Colorectal Disease and the Gut Microbiome: What a Surgeon Needs to Know.

The gut microbiome is defined as the microorganisms that reside within the gastrointestinal tract and produce a variety of metabolites that impact human health. These microbes play an intricate role in human health, and an imbalance in the gut microbiome, termed gut dysbiosis, has been implicated in the development of varying diseases. The purpose of this review is to highlight what is known about the microbiome and its impact on colorectal cancer, inflammatory bowel disease, constipation, Clostridioides difficile infection, the impact of bowel prep, and anastomotic leaks.

Combining proteins with n-3 PUFAs (EPA + DHA) and their inflammation pro-resolution mediators for preservation of skeletal muscle mass.

The optimal feeding strategy for critically ill patients is still debated, but feeding must be adapted to individual patient needs. Critically ill patients are at risk of muscle catabolism, leading to loss of muscle mass and its consequent clinical impacts. Timing of introduction of feeding and protein targets have been explored in recent trials. These suggest that "moderate" protein provision (maximum 1.2 g/kg/day) is best during the initial stages of illness. Unresolved inflammation may be a key factor in driving muscle catabolism. The omega-3 (n-3) fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are substrates for synthesis of mediators termed specialized pro-resolving mediators or SPMs that actively resolve inflammation. There is evidence from other settings that high-dose oral EPA + DHA increases muscle protein synthesis, decreases muscle protein breakdown, and maintains muscle mass. SPMs may be responsible for some of these effects, especially upon muscle protein breakdown. Given these findings, provision of EPA and DHA as part of medical nutritional therapy in critically ill patients at risk of loss of muscle mass seems to be a strategy to prevent the persistence of inflammation and the related anabolic resistance and muscle loss.

Browning of white adipose tissue may be an appropriate adaptive response to critical illness.

Both the baseline amount of brown adipose tissue (BAT) and the capacity to stimulate browning of white adipose tissue (WAT) may provide a protective effect to the patient in a critical care setting. Critical illness is associated with reduced mitochondrial volume and function resulting in the increased production of reactive oxygen species, greater demand for adenosine triphosphate, a switch to uncoupled fat metabolism, and hibernation of the organelle, which all contribute to multiple organ failure. Increasing insulin resistance, decreasing fatty acid oxidation, and dependence on carbohydrate metabolism result. Browning of WAT may oppose many of these adverse effects. The presence of BAT and the changes associated with browning may help dissipate oxidative stress, increase consumption and utilization of metabolites, and reduce pro-inflammatory actions. The number of mitochondria increases, and there is greater infiltration of macrophages into adipose tissue. A shift occurs in macrophage expression from the M1 to M2 phenotype, an effect which further dampens inflammation, increases insulin sensitivity, and improves tissue healing and remodeling. Any benefit from these responses may be lost in the disease states of chronic hypermetabolism (such as burns or cancer cachexia) in which the persistence of these physiologic effects may become detrimental, contributing to excessive weight loss, adipose wasting, and loss of lean body mass. This paper discusses the plasticity of adipose tissue and whether shifts in its physiology provide clinical advantages in the intensive care unit.

The importance of providing dietary fiber in medical and surgical critical care.

The early provision of soluble/insoluble fiber to the patient who is critically ill has been controversial in the past. Especially in the setting of hemodynamic instability, dysmotility, or impaired gastrointestinal transit, fear of inspissation of formula with precipitation of nonocclusive mesenteric ischemia (NOMI)/nonocclusive bowel necrosis (NOBN) limited its utilization by medical and surgical intensivists. The incidence of NOMI/NOBN has been estimated at 0.2%-0.3% for all intensive care unit (ICU) patients receiving enteral nutrition (EN), and the occurrence of inspissated formula is even less. The science supporting a benefit from providing fiber has recently increased exponentially. The fermentation of soluble fibers leading to the production of short chain fatty acids supports gut barrier function, modulates immune responses, and promotes refaunation of commensal organisms. The "butyrate effect" refers to local (gastrointestinal tract) and systemic anti-inflammatory responses mediated by the M2 polarization of macrophages, inhibition of histone deacetylase, and stimulation of ubiquitous G protein receptors. Both soluble and insoluble fiber have been shown to promote intestinal motility, reduce feeding intolerance, and shorten hospital length of stay. The benefit of providing dietary fiber early upon admission to the ICU outweighs its minimal associated risk. The point at which the intensivist determines that is safe to initiate EN, both soluble and insoluble fiber should be included in the enteral formulation.

Gut microbial metabolites and its impact on human health.

One of the primary methods by which the gut microbiome interacts with its host is through the interactions that occur through the production of the metabolites produced, either directly, or indirectly, through microbial metabolism. Decades of research has demonstrated that these metabolic products play a vital role in human health, either for its benefit or detriment. This review article highlights the main metabolites produced by the interactions between diet and the gut microbiome, bile acids and the gut microbiome, and products produced by the gut microbiome alone. Additionally, this article reviews the literature on the effects that these metabolites play on human health.

Prospective, multicenter study of antimicrobial-coated, noncrosslinked, acellular porcine dermal matrix (XenMatrix™ AB Surgical Graft) for hernia repair in all centers for disease control and prevention wound classes: 24-month follow-up cohort.

Prospective, multicenter, single-arm study of antimicrobial-coated, noncrosslinked, acellular porcine dermal matrix (AC-PDM) in a cohort involving all centers for disease control and prevention wound classes in ventral/incisional midline hernia repair (VIHR). Materials and methods: Seventy-five patients (mean age 58.6±12.7 years; BMI 31.3±4.9 kg/m2) underwent ventral/incisional midline hernia repair with AC-PDM. Surgical site occurrence (SSO) was assessed in the first 45 days post-implantation. Length of stay, return to work, hernia recurrence, reoperation, quality of life, and SSO were assessed at 1, 3, 6, 12, 18, and 24 months. Results: 14.7% of patients experienced SSO requiring intervention within 45 days post-implantation, and 20.0% thereafter (>45 d post-implantation). Recurrence (5.8%), definitely device-related adverse events (4.0%), and reoperation (10.7%) were low at 24 months; all quality-of-life indicators were significantly improved compared to baseline. Conclusion: AC-PDM exhibited favourable results, including infrequent hernia recurrence and definitely device-related adverse events, with reoperation and SSO comparable to other studies, and significantly improved quality of life.

Benefits and harm of probiotics and synbiotics in adult critically ill patients. A systematic review and meta-analysis of randomized controlled trials with trial sequential analysis.

BACKGROUND & AIMS: Several systematic reviews and meta-analyses of randomized controlled trials concluded that probiotics administration in critically ill patients was safe and associated with reduced rates of ventilator-associated pneumonia and diarrhea. However, a recent large multicenter trial found probiotics administration, compared to placebo, was not efficacious and increased adverse events. An updated meta-analysis that controls for type-1 and -2 errors using trial sequential analysis, with a detailed account of adverse events associated with probiotic administration, is warranted to confirm the safety and efficacy of probiotic use in critically ill patients. METHODS: RCTs that compared probiotics or synbiotics to usual care or placebo and reported clinical and diarrheal outcomes were searched in 4 electronic databases from inception to March 8, 2022 without language restriction. Four reviewers independently extracted data and assessed the study qualities using the Critical Care Nutrition (CCN) Methodological Quality Scoring System. Random-effect meta-analysis and trial sequential analysis (TSA) were used to synthesize the results. The primary outcome was ventilator-associated pneumonia (VAP). The main subgroup analysis compared the effects of higher versus lower quality studies (based on median CCN score). RESULTS: Seventy-five studies with 71 unique trials (n = 8551) were included. In the overall analysis, probiotics significantly reduced VAP incidence (risk ratio [RR] 0.70, 95% confidence interval [CI] 0.56-0.88; I2 = 65%; 16 studies). However, such benefits were demonstrated only in lower (RR 0.47, 95% CI 0.32, 0.69; I2 = 44%; 7 studies) but not higher quality studies (RR 0.89, 95% CI 0.73, 1.08; I2 = 43%; 9 studies), with significant test for subgroup differences (p = 0.004). Additionally, TSA showed that the VAP benefits of probiotics in the overall and subgroup analyses were type-1 errors. In higher quality trials, TSA found that future trials are unlikely to demonstrate any benefits of probiotics on infectious complications and diarrhea. Probiotics had higher adverse events than control (pooled risk difference: 0.01, 95% CI 0.01, 0.02; I2 = 0%; 22 studies). CONCLUSION: High-quality RCTs did not support a beneficial effect of probiotics on clinical or diarrheal outcomes in critically ill patients. Given the lack of benefits and the increased incidence of adverse events, probiotics should not be routinely administered to critically ill patients. PROSPERO REGISTRATION: CRD42022302278.

Novel nutrition strategies to enhance recovery after surgery.

Surgery and traumatic injury set off a cascade of metabolic changes that are becoming better understood. Recently, strategies and protocols have been developed for optimizing outcomes, and this has yielded beneficial results. This brief review evaluates three specific nutrition or metabolic interventions in the postoperative setting that attempt to optimize outcomes. We limited this to three subspecialty areas including oncologic surgery, orthopedic surgery, and cardiac surgery. These agents included fish oils, factors to prevent dysbiosis, and resistance exercise and its role in enhancing protein update. Where these novel agents fit into the basic tenets of postoperative nutrition interventions does not change the narrative: deliver graduated early enteral feeding to attenuate the metabolic response to surgical stress, maintain the gastrointestinal mucosal barrier, use immune/metabolic modulation to enhance immune response while attenuating excessive inflammation, and support the microbiome.

Chylothorax and chylous ascites: Overview, management, and nutrition.

Chyle leaks of any source or type can cause significant morbidity and mortality. Attention to the anatomy and physiology of the leak, followed by stepwise dietary and pharmacologic management, obviates the need for surgical intervention in a majority of patients. In this article, we review the importance, etiology, anatomy, diagnosis, nutrition and immunologic effects, and options for treatment of chylothorax and chylous ascites based on experience and prior literature. We propose a multidisciplinary approach to optimize these treatments including the primary surgical teams, pharmacists, and dietitians, with reoperation as a last resort to minimize the morbidity of this challenging complication.

New features of parenteral nutrition in home care and acute care setting for the older population.

PURPOSE OF REVIEW: The intent of this review is to highlight any recent changes in the delivery of parenteral nutrition to the geriatric population. The percentage of patients in the geriatric age group increases clinical awareness of the potential risks and benefits of appropriate parenteral nutrition delivery, which is crucial to well tolerated and optimum outcomes. RECENT FINDINGS: The major recent finding is the increased awareness of risk of parenteral nutrition in the elderly population. SUMMARY: The implications of this very brief review expose the need for further focused studies to better clarify the specifics of parenteral nutrition in this vulnerable ageing population. The importance of nutritional risk assessment cannot be overstated. With the rapidly expanding volume of geriatric population, the need for more data to better understand the delicate balance in parenteral nutrition therapy for both the acute care setting and home parenteral population is needed.

Nutrition for the high-risk surgical patient, when they need it most: Question and answer session.

Patients requiring complex or extensive surgery are often at high risk for perioperative and postoperative nutrition risk. Despite published guidelines, providing adequate nutrition to these patients continues to remain a clinical challenge. Using the case of a patient with preoperative nutrition risk who will need to undergo timely cancer resectional surgery, speakers presenting at the American Society for Parenteral and Enteral Nutrition 2022 Preconference discussed novel strategies to assess for nutrition risk, enhanced recovery after surgery, and preoperative and postoperative nutrition management in these often complex surgical patients.

Long-Term, Prospective, Multicenter Study of Poly-4-Hydroxybutyrate Mesh (Phasix Mesh) for Hernia Repair in Cohort at Risk for Complication: 60-Month Follow-Up.

BACKGROUND: Long-term resorbable mesh represents a promising technology for ventral and incisional hernia repair (VIHR). This study evaluates poly-4-hydroxybutyrate mesh (P4HB; Phasix Mesh) among comorbid patients with CDC class I wounds. STUDY DESIGN: This prospective, multi-institutional study evaluated P4HB VIHR in comorbid patients with CDC class I wounds. Primary outcomes included hernia recurrence and surgical site infection. Secondary outcomes included pain, device-related adverse events, quality of life, reoperation, procedure time, and length of stay. Evaluations were scheduled at 1, 3, 6, 12, 18, 24, 30, 36, and 60 months. A time-to-event analysis (Kaplan-Meier) was performed for primary outcomes; secondary outcomes were reported as descriptive statistics. RESULTS: A total of 121 patients (46 male, 75 female) 54.7 ± 12.0 years old with a BMI of 32.2 ± 4.5 kg/m 2 underwent VIHR with P4HB Mesh (mean ± SD). Fifty-four patients (44.6%) completed the 60-month follow-up. Primary outcomes (Kaplan-Meier estimates at 60 months) included recurrence (22.0 ± 4.5%; 95% CI 11.7% to 29.4%) and surgical site infection (10.1 ± 2.8%; 95% CI 3.3 to 14.0). Secondary outcomes included seroma requiring intervention (n = 9), procedure time (167.9 ± 82.5 minutes), length of stay (5.3 ± 5.3 days), reoperation (18 of 121, 14.9%), visual analogue scale-pain (change from baseline -3.16 ± 3.35 cm at 60 months; n = 52), and Carolinas Comfort Total Score (change from baseline -24.3 ± 21.4 at 60 months; n = 52). CONCLUSIONS: Five-year outcomes after VIHR with P4HB mesh were associated with infrequent complications and durable hernia repair outcomes. This study provides a framework for anticipated long-term hernia repair outcomes when using P4HB mesh.

Barriers to nutrition therapy in the critically ill patient with COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has created challenges for intensivists, as high ventilatory demands and prolonged hypermetabolism make it difficult to sustain nutrition status. The purpose of this survey was to determine current practices in nutrition therapy and identify barriers to its delivery. METHODS: A survey about delivering nutrition therapy to critically ill patients with COVID-19 was sent to clinicians at academic and community hospitals from September to December 2020. RESULTS: Of 440 who viewed the survey, 199 (45%) completed the questionnaire. Respondents were composed of 30%, physicians and 70% registered dietitians, with 51% representing community programs, 43% academic institutions, and 6% Veterans Affairs centers. Half (49%) had protocols for managing critically ill patients with COVID-19, and 21% had a protocol for nutrition therapy. Although most respondents (83%) attempted to feed by the intragastric route, only 9% indicated that energy/protein needs were met. The biggest barriers to delivery of enteral nutrition (EN) involved the patients unpredictable clinical course and fear of aspiration given the lack of respiratory reserve. Intensivists were reluctant to add supplemental parenteral nutrition (PN) because of perceived lack of benefit. CONCLUSION: The survey results would suggest that strategies for nutrition therapy based on the intragastric infusion of EN are unsuccessful in meeting the energy/protein needs of critically ill patients with COVID-19. It is likely these barriers exist in providing nutrition to non-Covid-19 critically ill patients. Intensivists need protocols that optimally deliver intragastric EN, consider early postpyloric infusion, and address adding supplemental PN in a deteriorating nutrition status.

Case presentation and panel discussion: Nutrition issues in cancer.

Advances in treatment of malignancy including novel pharmacologic therapies and surgical interventions has led to significant improvement in survival. As cancer becomes a chronic disease, nutrition interventions play an increasingly important role in short- and long-term outcomes. The current manuscript presents a case of a 66-year-old male with new diagnosis of pancreatic cancer diagnosed incidentally in the setting of COVID-19. Expert panelists in the field of nutrition discuss optimal strategies for diagnosis of malnutrition along with preoperative, perioperative, and postoperative optimization of nutrition. This discussion focuses on the use of probiotics, immune-modulating nutrition, fish oil, specialized proresolving mediators, and use of enteral and parenteral nutrition support.

Nutrition in cancer therapy: Overview for the cancer patient.

Despite significant advances in oncologic treatment, cancer-associated metabolic derangements largely remain poorly understood and are often neglected in cancer care. Cancer cachexia and metabolic changes exhibited by neoplastic cells pose formidable barriers to improving outcomes and quality of life. Although cancer has traditionally been viewed as a proliferative disease caused by genetic mutations, newer perspectives suggest that it is primarily a metabolic disease. This paper discusses the etiology of cachexia and sarcopenia and nutrition interventions that can address these wasting disorders. The role of inflammation in cancer and the methods for preventing and resolving inflammation with nutrition intervention are also explored. Several nutrition recommendations aimed at overcoming cachexia, resolving inflammation, and improving cancer outcomes are provided based on current literature. This manuscript selected only a few areas on which to focus and is not all-inclusive of the expansive literature available on the topic of cachexia.

ESPEN practical guideline: Clinical nutrition in surgery.

Early oral feeding is the preferred mode of nutrition for surgical patients. Avoidance of any nutritional therapy bears the risk of underfeeding during the postoperative course after major surgery. Considering that malnutrition and underfeeding are risk factors for postoperative complications, early enteral feeding is especially relevant for any surgical patient at nutritional risk, especially for those undergoing upper gastrointestinal surgery. The focus of this guideline is to cover both nutritional aspects of the Enhanced Recovery After Surgery (ERAS) concept and the special nutritional needs of patients undergoing major surgery, e.g. for cancer, and of those developing severe complications despite best perioperative care. From a metabolic and nutritional point of view, the key aspects of perioperative care include the integration of nutrition into the overall management of the patient, avoidance of long periods of preoperative fasting, re-establishment of oral feeding as early as possible after surgery, the start of nutritional therapy immediately if a nutritional risk becomes apparent, metabolic control e.g. of blood glucose, reduction of factors which exacerbate stress-related catabolism or impaired gastrointestinal function, minimized time on paralytic agents for ventilator management in the postoperative period, and early mobilization to facilitate protein synthesis and muscle function.

Identification of SARS-CoV-2 RNA in healthcare heating, ventilation, and air conditioning units.

Evidence continues to grow supporting the aerosol transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To assess the potential role of heating, ventilation, and air conditioning (HVAC) systems in airborne viral transmission, this study sought to determine the viral presence, if any, on air handling units in a healthcare setting where coronavirus disease 2019 (COVID-19) patients were being treated. The presence of SARS-CoV-2 RNA was detected in approximately 25% of samples taken from ten different locations in multiple air handlers. While samples were not evaluated for viral infectivity, the presence of viral RNA in air handlers raises the possibility that viral particles can enter and travel within the air handling system of a hospital, from room return air through high-efficiency MERV-15 filters and into supply air ducts. Although no known transmission events were determined to be associated with these specimens, the findings suggest the potential for HVAC systems to facilitate transfer of virions to locations remote from areas where infected persons reside. These results are important within and outside of healthcare settings and may present necessary guidance for building operators of facilities that are not equipped with high-efficiency filtration. Furthermore, the identification of SARS-CoV-2 in HVAC components indicates the potential utility as an indoor environmental surveillance location.

Multicenter Prospective Evaluation of Parenteral Nutrition Preparation Time and Resource Utilization: 3-Chamber Bags Compared With Hospital Pharmacy-Compounded Bags.

BACKGROUND: Parenteral nutrition (PN) is a complex and costly therapy that places significant demands on healthcare resources. Commercially manufactured 3-chamber bags (3CBs) offer potential time and cost advantages compared with hospital pharmacy-compounded bags (HCBs); however, no data are yet available from studies comparing these delivery systems in US hospitals. The primary aim of this study was to evaluate the PN preparation time and resource utilization required for 3CBs compared with HCBs in US hospitals. METHODS: A prospective, multicenter, time and motion study was performed to evaluate the time from transcription to completion of PN preparation and costs for 3CBs compared with HCBs. The cost per bag included labor, PN products, medical consumables, and equipment. RESULTS: One hundred thirty-six PN prescriptions were prepared during the study (66 prescriptions for 3CBs and 70 prescriptions for HCBs). The mean ± standard deviation total time required for transcription, review, validation, and preparation of PN was 5.5 ± 1.3 minutes for 3CBs vs 14.3 ± 6.2 minutes for HCBs (P < .001). The mean total cost per PN bag was $81.60 for 3CBs and $131.17 for HCBs (mean difference, -$49.57). CONCLUSION: Commercial 3CBs reduced staff time by 62% and direct costs by 37% compared with HCBs. The results demonstrate that 3CBs offer potential cost-savings for hospitalized patients who require PN in US hospitals.

Prospective, multicenter study of P4HB (Phasix™) mesh for hernia repair in cohort at risk for complications: 3-Year follow-up.

BACKGROUND: This study represents a prospective, multicenter, open-label study to assess the safety, performance, and outcomes of poly-4-hydroxybutyrate (P4HB, Phasix™) mesh for primary ventral, primary incisional, or multiply-recurrent hernia in subjects at risk for complications. This study reports 3-year clinical outcomes. MATERIALS AND METHODS: P4HB mesh was implanted in 121 patients via retrorectus or onlay technique. Physical exam and/or quality of life surveys were completed at 1, 3, 6,12, 18, 24, and 36 months, with 5-year (60-month) follow-up ongoing. RESULTS: A total of n = 121 patients were implanted with P4HB mesh (n = 75 (62%) female) with a mean age of 54.7 ± 12.0 years and mean BMI of 32.2 ± 4.5 kg/m2 (±standard deviation). Comorbidities included: obesity (78.5%), active smokers (23.1%), COPD (28.1%), diabetes mellitus (33.1%), immunosuppression (8.3%), coronary artery disease (21.5%), chronic corticosteroid use (5.0%), hypo-albuminemia (2.5%), advanced age (5.0%), and renal insufficiency (0.8%). Hernias were repaired via retrorectus (n = 45, 37.2% with myofascial release (MR) or n = 43, 35.5% without MR), onlay (n = 8, 6.6% with MR or n = 24, 19.8% without MR), or not reported (n = 1, 0.8%). 82 patients (67.8%) completed 36-month follow-up. 17 patients (17.9% ± 0.4%) experienced hernia recurrence at 3 years, with n = 9 in the retrorectus group and n = 8 in the onlay group. SSI (n = 11) occurred in 9.3% ± 0.03% of patients. CONCLUSIONS: Long-term outcomes following ventral hernia repair with P4HB mesh demonstrate low recurrence rates at 3-year (36-month) postoperative time frame with no patients developing late mesh complications or requiring mesh removal. 5-year (60-month) follow-up is ongoing.