Enteral nutrition in the hemodynamically unstable critically ill patient

Impact of Intravenous Fluids and Enteral Nutrition on the Severity of Gastrointestinal Dysfunction: A Systematic Review and Meta-analysis

Introduction

Gastrointestinal dysfunction (GDF) is one of the primary causes of morbidity and mortality in critically ill patients. Intensive care interventions, such as intravenous fluids and enteral feeding, can exacerbate GDF. There exists a paucity of high-quality literature on the interaction between these two modalities (intravenous fluids and enteral feeding) as a combined therapy on its impact on GDF.

Aim

To review the impact of intravenous fluids and enteral nutrition individually on determinants of gut function and implications in clinical practice.

Methods

Randomized controlled trials on intravenous fluids and enteral feeding on GDF were identified by a comprehensive database search of MEDLINE and EMBASE. Extraction of data was conducted for study characteristics, provision of fluids or feeding in both groups and quality of studies was assessed using the Cochrane criteria. A random-effects model was applied to estimate the impact of these interventions across the spectrum of GDF severity.

Results

Restricted/ goal-directed intravenous fluid therapy is likely to reduce ‘mild’ GDF such as vomiting (p = 0.03) compared to a standard/ liberal intravenous fluid regime. Enterally fed patients experienced increased episodes of vomiting (p = <0.01) but were less likely to develop an anastomotic leak (p = 0.03) and peritonitis (p = 0.03) compared to parenterally fed patients. Vomiting (p = <0.01) and anastomotic leak (p = 0.04) were significantly lower in the early enteral feeding group.

Conclusions

There is less emphasis on the combined approach of intravenous fluid resuscitation and enteral feeding in critically ill patients. Conservative fluid resuscitation and aggressive enteral feeding are presumably key factors contributing to severe life-threatening GDF. Future trials should evaluate the impact of cross-interaction between conservative and aggressive modes of these two interventions on the severity of GDF.

The Pathogenesis of Nonocclusive Mesenteric Ischemia: Implications for Research and Clinical Practice

Nonocclusive mesenteric ischemia (NOMI) is a condition that can encompass ischemia, inflammation, and infarction of the intestinal wall. In contrast to most patients with acute mesenteric ischemia, NOMI is distinguished by patent arteries and veins. The clinical presentation of NOMI is often insidious and nonspecific, resulting in a delayed diagnosis. Patients most at risk are those with severe acute and critical disease, including major surgery and trauma. Nonocclusive mesenteric ischemia is part of a spectrum, from mild, asymptomatic, and an unexpected finding on CT scanning, through to those exhibiting abdominal distension and peritonitis. Severe NOMI is associated with a significant mortality rate. This review of NOMI pathophysiology was conducted to document current concepts and evidence, to examine the implications for diagnosis and treatment, and to identify gaps in knowledge that might direct future research. The key pathologic mechanisms involved in the genesis of NOMI represent an exaggerated normal physiological response to maintain perfusion of vital organs at the expense of mesenteric perfusion. A supply-demand mismatch develops in the intestine due to the development of persistent mesenteric vasoconstriction resulting in reduced blood flow and oxygen delivery to the intestine, particularly to the vulnerable superficial mucosa. This mismatch can be exacerbated by raised intra-abdominal pressure, enteral nutrition, and the use of certain vasoactive drugs, ultimately resulting in the development of intestinal ischemia. Strategies for prevention, early detection, and treatment are urgently needed.

Practice Guidelines for Nutrition in Critically Ill Patients: A Relook for Indian Scenario

Background and Aim:

Intensive-care practices and settings may differ for India in comparison to other countries. While international guidelines are available to direct the use of enteral nutrition (EN), there are no recommendations specific to Indian settings. Advisory board meetings were arranged to develop the practice guidelines specific to Indian context, for the use of EN in critically ill patients and to overcome challenges in this field.

Methods:

Various existing guidelines, meta-analyses, randomized controlled trials, controlled trials, and review articles were reviewed for their contextual relevance and strength. A systematic grading of practice guidelines by advisory board was done based on strength of the supporting evidence. Wherever Indian studies were not available, references were taken from the international guidelines.

Results:

Based on the literature review, the recommendations for developing the practice guidelines were made as per the grading criteria agreed upon by the advisory board. The recommendations were to address challenges regarding EN versus parenteral nutrition; nutrition screening and assessment; nutrition in hemodynamically unstable; route of nutrition; tube feeding and challenges; tolerance; optimum calorie-protein requirements; selection of appropriate enteral feeding formula; micronutrients and immune-nutrients; standard nutrition in hepatic, renal, and respiratory diseases and documentation of nutrition practices.

Conclusion:

This paper summarizes the optimum nutrition practices for critically ill patients. The possible solutions to overcome the challenges in this field are presented as practice guidelines at the end of each section. These guidelines are expected to provide guidance in critical care settings regarding appropriate critical-care nutrition practices and to set up Intensive Care Unit nutrition protocols.