Gastric mucosal protection from enteral nutrients: role of motility

Early enteral nutrition versus delayed enteral nutrition in patients with gastrointestinal bleeding: A PRISMA-compliant meta-analysis

BACKGROUND

Controversy persists about whether early enteral nutrition administration is related to worse prognosis than delayed enteral nutrition for patients with gastrointestinal bleeding.

OBJECTIVES

To systematically evaluate the effect of early enteral nutrition on the patient with gastrointestinal bleeding through the meta-analysis.

METHODS

Such electronic databases including PubMed, EMBASE, Cochrane Library, CNKI, and CBM were searched from 1985 to March 2018. Randomized controlled trials that compared early enteral nutrition versus delayed enteral nutrition in patients with gastrointestinal bleeding were considered eligible. Data extraction and the methodological quality assessment of the included trials were carried out according to the Cochrane Handbook. We calculated the pooled risk ratio, weighted mean difference, and the corresponding 95% confidential interval using RevMan5.3.

RESULT

A total of 5 trials involving 313 patients were included. Compared with delayed enteral nutrition, there was a tendency for a decreased rebleeding rate in the early enteral nutrition group, but the trend was not statistically significant (risk ratio = 0.75, 95% confidential interval: 0.34-1.64, I = 0). As for mortality within 30 days, no significant difference was found between the 2 groups (risk ratio = 0.74, 95% confidential interval: 0.23-2.39, I = 0). In addition, the pooled analysis showed that early enteral nutrition was related to reduced hospitalized days (weighted mean difference = -1.69, 95% confidential interval: -2.15 to -1.23; I = 27%) CONCLUSION:: For patients with gastrointestinal bleeding, early enteral nutrition within 24 hours does not result in the significantly higher risk of rebleeding and mortality compared with delayed enteral nutrition, but decrease hospitalized days. Patients who are at low risk for rebleeding can be fed early and discharged early. However, larger, high-quality randomized controlled trials are needed to verify these findings, and when the gastrointestinal bleeding patient start enteral nutrition is worth studying.

The effects of palm vitamin E on stress hormone levels and gastric lesions in stress-induced rats

INTRODUCTION

This study examines the effects of palm vitamin E (PVE) or α-tocopherol (α-TF) supplementation on adrenocorticotropin hormone (ACTH), corticosterone and gastric lesions in rats exposed to water-immersion restraint stress (WIRS).

MATERIAL AND METHODS

Sixty male Sprague-Dawley rats (200-250 g) were divided into three groups. Group I: 20 rats as a control group were given a normal diet. Group II: 20 rats received oral supplementation of PVE at 60 mg/kg body weight. Group III: 20 rats received oral supplementation of α-TF at 60 mg/kg body weight. After the treatment period of 28 days, each group was further subdivided into two groups: 10 rats not exposed to stress, and the other 10 rats subjected to WIRS for 3.5 h. Blood samples were taken to measure the ACTH and corticosterone levels. The rats were then sacrificed and the stomach excised and opened along the greater curvature and examined for lesions.

RESULTS

Rats exposed to WIRS had lesions in their stomach mucosa. Our findings showed that dietary supplementation of PVE or α-TF was able to reduce gastric lesions significantly in comparison to the stressed controls. The WIRS increased plasma ACTH and corticosterone significantly. Palm vitamin E and α-TF treatments reduced these parameters significantly compared to the stressed controls.

CONCLUSIONS

Supplementation with either PVE or α-TF reduces the formation of gastric lesions, probably by inhibiting the elevation of ACTH and corticosterone levels induced by stress.

Protective effect of palm vitamin E and α-tocopherol against gastric lesions induced by water immersion restraint stress in Sprague-Dawley rats

OBJECTIVE

Stress can lead to various changes in the gastrointestinal tract of rats. The present study was designed to compare the effect of palm vitamin E (PVE) and α-tocopherol (α-TF) supplementations on the gastric parameters important in maintaining gastric mucosal integrity in rats exposed to water immersion restraint stress (WRS). These parameters include gastric acidity, plasma gastrin level, gastric prostaglandin E(2) (PGE(2)), and gastric lesions.

MATERIALS AND METHODS

Sixty male Sprague-Dawley rats (200-250 g) were divided into three equal groups: a control group, which received a normal rat diet (RC), and two treatment groups, receiving oral supplementation of either PVE or α-TF at 60 mg/kg body weight for 28 days. Each group was further divided into two groups: the nonstress and stress groups. The stress groups were subjected to 3.5 h of WRS once at the end of the treatment period. Blood samples were then taken to measure the gastrin level, after which the rats were killed. Gastric juice was collected for measurement of gastric acidity and gastric tissue was taken for measurement of gastric mucosal lesions and PGE(2).

RESULTS

Exposure to stress resulted in the production of gastric lesions. PVE and α-TF lowered the lesion indices as compared to the stress control group. Stress reduced gastric acidity but pretreatment with PVE and α-TF prevented this reduction. The gastrin levels in the stress group were lower as compared to that in the nonstress control. However, following treatment with PVE and α-TF, gastrin levels increased and approached the normal level. There was also a significant reduction in the gastric PGE(2) content with stress exposure, but this reduction was blocked with treatment with both PVE and α-TF.

CONCLUSION

In conclusion, WRS leads to a reduction in the gastric acidity, gastrin level, and gastric PGE(2) level and there is increased formation of gastric lesions. Supplementation with either PVE or α-TF reduces the formation of gastric lesions, possibly by blocking the changes in the gastric acidity, gastrin, and gastric PGE(2) induced by stress. No significant difference between PVE and α-TF was observed.

Supportive care in acute respiratory distress syndrome

Although the central focus of acute respiratory distress syndrome (ARDS) is the pathology within the lung, ARDS is very much a systemic disease. As such, the whole body needs care and support while the disease process within the lung runs its course. The issues of pain management, sedation, fluid balance, nutrition, metabolic and hormonal processes, infection control, and patient positioning are important for any patient in a critical care setting. For patients with ARDS, the required ventilatory support and ARDS-associated systemic inflammation mandate the above supportive measures.

Pathophysiology and prophylaxis of stress ulcer in intensive care unit patients

Gastrointestinal complications frequently occur in patients admitted to the intensive care unit. Of these, ulceration and bleeding related to stress-related mucosal disease (SRMD) can lengthen hospitalization and increase mortality. The purpose of this review is to discuss the many risk factors and underlying illnesses that have a role in the pathophysiology of SRMD and evaluate the evidence pertaining to SRMD prophylaxis in the intensive care unit population. Suppressing acid production is fundamental to preventing stress-related mucosal ulceration and clinically important gastrointestinal bleeding. Traditional prophylactic options for SRMD in critically ill patients include antacids, sucralfate, histamine 2 -receptor antagonists (H 2 RAs), and proton pump inhibitors. Many clinicians prescribe intermittent infusions of H 2 RAs for stress ulcer prophylaxis, a practice that has not been approved for this indication and may not provide the necessary degree or duration of acid suppression required to prevent stress ulcer-related bleeding. New data suggest that proton pump inhibitors suppress acid production more completely in critically ill patients, but more studies are required to assess their clinical effectiveness and safety for this indication. The prophylactic regimen chosen to prevent stress ulcer bleeding should take into account the risk factors and underlying disease state of individual patients to provide the best therapy to those most likely to benefit.

Intracerebroventricular calcitonin prevents stress-induced gastric dysfunction

BACKGROUND

Restraint stress produces gastric hypercontractility and acidity leading to stress ulceration. Intracerebroventricular (ICV) salmon calcitonin (sCT) decreases restraint injury and acidity, but its effects on restraint-induced hypercontractility are unknown.

METHODS

Using stereotactic guidance, ICV catheters were placed into the lateral ventricle of adult male rats and calibrated gastric strain gauge transducers were implanted 5 days prior to restraint stress. sCT rats (n = 8) were pretreated with 5 microg of calcitonin ICV (10 microl volume), while controls (n = 10) received 10 microl of ICV saline prior to restraint for 2 h at 20 degrees C followed by 2 h at 4 degrees C. Gastric motility data were collected with AT-CODAS and analyzed with ADVANCED CODAS. Gastric volume, pH, and lesions were recorded following the stress.

RESULTS

ICV calcitonin prevented gastric mucosal injury in all animals (0% vs 100%, P <.01) and elevated pH slightly (2.5 +/-.3 vs 1.6 +/-.1, P <.05). Stress caused the force of contractions to increase from 0.35 +/-.1 to 1.38 +/-.4 g in controls (P <.01), while treated animal's force fell from.42 +/-.1 to 0.2 +/-.05 g (P <.01 vs control). Stress did not affect contractions/min (3.4 +.6 vs 3.5 +.3), but sCT increased frequency (2.5 +.4 to 5.0 +.2, P <.01). Stress prolonged contraction duration (11.5 + 1 to 16.5 + 1.7 s, P <.01), but stress's effect was prevented by sCT (11.0 +.5 to 11.2 +.3, P <.01 vs control).

CONCLUSIONS

Pretreatment with 5 microg central sCT prevents the increased amplitude and duration of gastric contractions produced by restraint stress for 2 h, in association with gastroprotection.

Nutritional support

Despite the increasing obesity of the American population, many chronically ill patients are malnourished. When this malnutrition is combined with the hypermetabolic response and protein catabolism of an acute event, such as an operation, nutritional support becomes an important facet for optimal critical care. This chapter reviews the basic tenants of nutritional support with special emphasis on patients with pulmonary compromise. Important aspects of caloric and protein support are discussed and enteral nutrition is emphasized because of its numerous advantages and documented improvement in outcome.

Use of enteral nutrition for stress ulcer prophylaxis

OBJECTIVE

To review the controversies involving the use of enteral nutrition support for stress ulcer prophylaxis and formulate recommendations.

DATA SOURCES

A MEDLINE search (1966-December 2000) was conducted using the MeSH of nutrition, ulcer, critical care, and acid to identify relevant articles. References of selected articles were reviewed, and relevant abstracts from critical care or gastrointestinal journals identified.

DATA EXTRACTION

Animal and human data from prospective studies, retrospective studies, and case series were evaluated for the effects of enteral nutrition on gastric pH, intramucosal pH, gastrointestinal blood flow, development of macroscopic mucosal erosions, and hemorrhage.

DATA SYNTHESIS

Intragastric administration of enteral nutrition has variable effects on gastric pH, enhances regional distribution of gastrointestinal blood flow, and may lower intramucosal pH. All substrates (carbohydrate, lipid, amino acid), when administered into the stomach, reduce the occurrence of mucosal erosions but do not entirely prevent their development. Few studies of stress ulcer prophylaxis regimens have reported use of enteral nutrition. Limited retrospective data suggest enteral nutrition support may be effective for preventing gastrointestinal hemorrhage, but the results of prospective studies are confounded by poor study design.

CONCLUSIONS

Definitive recommendations regarding the role of enteral nutrition for stress ulcer prophylaxis are not possible due to the lack of prospective, randomized studies. Therefore, the use of enteral nutrition as the only therapeutic agent for stress ulcer prophylaxis should be discouraged until definitive data are available. Initiation and discontinuation of pharmacologic stress ulcer prophylaxis should be independent of enteral nutrition.

Acute gastrointestinal bleeding in the intensive care unit. The gastroenterologist's perspective

Although SRES-associated hemorrhage previously constituted a significant cause of bleeding in the ICU, improvements in ICU management and the institution of prophylactic measures in high-risk patients have significantly reduced SRES-associated hemorrhage since the 1980s. Antacids, H2-receptor antagonists, and sucralfate have been shown to be effective in preventing clinically significant bleeding resulting from SRES, particularly when the intragastric pH is maintained at greater than 4. A selective approach should be adopted in SRES prophylaxis: Patients on mechanical ventilation, with coagulopathy, or with two of the other known risk factors should receive prophylaxis. Although the drug of choice depends to some extent on local preferences, an H2-receptor antagonist by continuous intravenous infusion may represent the best option. No pharmacologic therapy is of proven value once hemorrhage begins, but the current interventional techniques are effective in controlling hemorrhage. Gastrointestinal bleeding from NOMV has become less common with improvements in the hemodynamic monitoring of critically ill patients, but this disease must always be considered when lower gastrointestinal bleeding occurs in the context of relative hypoperfusion. For SRES and NOMV, treatment of the underlying disease or diseases is the optimal route to prevention.

Are gastric, jejunal, or both forms of enteral feeding gastroprotective during stress?

BACKGROUND

Clinical data suggest enteral nutrition prevents stress ulceration and intragastric nutrients prevent restraint-induced gastric injury. The purpose of these studies was to determine if jejunal nutrients can protect without gastric contact and to determine if gastric pH, motility, or mucosal perfusion is affected.

METHODS

In Experiment 1, 27 rats were restrained for 2 h at room temperature followed by 2 h in cold (4 degrees C), with intragastric (IG) or intrajejunal (IJ) 2 ml/h infusions of saline or 25% glucose. Gastric lesions, pH, volumes, and glucose concentrations were measured postmortem. In Experiment 2, 23 rats had gastric strain gauges implanted >5 days prior to a 0.5 ml/h IG or IJ infusion during stress. In Experiment 3, 40 rats were anesthetized for laser Doppler measurements of gastric mucosal perfusion and arterial catheter monitoring of systemic hemodynamics. Rats received 0.5-ml boluses of concentrated glucose or saline IG or IJ, and were monitored for 60 min.

RESULTS

(1) The 2 ml/h IJ and IG glucose infusions prevented gastric injury, but the elevated gastric glucose concentrations suggested equal gastric contact. (2) The 0.5 ml/h glucose IG and IJ infusions decreased gastric injury without reflux of the IJ glucose into the stomach and suppressed stress-induced hypercontractility, but not acidity. (3) Systemic perfusion pressures were unaffected by enteral glucose. IG glucose had little effect on gastric mucosal perfusion, while IJ glucose decreased gastric perfusion within 5 min.

CONCLUSIONS

These studies show that large volumes of enteral glucose prevent restraint injury but IJ glucose refluxes into the stomach. The gastroprotective effects of small, nonrefluxing volumes of IJ glucose are associated with suppression of stress-induced gastric hypercontractility, but not with suppressed acidity or enhanced perfusion.