Metabolic basis for management of the septic surgical patient

Monitoring of gastric residual volume during enteral nutrition

BACKGROUND

The main goal of enteral nutrition (EN) is to manage malnutrition in order to improve clinical outcomes. However, EN may increase the risks of vomiting or aspiration pneumonia during gastrointestinal dysfunction. Consequently, monitoring of gastric residual volume (GRV), that is, to measure GRV periodically and modulate the speed of enteral feeding according to GRV, has been recommended as a management goal in many intensive care units. Yet, there is a lack of robust evidence that GRV monitoring reduces the level of complications during EN. The best protocol of GRV monitoring is currently unknown, and thus the precise efficacy and safety profiles of GRV monitoring remain to be ascertained.

OBJECTIVES

To investigate the efficacy and safety of GRV monitoring during EN.

SEARCH METHODS

We searched electronic databases including CENTRAL, MEDLINE, Embase, and CINAHL for relevant studies on 3 May 2021. We also checked reference lists of included studies for additional information and contacted experts in the field.

SELECTION CRITERIA

We included randomized controlled trials (RCTs), randomized cross-over trials, and cluster-RCTs investigating the effects of GRV monitoring during EN. We imposed no restrictions on the language of publication.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results for eligible studies and extracted trial-level information from each included study, including methodology and design, characteristics of study participants, interventions, and outcome measures. We assessed risk of bias for each study using Cochrane's risk of bias tool. We followed guidance from the GRADE framework to assess the overall certainty of evidence across outcomes. We used a random-effects analytical model to perform quantitative synthesis of the evidence. We calculated risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous and mean difference (MD) with 95% CIs for continuous outcomes.

MAIN RESULTS

We included eight studies involving 1585 participants. All studies were RCTs conducted in ICU settings. Two studies (417 participants) compared less-frequent (less than eight hours) monitoring of GRV against a regimen of more-frequent (eight hours or greater) monitoring. The evidence is very uncertain about the effect of frequent monitoring of GRV on mortality rate (RR 0.91, 95% CI 0.60 to 1.37; I² = 8%; very low-certainty evidence), incidence of pneumonia (RR 1.08, 95% CI 0.64 to 1.83; heterogeneity not applicable; very low-certainty evidence), length of hospital stay (MD 2.00 days, 95% CI -2.15 to 6.15; heterogeneity not applicable; very low-certainty evidence), and incidence of vomiting (RR 0.14, 95% CI 0.02 to 1.09; heterogeneity not applicable; very low-certainty evidence). Two studies (500 participants) compared no GRV monitoring with frequent (12 hours or less) monitoring. Similarly, the evidence is very uncertain about the effect of no monitoring of GRV on mortality rate (RR 0.87, 95% CI 0.62 to 1.23; I² = 51%; very low-certainty evidence), incidence of pneumonia (RR 0.70, 95% CI 0.43 to 1.13; heterogeneity not applicable; very low-certainty evidence), length of hospital stay (MD -1.53 days, 95% CI -4.47 to 1.40; I² = 0%; very low-certainty evidence), and incidence of vomiting (RR 1.47, 95% CI 1.13 to 1.93; I² = 0%; very low-certainty evidence). One study (322 participants) assessed the impact of GRV threshold (500 mL per six hours) on clinical outcomes. The evidence is very uncertain about the effect of the threshold for GRV at time of aspiration on mortality rate (RR 1.01, 95% CI 0.74 to 1.38; heterogeneity not applicable; very low-certainty evidence), incidence of pneumonia (RR 1.03, 95% CI 0.72 to 1.46; heterogeneity not applicable; very low-certainty evidence), and length of hospital stay (MD -0.90 days, 95% CI -2.60 to 4.40; heterogeneity not applicable; very low-certainty evidence). Two studies (140 participants) explored the effects of returning or discarding the aspirated/drained GRV. The evidence is uncertain about the effect of discarding or returning the aspirated/drained GRV on the incidence of vomiting (RR 1.00, 95% CI 0.06 to 15.63; heterogeneity not applicable; very low-certainty evidence) and volume aspirated from the stomach (MD -7.30 mL, 95% CI -26.67 to 12.06, I² = 0%; very low-certainty evidence) We found no studies comparing the effects of protocol-based EN strategies that included GRV-related criteria against strategies that did not include such criteria.

AUTHORS' CONCLUSIONS

The evidence is very uncertain about the effect of GRV on clinical outcomes including mortality, pneumonia, vomiting, and length of hospital stay.

Initial Nutritional Status and Clinical Outcomes in Patients with Deep Neck Infection

OBJECTIVES

The current study aims to determine the correlation between nutritional status upon presentation and disease severity, as well as treatment and survival outcomes.

METHODS

Patients who were diagnosed with deep neck infection, underwent at least one surgical drainage/debridement, and had more than 1 week of hospitalization at a tertiary medical center from 2007 to 2015 were retrospectively included. Thereafter, initial serum albumin, C-reactive protein (CRP), and body mass index (BMI) were reviewed.

RESULTS

A total of 135 patients were included in the final analysis. Accordingly, the proportion of patients with simultaneous mediastinitis (21.0%), necrotizing fasciitis (12.9%), disease extent >1 cervical level (72.6%), mean CRP (22.4 mg/dL), mean length of hospitalization (25.0 days), and mean 1-week follow-up CRP (7.2 mg/dL) was significantly higher in the hypoalbuminemia group (initial serum albumin <3.0 g/dL) than in the normoalbuminemia group (all P<0.05). No significant correlations had been observed according to BMI status. After adjusting for age and Charlson comorbidity index, odds ratios for the following outcomes were calculated in patients initially presenting with hypoalbuminemia: simultaneous mediastinitis (3.07), necrotizing fasciitis (7.89), disease extent >1 cervical level (2.12), initial serum CRP over 20 mg/dL (3.79), hospitalization of more than 14 days (4.10), 1-week follow-up CRP over 5 mg/dL (3.78), and increased duration for an over 50% decrease in initial CRP (2.70) (all P<0.05). Although intravascular albumin replenishment decreased the proportion of patients with hypoalbuminemia after 2 weeks (P<0.05), it did not significantly predict better treatment outcomes.

CONCLUSION

Among the markers reflecting an individual's nutritional state, an initial serum albumin of less than 3.0 g/dL was an independent serologic marker predicting increased disease severity and complications in patients with deep neck infection.

Inflammation: a way to understanding the evolution of portal hypertension

BACKGROUND

Portal hypertension is a clinical syndrome that manifests as ascites, portosystemic encephalopathy and variceal hemorrhage, and these alterations often lead to death.

HYPOTHESIS

Splanchnic and/or systemic responses to portal hypertension could have pathophysiological mechanisms similar to those involved in the post-traumatic inflammatory response.The splanchnic and systemic impairments produced throughout the evolution of experimental prehepatic portal hypertension could be considered to have an inflammatory origin. In portal vein ligated rats, portal hypertensive enteropathy, hepatic steatosis and portal hypertensive encephalopathy show phenotypes during their development that can be considered inflammatory, such as: ischemia-reperfusion (vasodilatory response), infiltration by inflammatory cells (mast cells) and bacteria (intestinal translocation of endotoxins and bacteria) and lastly, angiogenesis. Similar inflammatory phenotypes, worsened by chronic liver disease (with anti-oxidant and anti-enzymatic ability reduction) characterize the evolution of portal hypertension and its complications (hepatorenal syndrome, ascites and esophageal variceal hemorrhage) in humans.

CONCLUSION

Low-grade inflammation, related to prehepatic portal hypertension, switches to high-grade inflammation with the development of severe and life-threatening complications when associated with chronic liver disease.

Surgical management of intestinal failure

Surgery plays a key role in the management of both acute and, less frequently, chronic intestinal failure. Acute intestinal failure frequently requires surgical treatment when it arises as a consequence of intestinal fistulation or obstruction. In specialised clinical practice approximately 50% of acute intestinal failure is associated with intestinal fistulas and in approximately 50% of patients, this condition arises as part of the natural history or complicating treatment for Crohn's disease. A considerable proportion of such patients have abdominal infection and present complex nutritional and metabolic problems. The most important aspect of the surgical management of patients with acute intestinal failure associated with intra-abdominal infection is management of sepsis, since recovery is unlikely in the presence of active infection. Moreover, effective nutritional support and restoration of body composition is not possible if sepsis remains unresolved. Surgical strategies to deal with intra-abdominal infection may involve percutaneous drainage, laparotomy and resection of fistulating segments of intestine and, when infection is persistent and contamination extensive, laparostomy (a technique in which the abdomen is left open and allowed to heal by secondary intention). Surgical treatment should not only be timely and effective, but also aimed at preventing secondary damage to the small intestine, in order to minimise the risk of short bowel syndrome. In some cases a proximal defunctioning stoma may be required, with prolonged nutritional support, using either home total parenteral nutrition or feeding via the defunctioned distal gut (fistuloclysis), pending restoration of intestinal continuity. The role of surgical treatment for patients with short bowel syndrome is less clear. While surgery is frequently required for the management of complications of short bowel syndrome (including gallstones and possibly peptic ulcer disease), the role of intestinal lengthening and tapering procedures (to increase functional intestinal length), and artificial valves, reversed segments and colonic interposition (to reduce intestinal transit) remains controversial. For some patients with short bowel syndrome and, in particular, those with combined intestinal and hepatic failure, intestinal transplantation may become the treatment of choice as long-term results continue to improve.

Management of enterocutaneous fistulas

Despite advances in antimicrobial chemotherapy, nutritional support, and perioperative critical care, the development of an enterocutaneous fistula continues to represent a major therapeutic challenge, with appreciable morbidity and mortality. Specific problems that must be addressed for the successful management of patients with enterocutaneous fistulas are the control of sepsis, maintenance of adequate fluid and electrolyte balance, provision of adequate and complication-free nutritional support, and skin-stoma care. In addition, many patients with postoperative intestinal fistulation suffer from significant psychological morbidity, which must be addressed during often prolonged periods of rehabilitation. The complex nature of the care required for successful management of patients with enterocutaneous fistulas mandates a multidisciplinary team approach, with specialist nurses, dieticians, pharmacists, radiologists, physicians, and surgeons all having important roles to play.

Posttraumatic inflammation is a complex response based on the pathological expression of the nervous, immune, and endocrine functional systems

The successive phases that make up both the local and systemic posttraumatic acute inflammatory response could represent the expression of three concatenated pathological or "primitive" functional systems with trophic properties: the nervous, immune, and endocrine ones. The nervous functional system would play an important role in the phenomenon of ischemia-reperfusion, which would be represented by nutrition by diffusion that is either anaerobic (ischemia) or with defective use of oxygen (reperfusion) and, thus, with a limited energy requirement. The immune functional system would be represented by the infiltration of the tissues by inflammatory cells and bacteria, which would become mediators in providing nutrition to the injured tissues. Although the use of oxygen would still be defective, hypermetabolism and fever would occur. In these inflammatory response phases, the lymphatic is the most important circulation. The endocrine functional system would be the most specialized and would have high energy requirements because it would be represented by the blood capillary-mediated nutrition. Highly specialized epithelial cells would already possess a perfected oxidative metabolism. The successive expression of these three functional systems during embryonic development and also during the evolutionary development of our species could explain why the inflammatory response is a ubiquitous mechanism that is common to multiple diseases, because it is an integrator of the ontogeny and phylogeny.

Neuro-immune-endocrine functional system and vascular pathology

A new interpretation of the response to injury by the nervous, immune and endocrine system is proposed, in order to integrate biochemical knowledge into the respective clinical areas. The discovery that the signaling molecules of the classical nervous, immune and endocrine systems, that is, the neurotransmitters, cytokines and hormones, respectively, are expressed and perceived by the three systems, has enabled us to establish a functional concept of these systems. The hypothetical integration of different pathological processes in a functional response made up by three phases, the immediate or nervous, intermediate or immune and late or endocrine ones, makes it possible to consider that all of them represent different forms of expression of a functional response whose meaning is always the same, that is, inflammation. If the functions that characterize each one of these three phases represent the activity of the nervous, immune and endocrine systems, the biochemical knowledge could be integrated into the functional meaning of each system.