Intolerance to enteral feeding in the brain-injured patient

Binary classification model of machine learning detected altered gut integrity in controlled-cortical impact model of traumatic brain injury

Aim of the study: To examine the effect of controlled-cortical impact (CCI), a preclinical model of traumatic brain injury (TBI), on intestinal integrity using a binary classification model of machine learning (ML).Materials and methods: Adult, male C57BL/6 mice were subjected to CCI surgery using a stereotaxic impactor (Impact One™). The rotarod and hot-plate tests were performed to assess the neurological deficits.Results: Mice underwent CCI displayed a remarkable neurological deficit as noticed by decreased latency to fall and lesser paw withdrawal latency in rotarod and hot plate test, respectively. Animals were sacrificed 3 days post-injury (dpi). The colon sections were stained with hematoxylin and eosin (H&E) to integrate with machinery tool-based algorithms. Several stained colon images were captured to build a dataset for ML model to predict the impact of CCI vs sham procedure. The best results were obtained with VGG16 features with SVM RBF kernel and VGG16 features with stacked fully connected layers on top. We achieved a test accuracy of 84% and predicted the disrupted gut permeability and epithelium wall of colon in CCI group as compared to sham-operated mice.Conclusion: We suggest that ML may become an important tool in the development of preclinical TBI model and discovery of newer therapeutics.

Dysregulated brain-gut axis in the setting of traumatic brain injury: review of mechanisms and anti-inflammatory pharmacotherapies

Traumatic brain injury (TBI) is a chronic and debilitating disease, associated with a high risk of psychiatric and neurodegenerative diseases. Despite significant advancements in improving outcomes, the lack of effective treatments underscore the urgent need for innovative therapeutic strategies. The brain-gut axis has emerged as a crucial bidirectional pathway connecting the brain and the gastrointestinal (GI) system through an intricate network of neuronal, hormonal, and immunological pathways. Four main pathways are primarily implicated in this crosstalk, including the systemic immune system, autonomic and enteric nervous systems, neuroendocrine system, and microbiome. TBI induces profound changes in the gut, initiating an unrestrained vicious cycle that exacerbates brain injury through the brain-gut axis. Alterations in the gut include mucosal damage associated with the malabsorption of nutrients/electrolytes, disintegration of the intestinal barrier, increased infiltration of systemic immune cells, dysmotility, dysbiosis, enteroendocrine cell (EEC) dysfunction and disruption in the enteric nervous system (ENS) and autonomic nervous system (ANS). Collectively, these changes further contribute to brain neuroinflammation and neurodegeneration via the gut-brain axis. In this review article, we elucidate the roles of various anti-inflammatory pharmacotherapies capable of attenuating the dysregulated inflammatory response along the brain-gut axis in TBI. These agents include hormones such as serotonin, ghrelin, and progesterone, ANS regulators such as beta-blockers, lipid-lowering drugs like statins, and intestinal flora modulators such as probiotics and antibiotics. They attenuate neuroinflammation by targeting distinct inflammatory pathways in both the brain and the gut post-TBI. These therapeutic agents exhibit promising potential in mitigating inflammation along the brain-gut axis and enhancing neurocognitive outcomes for TBI patients.

Beyond the brain: General intensive care considerations in pediatric neurocritical care

Managing children with critical neurological conditions requires a comprehensive understanding of several principles of critical care. Providing a holistic approach that addresses not only the acute interactions between the brain and different organ systems, but also critical illness-associated complications and recovery is essential for improving outcomes in these patients. The brain reacts to an insult with autonomic responses designed to optimize cardiac output and perfusion, which can paradoxically be detrimental. Managing neuro-cardiac interactions therefore requires balancing adequate cerebral perfusion and minimizing complications. The need for intubation and airway protection in patients with acute encephalopathy should be individualized following careful risk/benefit deliberations. Ventilatory strategies can have profound impact on cerebral perfusion. Therefore, understanding neuro-pulmonary interactions is vital to optimize ventilation and oxygenation to support a healing brain. Gastrointestinal dysfunction is common and often complicates the care of patients with critical neurological conditions. Kidney function, along with fluid status and electrolyte derangements, should also be carefully managed in the acutely injured brain. While in the pediatric intensive care unit, prevention of critical illness-associated complications such as healthcare-associated infections and deep vein thrombosis is vital in improving outcomes. As the brain emerges from the acute injury, rehabilitation and management of delirium and paroxysmal sympathetic hyperactivity is paramount for optimal recovery. All these considerations provide a foundation for the care of pediatric patients with critical neurological conditions in the intensive care unit.

Crosstalk Between the Nervous System and Systemic Organs in Acute Brain Injury

Organ crosstalk is a complex biological communication between distal organs mediated via cellular, soluble, and neurohormonal actions, based on a two-way pathway. The communication between the central nervous system and peripheral organs involves nerves, endocrine, and immunity systems as well as the emotional and cognitive centers of the brain. Particularly, acute brain injury is complicated by neuroinflammation and neurodegeneration causing multiorgan inflammation, microbial dysbiosis, gastrointestinal dysfunction and dysmotility, liver dysfunction, acute kidney injury, and cardiac dysfunction. Organ crosstalk has become increasingly popular, although the information is still limited. The present narrative review provides an update on the crosstalk between the nervous system and systemic organs after acute brain injury. Future research might help to target this pathophysiological process, preventing the progression toward multiorgan dysfunction in critically ill patients with brain injury.

Impact of resuscitative endovascular balloon occlusion of the aorta on gastrointestinal function with a matched cohort study

Background

Resuscitative endovascular balloon occlusion of the aorta (REBOA) can temporarily control arterial hemorrhage in torso trauma; however, the abdominal visceral blood flow is also blocked by REBOA. The aim of this study was to evaluate the influence of REBOA on gastrointestinal function.

Methods

A retrospective review identified all trauma patients admitted to our trauma center between 2008 and 2019. We used propensity score matching analysis to compare the gastrointestinal function between subjects who underwent REBOA and those who did not. Data on demographics, feeding intolerance (FI), time to feeding goal achievement, and complications were retrieved.

Results

During the study period, 55 patients underwent REBOA. A total of 1694 patients met the inclusion criteria, 27 of whom were a subset of those who underwent REBOA. After 1:1 propensity score matching, the REBOA and no-REBOA groups were assigned 22 patients each. Patients in the REBOA group had a significantly higher incidence of FI (77% vs. 27%; OR, 9.1; 95% CI, 2.31 to 35.7; p=0.002) and longer time to feeding goal achievement (8 vs. 6 days, p=0.022) than patients in the no-REBOA group. Patients in the REBOA group also showed significantly prolonged durations of ventilator use (8 vs. 4 days, p=0.023). Furthermore, there was no difference in the mortality rate between the groups (9% vs. 9%, p=1.000).

Conclusions

REBOA was associated with gastrointestinal dysfunction. Our study findings can be useful in providing guidance on managing nutrition in trauma patients who undergo REBOA.

Level of evidence

Level IV.

Study type

Care management.

Host-Microbiome Interactions: Tryptophan Metabolism and Aromatic Hydrocarbon Receptors after Traumatic Brain Injury

Traumatic brain injury refers to the damage caused to intracranial tissues by an external force acting on the head, leading to both immediate and prolonged harmful effects. Neuroinflammatory responses play a critical role in exacerbating the primary injury during the acute and chronic phases of TBI. Research has demonstrated that numerous neuroinflammatory responses are mediated through the "microbiota-gut-brain axis," which signifies the functional connection between the gut microbiota and the brain. The aryl hydrocarbon receptor (AhR) plays a vital role in facilitating communication between the host and microbiota through recognizing specific ligands produced directly or indirectly by the microbiota. Tryptophan (trp), an indispensable amino acid in animals and humans, represents one of the key endogenous ligands for AhR. The metabolites of trp have significant effects on the functioning of the central nervous system (CNS) through activating AHR signalling, thereby establishing bidirectional communication between the gut microbiota and the brain. These interactions are mediated through immune, metabolic, and neural signalling mechanisms. In this review, we emphasize the co-metabolism of tryptophan in the gut microbiota and the signalling pathway mediated by AHR following TBI. Furthermore, we discuss the impact of these mechanisms on the underlying processes involved in traumatic brain injury, while also addressing potential future targets for intervention.

Early supplemental parenteral nutrition for the achievement of nutritional goals in subarachnoid hemorrhage patients: An observational cohort study

Purpose

Enteral nutrition (EN) often fails to achieve nutritional goals in neurocritical care patients. We sought to investigate the safety and utility of supplemental parenteral nutrition (PN) in subarachnoid hemorrhage (SAH) patients.

Materials and methods

Data of 70 consecutive patients with non-traumatic SAH admitted to the neurological intensive care unit of a tertiary referral center were prospectively collected and retrospectively analyzed. We targeted the provision of 20–25 kilocalories per kilogram bodyweight per day (kcal/kg/d) by enteral nutrition. Supplemental PN was given when this target could not be reached. Nutritional data were analyzed for up to 14 days of ICU stay. Hospital complications were tested for associations with impaired enteral feeding. The amounts of EN and PN were tested for associations with the level of protein delivery and functional outcome. Repeated measurements within subjects were handled utilizing generalized estimating equations.

Results

Forty (27 women and 13 men) of 70 screened patients were eligible for the analysis. Median age was 61 (IQR 49–71) years, 8 patients (20%) died in the hospital. Thirty-six patients (90%) received PN for a median duration of 8 (IQR 4–12) days. The provision of 20 kcal/kg by EN on at least 1 day of ICU stay was only achieved in 24 patients (60%). Hydrocephalus (p = 0.020), pneumonia (p = 0.037) and sepsis (p = 0.013) were associated with impaired enteral feeding. Neither the amount nor the duration of PN administration was associated with an increased risk of severe complications or poor outcome. Supplemental PN was associated with significantly increased protein delivery (p<0.001). In patients with sepsis or pneumonia, there was an association between higher protein delivery and good functional outcome (p<0.001 and p = 0.031), but not in the overall cohort (p = 0.08).

Conclusions

Enteral feeding was insufficient to achieve nutritional goals in subarachnoid hemorrhage patients. Supplemental PN was safe and associated with increased protein delivery. A higher protein supply was associated with good functional outcome in patients who developed sepsis or pneumonia.

Brain-gut axis dysfunction in the pathogenesis of traumatic brain injury

Traumatic brain injury (TBI) is a chronic and progressive disease, and management requires an understanding of both the primary neurological injury and the secondary sequelae that affect peripheral organs, including the gastrointestinal (GI) tract. The brain-gut axis is composed of bidirectional pathways through which TBI-induced neuroinflammation and neurodegeneration impact gut function. The resulting TBI-induced dysautonomia and systemic inflammation contribute to the secondary GI events, including dysmotility and increased mucosal permeability. These effects shape, and are shaped by, changes in microbiota composition and activation of resident and recruited immune cells. Microbial products and immune cell mediators in turn modulate brain-gut activity. Importantly, secondary enteric inflammatory challenges prolong systemic inflammation and worsen TBI-induced neuropathology and neurobehavioral deficits. The importance of brain-gut communication in maintaining GI homeostasis highlights it as a viable therapeutic target for TBI. Currently, treatments directed toward dysautonomia, dysbiosis, and/or systemic inflammation offer the most promise.

Multipotential and systemic effects of traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of disability and mortality of people at all ages. Biochemical, cellular and physiological events that occur during primary injury lead to a delayed and long-term secondary damage that can last from hours to years. Secondary brain injury causes tissue damage in the central nervous system and a subsequent strong and rapid inflammatory response that may lead to persistent inflammation. However, this inflammatory response is not limited to the brain. Inflammatory mediators are transferred from damaged brain tissue to the bloodstream and produce a systemic inflammatory response in peripheral organs, including the cardiovascular, pulmonary, gastrointestinal, renal and endocrine systems. Complications of TBI are associated with its multiple and systemic effects that should be considered in the treatment of TBI patients. Therefore, in this review, an attempt was made to examine the systemic effects of TBI in detail. It is hoped that this review will identify the mechanisms of injury and complications of TBI, and open a window for promising treatment in TBI complications.

Bidirectional Brain-Systemic Interactions and Outcomes After TBI

Traumatic brain injury (TBI) is a debilitating disorder associated with chronic progressive neurodegeneration and long-term neurological decline. Importantly, there is now substantial and increasing evidence that TBI can negatively impact systemic organs, including the pulmonary, gastrointestinal (GI), cardiovascular, renal, and immune system. Less well appreciated, until recently, is that such functional changes can affect both the response to subsequent insults or diseases, as well as contribute to chronic neurodegenerative processes and long-term neurological outcomes. In this review, we summarize evidence showing bidirectional interactions between the brain and systemic organs following TBI and critically assess potential underlying mechanisms.

A Study to Ascertain the Expression of Aquaporin 4 and Neuropeptide Y in the Jejunal Mucosa Secondary to Traumatic Brain Injury in Humans

Introduction Gastrointestinal (GI) dysfunction is a common complication in patients with traumatic brain injury (TBI). Studies in rats have shown alterations in intestinal mucosa to correlate with severity and duration of TBI. There is lack of such evidence in humans. So we intended to find correlation between histopathological changes and expression of aquaporin 4 (AQ4) and neuropeptide Y (NPY) in jejunal mucosa in post TBI patients.

Materials and Methods Autopsy specimens of jejunum were obtained from patients who had died due to TBI (n = 20), patients dying due to traumatic injury other than TBI, and patients who were brought dead (diseased controls n = 20). Abdominal trauma was the exclusion criterion for both. Jejunal specimens were grossly examined and then analyzed histopathologically and graded immunohistochemically for AQ4 and NPY. Unpaired t-test was used to compare results.

Results After exclusion, 19 cases and 17 controls were studied. No significant difference was observed in the microscopic findings between cases and controls (p-value = 0.70). The expression of AQ4 was more in cases (p-value = 0.04). NPY expression was not significantly different (p-value = 0.93).

Conclusion AQ4 can hence be used as a marker of GI injury post TBI. Histopathological examination cannot distinguish between these changes.

Clinical Outcomes of Enteral Feeding Protocol Via Percutaneous Endoscopic Gastrostomy: A Single-Center, Retrospective Study

BACKGROUND

The development of the endoscopic technique has resulted in an increasing number of patients undergoing percutaneous endoscopic gastrostomy (PEG) insertion; however, the protocols for increasing the volume of feeding formula after PEG insertion have not been established. Therefore, we compared the clinical outcomes of patients receiving low- and high-volume increase in enteral feeding formula.

METHODS

A total of 215 patients who underwent PEG insertion between January 2016 and March 2019 were included. They were divided into 2 groups according to the increase in volume of feeding formula: the low-volume group (n = 135) received ≤150 mL/d, and the high-volume group (n = 80) received ≥300 mL/d. Patient characteristics, procedure, and feeding-related clinical outcomes were retrospectively reviewed using medical records.

RESULTS

The adverse events of the feeding protocol did not significantly differ between the 2 groups. The number of days needed to attain the calorie targets was significantly lower in the high-volume group than in the low-volume group (5.4 ± 3.0 vs 2.4 ± 1.5; P < .001). The duration of supplemental parenteral nutrition and the length of hospitalization were also significantly lower in the high-volume group (3.9 ± 3.3 vs 1.2 ± 2.2; P < .001 and 5.8 ± 2.7 vs 4.6 ± 2.6; P = .007, respectively).

CONCLUSION

To rapidly attain the calorie targets in appropriately selected patients with PEG insertion, a high-volume increase in daily feeding can safely be recommended given the favorable outcomes.

Incidence of diarrhea and associated risk factors in patients with traumatic brain injury and enteral nutrition

To determine the occurrence of diarrhea and associated factors in critically ill patients with traumatic brain injury (TBI) in use of nutritional therapy. Prospective cohort study conducted in an Intensive Care Unit (ICU) of a General Hospital reference in trauma. We evaluated TBI patients who stayed less than 72 h in the ICU, who were using EN for at least 48 h. Definition of diarrhea it was considered three or more episodes of liquid stools or semi-liquid at 24 h. For analysis were evaluated demographic, epidemiological, clinical and nutritional data. Twenty-three patients were evaluated, being 86.9% male, median 33 years old (IQR = 25-52 years) and 16-day ICU stay (IQR = 10-26 days). Diarrhea occurred in 69.6% of the patients and they had a longer time in the ICU (p = 0.007). All patients who used combination prokinetic therapy (metoclopramide and erythromycin) and used antibiotics for more than 8 days had diarrhea (p = 0.057 and p = 0.007, respectively). The incidence of diarrhea was high in TBI patients with enteral nutrition and was associated with the use of antibiotics for more than one week.

Factors affecting the caloric and protein intake over time in critically ill trauma patients

BACKGROUND

Major trauma leads to increased nutritional requirements. However, little is known about the actual amount of calories and protein administered and the factors affecting the intake over time in critically ill trauma patients.

METHODS

Prospective study including 100 trauma patients admitted to the Los Angeles County + University of Southern California Medical Center intensive care unit between March 2014 and October 2014. Inclusion criteria were age > 16 y, surgery at admission, and no oral nutrition. The caloric and protein intake was recorded, and requirements were calculated daily for 28 d. The nutritional intake and the impact of clinical factors on the intake over time were assessed using mixed model analysis.

RESULTS

The caloric and protein intake significantly increased over time, but the median intake did not meet the median calculated requirements at any time. Multivariable analysis revealed a smaller increase of the nutritional intake over time in patients with an injury severity score > 45, whereas penetrating injury and laparotomy were associated with a higher increase of the intake. Body mass index scores ≥ 30 kg/m², traumatic brain injury, and gastrointestinal tract injuries were associated with a smaller increase of the caloric intake over time.

CONCLUSIONS

The median nutritional intake did not meet the median calculated requirements over time. A smaller increase of the nutritional intake over time was found in patients with a higher injury burden, whereas penetrating injury and laparotomy were associated with a higher increase of the intake. Higher body mass index scores, traumatic brain injury, and gastrointestinal tract injuries were associated with a smaller increase of the caloric intake over time. These clinical factors can help to adjust the nutritional support in critically ill trauma patients.

Comparison of erythromycin versus metoclopramide for gastric feeding intolerance in patients with traumatic brain injury: A randomized double-blind study

Background:

No randomized controlled trial demonstrates the efficacy of erythromycin or metoclopramide in patients with traumatic brain injury (TBI). This study was conducted to determine the efficacy of metoclopramide and erythromycin for improving gastric aspirate volume (GAV) in patients with TBI.

Materials and Methods:

Patients with Glasgow coma score more than 5 admitted to trauma Intensive Care Unit within 72 h of head injury were assessed for eligibility. 115 patients were prospectively randomized to receive metoclopramide, erythromycin, or placebo eighth hourly. Gastric feeding intolerance was defined as GAV more than 150 ml with abdominal symptoms. Two consecutive high GAV was defined as feeding failure. Feeding failure was treated by increasing the frequency of dose to 6 hourly in metoclopramide and erythromycin group. Combination therapy with both drugs was given as rescue in the placebo group.

Results:

Incidence of high GAV was as high as 60.5% in placebo group. Use of erythromycin was associated with a decrease in the incidence of feeding intolerance to 28.9% (P = 0.006). Although feed intolerance decreased to 43.6% in metoclopramide group, values did not reach statistical significance. The proportion of patients not having high GAV at different days were significantly higher in erythromycin group (P = 0.027, log-rank test). There was no difference in the proportion of patients not having feeding failure in three groups with increasing number of days.

Conclusion:

There was a significant decrease in the incidence of high GAV with the use of erythromycin when compared to metoclopramide and placebo.

Gastric vs Small Bowel Feeding in Critically Ill Neurologically Injured Patients: Results of a Multicenter Observational Study

BACKGROUND

To evaluate gastric compared with small bowel feeding on nutrition and clinical outcomes in critically ill, neurologically injured patients.

MATERIALS AND METHODS

International, prospective observational studies involving 353 intensive care units (ICUs) were included. Eligible patients were critically ill, mechanically ventilated with neurological diagnoses who remained in the ICU and received enteral nutrition (EN) exclusively for at least 3 days. Sites provided data, including patient characteristics, nutrition practices, and 60-day outcomes. Patients receiving gastric or small bowel feeding were compared. Covariates including age, sex, body mass index, and Acute Physiology and Chronic Health Evaluation II score were used in the adjusted analyses.

RESULTS

Of the 1691 patients who met our inclusion criteria, 1407 (94.1%) received gastric feeding and 88 (5.9%) received small bowel feeding. Adequacy of calories from EN was highest in the gastric group (60.2% and 52.3%, respectively, unadjusted analysis; P = .001), but this was not significant in the adjusted model (P = .428). The likelihood of EN interruptions due to gastrointestinal (GI) complications was higher for the gastric group (19.6% vs 4.7%, unadjusted model; P = .015). There were no significant differences in the rate of discontinuation of mechanical ventilation (hazard ratio [HR], 0.86; 95% confidence interval [CI], 0.66-1.12; P = .270) or the rate of being discharged alive from the ICU (HR, 0.94; 95% CI, 0.72-1.23; P = .641) and hospital (HR, 1.16; 95% CI, 0.87-1.55; P = .307) after adjusting for confounders.

CONCLUSIONS

Despite a higher likelihood of EN interruptions due to GI complications, gastric feeding may be associated with better nutrition adequacy, but neither route is associated with better clinical outcomes.

Randomized trial to evaluate nutritional status and absorption of enteral feeding after brain death

CONTEXT

Catecholamines and inflammatory mediators, with elevated levels after brain death, are associated with reduced function and survival of transplanted organs. Enteral nutrition reduces tissue damage and may benefit organs.

OBJECTIVE

To evaluate the effects of immunomodulating enteral nutrition in organ donors.

DESIGN

Prospective, randomized, open-label study.

SETTING

Intensive care unit.

PATIENTS

Thirty-six brain-dead organ donors.

INTERVENTIONS

Donors were randomized to receive enteral nutrition containing omega-3 polyunsaturated fatty acid, antioxidants, and glutamine or standard care (fasting). Donors received hormonal replacement therapy of corticosteroid, levothyroxine, dextrose, and insulin.

MAIN OUTCOME MEASURES

Gastrointestinal assimilation (measured by 13 carbon-labeled uracil breath analysis), quantity of organs recovered, resting energy expenditure, urine level of urea nitrogen, and serum levels of albumin, prealbumin, interleukin 6, tumor necrosis factor-α, and C-reactive protein were evaluated.

RESULTS

Thirteen patients (36%) assimilated 13C-labeled uracil. Resting energy expenditure was significantly higher than predicted between 10 and 14 hours after baseline in 33 donors (P= .007). Other measures were not conclusively different between fed and fasting groups. No adverse events occurred that were related to the enteral feeding.

CONCLUSIONS

About 30% of donors metabolized 13C-labeled uracil, although no difference in oxidation rate was found between fasting and fed donors. Corticosteroid administration lowers plasma levels of interleukin 6 and most likely contributes to greater than predicted resting energy expenditure. Thus energy needs may not be met during fasting if hormones are given. Consequences of this possible energy deficit warrant further study.

Effects of traumatic brain injury on intestinal contractility

BACKGROUND

Patients with traumatic brain injury (TBI) often suffer from gastrointestinal dysfunction including intolerance to enteral feedings. However, it is unclear how TBI affects small intestinal contractile activity. The purpose of this study was to determine if TBI affects intestinal smooth muscle function.

METHODS

Sprague-Dawley rats were subjected to controlled cortical impact injury (TBI). Sham animals underwent a similar surgery but no injury (SHAM). Animals were sacrificed 1, 3, and 7 days after TBI and intestinal smooth muscle tissue was collected for measurement of contractile activity and transit, NF-kB activity, and cytokine levels. Brains were collected after sacrifice to determine volume loss due to injury.

KEY RESULTS

Contractile activity decreased significantly in ileum, but not jejunum, in the TBI group 7 days after injury compared with SHAM. Brain volume loss increased significantly 7 days after injury compared with 3 days and correlated significantly with the contractile activity 1 day after injury. In the intestinal smooth muscle, NF-kB activity increased significantly in the TBI group 3 and 7 days after injury vs SHAM. Wet to dry weight ratio, indicating edema, also increased significantly in the TBI group. Interleukin-1α, -1β, and -17 increased significantly in the TBI group compared with SHAM.

CONCLUSIONS & INFERENCES

Traumatic brain injury causes a delayed but significant decrease in intestinal contractile activity in the ileum leading to delayed transit. The decreased intestinal contractile activity is attributed to secondary inflammatory injury as evidenced by increased NF-kB activity, increased edema, and increased inflammatory cytokines in the intestinal smooth muscle.

[Nutritional therapy in traumatic brain injury : Update 2012]

Severe traumatic brain injury ranks among the most common causes of death in young adults in western countries. Severe traumatic brain injury is typically followed by a pronounced pathophysiological cascade that accounts for many deaths. The aim of intensive care medicine after traumatic brain injury is to minimize and to control the consequences of this potentially fatal cascade. The avoidance of hypoxemia, arterial hypotension, intracranial hypertension, hyperthermia, hyperglycemia, hypoglycemia and thromboembolic complications is essential in preventing this cascade. The effect of nutrition has been rather underestimated as a means of improving the outcome after traumatic brain injury. Nutrition should be started within the first 24 h after trauma. Enteral, wherever applicable, should be the route of administration of nutrition. Enteral administration of the whole calculated calorie requirement on day 1 after trauma, if possible, lowers the infection and overall complication rates. The present review gives an update of a practical approach to nutrition in traumatic brain injury.

Biphasic regulation of myosin light chain phosphorylation by p21-activated kinase modulates intestinal smooth muscle contractility

Supraphysiological mechanical stretching in smooth muscle results in decreased contractile activity. However, the mechanism is unclear. Previous studies indicated that intestinal motility dysfunction after edema development is associated with increased smooth muscle stress and decreased myosin light chain (MLC) phosphorylation in vivo, providing an ideal model for studying mechanical stress-mediated decrease in smooth muscle contraction. Primary human intestinal smooth muscle cells (hISMCs) were subjected to either control cyclical stretch (CCS) or edema (increasing) cyclical stretch (ECS), mimicking the biophysical forces in non-edematous and edematous intestinal smooth muscle in vivo. ECS induced significant decreases in phosphorylation of MLC and MLC phosphatase targeting subunit (MYPT1) and a significant increase in p21-activated kinase (PAK) activity compared with CCS. PAK regulated MLC phosphorylation in an activity-dependent biphasic manner. PAK activation increased MLC and MYPT1 phosphorylation in CCS but decreased MLC and MYPT1 phosphorylation in hISMCs subjected to ECS. PAK inhibition had the opposite results. siRNA studies showed that PAK1 plays a critical role in regulating MLC phosphorylation in hISMCs. PAK1 enhanced MLC phosphorylation via phosphorylating MYPT1 on Thr-696, whereas PAK1 inhibited MLC phosphorylation via decreasing MYPT1 on both Thr-696 and Thr-853. Importantly, in vivo data indicated that PAK activity increased in edematous tissue, and inhibition of PAK in edematous intestine improved intestinal motility. We conclude that PAK1 positively regulates MLC phosphorylation in intestinal smooth muscle through increasing inhibitory phosphorylation of MYPT1 under physiologic conditions, whereas PAK1 negatively regulates MLC phosphorylation via inhibiting MYPT1 phosphorylation when PAK activity is increased under pathologic conditions.

Enteral nutrition in patients with severe traumatic brain injury: reasons for intolerance and medical management

Approximately, 50% of patients with severe traumatic brain injury (TBI) exhibit intolerance to enteral nutrition (EN). This intolerance hampers the survival and rehabilitation of this subpopulation to a great extent, and poses various difficulties for clinicians due to its complex underlying mechanisms. This review discusses the possible reasons for intolerance to EN following severe TBI, current trends in medical management, as well as other related issues that are experienced by many clinicians.

Critical illness, gastrointestinal complications, and medication therapy during enteral feeding in critically ill adult patients

Critically ill patients who are subjected to high stress or with severe injury can rapidly break down their body protein and energy stores. Unless adequate nutrition is provided, malnutrition and protein wasting may occur, which can negatively affect patient outcome. Enteral nutrition (EN) is the mainstay of nutrition support therapy in patients with a functional gastrointestinal (GI) tract who cannot take adequate oral nutrition. EN in critically ill patients provides the benefits of maintaining gut functionality, integrity, and immunity as well as decreasing infectious complications. However, the ability to provide timely and adequate EN to critically ill patients is often hindered by GI motility disorders and complications associated with EN. This paper reviews the GI complications and intolerances associated with EN in critically ill patients and provides recommendations for their prevention and treatment. It also addresses the role of commonly used medications in the intensive care unit and their impact on GI motility and EN delivery.

Disparate response to metoclopramide therapy for gastric feeding intolerance in trauma patients with and without traumatic brain injury

Patients with traumatic brain injury (TBI) have delayed gastric emptying and often require prokinetic drug therapy to improve enteral feeding tolerance. The authors hypothesized that metoclopramide was less efficacious for improving gastric feeding tolerance for trauma patients with TBI compared to trauma patients without TBI. A retrospective analysis was conducted of patients admitted to the trauma or neurosurgical intensive care unit who received gastric feeding from January 2006 to April 2008. Gastric feeding intolerance was defined by a gastric residual volume >200 mL or emesis with abdominal distension or discomfort. Patients with gastric feeding intolerance were given metoclopramide 10 mg intravenously every 6 hours, followed by a dose escalation to 20 mg, and then combination therapy with metoclopramide and erythromycin 250 mg intravenously every 6 hours if intolerance persisted. In total, 882 trauma patients (49% with TBI) were evaluated. TBI patients had a higher incidence of gastric feeding intolerance than those without TBI (18.6% vs 10.4%, P < or = .001). Efficacy rates for metoclopramide 10 mg, metoclopramide 20 mg, and metoclopramide-erythromycin were 55%, 62%, and 79%, respectively (P < or = .03). Metoclopramide failure occurred in 54% of patients with TBI compared to 35% of patients without TBI, respectively (P < or = .02), due to a greater prevalence of tachyphylaxis. Single-drug therapy with metoclopramide was less effective for TBI trauma patients compared to trauma patients without TBI. Combination therapy with erythromycin as first-line therapy for TBI trauma patients with gastric feeding intolerance is indicated if there are no contraindications or significant drug interactions.

Increased intestinal permeability in rats subjected to traumatic frontal lobe percussion brain injury

BACKGROUND

Dysfunction of the gastrointestinal tract is a common occurrence after traumatic brain injury (TBI). We hypothesized that increased intestinal permeability may result from a precisely controlled percussion injury to the exposed brains of anesthetized rats and that such an effect could be assessed in vitro using excised intestinal mucosae mounted in Ussing chambers.

METHODS

After craniotomy over the left medial prefrontal cortex on anesthetized rats, neurotrauma was produced using a pneumatically driven impactor on the exposed brain. Control rats were subjected to identical procedures but did not receive an impact. Muscle-stripped rat intestinal ileal and colonic segments were mounted in Ussing chambers within 30 minutes of death. Transepithelial electrical resistance (TEER) and the apparent permeability coefficient (Papp) of [C]-mannitol were recorded from intestinal tissue for 120 minutes. Histopathologic analysis was also performed to determine any gross morphologic changes in the intestine.

RESULTS

Ileal and colonic mucosae showed no differences in TEER in ileum or colon of TBI rats compared with controls. The Papp of mannitol was significantly increased in ilea from rats previously exposed to TBI compared with controls. Histologic analysis showed gross changes to 50% of the ileal but not the colonic sections from TBI rats.

CONCLUSION

TBI results in significantly reduced ileal barrier function, most likely mediated by open tight junctions. For patients with acute head injury, this may have implications for subsequent oral absorption of nutrients. Systemic delivery of luminal endotoxins may contribute to multiple organ failure.

Nutritional support for head-injured patients

BACKGROUND

Head injury increases the body's metabolic responses, and therefore nutritional demands. Provision of an adequate supply of nutrients is associated with improved outcome. The best route for administering nutrition (parenterally (TPN) or enterally (EN)), and the best timing of administration (for example, early versus late) of nutrients needs to be established.

OBJECTIVES

To quantify the effect on mortality and morbidity of alternative strategies of providing nutritional support following head injury.

SEARCH STRATEGY

Trials were identified by computerised searches of the Cochrane Injuries Group specialised register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, National Research Register, Web of Science and other electronic trials registers. Reference lists of trials and review articles were checked. The searches were last updated in July 2006.

SELECTION CRITERIA

Randomised controlled trials of timing or route of nutritional support following acute traumatic brain injury.

DATA COLLECTION AND ANALYSIS

Two authors independently abstracted data and assessed trial quality. Information was collected on death, disability, and incidence of infection. If trial quality was unclear, or if there were missing outcome data, trialists were contacted in an attempt to get further information.

MAIN RESULTS

A total of 11 trials were included. Seven trials addressed the timing of support (early versus delayed), data on mortality were obtained for all seven trials (284 participants). The relative risk (RR) for death with early nutritional support was 0.67 (95% CI 0.41 to 1.07). Data on disability were available for three trials. The RR for death or disability at the end of follow-up was 0.75 (95% CI 0.50 to 1.11). Seven trials compared parenteral versus enteral nutrition. Because early support often involves parenteral nutrition, three of the trials are also included in the previous analyses. Five trials (207 participants) reported mortality. The RR for mortality at the end of follow-up period was 0.66 (0.41 to 1.07). Two trials provided data on death and disability. The RR was 0.69 (95% Cl 0.40 to 1.19). One trial compared gastric versus jejunal enteral nutrition, there were no deaths and the RR was not estimable.

AUTHORS' CONCLUSIONS

This review suggests that early feeding may be associated with a trend towards better outcomes in terms of survival and disability. Further trials are required. These trials should report not only nutritional outcomes but also the effect on death and disability.

Validation the use of refractometer and mathematic equations to measure dietary formula contents for clinical application

BACKGROUND AND AIMS

Gastric residual volumes are widely used to evaluate gastric emptying for patients receiving enteral feeding, but controversy exists about what constitutes gastric residual volume. We have developed a method by using refractometer and derived mathematical equations to calculate the formula concentration, total residual volume (TRV), and formula volume. In this study, we like to validate these mathematical equations before they can be implemented for clinical patient care.

METHODS

Four dietary formulas were evaluated in two consecutive validation experiments. Firstly, dietary formula volume of 50, 100, 200, and 400 ml were diluted with 50 ml water, and then the Brix value (BV) was measured by the refractometer. Secondly, 50 ml of water, then 100 ml of dietary formula were infused into a beaker, and followed by the BV measurement. After this, 50 ml of water was infused and followed by the second BV measurement. The entire procedure of infusing of dietary formula (100 ml) and waster (50 ml) was repeated twice and followed by the BV measurement.

RESULTS

The formula contents (formula concentration, TRV, and formula volume) were calculated by mathematical equations. The calculated formula concentrations, TRVs, and formula volumes measured from mathematic equations were strongly close to the true values in the first and second validation experiments (R2>0.98, P<0.001).

CONCLUSIONS

Refractometer and the derived mathematical equations may be used to accurately measure the formula concentration, TRV, and formula volume and served as a tool to monitor gastric emptying for patients receiving enteral feeding.

Percutaneous endoscopic gastrostomy: a safe and effective bridge for enteral nutrition in neurological or non-neurological conditions

Percutaneous endoscopic gastrostomy (PEG) is one of the most commonly used methods for nutritional support in patients who are unable to take food orally. Traditional surgical gastrostomy, percutaneous radiologic gastrostomy, and laparoscopic gastrostomy are the alternatives. The most common indication is neurogenic dysphagia followed by obstructive causes such as head and neck tumors. Ethically justified and clinically comprehensive guidelines should be followed during the decision-making process for PEG tube placement. A limited life expectancy; technical difficulties, such as the inability to bring the anterior gastric wall in apposition to the abdominal wall; or pharyngeal/esophageal obstruction, which compromise tube insertion, peritonitis, and uncorrectable coagulopathy are absolute contraindications. The "pull method" is the first described and still the most performed technique of PEG tube placement. The procedure is simple, safe, and effective and fulfills all requirements to provide an ideal route for nutritional support. This article summarizes the reported experience on PEG in the current literature and discusses its utility in patients with neurological conditions.

Blind transpyloric nasojejunal versus nasogastric tube intubation in severe head injuries: A preliminary report

AIM

To compare the efficacy of blind transpyloric placement using a specifically designed nasojejunal tube (NJT) versus a standard nasogastric tube (NGT) in severe head injury (SHI).

METHODS

This was a randomised trial conducted in a neurosurgical intensive care unit. Fourteen patients were enrolled with a Glasgow Coma Score (GCS) less than 8 (mean 6.8 SEM+/-0.36). Patients were randomised to receive either NJT or NGT.

RESULTS

There was an 83% (5/6 patients) spontaneous jejunal placement rate of NJT past the ligament of Treitz. The 17% (1/6 patients) jejunal placement failure rate for NJT was due to inappropriate technique. A 100% (8/8 patients) failure of the unweighted NGTs to pass through the pylorus into the jejunum was recorded (P=0.002).

CONCLUSION

In SHI, the specifically designed self-propelling NJT was effective in spontaneous transpyloric placement past the ligament of Treitz within 12h of introduction into the gastric cavity. The standard un-weighted NGT was ineffective. Additional studies are warranted to determine the clinical efficacy of this self-propelling NJT.

Comparative tolerability of sedative agents in head-injured adults

Sedative agents are widely used in the management of patients with head injury. These drugs can facilitate assisted ventilation and may provide useful reductions in cerebral oxygen demand. However, they may compromise cerebral oxygen delivery via their cardiovascular effects. In addition, individual sedative agents have specific and sometimes serious adverse effects. This review focuses on the different classes of sedative agents used in head injury, with a discussion of their role in the context of clinical pathophysiology. While there is no sedative that has all the desirable characteristics for an agent in this clinical setting, careful titration of dose, combination of agents, and a clear understanding of the pathophysiology and pharmacology of these agents will allow safe sedative administration in head injury.

Levels of vasoactive intestinal peptide, cholecystokinin and calcitonin gene-related peptide in plasma and jejunum of rats following traumatic brain injury and underlying significance in gastrointestinal dysfunction

AIM: To study the alterations of brain-gut peptides following traumatic brain injury (TBI) and to explore the underlying significance of these peptides in the complicated gastrointestinal dysfunction.

METHODS: Rat models of focal traumatic brain injury were established by impact insult method, and divided into 6 groups (6 rats each group) including control group with sham operation and TBI groups at postinjury 3, 12, 24, 72 h, and d 7. Blood and proximal jejunum samples were taken at time point of each group and gross observations of gastrointestinal pathology were recorded simultaneously. The levels of vasoactive intestinal peptide (VIP) in plasma, calcitonin gene-related peptide (CGRP) and cholecystokinin (CCK) in both plasma and jejunum were measured by enzyme immunoassay (EIA). Radioimmunoassay (RIA) was used to determine the levels of VIP in jejunum.

RESULTS: Gastric distension, delayed gastric emptying and intestinal dilatation with a large amount of yellowish effusion and thin edematous wall were found in TBI rats through 12 h and 72 h, which peaked at postinjury 72 h. As compared with that of control group (247.8 ± 29.5 ng/L), plasma VIP levels were significantly decreased at postinjury 3, 12 and 24 h (106.7 ± 34.1 ng/L, 148.7 ± 22.8 ng/L, 132.8 ± 21.6 ng/L, respectively), but significantly increased at 72 h (405.0 ± 29.8 ng/L) and markedly declined on d 7 (130.7 ± 19.3 ng/L). However, Plasma levels CCK and CGRP were significantly increased through 3 h and 7 d following TBI (126-691% increases), with the peak at 72 h. Compared with control (VIP, 13.6 ± 1.4 ng /g; CGRP, 70.6 ± 17.7 ng/g); VIP and CGRP levels in jejunum were significantly increased at 3 h after TBI (VIP, 35.4 ± 5.0 ng/g; CGRP, 103.8 ± 22.1 ng/g), and declined gradually at 12 h and 24 h (VIP, 16.5 ± 1.8 ng/g, 5.5 ± 1.4 ng/g; CGRP, 34.9 ± 9.7 ng/g, 18.5 ± 7.7 ng/g), but were significantly increased again at 72 h (VIP, 48.7 ± 9.5 ng/g; CGRP, 142.1 ± 24.3 ng/g), then declined in various degrees on d 7 (VIP, 3.8 ± 1.1 ng/g; CGRP, 102.5 ± 18.1 ng/g). The CCK levels in jejunum were found to change in a similar trend as that in plasma with the concentrations of CCK significantly increased following TBI (99-517% increases) and peaked at 72 h.

CONCLUSION: Traumatic brain injury can lead to significant changes of brain-gut peptides in both plasma and small intestine, which may be involved in the pathogenesis of complicated gastrointestinal dysfunction.

Bio-ecological control of perioperative and ITU morbidity

BACKGROUND

Perioperative and intensive therapy unit (ITU) morbidity and mortality has remained unchanged during the past several decades, and this at an unacceptably high level. It is most likely, in the EU countries annually, that more than 1 million people suffer severe sepsis and some 300,000 die. Pharmaceutical attempts at prevention and treatment have, despite extensive efforts, hitherto failed to improve outcome more significantly. Much supports the fact that sepsis and its severe consequences are results of a malfunctioning innate immune system, impaired by both lifestyle and disease. A series of mostly simple measures to prevent further deterioration of the immune system, and to boost it, is recommended. Among the measures recommended are some modifications of surgical and postoperative management: restricted use of antibiotics, attempts made to maintain salivation and GI secretions, omission of prophylactic gastric decompression, postoperative drainage and preoperative bowel preparation, restricted use of stored blood, avoidance of overload with nutrients, uninterrupted enteral nutrition but also tight blood glucose control, supply of antioxidants, administration of prebiotic fibre and probiotic lactic acid bacteria. Nutritional control of postoperative morbidity includes use of so-called synbiotics, e.g. a combination of bioactive lactic acid bacteria (LAB) and bioactive plant fibres.

RESULTS

Dramatic reduction in (in reality, almost abolishment of) septic morbidity is reported following supplementation of specific bioactive lactic bacteria in combination with prebiotic plant fibres, as tried in controlled studies in connection with extensive abdominal operations, liver transplantation and severe acute pancreatitis.

To determine the effect of metoclopramide on gastric emptying in severe head injuries: a prospective, randomized, controlled clinical trial

To determine the effect of 8-hourly administration of 10 mg intravenous metoclopramide, over a 48-h period on gastric emptying in severe head injury (SHI), 22 patients were prospectively randomized (Glasgow Coma Score of 3-8) to receive 2 ml of intravenous metoclopramide or 2 ml of 5% saline 8-hourly for 48 h. Baseline and serial blood paracetamol absorption assays were performed at time (t) = 0, 15, 30, 45, 60, 90 and 120 min on day 0 and day 2. The area under the curve between the day 0 and day 2 was used to measure the degree of gastric emptying. In SHI, sequential doses of metoclopramide did not appear to improve gastric motility within subject comparisons (p = 0.65) and between subject comparisons (placebo p = 0.4 and drug p = 0.12). Metoclopramide has no significant prokinetic effect on gastric emptying in SHI patients when given in the early postinjury period.

When is the seriously ill patient ready to be fed?

BACKGROUND

After assessing the critically ill patient for risk of aspiration, the clinician still must decide if the patient is ready to be fed. The goal is to identify critically ill patients who are likely to tolerate enteral nutrition and attempt to minimize complications.

METHODS

A synthesis of the both clinical and animal studies to identify factors related to patient readiness for enteral nutrition.

RESULTS

The key issue to be resolved is adequacy of resuscitation and restoration of mesenteric perfusion. Currently, there is no reliable clinical tool to measure gut perfusion. The best indicators currently are stabilization of vital signs, decreasing fluid and blood requirements, normalization of the base deficit, and lactate and removal of inotropic or vasopressor support.

CONCLUSIONS

Most critically ill patients should be ready for enteral nutrition within 24 to 48 hours of intensive care unit admission. Critically ill patients who need catecholamine support, heavy sedation, or therapeutic neuromuscular blockade should probably not receive enteral nutrition until they have been stabilized.