Umbrella review of the efficacy of perioperative immunonutrition in visceral surgery

Nutritional Prehabilitation in Patients Undergoing Abdominal Surgery-A Narrative Review

Malnutrition plays a crucial role as a risk factor in patients undergoing major abdominal surgery. To mitigate the risk of complications, nutritional prehabilitation has been recommended for malnourished patients and those at severe metabolic risk. Various approaches have been devised, ranging from traditional short-term conditioning lasting 7-14 days to longer periods integrated into a comprehensive multimodal prehabilitation program. However, a significant challenge is the considerable heterogeneity of nutritional interventions, leading to a lack of clear, synthesizable evidence for specific dietary recommendations. This narrative review aims to outline the concept of nutritional prehabilitation, offers practical recommendations for clinical implementation, and also highlights the barriers and facilitators involved.

Pharmaconutrition: Which substrates?

With the term "pharmaconutrition" or "immunonutrition" is intended the use of specific nutritional substrates having the ability of modulating specific mechanisms involved in several immune and inflammatory pathways. To achieve these goals, these substrates have to be administered with over physiologic dose. Glutamine and omega-3 polyunsaturated fatty acids, used as single substrate, did not show clear clinical advantages on solid endpoints such as postoperative complications. Despite several multiple substrate enteral feeds are available on the market, very few of them have been tested in randomized clinical trial to prove efficacy. The most extensive investigated formulation is a combination of arginine, omega-3 fatty acids, ribonucleic acid with or without glutamine. Several meta-analyses of randomized clinical trials have been conducted to compare the effects of enteral immunonutrition with control diets on post-surgical morbidity. The results consistently showed that the use of enteral multiple substrate formulas significantly reduced infectious complications and duration of hospitalization. In a more contemporary view, pharmaconutrition should be tested more accurately in the contest of enhanced recovery programs, during neoadjuvant chemotherapy, and in the prehabilitation setting.

Postoperative nutrition in the setting of enhanced recovery programmes

Patients undergoing major surgery for gastrointestinal cancer are at high risk of developing or worsening malnutrition and sarcopenia. In malnourished patients, preoperative nutritional support may not be sufficient and so postoperative support is advised. This narrative review addresses several aspects of postoperative nutritional care in the setting of enhanced recovery programmes. Early oral feeding, therapeutic diet, oral nutritional supplements, immunonutrition, and probiotics are discussed. When postoperative intake is insufficient, nutritional support favouring the enteral route is recommended. Whether this approach should use a nasojejunal tube or jejunostomy is still a matter of debate. In the setting of enhanced recovery programmes with early discharge, nutritional follow-up and care should be continued beyond the short time in hospital. In enhanced recovery programmes, the main specific aspects of nutrition are patient education, early oral intake, and post-discharge care. The other aspects do not differ from conventional care.

ESPEN Guidelines on Clinical nutrition in surgery - Special issues to be revisited

The ESPEN Guidelines on Clinical nutrition in Surgery from 2017 has been also available as practical guideline with algorithms since 2021 (www.espen.org). An update will be perfomed in the near future. This review focuses on recent data with regard to special issues and topics to be revisited in the guidelines: These are nutritional assessment, sarcopenic obesity, prehabilitation, oral/enteral immunonutrition, postoperative oral supplementation in hospital and after discharge.

Improving geriatric outcomes through nutritional and immunonutritional strategies: Focus on surgical setting by a comprehensive evidence review

The aging population worldwide has led to an increased request for surgical interventions in older, geriatric, and frail patients. However, all the physiological changes related to aging are associated with many challenges in the perioperative period, strongly impacting surgical outcomes. Nutritional status plays a pivotal role in determining the resilience of older adults to surgical stress and their ability to recover postoperatively. It is well known that malnutrition, a prevalent concern in geriatrics, is linked to increased adverse outcomes, including morbidity and mortality. Recognizing the significance of preoperative nutritional screening, assessment, diagnosis, intervention, and monitoring is essential for optimizing surgical outcomes. In this context, immunonutrition, which involves the supplementation of specific nutrients to modulate immune responses, emerges as a promising strategy to mitigate the increased inflammatory response observed in geriatric surgical patients. This study reviews current literature on the impact of nutrition and immunonutrition on surgical outcomes in geriatrics, highlighting the potential benefits in terms of reduced complications, enhanced wound healing, and shortened hospital stays. Recognizing and addressing the specific nutritional needs of older persons undergoing surgery is essential for promoting successful surgical outcomes and improving overall quality of life in this vulnerable population.

Immunonutrition in patients who underwent major abdominal surgery: A comprehensive systematic review and component network metanalysis using GRADE and CINeMA approaches

BACKGROUND

The benefits of immunonutrition in patients who underwent major abdominal surgery have been recently established, but the optimal combination of immunonutrients has remained unclear. The aim is to clarify this point.

METHODS

A systematic search of randomized clinical trials about immunonutrition in major abdominal surgery was made. A frequentist random-effects component network meta-analysis was conducted, reporting the P score and odds ratio or mean difference with a 95% confidence interval. The best components and best plausible strategies were described. The critical endpoints were morbidity and mortality rates. The important endpoints were infectious complication rate and length of stay.

RESULTS

The meta-analysis includes 87 studies and 8,375 patients. The best approach for morbidity rate, with a moderate grade of certainty, was the use of perioperative enteral/oral immunonutrition with arginine, glutamine, and polyunsaturated fatty acids (odds ratio 0.32; 0.10 to 0.98; P score of 0.93). The mortality rate was reduced by postoperative enteral immunonutrition with RNA, arginine, and polyunsaturated fatty acids (odds ratio 59; 0.29 to 1.22; P score 0.84) but with a low grade of certainty. No significant heterogeneity or incoherence is observed. The length of stay and infectious results are "at risk" for high heterogeneity or network meta-analysis incoherence. The component analysis confirmed that postoperative oral/enteral use of 2 or 3 components is crucial to reducing morbidity rate.

CONCLUSION

The oral/enteral immunonutrition in the postoperative period, with multiple immunonutrients, can reduce the morbidity rate in patients undergoing major abdominal surgery. The effect of immunonutrition on mortality, infectious disease, and length of stay is unclear.

Perioperative nutritional assessment and support in visceral surgery

Malnutrition in visceral surgery is frequent; it calls for screening prior to an operation, and its postoperative occurrence should be sought out and prevented, if possible. Organization of an individualized nutritional support strategy is based on systematic nutritional assessment and adapted to the type of surgery, the objectives being to forestall malnutrition and to reduce induced morbidity (immunosuppression, delayed wound healing, anastomotic fistulas…). Nutritional support is part and parcel of enhanced recovery after surgery (ERAS), and has shown effectiveness in the field of visceral surgery. Oral feeding should always be privileged to the greatest possible extent, complemented if necessary by nutritional supplements. If nutritional support is required, enteral nutrition should be favored over parenteral nutrition. As for the role of pharmaco-nutrition or immuno-nutrition, it remains ill-defined. Lastly, each type of visceral surgery entails specific modifications of the anatomy of the digestive system and is liable to have specific functional consequences, which should be known and taken into account in view of effectively tailoring nutritional support.

Immunonutrients and intestinal microbiota: a gap in the literature

The human intestinal microbiota is composed of a wide variety of microorganisms that play an important role in intestinal permeability, digestion, and especially, in the maturation of host's immune system. At the same time, effectiveness of immunomodulatory nutrients is known, especially in situations of stress and in strengthening body's defenses. However, the influence of the use of immunonutrients on microbiota's composition and variability is still poorly investigated. Studies indicate that the use of immunomodulators such as omega 3, glutamine, and arginine, can play a role in its modulation, through the immunological enhancement of the hosts. Therefore, this article sought to concentrate the latest evidence on the influence of the use of the main immunonutrients used in clinical practice on human gut microbiota, and their potential benefits.

Optimizing Nutritional Status of Patients Prior to Major Surgical Intervention

In patients undergoing elective cardiovascular and thoracic surgery, malnutrition and the deterioration of nutritional status are associated with negative outcomes. Recognition of the contributory factors and the complications stemming from surgical stress is important for the prevention and management of these patients. We have reviewed the literature available and focused on the nutritional and metabolic aspects affecting surgical patients, with emphasis on the recommendations of enhanced recovery protocols. The implementation of enhanced recovery protocols and nutritional support guidelines focusing on the surgical patient as part of a multidisciplinary approach would improve the nutritional status of surgical patients at risk for negative outcomes.

Effects of Omega-3 Fatty Acids on Postoperative Inflammatory Response: A Systematic Review and Meta-Analysis

Initial evidence indicates that preoperatively initiated administration of omega-3 fatty acids (FAs) attenuates the postoperative inflammatory reaction. The effects of immunonutrition containing omega-3 FAs, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on the inflammatory response to abdominal surgery continues to be unclear, although improved outcomes have been reported. Therefore, we determined the effectiveness of preoperatively initiated omega-3 FAs administration on postoperative inflammation defined as CRP (C-Reactive Protein), IL-6 (Interleukin 6), and WBC (White Blood Count) and potential effects on postoperative length of hospital stay (LOS) due to an improved inflammatory response.

METHODS

a literature search of Cochrane Library was conducted to identify all randomized controlled trials (RCTs) investigating the effects of preoperatively initiated omega-3 to standard care, placebo, or other immunonutrients excluding omega-3 FAs in patients undergoing abdominal surgery until the end of December 2022.

RESULTS

a total of 296 articles were found during the initial search. Thirteen RCTs involving 950 patients were identified that met the search criteria. These were successively analyzed and included in this meta-analysis. There was no significant difference between the groups with respect to inflammatory markers IL-6: -0.55 [-1.22; 0.12] p = 0.10, CRP: -0.14 [-0.67; 0.40] p = 0.55, WBC: -0.58 [-3.05; 1.89] p = 0.42, or hospital stay -0.5 [-1.43; 0.41] p = 0.2.

CONCLUSION

although reduced inflammatory markers were observed, preoperative administration of omega-3 FAs immunonutrients had no significant effect on the postoperative inflammatory response in patients undergoing abdominal surgeries. Yet, results obtained from this study are inconclusive, likely attributed to the limited number of trials and patients included. Further studies are required to obtain a better educated verdict.

The Role of Immunonutrition in Patients

Immunonutrition (IN) is defined as "the use of specific nutritional substrates, called «immunonutrients» having the ability of modulating specific mechanisms involved in several immune and inflammatory pathways" [...].

Prehabilitation: high-quality evidence is still required

Prehabilitation comprises multidisciplinary healthcare interventions, including exercise, nutritional optimisation, and psychological preparation, which aim to dampen the metabolic response to surgery, shorten the period of recovery, reduce complications, and improve the quality of recovery and quality of life. This editorial evaluates the potential benefits and limitations of and barriers to prehabilitation in surgical patients. The results of several randomised clinical trials and meta-analyses on prehabilitation show differing results, and the strength of the evidence is relatively weak. Heterogeneity in patient populations, interventions, and outcome measures, with a wide range for compliance, contribute to this variation. Evidence could be strengthened by the conduct of large-scale, appropriately powered multicentre trials that have unequivocal clinically relevant and patient-centric endpoints. Studies on prehabilitation should concentrate on recruiting patients who are frail and at high risk. Interventions should be multimodal and exercise regimens should be tailored to each patient's ability with longitudinal measurements of impact.

Unresolved issues in perioperative nutrition: A narrative review

Surgical patients are at an increased risk of negative outcomes if they are malnourished or at risk of malnutrition preoperatively. Optimisation of nutritional status should be a focus throughout the perioperative continuum to promote improved surgical outcomes. Enhanced Recovery after Surgery (ERAS) protocols are increasingly applied in the surgical setting but are not yet widespread. This narrative review focused on areas of perioperative nutrition that are perceived as controversial or are lacking in agreement. A search for available literature was conducted on 1 March 2022 and relevant high-quality articles published since 2015 were considered for inclusion. Most malnutrition screening tools are not specific to the surgical population except for the Perioperative Nutrition Screen (PONS) although more large-scale initiatives are needed to improve the prevalence of preoperative nutrition screening. Poor muscle health is common in patients with malnutrition and further exacerbates negative health outcomes indicating that prevention, detection and treatment is of high importance in this population. Although a lack of consensus remains for who should receive preoperative nutritional therapy, evidence suggests a positive impact on muscle health. Additionally, postoperative nutritional support benefits surgical outcomes, with some patients requiring enteral and/or parenteral feeding routes and showing benefit from immunonutrition. The importance of nutrition extends beyond the time in hospital and should remain a priority post-discharge. The impact of individual or personalised nutrition based on select patient characteristics remains to be further investigated. Overall, the importance of perioperative nutrition is evident in the literature despite select ongoing areas of contention.