Enteral Nutrition in the Critically Ill: Myths and Misconceptions

Nutritional support for the trauma and emergency general surgery patient: What you need to know

ABSTRACT

Decades of research have provided insight into the benefits of nutritional optimization in the elective surgical patient. Patients who are nutritionally prepared for surgery enjoy reduced length of hospital and intensive care unit stays and suffer fewer complications. In the trauma and emergency general surgery patient populations, we are not afforded the preoperative period of optimization and patients often suffer longer lengths of hospital stay, discharge to nonhome destinations, and higher infectious and mortality rates. Nonetheless, ongoing research in this vulnerable and time critical diagnosis population has revealed significant outcomes benefits with the meticulous nutritional support of these patients. However, it is important to note that optimal nutritional support in this challenging patient population is not simply a matter of "feeding more and feeding earlier." In this review, we will address assessing nutritional needs, the provision of optimal nutrition, the timing and route of nutrition, and monitoring outcomes and discuss the management of nutrition in the complex trauma and emergency general surgery patient.

LEVEL OF EVIDENCE

Literature Synthesis and Expert Opinion; Level V.

A new strategy of enteral nutrition intervention for ICU patients targeting intestinal flora

BACKGROUND

Enteral nutrition (EN) therapy is a routine supportive method for patients in the intensive care unit (ICU). However, the incidence of EN intolerance is prevalent, because most ICU patients suffer intestinal mucosal barrier damage and gastrointestinal motility disorder. There is no definite index to predict EN intolerance, and the current treatment methods are not effective in alleviating EN intolerance. Gut microbiota is an important component of the intestinal micro-ecological environment, and alterations in its structure and composition can reflect changes in intestinal function and microenvironment. The purpose of this study is to investigate the effect of EN on the gut microbiota of ICU patients by monitoring the dynamic alterations of gut microbiota and to screen out the microbial markers that can be used to predict the incidence of EN intolerance.

METHODS

One hundred ICU patients with trauma or in a period of acute stress after surgery will be enrolled, and their fecal samples will be collected at different timepoints for microbial sequencing and analysis. General clinical data (demographic information, surgical data, laboratory parameters, illness severity scores, and therapeutic drugs), nutritional status data (nutritional status assessment and nutrition therapy monitoring data), as well as clinical outcomes, will be recorded. The microbial and clinical data will be combined to analyze the baseline characteristics and dynamic alterations of gut microbiota along with the incidence of EN intolerance. Data related to the gut microbiota will be statistically analyzed by R software, and other data performed by SPSS23.0 software.

CONCLUSIONS

The effect of EN on gut microbiota and microbial markers predicting the intolerance of EN will lead us to develop a new nutrition intervention strategy for ICU patients. Furthermore, the results of this study will provide a basis for the discovery of potential probiotics used for the prevention and treatment of EN intolerance.

Effect of Early Versus Delayed Parenteral Nutrition on the Health Outcomes of Critically Ill Adults: A Systematic Review

Objectives

This systematic review aims to evaluate and summarise the findings of all relevant studies which identified the effect of early vs delayed parenteral nutrition (PN), early PN vs early supplemental PN and early PN vs standard care for critically ill adults.

Methods

The literature search was undertaken using PubMed, Embase, Medline, Clinical Key, and Ovid discovery databases. The reference lists of studies published from 2000 till June 2020 were hand searched.

Result

On screening 2088 articles, a total of five RCTs with 6,277 patients were included in this review. Only one clinical trial compared early PN and late PN; the results reported significantly shorter periods in intensive care unit (ICU) stay (p=0.02) and less ICU related infections (p=0.008) in the late PN group compared to the Early PN group. Two trials compared total parenteral nutrition (TPN) and enteral nutrition (EN) +TPN groups. Both found a significantly longer hospital stay duration (p<0.05 and p<0.01) with a higher mortality rate in the TPN group compared to the EN+TPN group. A statistically significant improvement was observed in patients' quality of life receiving early PN compared to standard care (p=0.01). In contrast, no significant difference was found in the supplemental PN vs the standard care group.

Conclusion

The supplemental PN patients had shorter ICU stay and lower mortality rates than TPN. However, these findings should be interpreted carefully as included studies have different initiation timing of nutritional support, and the patients' diagnosis varied.

Assessment of Electrolyte Replacement in Critically Ill Patients During a Drug Shortage

Purpose: The purpose of this study was to determine if national drug shortages of electrolyte replacement products negatively impact patient care. Methods: This study was a single-center, retrospective, observational cohort of adults admitted to the medical, surgical, or trauma intensive care unit (ICU) that were ordered or would have qualified for the general or continuous renal replacement therapy electrolyte replacement protocol (ERP) between April 2017 and August 2018. In October 2017, ERP use was suspended and enteral replacement was promoted due to inability to maintain consistent inventory of intravenous replacement products. The primary objective was to compare the percentage of patient days that at least 1 critically low value of potassium, magnesium, and/or phosphorus existed between protocolized and nonprotocolized electrolyte replacement. Secondary objectives included characterizing the ratio of enteral replacement to duration of critically low electrolyte values during protocolized and nonprotocolized electrolyte replacement. Results: A total of 288 patients were included. The mean percentage of ICU days with low electrolyte levels in the protocolized period was significantly higher than in the nonprotocolized period (21.4% vs 17.5%, P = .0238). There was a negative relationship between the total electrolyte replacement that was given enterally and the percentage of patient days with critically low values indicating that as enteral replacement increased, percentage of days with low values decreased. The association between percentage of enteral replacement and days with critically low electrolyte values was significantly lower in the protocolized period. Conclusion: Intravenous electrolyte replacement product shortages did not result in an increased incidence of critically low electrolyte values. Enteral replacement was associated with a decreased incidence of low electrolyte values.

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.

Vasopressors and Nutrition Therapy: Safe Dose for the Outset of Enteral Nutrition?

Background and Aims

Patients with hemodynamic instability need to receive intensive treatment as fluid replacement and vasoactive drugs. In the meantime, it is supposed to initiate nutritional therapy within 24 to 48 hours after admission to the intensive care unit (ICU), as an essential part of patient's intensive care and better outcomes. However, there are many controversies tangential to the prescription of enteral nutrition (EN) concomitant to the use of vasopressor and its doses. In this way, the present study aimed to identify what the literature presents of evidence to guide the clinical practice concerning the safe dose of vasopressors for the initiation of nutritional therapy in critically ill patients.

Methods

This review was carried out in PubMed, ProQuest, Web of Science, and Medline databases. The descriptors were used to perform the search strategy: Critical Care, Intensive Care Units, Vasoconstrictor Agents, and Enteral Nutrition. Inclusion criteria were patients of both genders, over 18 years of age, using vasoactive drugs, with the possibility of receiving EN therapy, and articles written in English, Portuguese, and Spanish. In addition, exclusion criteria were case reports, non-papers, and repeated papers.

Results

10 articles met our inclusion criteria.

Conclusion

It was observed that there are many controversies about the supply of EN in critically ill patients using vasopressor, especially about the safe dose, and it was not possible to identify a cutoff value for the beginning therapy. Despite the drug doses, clinical signs are still the most important parameters in the evaluation of EN tolerance.

Epidemiological Study on the Status of Nutrition-Support Therapies by Emergency Physicians in China

Objectives

This study aimed to investigate the current status of nutrition-support therapies by emergency physicians in China and to provide an evidence-based case to improve the regulation of enteral and parenteral nutrition-support therapies.

Methods

Physicians from the Emergency Branch of the China Geriatrics Society were enrolled in the present survey. A questionnaire related to nutrition-support therapy, including the time, location, ways, indications, complications, and nutrition-support training for physicians was answered.

Results

527 questionnaires were collected from over 300 hospitals in 25 provinces of China. The time to initiation of emergency nutrition support was often delayed. Furthermore, the treatment intensity and standardized training of physicians are weaknesses concerning nutrition support. Treatment standardization has been significantly improved, including blood glucose monitoring, precaution and management of complications, and the use of immunomodulators.

Conclusions

Emergency physicians should pay attention to early identifying and providing nutrition support to those patients who need it. Finally, standardized training should be developed for emergency nutrition-support therapy.

Science and fiction in critical care: established concepts with or without evidence?

In the absence of evidence, therapies are often based on intuition, belief, common sense or gut feeling. Over the years, some treatment strategies may become dogmas that are eventually considered as state-of-the-art and not questioned any longer. This might be a reason why there are many examples of "strange" treatments in medical history that have been applied in the absence of evidence and later abandoned for good reasons.In this article, five dogmas relevant to critical care medicine are discussed and reviewed in the light of the available evidence. Dogma #1 relates to the treatment of oliguria with fluids, diuretics, and vasopressors. In this context, it should be considered that oliguria is a symptom rather than a disease. Thus, once hypovolaemia can be excluded as the underlying reason, there is no justification for giving fluids, which may do more harm than good in euvolaemic or hypervolaemic patients. Similarly, there is no solid evidence for forcing diuresis by administering vasopressors and loop diuretics. Dogma #2 addresses the treatment of crush syndrome patients with aggressive fluid therapy using NaCl 0.9%. In fact, this treatment may aggravate renal injury by iatrogenic metabolic acidosis and subsequent renal hypoperfusion. Dogma #3 concerns the administration of NaCl 0.9% to patients undergoing kidney transplantation. Since these patients are usually characterised by hyperkalaemia, the potassium-free solution NaCl 0.9%, containing exclusively 154 mmol/l of sodium and chloride ions each, is often considered as the fluid of choice. However, large volumes of chloride-rich solutions cause hyperchloraemic acidosis in a dose-dependent manner and induce a potassium shift to the extracellular space, thereby increasing serum potassium levels. Thus, balanced electrolyte solutions are to be preferred in this setting. Dogma #4 relates to the fact that enteral nutrition is often withheld for patients with high residual gastric volume due to the theoretical risk of gastro-oesophageal reflux, potentially resulting in aspiration pneumonitis. Despite controversial discussions, there is no clinical data supporting that residual gastric volume should be generally measured, especially not in patients without a gastro-intestinal surgery and/or motility disorders. Clinical evidence rather suggests that abandoning residual gastric volume monitoring does not increase the incidence of pneumonia, but may benefit patients by facilitating adequate enteral feeding. Finally, dogma #5 is about sedating all mechanically ventilated patients because "fighting" against the respirator may cause insufficient ventilation. This concern needs to be balanced against the unwanted consequences of sedation, such as prolonged mechanical ventilation and intensive care unit length of stay as well as increased risk of delirium. Modern concepts based on adequate analgesia and moderate to no sedation appear to be more suitable.In conclusion, dogmas are still common in clinical practice. Since science rather than fiction should govern our actions in intensive care medicine, it is important to remain critical and challenge long established concepts, especially when the underlying evidence is weak or non-existing.

Enteral tolerance in critically ill patients

Enteral nutrition (EN) can maintain the structure and function of the gastrointestinal mucosa better than parenteral nutrition. In critically ill patients, EN must be discontinued or interrupted, if gastrointestinal complications, particularly vomiting and bowel movement disorders, do not resolve with appropriate management. To avoid such gastrointestinal complications, EN should be started as soon as possible with a small amount of EN first and gradually increased. EN itself may also promote intestinal peristalsis. The measures to decrease the risk of reflux and aspiration include elevation the head of the bed (30° to 45°), switch to continuous administration, administration of prokinetic drugs or narcotic antagonists to promote gastrointestinal motility, and switch to jejunal access (postpyloric route). Moreover, the control of bowel movement is also important for intensive care and management. In particular, prolonged diarrhea can cause deficiency in nutrient absorption, malnutrition, and increase in mortality. In addition, diarrhea may cause a decrease the circulating blood volume, metabolic acidosis, electrolyte abnormalities, and contamination of surgical wounds and pressure ulcers. If diarrhea occurs in critically ill patients on EN management, it is important to determine whether diarrhea is EN-related or not. After ruling out the other causes of diarrhea, the measures to prevent EN-related diarrhea include switch to continuous infusion, switch to gastric feeding, adjustment of agents that improve gastrointestinal peristalsis or laxative, administration of antidiarrheal drugs, changing the type of EN formula, and semisolidification of EN formula. One of the best ways to success for EN management is to continue as long as possible without interruption and discontinuation of EN easily by appropriate measures, even if gastrointestinal complications occur.

Pathophysiology and Treatment of Gastrointestinal Motility Disorders in the Acutely Ill

Gastrointestinal dysmotility causes delayed gastric emptying, enteral feed intolerance, and functional obstruction of the small and large intestine, the latter functional obstructions being frequently termed ileus and Ogilvie syndrome, respectively. In addition to meticulous supportive care, drug therapy may be appropriate in certain situations. There is, however, considerable variation among individuals regarding what gastric residual volume identifies gastric dysmotility and would encourage use of a promotility drug. While the administration of either metoclopramide or erythromycin is supported by evidence it appears that, dual-drug therapy (erythromycin and metoclopramide) reduces the rate of treatment failure. There is a lack of evidence to guide drug therapy of ileus, but neither erythromycin nor metoclopramide appear to have a role. Several drugs, including ghrelin agonists, highly selective 5-hydroxytryptamine receptor agonists, and opiate antagonists are being studied in clinical trials. Neostigmine, when infused at a relatively slow rate in patients receiving continuous hemodynamic monitoring, may alleviate the need for endoscopic decompression in some patients.

Assessment of parenteral nutrition prescription in Canadian acute care settings

BACKGROUND

Parenteral nutrition (PN) prescription can be challenging in patients with complex conditions and has potential complications.

OBJECTIVE

To assess PN prescription, monitoring, and PN-related complications in a Canadian acute care setting.

METHODS

This was a prospective cohort study in which patients receiving PN were assessed by an auditor for nutritional status, PN-related prescription, monitoring, and complications. In addition, length of stay and mortality were recorded.

RESULTS

147 patients (mean ± SD 56.1 ± 16.4 y) with complex diseases (Charlson comorbidity index, median [p25-p75] 2 [1-4]) were enrolled. Before starting PN, 18.6%, 63.9%, and 17.5% of patients were classified as subjective global assessment A, B, and C, respectively. Body mass index remained unchanged during the period on PN. On average, 89% and 73% of patients received <90% of their energy and protein requirements, respectively, but 65% received oral or enteral nutrition at some point during PN. The average daily energy provided by PN increased and stabilized on day 10, reaching 87.2 ± 20.1% of the requirements. Line sepsis (6.8% of patients) and hyperglycemia (6.9%) were the most common complications. The overall mortality was 15.6%. For those alive, length of stay was 30 (range: 4-268) d. PN was discontinued because of transitioning to an oral diet (56.6%), enteral nutrition (17.6%), home PN (14.7%), palliative care (5.1%), death (4.4%), or other (1.5%).

CONCLUSION

Most patients were malnourished at the start of PN. Energy and protein provided from PN were less than requirements, and the goals were reached with delay. Mortality was high, possibly as a result of complex diseases.

Paediatric intensive care nurses' decision-making around gastric residual volume measurement

BACKGROUND

Measuring gastric residual volume (GRV) to guide enteral feeding is a common nursing practice in intensive care units, yet little evidence supports this practice. In addition, this practice has been shown to potentially contribute to inadequate energy delivery in intensive care, which remains a problem in critically ill children.

AIMS

We aimed to explore paediatric intensive care nurses' decision-making surrounding this practice.

METHODS

This is a cross-sectional electronic survey in a single mixed general and cardiac surgical PICU in the UK.

RESULTS

The response rate was 59% (91/154), and responding nurses were experienced, with a mean PICU experience of 10·5 years (SD 8·09). The three main reasons for stopping or withholding enteral feeds were: the volume of GRV obtained (67%), the appearance of this gastric aspirate (40%) and the overall clinical condition of the child (23%). Most nurses reported checking GRV primarily to determine 'feed tolerance' (97%) as well as confirming feeding tube position (94%). Nurses' perceived harms from high GRV were: the risk of pulmonary aspiration (44%), malabsorption of feeds (20%) and the risk of vomiting (19%). GRV was measured frequently in this PICU, with 58% measuring GRV before every feed, 27% measuring every 4 h and 17% measuring every 6 h. The majority of nurses (84%) stated they would be worried or very worried if they could not measure GRV routinely.

CONCLUSIONS

PICU nurses' decision-making surrounding initiating and withholding enteral feeds and determining 'feed tolerance' remains heavily based on GRV. PICU nurses have significant fears around patient harm if they do not measure GRV routinely.

RELEVANCE TO CLINICAL PRACTICE

This nursing practice is likely to be one of the factors that impair the delivery of enteral nutrition in critically ill children, and as such, its validity and usefulness needs to be challenged and studied in future research.

Abdominal paracentesis drainage improves tolerance of enteral nutrition in acute pancreatitis: a randomized controlled trial

OBJECTIVE

The objective of this study is to determine whether abdominal paracentesis drainage (APD) could improve the administration of enteral nutrition (EN) in acute pancreatitis.

METHODS

Between January 2015 and April 2016, a total of 161 acute pancreatitis patients were enrolled and randomly assigned to either the APD group or the non-APD group. Several indexes associated with the administration of EN, including the gastroparesis cardinal symptom index (GCSI), the incidence of gastrointestinal adverse events, and the clinical outcomes, were recorded.

RESULTS

The mean GCSI scores were 13.6 ± 2.1 before randomization and 7.1 ± 2.3 after a week in the APD group. These scores were 13.9 ± 2.4 and 9.7 ± 1.9 in the non-APD group. The incidences of gastrointestinal adverse events in the two groups were similar (p > .05), except for diarrhea. However, the patients in the APD group spent less time achieving the nutrition target (25 per kilogram of body weight per day) and fully tolerated the oral diet (p < .05). Additionally, the clinical outcomes of the APD group were better compared with those of the non-APD group.

CONCLUSION

APD can improve the administration of EN in acute pancreatitis. Given the positive effect of EN on clinical outcomes, this phenomenon possibly explains why APD could improve the clinical outcomes of acute pancreatitis patients in some aspects.

Energy-Dense Formulae May Slow Gastric Emptying in the Critically Ill

BACKGROUND

Enteral feed intolerance occurs frequently in critically ill patients and can be associated with adverse outcomes. "Energy-dense formulae" (ie, >1 kcal/mL) are often prescribed to critically ill patients to reduce administered volume and are presumed to maintain or increase calorie delivery. The aim of this study was to compare gastric emptying of standard and energy-dense formulae in critically ill patients.

METHODS

In a retrospective comparison of 2 studies, data were analyzed from 2 groups of patients that received a radiolabeled 100-mL "meal" containing either standard calories (1 kcal/mL) or concentrated calories (energy-dense formulae; 2 kcal/mL). Gastric emptying was measured using a scintigraphic technique. Radioisotope data were collected for 4 hours and gastric emptying quantified. Data are presented as mean ± SE or median [interquartile range] as appropriate.

RESULTS

Forty patients were studied (n = 18, energy-dense formulae; n = 22, standard). Groups were well matched in terms of demographics. However, patients in the energy-dense formula group were studied earlier in their intensive care unit admission (P = .02) and had a greater proportion requiring inotropes (P = .002). A similar amount of calories emptied out of the stomach per unit time (P = .57), but in patients receiving energy-dense formulae, a greater volume of meal was retained in the stomach (P = .045), consistent with slower gastric emptying.

CONCLUSIONS

In critically ill patients, the administration of the same volume of a concentrated enteral nutrition formula may not result in the delivery of more calories to the small intestine over time because gastric emptying is slowed.

Nutritional controversies in critical care: revisiting enteral glutamine during critical illness and injury

PURPOSE OF REVIEW

This article examines some of the articles that inspired recent changes to critical care guidelines related to glutamine in enteral nutrition.

RECENT FINDINGS

Two recent multicenter randomized controlled trials involving enteral glutamine have reported increased mortality rates in groups of mechanically ventilated adult patients, while demonstrating no additional benefits to other outcomes, such as nosocomial infections.

SUMMARY

Recent studies suggest that enteral glutamine supplementation may not provide significant clinical benefits to adult patients on mechanical ventilation with multiple organ failure, but more information is still needed when attempting to apply these results to other groups of critical care patients.

WITHDRAWN: Early enteral nutrition versus late enteral nutrition for burns patients: A systematic review and meta-analysis

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Pediatric airway anatomy may not be what we thought: implications for clinical practice and the use of cuffed endotracheal tubes

One of the long held tenets of pediatric anesthesia has been the notion that the pediatric airway is conical shape with the narrowest area being the cricoid region. However, recent studies using radiologic imaging techniques (magnetic resonance imaging and computed tomography) or direct bronchoscopic observation have questioned this suggesting that the narrowest segment may be at or just below the glottic opening. More importantly, it has been clearly demonstrated that the airway is elliptical in shape rather than circular with the anterior-posterior dimension being greater than the transverse dimension. These findings coupled with the development of a new generation of cuffed endotracheal tubes (ETTs) with a thin, polyurethane cuff have caused a transition in the practice of pediatric anesthesiology with an increased use of cuffed ETTs, even in neonates and infants. The following article reviews the historical data leading to the assumption that the pediatric airway is conical as well as the more recent imaging and direct bronchoscopic observational studies which refute this tenet. The transition to the use of cuffed ETTs is discussed and potential advantages presented in both the operating room and the intensive care unit. Issues regarding the monitoring of intracuff pressure and techniques to limit potential morbidity related to a high intracuff pressure are outlined.