed gastric residual volume (GRV) as a tool to guide enteral nutrition. The aim of this contribution is to briefly discuss corresponding studies.

METHODS

We electronically searched MEDLINE, EMBASE, and CINAHL for studies relevant to the subject.

RESULTS

Six randomized controlled trials (RCTs) and six prospective observational studies were identified. Each analyzed different thresholds of GRV to guide enteral nutrition and to avoid complications (e.g., vomiting, aspiration, nosocomial pneumonia) in artificially ventilated patients. Due to heterogeneity in outcome measures, patient populations, type and diameter of feeding tubes, and randomization procedures, combination of the results of the six RCTs into a meta-analysis was not appropriate. High-quality RCTs studying medical patients could not demonstrate an association between complication rate and the magnitude of GRV. The only observational study that adjusted results to potential confounders and that studied surgical patients found, however, that the frequency of aspiration increased significantly if a GRV > 200 mL was registered more than once.

CONCLUSION

For mechanically ventilated patients with a medical diagnosis at admission to the intensive care unit, monitoring of GRV appears unnecessary to guide nutrition. Surgical patients might profit, however, from a low GRV threshold (200 mL).

Nutrition support in the critically ill

PURPOSE OF REVIEW

To highlight the recent developments in nutritional support for critically ill patients.

RECENT FINDINGS

Increasing data support the benefits of early initiation of enteral nutrition, with improvements in small intestinal absorption and clinical outcomes. In contrast to the previous belief, recent data suggest caloric administration of greater than 65-70% of daily requirement is associated with poorer clinical outcomes, especially when supplemental parenteral nutrition is used to increase the amount of caloric delivery. The role of supplementary micronutrients and anti-inflammatory lipids has been further evaluated but remains inconclusive, and is not currently recommended.

SUMMARY

Together, current findings indicate that intragastric enteral nutrition should be initiated within 24 h of admission to ICU and supplementary parenteral nutrition should be avoided. Future research should aim to clarify the optimal energy delivery for best clinical outcomes, and the role of small intestinal function and its flora in nutritional care and clinical outcomes.

Nasogastric tube feedings and gastric residual volume: a regional survey

OBJECTIVES

To maintain adequate nutrition for patients who are in need, enteral feeding via nasogastric tube (NGT) is necessary. Although the literature suggests the safety of continued NGT feeding at a gastric residual volume of <400 mL, inconsistencies in withholding tube feeding based on residual volume have been observed in clinical practice. We performed a regional survey to determine the range of current practice among nursing staff regarding the decision to withhold NGT feeding based on residual volume and the factors that influence the decision-making process.

METHODS

A questionnaire was designed to evaluate nursing practice patterns regarding the decision of withholding NGT feeding based on a certain residual volume, which was distributed to the nursing staff at all major hospitals in the Oklahoma City metropolitan area. Statistical analysis was done with the Fisher exact test. All of the statistical tests were carried out at α = 0.05.

RESULTS

A total of 582 nurses completed the survey. Residual volumes (milliliters) resulting in the termination of NGT feeding occurred in 89% of nurses at volumes <300 mL and only 3% of nurses at volumes >400 mL. Three main reasons for nurses to withhold NGT feeding were risk of aspiration (90%), potential feeding intolerance (81%), and risk of regurgitation (67%). Other less common concerns were abdominal distension and abdominal discomfort.

CONCLUSIONS

The decision of withholding NGT feeding varied among the nursing staff that were surveyed. A consensus is necessary for the standardization of withholding NGT feeding in clinical practice among nursing staff.

Severity of illness influences the efficacy of enteral feeding route on clinical outcomes in patients with critical illness

BACKGROUND

Few trials have studied the influence of illness severity on clinical outcomes of different tube-feeding routes. Whether gastric or postpyloric feeding route is more beneficial to patients receiving enteral nutrition remains controversial.

OBJECTIVE

To test whether illness severity influences the efficacy of enteral feeding route on clinical outcomes in patients with critical illness.

DESIGN

A 2-year prospective, randomized, clinical study was conducted to assess the differences between the nasogastric (NG) and nasoduodenal (ND) tube feedings on clinical outcomes.

PARTICIPANTS/SETTING

One hundred one medical adult intensive care unit (ICU) patients requiring enteral nutrition were enrolled in this study.

INTERVENTION

Patients were randomly assigned to the NG (n=51) or ND (n=50) feeding route during a 21-day study period. Illness severity was dichotomized as "less severe" and "more severe," with the cutoff set at Acute Physiology and Chronic Health Evaluation II score of 20.

MAIN OUTCOME MEASURES

Daily energy and protein intake, feeding complications (eg, gastric retention/vomiting/diarrhea/gastrointestinal bleeding), length of ICU stay, hospital mortality, nitrogen balance, albumin, and prealbumin.

STATISTICAL ANALYSES PERFORMED

Two-tailed Student t tests and Mann-Whitney U tests were used to analyze significant differences between variables in the study groups. Multiple regression was used to assess the effects of illness severity and enteral feeding routes on clinical outcomes.

RESULTS

Among less severely ill patients, no differences existed between the NG and ND groups in daily energy and protein intake, feeding complications, length of ICU stay, and nitrogen balance. Among more severely ill patients, the NG group experienced lower energy and protein intake, more tube feeding complications, longer ICU stay, and poorer nitrogen balance than the ND group.

CONCLUSIONS

To optimize nutritional support and taking medical resources into account, the gastric feeding route is recommended for less severely ill patients and the postpyloric feeding route for more severely ill patients.

Nutritional support in acute and chronic pancreatitis

Nutritional support can have a significant beneficial impact on the course of moderate to severe acute pancreatitis. Enteral nutrition is preferred, with emphasis on establishment of jejunal access; however, parenteral nutrition can also be of value if intestinal failure is present. Early initiation of nutritional support is critical, with benefits decreasing rapidly if begun after 48 hours from admission. Severe malnutrition in chronic pancreatitis can be avoided or treated with dietary modifications or enteral nutrition.

Energy imbalance and the risk of overfeeding in critically ill children

OBJECTIVE

To examine the role of targeted indirect calorimetry in detecting the adequacy of energy intake and the risk of cumulative energy imbalance in a subgroup of critically ill children suspected to have alterations in resting energy expenditure. We examined the accuracy of standard equations used for estimating resting energy expenditure in relation to measured resting energy expenditure in relation to measured resting energy expenditure and cumulative energy balance over 1 week in this cohort.

DESIGN

A prospective cohort study.

SETTING

Pediatric intensive care unit in a tertiary academic center.

INTERVENTIONS

A subgroup of critically ill children in the pediatric intensive care unit was selected using a set of criteria for targeted indirect calorimetry.

MEASUREMENTS

Measured resting energy expenditure from indirect calorimetry and estimated resting energy expenditure from standard equations were obtained. The metabolic state of each patient was assigned as hypermetabolic (measured resting energy expenditure/estimated resting energy expenditure >110%), hypometabolic (measured resting energy expenditure/estimated resting energy expenditure <90%), or normal (measured resting energy expenditure/estimated resting energy expenditure = 90-110%). Clinical variables associated with metabolic state and factors influencing the adequacy of energy intake were examined.

MAIN RESULTS

Children identified by criteria for targeted indirect calorimetry, had a median length of stay of 44 days, a high incidence (72%) of metabolic instability and alterations in resting energy expenditure with a predominance of hypometabolism in those admitted to the medical service. Physicians failed to accurately predict the true metabolic state in a majority (62%) of patients. Standard equations overestimated the energy expenditure and a high incidence of overfeeding (83%) with cumulative energy excess of up to 8000 kcal/week was observed, especially in children <1 yr of age. We did not find a correlation between energy balance and respiratory quotient (RQ) in our study.

CONCLUSIONS

We detected a high incidence of overfeeding in a subgroup of critically ill children using targeted indirect calorimetry The predominance of hypometabolism, failure of physicians to correctly predict metabolic state, use of stress factors, and inaccuracy of standard equations all contributed to overfeeding in this cohort. Critically ill children, especially those with a longer stay in the PICU, are at a risk of unintended overfeeding with cumulative energy excess.

An evaluation of enteral feeding practices in critically ill children

BACKGROUND

Establishing and sustaining enteral feeding in critically ill children is challenging and has met with many problems.

AIMS AND OBJECTIVES

The aim of this study was to investigate (a) how actual calorie intake compared with estimated caloric requirements and (b) whether feeding guideline adherence resulted in improved nutritional intake.

DESIGN AND METHODS

A prospective observational study was undertaken over 1 month in a tertiary referral paediatric intensive care unit (PICU) in the northwest of England.

RESULTS

Forty-seven children were studied, with a wide range of diagnoses in a 1-month period. Only 47% of the children had enteral feeds started within our 6 h post-admission target. Over half (55%) of the children received less than half of their estimated calorie requirements, but if feeding guidelines were followed, this resulted in a significantly higher (p = 0.004) delivery of the child's estimated requirements.

CONCLUSIONS

This study found that many children are not receiving adequate nutrition in PICU and that the use of feeding guidelines significantly improves calorie delivery in PICU patients.

RELEVANCE TO CLINICAL PRACTICE

This paper highlights the dearth of research related to enteral feeding in critically ill children. We found that the use of feeding guidelines improved calorie delivery and so units should be encouraged to develop their own guidelines based on the best evidence available.

Gastric residual volumes in critical illness: what do they really mean?

The practice of measuring gastric residual volumes (GRVs) has become a routine part of enteral feeding protocols in the critical care setting. However, little scientific evidence indicates that their use improves patient outcomes. The use of GRVs is more of a tradition, which unfortunately guides the delivery of enteral nutrition (EN). The practice of GRVs is predicated on several flawed assumptions. Using GRVs in hospitalized patients assumes that the practice is well standardized, that GRVs reliably and accurately measure gastric contents, and that they sufficiently distinguish normal from abnormal emptying. The practice also assumes that GRVs are easy to interpret, that a tight correlation exists between GRVs and aspiration, and that continuing EN after a high value for GRV is obtained leads to pneumonia and adverse patient outcomes. And finally, clinicians assume that GRVs are an inexpensive "poor man's test" for determining tolerance of EN. This article reviews studies showing the fallacies of these assumptions. Although clinicians are unlikely to stop using GRVs, interpretation of these must be modified so as not to interrupt the delivery of EN. Using a protocol that directs appropriate responses to elevated GRVs should promote the delivery of EN and improve patient outcome.

Providing optimal nutritional support on the intensive care unit: key challenges and practical solutions

Many patients in the intensive care unit are malnourished or unable to eat. Feeding them correctly has the potential to reduce morbidity and even mortality but is a very complex procedure. The inflammatory response induced by surgery, trauma or sepsis will alter metabolism, change the ability to utilise nutrients and can lead to rapid loss of lean mass. Both overfeeding and underfeeding macronutrients can be harmful but generally it would seem optimal to give less during metabolic stress and immobility and increase in recovery. Physical intolerance of feeding such as diarrhoea or delayed gastric emptying is common in the intensive care unit. Diarrhoea can be treated with fibre or peptide feeds and anti-diarrhoeal drugs; however, the use of probiotics is controversial. Gastric dysfunction problems can often be overcome with prokinetic drugs or small bowel feeding tubes. New feeds with nutrients such as n-3 fatty acids that have the potential to attenuate excessive inflammatory responses show great promise in favourably improving metabolism and substrate utilisation. The importance of changing nutrient provision according to metabolic and physical tolerance cannot be understated and although expert groups have produced many guidelines on nutritional support of the critically ill, correct interpretation and implementation can be difficult without a dedicated nutrition health care professional such as a dietitian or a multidisciplinary nutritional support team.

The intestinal fatty acid binding protein diagnosing gut dysfunction in acute pancreatitis: a pilot study

OBJECTIVES

To study the use of intestinal fatty acid binding protein (I-FABP) in diagnosing gut dysfunction in patients with acute pancreatitis (AP).

METHODS

Thirty-two patients with AP onset within 7 days were enrolled in our study. The severity of disease and the gut dysfunction were evaluated as follows: on admission, on the seventh day of disease attack, and on the third day after enteral nutrition. Serum levels of I-FABP, citrulline, and C-reactive protein (CRP) and the lactulose and mannitol absorption ratio in urine were measured in parallel.

RESULTS

The serum level of I-FABP increased on admission, and it was more pronounced in severe attacks. All patients had increased gut dysfunction score, serum level of CRP, and urine level of lactulose and mannitol absorption ratio with decreased serum level of citrulline. A positive correlation was found between the following pairs of measurement on admission: serum level of I-FABP and gut dysfunction score, serum level of I-FABP and Acute Physiology and Chronic Health Evaluation II score, I-FABP and serum level of CRP, and serum level of I-FABP and the length of ICU stay. A reverse correlation between the serum level of I-FABP and the serum level of citrulline was found.

CONCLUSIONS

The serum level of I-FABP can be used for assessing the gut dysfunction and disease severity of AP.

To return or to discard? Randomised trial on gastric residual volume management

BACKGROUND

The control of gastric residual volume (GRV) is a common nursing intervention in intensive care; however the literature shows a wide variation in clinical practice regarding the management of GRV, potentially affecting patients' clinical outcomes. The aim of this study is to determine the effect of returning or discarding GRV, on gastric emptying delays and feeding, electrolyte and comfort outcomes in critically ill patients.

METHOD

A randomised, prospective, clinical trial design was used to study 125 critically ill patients, assigned to the return or the discard group. Main outcome measure was delayed gastric emptying. Feeding outcomes were determined measuring intolerance indicators, feeding delays and feeding potential complications. Fluid and electrolyte measures included serum potassium, glycaemia control and fluid balance. Discomfort was identified by significant changes in vital signs.

RESULTS

Patients in both groups presented similar mean GRV with no significant differences found (p=0.111), but participants in the intervention arm showed a lower incidence and severity of delayed gastric emptying episodes (p=0.001). No significant differences were found for the rest of outcome measurements, except for hyperglycaemia.

CONCLUSIONS

The results of this study support the recommendation to reintroduce gastric content aspirated to improve GRV management without increasing the risk for potential complications.

Retroperitoneal repair of abdominal aortic aneurysm reduces bowel dysfunction

OBJECTIVE

To assess the effect of intestinal manipulation and mesenteric traction on gastro-intestinal function and postoperative recovery in patients undergoing abdominal aortic aneurysm (AAA) repair.

METHODS

Thirty-five patients undergoing AAA repair were randomised into 3 groups. Group I (n = 11) had repair via retroperitoneal approach while Group II (n = 12) and Group III (n = 12) were repaired via transperitoneal approach with bowel packed within the peritoneal cavity or exteriorised in a bowel bag respectively. Gastric emptying was measured pre-operatively (day 0), day 1 and day 3 using paracetamol absorption test (PAT) and area under curve (P(AUC)) was calculated. Intestinal permeability was measured using the Lactulose-Mannitol test.

RESULTS

Aneurysm size, operation time and PAT (on day 0 and day 3) were similar in the three groups. On day 1, the P(AUC) was significantly higher in Group I, when compared with Group II and Group III (P = .02). Resumption of diet was also significantly earlier in Group I as compared to Group II and Group III. The intestinal permeability was significantly increased in Group II and Group III at day 1 when compared with day 0, with no significant increase in Group I. Retroperitoneal repair was also associated with significantly shorter intensive care unit (P = .04) and hospital stay (P = .047), when compared with the combined transperitoneal repair group (Group II and III).

CONCLUSION

Retroperitoneal AAA repair minimises intestinal dysfunction and may lead to quicker patient recovery when compared to transperitoneal repair.

Prokinetic therapy for feed intolerance in critical illness: one drug or two?

OBJECTIVE

To compare the efficacy of combination therapy, with erythromycin and metoclopramide, to erythromycin alone in the treatment of feed intolerance in critically ill patients.

DESIGN

Randomized, controlled, double-blind trial.

SETTING

Mixed medical and surgical intensive care unit.

PATIENTS

Seventy-five mechanically ventilated, medical patients with feed intolerance (gastric residual volume > or =250 mL).

INTERVENTIONS

Patients received either combination therapy (n = 37; 200 mg of intravenous erythromycin twice daily + 10 mg of intravenous metoclopramide four times daily) or erythromycin alone (n = 38; 200 mg of intravenous erythromycin twice daily) in a prospective, randomized fashion. Gastric feeding was re-commenced and 6-hourly gastric aspirates performed. Patients were studied for 7 days. Successful feeding was defined as a gastric residual volume <250 mL with the feeding rate > or =40 mL/hr, over 7 days. Secondary outcomes included daily caloric intake, vomiting, postpyloric feeding, length of stay, and mortality.

MEASUREMENTS AND MAIN RESULTS

Demographic data; use of inotropes, opioids, or benzodiazepines; and pretreatment gastric residual volume were similar between the two groups. The gastric residual volume was significantly lower after 24 hrs of treatment with combination therapy, compared with erythromycin alone (136 +/- 23 mL vs. 293 +/- 45 mL, p = .04). Over the 7 days, patients treated with combination therapy had greater feeding success, received more daily calories, and had a lower requirement for postpyloric feeding, compared with erythromycin alone. Tachyphylaxis occurred in both groups but was less with combination therapy. Sedation, higher pretreatment gastric residual volume, and hypoalbuminemia were significantly associated with a poor response. There was no difference in the length of hospital stay or mortality rate between the groups. Watery diarrhea was more common with combination therapy (20 of 37 vs. 10 of 38, p = .01) but was not associated with enteric infections, including Clostridium difficile.

CONCLUSIONS

In critically ill patients with feed intolerance, combination therapy with erythromycin and metoclopramide is more effective than erythromycin alone in improving the delivery of nasogastric nutrition and should be considered as the first-line treatment.

The relationship between blood glucose control and intolerance to enteral feeding during critical illness

OBJECTIVE

To assess the relationship between blood glucose concentrations (BSL) and intolerance to gastric feeding in critically ill patients.

DESIGN

Prospective, case-controlled study.

PATIENTS AND PARTICIPANTS

Two-hourly BSL and insulin requirements over the first 10 days after admission were assessed in 95 consecutive feed-intolerant (NG aspirate > 250 ml during feed) critically ill patients and 50 age-matched, feed-tolerant patients who received feeds for at least 3 days. Patients with diabetes mellitus were excluded. A standard insulin protocol was used to maintain BSL at 5.0-7.9 mmol.

MEASUREMENTS AND RESULTS

The peak BSLs were significantly higher before and during enteral feeding in feed-intolerant patients. The mean and trough BSLs were, however, similar between the two groups on admission, 24 h prior to feeding and for the first 4 days of feeding. The variations in BSLs over 24 h before and during enteral feeding were significantly greater in feed-intolerant patients. A BSL greater than 10 mmol/l was more prevalent in patients with feed intolerance during enteral feeding. The time taken to develop feed intolerance was inversely related to the admission BSL (r= -0.40). The amount of insulin administered before and during enteral feeding was similar between the two groups.

CONCLUSIONS

Feed intolerance in critically ill patients is associated with a greater degree of glycaemic variation, with a greater number of patients with transient hyperglycaemia. These data suggest more intensive insulin therapy may be required to minimize feed intolerance, an issue that warrants further study.