Gastric emptying in head-injured patients

Importance of good hosting: reviewing the bi-directionality of the microbiome-gut-brain-axis

Gut microorganisms have been shown to significantly impact on central function and studies that have associated brain disorders with specific bacterial genera have advocated an anomalous gut microbiome as the pathophysiological basis of several psychiatric and neurological conditions. Thus, our knowledge of brain-to-gut-to microbiome communication in this bidirectional axis seems to have been overlooked. This review examines the known mechanisms of the microbiome-to-gut-to-brain axis, highlighting how brain-to-gut-to-microbiome signaling may be key to understanding the cause of disrupted gut microbial communities. We show that brain disorders can alter the function of the brain-to-gut-to-microbiome axis, which will in turn contribute to disease progression, while the microbiome-to gut-to brain direction presents as a more versatile therapeutic axis, since current psychotropic/neurosurgical interventions may have unwanted side effects that further cause disruption to the gut microbiome. A consideration of the brain-to-gut-to-microbiome axis is imperative to better understand how the microbiome-gut-brain axis overall is involved in brain illnesses, and how it may be utilized as a preventive and therapeutic tool.

Ten good reasons to consider gastrointestinal function after acute brain injury

The brain-gut axis represents a bidirectional communication linking brain function with the gastrointestinal (GI) system. This interaction comprises a top-down communication from the brain to the gut, and a bottom-up communication from the gut to the brain, including neural, endocrine, immune, and humoral signaling. Acute brain injury (ABI) can lead to systemic complications including GI dysfunction. Techniques for monitoring GI function are currently few, neglected, and many under investigation. The use of ultrasound could provide a measure of gastric emptying, bowel peristalsis, bowel diameter, bowel wall thickness and tissue perfusion. Despite novel biomarkers represent a limitation in clinical practice, intra-abdominal pressure (IAP) is easy-to-use and measurable at bedside. Increased IAP can be both cause and consequence of GI dysfunction, and it can influence cerebral perfusion pressure and intracranial pressure via physiological mechanisms. Here, we address ten good reasons to consider GI function in patients with ABI, highlighting the importance of its assessment in neurocritical care.

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.

Factors associated with gastrointestinal dysmotility in critically ill patients

Critical illness may disrupt nutritional, protective, immune, and endocrine functions of the gastrointestinal tract, leading to a state of gastrointestinal dysmotility. We aimed to identify factors associated with the occurrence of gastrointestinal dysmotility in critically ill patients. A cross-sectional retrospective study was conducted, using patient files as a source of data. The study included 185 critically ill patients treated in the intensive care unit of the University Clinical Center, Kragujevac, Serbia, from January 1, 2016, to January 1, 2022. Significant risk factors associated with some form of gastrointestinal dysmotility were acute kidney injury (with paralytic ileus, nausea, vomiting, and constipation), recent abdominal surgery (with ileus, nausea, vomiting, and constipation), mechanical ventilation (with ileus, and nausea), age (with ileus and constipation), and use of certain medication such as opioids (with ileus, gastro-esophageal reflux, nausea, vomiting, and constipation), antidepressants (with ileus, nausea, and vomiting), and antidiabetics (with ileus). On the other hand, Charlson comorbidity index had divergent effects, depending on the form of gastrointestinal dysmotility: it increased the risk of gastro-esophageal reflux but protected against ileus, nausea, and vomiting. In clonclusion, recognition of factors associated with gastrointestinal dysmotility should initiate preventative measures and, thus, accelerate the recovery of critically ill.

Gastrointestinal Motility Disorders Correlate with Intracranial Bleeding, Opioid Use, and Brainstem Edema in Neurosurgical Patients

BACKGROUND

Gastrointestinal (GI) motility disorders may be directly associated with the intensity of acute brain injury, edema of the brainstem, and opioid use in neurosurgical patients.

METHODS

In this retrospective study, patient demographic characteristics, computed tomography (CT) scans, the occurrence of gastroparesis, constipation, and opioid use were registered during the intensive care unit (ICU) stay and correlated with days of mechanical ventilation, length of ICU stay, and survival. Gastroparesis was defined as residual gastric volume > 250 mL per day, and constipation was defined as the absence of stool for 3 days or more during the ICU stay.

RESULTS

Of 207 neurosurgical patients screened, 69 adult patients who spent more than 4 days in the ICU were included in the study. Gastroparesis was observed in 48 (69.6%) patients, constipation was observed in 67 (97.1%) patients, and stress ulcers were observed in 4 (5.8%) patients. Patients with brainstem edema (n = 57, 82.6%) had the first stool evacuation later compared with patients with no edema (8 [interquartile range (IQR) 5.25-9.75] vs. 3.5 [IQR 2.25-4] days; P < 0.001). In the logistic regression analysis, factors that were associated with GI dysmotility were central nervous system (CNS) bleeding (odds ratio [OR] 5.1, 95% confidence interval [CI] 1.26-20.8, P = 0.02), opioid use > 19.3 morphine equivalents (ME) per day (OR 5.37, 95% CI 1.1-27.1, P = 0.04), and brainstem edema (OR 4.9, 95% CI 1.1-21.6, P = 0.04). A receiver operating characteristic curve analysis confirmed that the cutoff value of > 6.78 ME per day was a good predictor determining GI dysmotility, with 89.5% sensitivity and 72.7% specificity (95% CI 0.67-0.88, area under the curve 0.784, Youden index 0.62, P = 0.001). Poor survival correlated with lower Glasgow Coma Score values (ρ =  - 520, P < 0.001), CNS bleeding (ρ = 0.393, P < 0.001), associated cardiac diseases (ρ = 0.279, P < 0.001), and cardiorespiratory arrest on admission (ρ = 0.315, P < 0.001), but not with GI dysmotility (ρ = 0.175, P = 0.402).

CONCLUSIONS

Significant correlation was registered between brainstem edema, gastrointestinal dysmotility, and opioids. CNS bleeding was the most important single factor influencing GI dysmotility. Further studies with opioid and nonopioid sedation may distinguish the influence of acute brain lesions versus drugs on GI dysmotility.

Progress in research on the role of clinical nutrition in treating traumatic brain injury affecting the neurovascular unit

The neurovascular unit (NVU) is composed of neurons, glial cells, and blood vessels. NVU dysfunction involves the processes of neuroinflammation, and microcirculatory disturbances, as well as neuronal injury after traumatic brain injury (TBI). Traditional anti-inflammatory drugs have limited efficacy in improving the prognosis of TBI. Thus, treatments that target NVU dysfunction may provide a breakthrough. A large number of clinical studies have shown that the nutritional status of patients with TBI was closely related to their conditions and prognoses. Nutrient complexes and complementary therapies for the treatment of TBI are therefore being implemented in many preclinical studies. Importantly, the mechanism of action for this treatment may be related to repair of NVU dysfunction by ensuring adequate omega-3 fatty acids, curcumin, resveratrol, apigenin, vitamins, and minerals. These nutritional supplements hold promise for translation to clinical therapy. In addition, dietary habits also play an important role in the rehabilitation of TBI. Poor dietary habits may worsen the pathology and prognosis of TBI. Adjusting dietary habits, especially with a ketogenic diet, may improve outcomes in patients with TBI. This article discusses the impact of clinical nutrition on NVU dysfunction after TBI, focusing on nutritional complexes and dietary habits.

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.

Ultrasonic evaluation of metoclopramide's effect on gastric motility in emergency trauma patients

Objective: The present study aimed to use bedside ultrasound to evaluate the effects of metoclopramide on gastric motility in patients being treated for trauma in the emergency department. Methods: Fifty patients underwent an ultrasound immediately after attending the emergency department of Zhang Zhou Hospital due to trauma. The patients were randomly divided into two groups: a metoclopramide group (group M, n = 25) and a normal saline group (group S, n = 25). The cross-sectional area (CSA) of the gastric antrum was measured at 0, 30, 60, 90, and 120 min (T = time). The gastric emptying rate (GER, GER=-AareaTn/AareaTn-30-1×100), GER/min (GER divided by the corresponding interval time), gastric content properties, Perlas grade at different time points, T120 gastric volume (GV), and GV per unit of body weight (GV/W) were evaluated. The risk of vomiting, reflux/aspiration, and type of anesthetic treatment were also evaluated. Results: The differences between the two groups in the CSA of the gastric antrum at each time point were statistically significant (p < 0.001). The CSAs of the gastric antrum in group M were lower than those in group S, and the greatest difference between the two groups occurred at T30 (p < 0.001). The differences between the two groups in GER and GER/min were also statistically significant (p < 0.001); those differences in group M were higher than those in group S, and the greatest differences between the two groups occurred at T30 (p < 0.001). There were no obvious change trends in the properties of the gastric contents and the Perlas grades in either group, and the differences between the two groups were not statistically significant (p = 0.97). The differences between the two groups in the GV and GV/W at T120 were statistically significant (p < 0.001), as was the risk of reflux and aspiration at T120 (p < 0.001). Conclusion: When metoclopramide was used in satiated emergency trauma patients, it accelerated gastric emptying within 30 min and reduced the risk of accidental reflux. However, a normal gastric emptying level was not achieved, which can be attributed to the delaying effect of trauma on gastric emptying.

Nutrition Management in Patients With Traumatic Brain Injury: A Narrative Review

Traumatic brain injury (TBI) is a major cause of long-term physical and psychological disability and death. In patients with TBI, undernutrition is associated with an increased mortality rate, more infectious complications, and worse neurologic outcomes. Therefore, timely and effective nutritional therapy is particularly crucial in the management of TBI to improve patients' prognoses. This narrative review summarizes the issues encountered in clinical practice for patients with neurotrauma who receive acute and post-acute in-patient rehabilitation services, and it comprehensively incorporates a wide range of studies, including recent clinical practice guidelines (CPGs), with the aim of better understanding the current evidence for optimal nutritional therapy focused on TBI patients. Recent CPGs were reviewed for 6 topics: 1) hypermetabolism and variation in energy expenditure in patients with TBI, 2) delayed gastric emptying and intolerance to enteral nutrition, 3) decision-making on the route and timing of access in patients with TBI who are unable to maintain volitional intake (enteral nutrition versus parenteral nutrition), 4) decision-making on the enteral formula (standard or immune-modulating formulas), 5) glycemic control, and 6) protein support. We also identified areas that need further research in the future.

Hypermagnesemia and feeding intolerance in preterm infants: a cohort study

BACKGROUND

Feeding intolerance (FI) is a common clinical problem in preterm infants often caused by some neonatal disorders and drugs, including antenatal exposure to magnesium sulfate (MgSO₄ ).

OBJECTIVE

To evaluate the association between hypermagnesemia at birth and FI in preterm infants during the first 72 hours of life.

METHOD

This was a cohort study conducted with preterm infants < 34 weeks of gestation. Infants presenting at least two of the following signs were considered as having FI: vomiting, abdominal distension, the need for continuous intermittent feeding, and delayed meconium passage. Hypermagnesemia was characterized by umbilical serum magnesium levels >2.5 mEq/l.

RESULTS

251 infants were evaluated. The median birth weight and gestational age were 1390 (IQR 1020 -1070) g and 31 (IQR 28-32) weeks, respectively. The FI rate was 17.5%. The exposure rate to MgSO₄ was similar in the tolerant and intolerant groups (53.1% x 63.6%, p=0.204), but hypermagnesemia was more frequent in the FI group (40.9% x 24.2%, p= 0.024). The univariate analysis showed that infants with hypermagnesemia were two-fold more likely to present FI (OR 2.16 95% CI 1.09-4.26). In the multiple logistic regression analysis, we found that hypermagnesemia was independently associated with FI (OR 2.51 - 95% CI 1.06-5.91), as well as maternal diabetes mellitus (OR 2.56 95% CI 1.07 - 6.14), SNAPPE-II (OR 1.051 95% CI 1.025-1.078), and brain hemorrhage (OR 3.61 95% CI 1.31 - 9.91).

CONCLUSION

In addition to other factors, hypermagnesemia at birth was independently associated with early feeding intolerance in preterm infants. This article is protected by copyright. All rights reserved.

The intensivist's assessment of gastrointestinal function: A pilot study

Gastrointestinal dysfunction/failure (GDF) is a common cause of concern in critically ill patients. Although the gut plays an important role in the genesis of organ failure, its exclusion from organ severity scoring systems has made it challenging for intensivists to score it sufficiently at the bedside. We aimed to survey intensive care specialists about their perceptions, attitudes, and approaches towards the assessment of the gut in Australia and New Zealand intensive care units (ICUs). An electronic (online) questionnaire was used to survey intensive care specialists from the Australia and New Zealand Intensive Care Society (ANZICS). The survey comprised 10 questions focused on four key areas: (i) the extent of the problem with GDF in ICUs, (ii) the use and reliability of the current gut scoring tools, (iii) personal approaches and practices associated with GDF assessment, and (4) potential value of a novel GDF scoring system and its incorporation into an organ severity score. Our results showed that GDF was a significant concern amongst ICUs in Australia and New Zealand intensivists (84%; 66/79), with a small number of participants (14%; 3/79) using a gut scoring tool in their ICUs. Despite this, we have no established objective scoring tool for its assessment. The survey highlighted the need for developing a novel scoring tool to assess the gut was considered important amongst majority of the intensivists (92%; 72/78), which would prove useful in clinical practice and potentially lead to incorporation into an organ severity score in the future.

The prevalence and possible causes of enteral tube feeding intolerance in critically ill patients: A cross-sectional study

Background:

Enteral tube feeding intolerance (ETFI) is one of the most common complications of enteral nutrition (EN), which may lead to increased mortality and length of intensive care unit (ICU) stay. This study aimed to determine the prevalence of ETFI and effects on feeding intolerance on nutrition and clinical outcomes in Iran.

Materials and Methods:

This cross-sectional study was conducted in 2019 at the three general ICUs of Imam Reza Hospital in Mashhad, Iran, during 7 days on 245 patients. The collected data included demographic characteristics, primary diagnosis, the Acute Physiology and Chronic Health Evaluation II (APACHE ІІ) score, Sequential Organ Failure Assessment (SOFA) score, duration of mechanical ventilation, and length of ICU stay. Feeding intolerance was assessed using daily questionnaires for 7 days. ETFI was determined as the interruption of EN based on gastrointestinal causes, including large gastric residuals, abdominal distension, vomiting, diarrhea, and subjective discomfort.

Results:

Overall, 245 critically ill patients (122 males and 123 females) were included in this study, with a mean age of 58.43 ± 19.2 years in three general ICUs. The highest prevalence rate of ETFI was 91.8%, which occurred on the 2^nd day although the rate decreased in the following days. The minimum ETFI was observed on the last day (38.8%). Feeding intolerance was associated with the increased APACHE II scores (P = 0.04), SOFA scores (P < 0.001), and duration of mechanical ventilation (P < 0.001) compared with the tolerant patients. The most common causes of ETFI in the patients admitted to the ICU were gastric residual volume (GRV), large GRV, vomiting, and distension.

Conclusion:

ETFI was prevalent in almost two-third (66%) of the critically ill patients receiving EN based on the GRV. ETFI was associated with deteriorated nutritional status and clinical outcomes.

Oropharyngeal Dysphagia and Impaired Motility of the Upper Gastrointestinal Tract-Is There a Clinical Link in Neurocritical Care?

Patients in the neurological ICU are at risk of suffering from disorders of the upper gastrointestinal tract. Oropharyngeal dysphagia (OD) can be caused by the underlying neurological disease and/or ICU treatment itself. The latter was also identified as a risk factor for gastrointestinal dysmotility. However, its association with OD and the impact of the neurological condition is unclear. Here, we investigated a possible link between OD and gastric residual volume (GRV) in patients in the neurological ICU. In this retrospective single-center study, patients with an episode of mechanical ventilation (MV) admitted to the neurological ICU due to an acute neurological disease or acute deterioration of a chronic neurological condition from 2011–2017 were included. The patients were submitted to an endoscopic swallowing evaluation within 72 h of the completion of MV. Their GRV was assessed daily. Patients with ≥1 d of GRV ≥500 mL were compared to all the other patients. Regression analysis was performed to identify the predictors of GRV ≥500 mL/d. With respect to GRV, the groups were compared depending on their FEES scores (0–3). A total of 976 patients were included in this study. A total of 35% demonstrated a GRV of ≥500 mL/d at least once. The significant predictors of relevant GRV were age, male gender, infratentorial or hemorrhagic stroke, prolonged MV and poor swallowing function. The patients with the poorest swallowing function presented a GRV of ≥500 mL/d significantly more often than the patients who scored the best. Conclusions: Our findings indicate an association between dysphagia severity and delayed gastric emptying in critically ill neurologic patients. This may partly be due to lesions in the swallowing and gastric network.

Drosophila as a model to explore secondary injury cascades after traumatic brain injury

Drosophilae are emerging as a valuable model to study traumatic brain injury (TBI)-induced secondary injury cascades that drive persisting neuroinflammation and neurodegenerative pathology that imposes significant risk for long-term neurological deficits. As in mammals, TBI in Drosophila triggers axonal injury, metabolic crisis, oxidative stress, and a robust innate immune response. Subsequent neurodegeneration stresses quality control systems and perpetuates an environment for neuroprotection, regeneration, and delayed cell death via highly conserved cell signaling pathways. Fly injury models continue to be developed and validated for both whole-body and head-specific injury to isolate, evaluate, and modulate these parallel pathways. In conjunction with powerful genetic tools, the ability for longitudinal evaluation, and associated neurological deficits that can be tested with established behavioral tasks, Drosophilae are an attractive model to explore secondary injury cascades and therapeutic intervention after TBI. Here, we review similarities and differences between mammalian and fly pathophysiology and highlight strategies for their use in translational neurotrauma research.

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.

Gastrointestinal Complications in Critically Ill Children: Experience from A Resource-Limited Country

Objectives:

To determine the frequency and predictors of outcome of gastrointestinal complications (GIC) in critically ill children.

Methods:

This descriptive study was prospectively conducted in The Pediatric Intensive Care Unit (PICU), The Aga Khan University Hospital (AKUH), Karachi, from September 2015 to January 2017. After obtaining approval from the Ethical Review Committee of AKUH and informed consent from the parents, all children (aged one month to 18 years), of either gender, admitted to the Pediatric Intensive Care Unit (PICU) during the study period were included. The frequency of the defined GIC: vomiting, high gastric residue volume (GRV), diarrhea, constipation, and gastrointestinal bleed were recorded daily for the first week of the PICU stay. The data was collected by the primary investigator on a predesigned data collection form with inclusion of variables and predictors in light of existing literature and local expertise. The questionnaire was shared with the Pediatric Critical Care Medicine faculty and a consensus was sought on the elements to be incorporated.

Results:

GIC developed within the first 48 hours of admission in 78 (41%) patients. Of the patients who developed GIC, 37 (47.4%) patients developed high GRV: 31 (39.7%) patients developed constipation, 18 (23.1%) patients developed vomiting, 14 (17.9%) patients developed abdominal distension. With regards to prevalence by occurrence, 32/78 (41%) of patients presented with two GI complications, followed by 21 patients (27%) who presented with a single GIC. Only 11 patients (14%) presented with more than three complications. Median length of stay was higher in patients with GIC (8 days) than with those who did not develop GIC (4 days). The frequency of gastrointestinal complications was significantly higher in children receiving mechanical ventilation, on sedatives and relaxants and those with multiorgan dysfunction syndrome (MODS) and inotropes

Conclusion:

GI complications are a frequent occurrence in the PICU and are associated with worse clinical outcomes. The use of sedative drugs and the presence of shock with MODS were amongst the important contributing factors.

Acute colitis during chronic experimental traumatic brain injury in mice induces dysautonomia and persistent extraintestinal, systemic, and CNS inflammation with exacerbated neurological deficits

BACKGROUND

Disruptions of brain-gut axis have been implicated in the progression of a variety of gastrointestinal (GI) disorders and central nervous system (CNS) diseases and injuries, including traumatic brain injury (TBI). TBI is a chronic disease process characterized by persistent secondary injury processes which can be exacerbated by subsequent challenges. Enteric pathogen infection during chronic TBI worsened cortical lesion volume; however, the pathophysiological mechanisms underlying the damaging effects of enteric challenge during chronic TBI remain unknown. This preclinical study examined the effect of intestinal inflammation during chronic TBI on associated neurobehavioral and neuropathological outcomes, systemic inflammation, and dysautonomia.

METHODS

Dextran sodium sulfate (DSS) was administered to adult male C57BL/6NCrl mice 28 days following craniotomy (Sham) or TBI for 7 days to induce intestinal inflammation, followed by a return to normal drinking water for an additional 7 to 28 days for recovery; uninjured animals (Naïve) served as an additional control group. Behavioral testing was carried out prior to, during, and following DSS administration to assess changes in motor and cognitive function, social behavior, and mood. Electrocardiography was performed to examine autonomic balance. Brains were collected for histological and molecular analyses of injury lesion, neurodegeneration, and neuroinflammation. Blood, colons, spleens, mesenteric lymph nodes (mLNs), and thymus were collected for morphometric analyses and/or immune characterization by flow cytometry.

RESULTS

Intestinal inflammation 28 days after craniotomy or TBI persistently induced, or exacerbated, respectively, deficits in fine motor coordination, cognition, social behavior, and anxiety-like behavior. Behavioral changes were associated with an induction, or exacerbation, of hippocampal neuronal cell loss and microglial activation in Sham and TBI mice administered DSS, respectively. Acute DSS administration resulted in a sustained systemic immune response with increases in myeloid cells in blood and spleen, as well as myeloid cells and lymphocytes in mesenteric lymph nodes. Dysautonomia was also induced in Sham and TBI mice administered DSS, with increased sympathetic tone beginning during DSS administration and persisting through the first recovery week.

CONCLUSION

Intestinal inflammation during chronic experimental TBI causes a sustained systemic immune response and altered autonomic balance that are associated with microglial activation, increased neurodegeneration, and persistent neurological deficits.

Optimal dose and duration of enteral erythromycin as a prokinetic: A surgical intensive care experience

BACKGROUND

Enteral feeding has various advantages over parenteral feeding in critically ill patients. Acutely ill patients are at risk of developing enteral feeding intolerance. Prokinetic medications improve gastrointestinal mobility and enteral feed migration and absorption. Among the available prokinetic agents, erythromycin is the most potent. Erythromycin is used in different dosages and durations with variable efficacy. Intravenous erythromycin has an early and high rate of tachyphylaxis; hence, enteral route is preferred. Recently, the combination of prokinetic medications has been increasingly used because they accelerate the prokinetic action and decrease the adverse effects.

AIM

This study aimed to determine the optimal effective prokinetic dose and duration of administering enteral erythromycin in combination with metoclopramide in critically ill patients.

PATIENTS AND METHODS

This study has a prospective observation design. After obtaining permission from the medical research center of the institution, all patients in the surgical and trauma intensive care unit having enteral feed intolerance and those who were already on metoclopramide for 24 hour (h) were enrolled in the study. Patients' demographic data, diagnosis, surgical intervention, disease severity scores, erythromycin dose, duration of administration, any adverse effects, factors affecting erythromycin response, and outcome were recorded. All patients received 125 mg syrup erythromycin twice daily through a nasogastric tube (NGT). The NGT was clamped for 2 h, and half amount of previous enteral feeds was resumed. If the patient did not tolerate the feeds, the erythromycin dose was increased every 24 h in the increment of 250, 500, and 1000 mg (Figure 1). Statistical significance was considered at P <  0.05. A total of 313 patients were enrolled in the study. Majority of the patients were male, and the mean age was 45 years.

RESULTS

Majority (48.2%) of the patients (96) with feed intolerance were post laparotomy. Ninety percent (284) of the patients responded to prokinetic erythromycin therapy, and 54% received lower dose (125 mg twice daily). In addition, 14% had diarrhea, and none of these patients tested positive for Clostridium difficile toxin or multidrug resistance bacteria. The mean duration of erythromycin therapy was 4.98 days. The most effective prokinetic dose of erythromycin was 125 mg twice daily (P = 0.001). Erythromycin was significantly effective in patients with multiple organ dysfunction and shock (P = 0.001). Patients with high disease severity index and multiple organ dysfunction had significantly higher mortality (p < 0.05). Patients not responding to erythromycin therapy also had a significant higher mortality (p = 0.001).

CONCLUSION

Post-laparotomy patients had high enteral feed intolerance. Enteral erythromycin in combination with metoclopramide was effective in low dose and was required for short duration. Patients who did not tolerate feeds despite increasing dose of erythromycin had higher mortality.

Altered physiology of gastrointestinal vagal afferents following neurotrauma

The adaptability of the central nervous system has been revealed in several model systems. Of particular interest to central nervous system-injured individuals is the ability for neural components to be modified for regain of function. In both types of neurotrauma, traumatic brain injury and spinal cord injury, the primary parasympathetic control to the gastrointestinal tract, the vagus nerve, remains anatomically intact. However, individuals with traumatic brain injury or spinal cord injury are highly susceptible to gastrointestinal dysfunctions. Such gastrointestinal dysfunctions attribute to higher morbidity and mortality following traumatic brain injury and spinal cord injury. While the vagal efferent output remains capable of eliciting motor responses following injury, evidence suggests impairment of the vagal afferents. Since sensory input drives motor output, this review will discuss the normal and altered anatomy and physiology of the gastrointestinal vagal afferents to better understand the contributions of vagal afferent plasticity following neurotrauma.

Gastroparesis in the Hospital Setting

Gastroparesis (GP) is commonly seen in hospitalized patients. Refractory vomiting and related dehydration, electrolyte abnormalities, and malnutrition are indications for hospital admission. In addition, tube feeding intolerance is a common sign of gastric dysmotility in critically ill patients. The diagnosis and management of GP in the hospital setting can be quite challenging. Diagnostic tests are often deferred because of patient intolerance of the oral meal for standard scintigraphy or severity of the primary disease. The diagnosis of GP is often established on the basis of clinical scenario and risk factors for gastric motor dysfunction. Medical therapy in GP is directed toward controlling nausea and vomiting by prokinetic and antinausea medications and correcting nutrition risks or treating malnutrition with nutrition therapy. Enteral nutrition is the preferred nutrition intervention for patients with GP. Delayed gastric emptying in critically ill patients has a negative impact on the timely delivery of enteral feeding and meeting the energy and protein goals. Measures to improve gastric tolerance or provide feeding beyond the stomach are often needed, since early enteral nutrition has been an important target of therapy for critically ill patients. This review will address the current understanding of the mechanisms of GP and feeding intolerance in critical illness, diagnostic workup, drug therapies, and interventions to improve the provision of enteral nutrition in hospital settings when gastric dysmotility is present or suspected.

Traumatic brain injury causing intestinal dysfunction: A review

Traumatic brain injuries (TBI) and its sequelae are becoming one of the most pressing public health concerns worldwide. It is one of the leading causes of increased morbidity and mortality. The primary insult to the brain can cause ischemic brain injury, paralysis, concussions, death, and other serious complications. Brain injury also involves other systems through a secondary pathway resulting in multiple complications during and after hospitalization. The focus of our article is to assess the literature available on traumatic brain injury and intestinal dysfunctional to highlight the aspects of epidemiology, pathophysiology, and different diagnostic approaches for early diagnosis of gut dysfunction. We review studies done in both humans and animals, to better understand this underrated topic, as it costs billions of dollars to the healthcare industry because of delayed diagnosis.

Nutritional and metabolic supplementation for the injured brain: an update

PURPOSE OF REVIEW

Energy dysfunction is increasingly recognized as a key factor in the pathogenesis of acute brain injury (ABI). This one characterized by a high metabolic rate and nitrogen loss is often associated with an undernutrition support. We review the metabolism evolution and nutritional status in brain injured patient and summarize evidence on nutritional support in this condition.

RECENT FINDINGS

The role of nutrition support for improving prognosis in brain injured patient has been underlined recently. A fast nutrition institution whatever the route is essential to prevent an imbalance in caloric support. Moreover, hypermetabolic state must be prevented with a sufficient nitrogen support. Glycemic control is particularly relevant in this group of patient, with the discovery of new fuel that could potentially improve cerebral metabolism and replace glucose. Few data support also the use of immunonutrition input in this group of patients.

SUMMARY

Nutritional support is a key parameter in brain injured patient and must be initiated quickly to counteract hypermetabolic state by caring to improve caloric and nitrogen input. Recent clinical data support the use of immunonutrition, glutamine and zinc in this particular setting.

Approaches to Monitor Circuit Disruption after Traumatic Brain Injury: Frontiers in Preclinical Research

Mild traumatic brain injury (TBI) often results in pathophysiological damage that can manifest as both acute and chronic neurological deficits. In an attempt to repair and reconnect disrupted circuits to compensate for loss of afferent and efferent connections, maladaptive circuitry is created and contributes to neurological deficits, including post-concussive symptoms. The TBI-induced pathology physically and metabolically changes the structure and function of neurons associated with behaviorally relevant circuit function. Complex neurological processing is governed, in part, by circuitry mediated by primary and modulatory neurotransmitter systems, where signaling is disrupted acutely and chronically after injury, and therefore serves as a primary target for treatment. Monitoring of neurotransmitter signaling in experimental models with technology empowered with improved temporal and spatial resolution is capable of recording in vivo extracellular neurotransmitter signaling in behaviorally relevant circuits. Here, we review preclinical evidence in TBI literature that implicates the role of neurotransmitter changes mediating circuit function that contributes to neurological deficits in the post-acute and chronic phases and methods developed for in vivo neurochemical monitoring. Coupling TBI models demonstrating chronic behavioral deficits with in vivo technologies capable of real-time monitoring of neurotransmitters provides an innovative approach to directly quantify and characterize neurotransmitter signaling as a universal consequence of TBI and the direct influence of pharmacological approaches on both behavior and signaling.

Anesthesia for Patients with Extensive Trauma

Trauma anesthesiology is a unique and growing subspecialty. With the growing number of adult and pediatric trauma centers in the United States, a thorough understanding of the early management of severely injured patients with trauma is an important aspect of anesthesia. Trauma anesthesiology requires the ability to adapt to different work environments, including the trauma bay, the operating room, and even the intensive care unit, where a patient room may require conversion to an operating suite for emergencies. This article provides a review of the anesthetic management for patients with extensive trauma, focusing on physiology, pharmacology, and bedside management.

Splenectomy does not affect the development of pneumonia following severe traumatic brain injury

The cholinergic anti-inflammatory pathway offers a proposed mechanism to describe the increased risk of pneumonia following severe traumatic brain injury (sTBI). Vagal activity transmitted to the spleen results in decreased inflammatory cytokine production and immunosuppression. However, no clinical evidence exists. We sought to compare pneumonia rates among patients with TBI and splenectomy using a retrospective analysis of all trauma patients with splenic injury requiring splenectomy or TBI admitted to an ACS verified level one trauma center from 2011 to 2016. Admission Glasgow Coma Score (GCS) ≤ 8 was used to identify sTBI. Pneumonia was defined by respiratory culture obtained by bronchoalveolar lavage. Analysis included χ2 and one-way analysis of variance followed by multivariate logistic regression to determine the association of sTBI and splenectomy of development of pneumonia. Four hundred and twenty-seven patients were included for primary analysis, 247 with sTBI, 180 with splenectomy, and 14 with both sTBI and splenectomy. Rates of pneumonia were increased, although not significant among patients with sTBI and splenectomy and both sTBI alone (71.4 vs. 49.4%, p = 0.11). On multivariate regression, the risk of pneumonia was increased with both splenectomy and sTBI (OR 3.18; 95% CI, 0.75-13.45) and sTBI alone, although significant in the latter only (OR 3.56; 95% CI, 2.12-5.97). Based on these results, splenectomy does not appear to influence the development of pulmonary immunosuppression and pneumonia following sTBI.

Infusion of HIV-1 Nef-expressing astrocytes into the rat hippocampus induces enteropathy and interstitial pneumonitis and increases blood-brain-barrier permeability

Even though HIV-1 replication can be suppressed by combination antiretroviral therapy (cART) inflammatory processes still occur, contributing to comorbidities. Comorbidities are attributed to variety of factors, including HIV-1 mediated inflammation. Several HIV-1 proteins mediate central nervous system (CNS) inflammation, including Nef. Nef is an early HIV-1 protein, toxic to neurons and glia and is sufficient to cause learning impairment similar to some deficits observed in HIV-1 associated neurocognitive disorders. To determine whether hippocampal Nef expression by astrocytes contributes to comorbidities, specifically peripheral inflammation, we infused Sprague Dawley rats with GFP- (control) or Nef-transfected astrocytes into the right hippocampus. Brain, lung, and ileum were collected postmortem for the measurement of inflammatory markers. Increased blood-brain-barrier permeability and serum IL-1β levels were detected in the Nef-treated rats. The lungs of Nef-treated rats demonstrated leukocyte infiltration, macrophage upregulation, and enhanced vascular permeability. Ileal tissue showed reactive follicular lymphoid hyperplasia, increased permeability and macrophage infiltration. The intracerebroventricular application of IL-1 receptor antagonist reduced infiltration of immune cells into ileum and lung, indicating the important role of IL-1β in mediating the spread of inflammation from the brain to other tissues. This suggests that localized expression of a single viral protein, HIV-1 Nef, can contribute to a broader inflammatory response by upregulation of IL-1β. Further, these results suggest that Nef contributes to the chronic inflammation seen in HIV patients, even in those whose viremia is controlled by cART.

Endoscopic control of gastric emptying after administration of intravenous erythromycin in an awake patient scheduled for urgent rigid bronchoscopy

Certain interventional pulmonology procedures such as the placement of a tracheal stent or resection of stenosing tracheal tumours require rigid bronchoscopy under general anaesthesia. Unlike an endotracheal tube with a cuff, the rigid bronchoscope only partially protects the airway from bronchoaspiration. For this reason, this procedure is performed on an elective basis in fasted patients. We describe the case of a 60-year-old man with acute respiratory distress requiring emergent rigid bronchoscopy following distal migration of a tracheal stent. One hour before the procedure, the patient had eaten a full meal. Gastric emptying was accelerated by perfusion of intravenous erythromycin and verified by endoscopy with a small diameter gastric endoscope under local anaesthesia. This 1 min procedure was very well tolerated by the patient and allowed to verify with certainty that the stomach was empty. The urgent rigid bronchoscopy for stent retrieval could then be performed safely without any risk of bronchoaspiration.

Development and validation of a nomogram for predicting self-propelled postpyloric placement of spiral nasoenteric tube in the critically ill: Mixed retrospective and prospective cohort study

BACKGROUND & AIMS

Equipment-aided or experience-dependent methods for postpyloric nasoenteric tube placement are not so readily accessible in the critically ill setting. Self-propelled postpyloric placement of a spiral nasoenteric tube can serve as an alternative approach. However, the success rate of this method is relatively low despite using prokinetics. This study aims to develop a user-friendly nomogram incorporating clinical markers to individually predict the probability of successful postpyloric nasoenteric tube placement and facilitate intensivists with improved decision-making before tube insertion.

METHODS

Patients consecutively recruited in the stage between May 2012 through December 2016 constituted the development cohort for retrospective analysis to internally test the nomogram, and patients in the stage between January 2017 through March 2018 constituted the validation cohort for prospective analysis to external validate the nomogram. A multivariate logistic regression analysis was firstly performed in the development cohort by a backward stepwise method to identify the best-fit model, from which a nomogram was obtained. The nomogram was validated in the independent external validation cohort concerning discrimination, calibration. A decision curve analysis was also performed to evaluate the net benefit of insertion decision with the nomogram.

RESULTS

A total of 364 and 119 patients, 52.7% and 55.5% with successful postpyloric placement, were included in the development and validation cohort, respectively. Predictors contained in the prediction nomogram included primary diagnosis, APACHE II score, AGI grade. The derived model showed good discrimination, with an area under the receiver operating characteristic curve (AUROC) of 0.809 (95%CI, 0.765-0.853) and good calibration. Application of the nomogram in the validation cohort also gave good discrimination with an AUROC of 0.776 (95%CI, 0.694-0.859) and good calibration. The decision curve analysis of the nomogram provided better net benefit than the alternate options (insert-all or insert-none).

CONCLUSIONS

A prediction nomogram that incorporates primary diagnosis, together with APACHE II score and AGI grade can be conveniently used to facilitate the pre-insertion individualized prediction of postpyloric nasoenteric tube placement in critically ill patients.

Traumatic Brain Injury in Mice Induces Acute Bacterial Dysbiosis Within the Fecal Microbiome

The secondary injury cascade that is activated following traumatic brain injury (TBI) induces responses from multiple physiological systems, including the immune system. These responses are not limited to the area of brain injury; they can also alter peripheral organs such as the intestinal tract. Gut microbiota play a role in the regulation of immune cell populations and microglia activation, and microbiome dysbiosis is implicated in immune dysregulation and behavioral abnormalities. However, changes to the gut microbiome induced after acute TBI remains largely unexplored. In this study, we have investigated the impact of TBI on bacterial dysbiosis. To test the hypothesis that TBI results in changes in microbiome composition, we performed controlled cortical impact (CCI) or sham injury in male 9-weeks old C57BL/6J mice. Fresh stool pellets were collected at baseline and at 24 h post-CCI. 16S rRNA based microbiome analysis was performed to identify differential abundance in bacteria at the genus and species level. In all baseline vs. 24 h post-CCI samples, we evaluated species-level differential abundances via clustered and annotated operational taxonomic units (OTU). At a high-level view, we observed significant changes in two genera after TBI, Marvinbryantia, and Clostridiales. At the species-level, we found significant decreases in three species (Lactobacillus gasseri, Ruminococcus flavefaciens, and Eubacterium ventriosum), and significant increases in two additional species (Eubacterium sulci, and Marvinbryantia formatexigens). These results pinpoint critical changes in the genus-level and species-level microbiome composition in injured mice compared to baseline; highlighting a previously unreported acute dysbiosis in the microbiome after TBI.

Pathophysiology and Treatment of Gastrointestinal Motility Disorders in the Acutely Ill

Gastrointestinal dysmotility causes delayed gastric emptying, enteral feed intolerance, and functional obstruction of the small and large intestine, the latter functional obstructions being frequently termed ileus and Ogilvie syndrome, respectively. In addition to meticulous supportive care, drug therapy may be appropriate in certain situations. There is, however, considerable variation among individuals regarding what gastric residual volume identifies gastric dysmotility and would encourage use of a promotility drug. While the administration of either metoclopramide or erythromycin is supported by evidence it appears that, dual-drug therapy (erythromycin and metoclopramide) reduces the rate of treatment failure. There is a lack of evidence to guide drug therapy of ileus, but neither erythromycin nor metoclopramide appear to have a role. Several drugs, including ghrelin agonists, highly selective 5-hydroxytryptamine receptor agonists, and opiate antagonists are being studied in clinical trials. Neostigmine, when infused at a relatively slow rate in patients receiving continuous hemodynamic monitoring, may alleviate the need for endoscopic decompression in some patients.

Nutritional and Bioenergetic Considerations in Critically Ill Patients with Acute Neurological Injury

The brain, due to intensive cellular processes and maintenance of electrochemical gradients, is heavily dependent on a constant supply of energy. Brain injury, and critical illness in general, induces a state of increased metabolism and catabolism, which has been proven to lead to poor outcomes. Of all the biochemical interventions undertaken in the ICU, providing nutritional support is perhaps one of the most undervalued, but potentially among the safest, and most effective interventions. Adequate provisions of calories and protein have been shown to improve patient outcomes, and guidelines for the nutritional support of the critically ill patient are reviewed. However, there are no such specific guidelines for the critically ill patient with neurological injury. Patients with primary or secondary neurological disorders are frequently undernourished, while data suggest this population would benefit from early and adequate nutritional support, although comprehensive clinical evidence is lacking. We review the joint recommendations from the Society for Critical Care Medicine and the American Society for Parenteral and Enteral Nutrition, as they pertain to neurocritical care, and assess the recommendations for addressing nutrition in this patient population.

Gastrointestinal transit time and heart rate variability in patients with mild acquired brain injury

Background

Constipation is suspected to occur frequently after acquired brain injury (ABI). In patients with ABI, heart rate variability (HRV) is reduced suggesting autonomic dysfunction. Autonomic dysfunction may be associated with prolonged gastrointestinal transit time (GITT). The primary aim of this study was to investigate if GITT is prolonged in patients with ABI. Secondarily, HRV and its correlation with GITT was investigated.

Methods

We included 25 patients with ABI (18 men, median age: 61.3 years, range [30.7-74.5]). GITT was assessed using radio-opaque markers and HRV was calculated from 24-hour electrocardiograms. Medical records were reviewed for important covariates, including primary diagnosis, time since injury, functional independence measure, and use of medication. The GITT assessed in patients was compared to a control group of 25 healthy subjects (18 men, median age: 61.5 years, range [34.0-70.9]).

Results

In ABI patients, the mean GITT was significantly longer than in healthy controls (2.68 days, 95% CI [2.16-3.19] versus (1.92 days, 95% CI [1.62-2.22], p = 0.011)). No correlation was found between HRV and GITT.

Conclusion

Patients with mild to moderate ABI have prolonged GITT unrelated to the HRV.

Very high intact-protein formula successfully provides protein intake according to nutritional recommendations in overweight critically ill patients: a double-blind randomized trial

BACKGROUND

Optimal energy and protein provision through enteral nutrition is essential for critically ill patients. However, in clinical practice, the intake achieved is often far below the recommended targets. Because no polymeric formula with sufficient protein content is available, adequate protein intake can be achieved only by supplemental amino acids or semi-elemental formula administration. In the present study, we investigated whether protein intake can be increased with a new, very high intact-protein formula (VHPF) for enteral feeding.

METHODS

In this randomized, controlled, double-blind, multicenter trial, 44 overweight (body mass index ≥ 25 kg/m2) intensive care unit patients received either a VHPF (8 g/100 kcal) or a commercially available standard high protein formula (SHPF) (5 g/100 kcal). Protein and energy intake, gastrointestinal tolerance (gastric residual volume, vomiting, diarrhea, and constipation), adverse events, and serious adverse events were recorded. Total serum amino acid levels were measured at baseline and day 5.

RESULTS

The primary outcome, protein intake at day 5, was 1.49 g/kg body weight (95% CI 1.21-1.78) and 0.76 g/kg body weight (95% CI 0.49-1.03, P < 0.001) for VHPF and SHPF, respectively. Daily protein intake was statistically significantly higher in the VHPF group compared with the SHPF group from day 2 to day 10. Protein intake in the VHPF group as a percentage of target (1.5 g/kg ideal body weight) was 74.7% (IQR 53.2-87.6%) and 111.6% (IQR 51.7-130.7%) during days 1-3 and days 4-10, respectively. Serum amino acid concentrations were higher at day 5 in the VHPF group than in the SHPF group (P = 0.031). No differences were found in energy intake, measures of gastrointestinal tolerance, and safety.

CONCLUSIONS

Enteral feeding with VHPF (8 g/100 kcal) resulted in higher protein intake and plasma amino acid concentrations than an isocaloric SHPF (5 g/100 kcal), without an increase in energy intake. This VHPF facilitates feeding according to nutritional guidelines and is suitable as a first-line nutritional treatment for critically ill overweight patients.

TRIAL REGISTRATION

Netherlands Trial Register, NTR5643 . Registered on 2 February 2016.

In Search of the Ideal Promotility Agent: Optimal Use of Currently Available Promotility Agents for Nutrition Therapy of the Critically Ill Patient

PURPOSE OF REVIEW

Enteral nutrition therapy is essential in the management of critically ill patients. Prokinetic agents have been used successfully to aid in the delivery of nutrition and improve feeding tolerance in patients in the intensive care unit (ICU). The aim of this report is to review the existing promotility agents available for use in the critically ill as well as outline the role of potential investigative drugs in order to provide a guide to the management of this difficult and important clinical dilemma.

RECENT FINDINGS

While no single currently available agent currently meets all of the desired goals in the critical care setting, there are an increasing number of available agents from which to choose including motilin receptor agonists, 5HT4 receptor agonists, D2 receptor antagonists, and Mu opioid receptor antagonists. We recommend a multifaceted approach to optimizing enteral nutrition in the critical care setting which should include the early, prophylactic use of promotility agents and should focus on the management of reversible causes of impaired gastrointestinal motility.

Bidirectional brain-gut interactions and chronic pathological changes after traumatic brain injury in mice

OBJECTIVES

Traumatic brain injury (TBI) has complex effects on the gastrointestinal tract that are associated with TBI-related morbidity and mortality. We examined changes in mucosal barrier properties and enteric glial cell response in the gut after experimental TBI in mice, as well as effects of the enteric pathogen Citrobacter rodentium (Cr) on both gut and brain after injury.

METHODS

Moderate-level TBI was induced in C57BL/6mice by controlled cortical impact (CCI). Mucosal barrier function was assessed by transepithelial resistance, fluorescent-labelled dextran flux, and quantification of tight junction proteins. Enteric glial cell number and activation were measured by Sox10 expression and GFAP reactivity, respectively. Separate groups of mice were challenged with Cr infection during the chronic phase of TBI, and host immune response, barrier integrity, enteric glial cell reactivity, and progression of brain injury and inflammation were assessed.

RESULTS

Chronic CCI induced changes in colon morphology, including increased mucosal depth and smooth muscle thickening. At day 28 post-CCI, increased paracellular permeability and decreased claudin-1 mRNA and protein expression were observed in the absence of inflammation in the colon. Colonic glial cell GFAP and Sox10 expression were significantly increased 28days after brain injury. Clearance of Cr and upregulation of Th1/Th17 cytokines in the colon were unaffected by CCI; however, colonic paracellular flux and enteric glial cell GFAP expression were significantly increased. Importantly, Cr infection in chronically-injured mice worsened the brain lesion injury and increased astrocyte- and microglial-mediated inflammation.

CONCLUSION

These experimental studies demonstrate chronic and bidirectional brain-gut interactions after TBI, which may negatively impact late outcomes after brain injury.

Traumatic stress-induced persistent changes in DNA methylation regulate neuropeptide Y expression in rat jejunum

BACKGROUND

Stress-induced chronic neuropsychiatric conditions such as anxiety are often co-morbid with gastrointestinal malfunctions. While we find enduring anxiety-like symptoms following minimal traumatic brain injury (MTBI) in rats, gastrointestinal consequences of MTBI remain elusive.

METHODS

In this study, we examined the effects of MTBI on a major gut peptide, neuropeptide Y (NPY) and gut motility. DNA methylation was studied as a possible epigenetic mechanism operative in the regulation of NPY expression in the gut.

KEY RESULTS

Minimal traumatic brain injury reduced the gut motility 48 hours and 30 days after trauma. The expression of DNA methyltransferase isoforms (DNMT1, DNMT3a, and DNMT3b) was altered in the jejunum 48 hours and 30 days after MTBI. However, the mRNA levels of growth arrest and DNA damage 45 (GADD45) isoforms, GADD45a, and GADD45b, which are believed to be involved in active DNA demethylation, initially decreased at 48 hours but subsequently increased after 30 days of trauma. Similarly, DNA hypomethylation at the NPY promoter region in the jejunum was correlated with the increase in NPY mRNA and protein levels 30 days post-trauma. On the other hand, DNA hypomethylation at 48 hours was associated with a decline in NPY expression. Treatment with 5-azacytidine (5-AzaC), a DNMT inhibitor, retarded DNA methylation and restored the NPY mRNA levels in the jejunum of MTBI-induced rats.

CONCLUSIONS & INFERENCES

These results suggest that DNA demethylation could be operative as an epigenetic mechanism in the long-term regulation of NPY gene expression to alter the gut motility during traumatic stress.

Synchronized dual pulse gastric electrical stimulation improves gastric emptying and activates enteric glial cells via upregulation of GFAP and S100B with different courses of subdiaphragmatic vagotomy in rats

Previous research and clinical practice have indicated that damage to the vagal nerve may seriously affect gastrointestinal physiological movement behavior. The aim of the current study was to observe the change of gastric motility, as well as enteric glial cells (EGCs) in the stomach with different courses of vagal nerve transection in rats prior to and following synchronized dual pulse gastric electrical stimulation. The gastric emptying rates were measured to assess the gastric motility. The glial markers, containing calcium binding protein (S100B) and glial fibrillary acidic protein (GFAP), were detected by reverse transcription‑quantitative polymerase chain reaction and double‑labeling immunofluorescence analysis. Ultrastructural changes of EGCs were observed using transmission electron microscopy. Gastric emptying was delayed in the terminal vagotomy group, compared with the terminal control group. The effect of long‑term synchronized dual pulse gastric electrical stimulation (SGES) was superior to short‑term SGES in terminal groups. The expression levels of S100B/GFAP were markedly decreased in the terminal vagotomy group compared with the terminal control group. Following short‑term or long‑term SGES, S100B/GFAP gene and protein expression increased in terminal groups. However, long‑term SGES was more effective than short‑term SGES and the difference was statistically significant. Vagal nerve damage leads to gastric motility disorder and weakens the function of EGCs. Therefore, SGES may improve stomach movement behavior and restore the impaired EGCs. The underlying mechanism of the effect remains elusive, but maybe associated with activation of EGCs.

Early Enteral Combined with Parenteral Nutrition Treatment for Severe Traumatic Brain Injury: Effects on Immune Function, Nutritional Status and Outcomes

Objective To compare the conjoint effect of enteral nutrition (EN) and parenteral nutrition (PN) with single EN or PN on immune function, nutritional status, complications and clinical outcomes of patients with severe traumatic brain injury (STBI). Methods A prospective randomized control trial was carried out from January 2009 to May 2012 in Neurological Intensive Care Unit (NICU). Patients of STBI who met the enrolment criteria (Glasgow Coma Scale score 6~8; Nutritional Risk Screening ≥3) were randomly divided into 3 groups and were admi- nistrated EN, PN or EN+PN treatments respectively. The indexes of nutritional status, immune function, complications and clinical outcomes were examined and compared statistically. Results There were 120 patients enrolled in the study, with 40 pationts in each group. In EN+PN group, T lymthocyte subsets CD3+%, CD4+%, ratio of CD3+/CD25+, ratio of CD4+/CD8+, the plasma levels of IgA, IgM, and IgG at 20 days after nutritional treatment were significantly increased compared to the baseline(t=4.32-30.00, P<0.01), and they were significantly higher than those of PN group (t=2.44-14.70; P<0.05,or P<0.01) with exception of CD4+/CD8+, higher than those of EN group (t=2.49-13.31, P<0.05, or P<0.01) with exceptions of CD3+/CD25+, CD4+/CD8+, IgG and IgM. For the nutritional status, the serum total protein, albumin, prealbumin and hemoglobin were significantly higher in the EN (t=5.87-11.91; P<0.01) and EN+PN groups (t=6.12-13.12; P<0.01) than those in PN group after nutrition treatment. The serum prealbumin was higher in EN+PN group than that in EN group (t=2.08; P<0.05). Compared to the PN group, the complication occurrence rates of EN+PN group were significantly lower in stress ulcer (22.5% vs. 47.5%; χ²= 8.24, P<0.01), intracranial infection (12.5% vs 32.5%;χ²= 6.88, P<0.01) and pyemia (25.0% vs. 47.5%; χ²= 6.57, P<0.05). Compared to the EN group, the complication occurrence rates of EN+PN group were significantly lower in aspirated pneumonia (27.5% vs. 50.0%; χ²= 6.39, P<0.05), hypoproteinemia (17.5% vs. 55.0%; χ²= 18.26, P<0.01) and diarrhea (20.0% vs. 60.0%; χ²= 20.00, P<0.01). The EN+PN group also had significant less length of stay in NICU (t=2.51, 4.82; P<0.05, P<0.01), number of patients receiving assisted mechanical ventilation (χ²= 6.08, 12.88; P<0.05, P<0.01) and its durations (t=3.41, 9.08; P<0.05, P<0.01), and the death rate (χ²=7.50, 16.37; P<0.05, P<0.01) than those of EN or PN group. Conclusion Early EN+PN treatment could promote the recovery of the immune function, enhance nutritional status, decrease complications and improve the clinical outcomes in patients with severe traumatic brain injury.

Tolerance and Efficacy of Enteral Nutrition in Traumatic Brain–Injured Patients Induced Into Barbiturate Coma

BACKGROUND

There is a paucity of data evaluating the efficacy of nutrition support in traumatic brain-injured patients induced into barbiturate coma for refractory intracranial hypertension. Our objective was to evaluate the efficacy of enteral nutrition in a select group of trauma patients.

METHODS

Prospective data were collected on severe traumatic brain-injured patients over a 4-year period. Patients were stratified by whether or not they were induced into a barbiturate coma. Barbiturate coma was defined as per American Association of Neurological Surgeons (AANS) guidelines. All patients were initially fed via the enteral route via a nasogastric feeding tube. Patients who did not tolerate feedings within 48 hours started receiving prokinetic agents. Feeding tolerance was defined as ability to tolerate enteral feedings with <150 mL of gastric residuals every 6 hours for >72 hours.

RESULTS

Fifty-seven patients were induced into a barbiturate coma. All were victims of blunt-force trauma. Forty-two of 57 (74%) patients were men, with a mean age of 37+/-12 years and a mean injury severity score of 24+/-10. Thirty-eight of the 57 (67%) patients had an isolated traumatic brain injury. All 57 patients failed enteral nutrition via the nasogastric route after the first 48 hours of nutrition initiation after barbiturate coma was fully achieved by protocol criteria. Prokinetic agents demonstrated no improvement in feeding tolerance after the subsequent 48-72 hours. Of the 12 patients who had a postpyloric feeding tube placed, only 25% tolerated enteral nutrition for >48 hours.

CONCLUSIONS

Patients with traumatic brain injury induced into barbiturate coma develop a significant ileus that is refractory to prokinetic agents. Only a marginal improvement is seen when the postpyloric route is obtained. Early parenteral nutrition should be considered in this patient population.

Correlation between colonic secretion and colonic motility in rats: Role of ghrelin

AIM

To explore the relationship between colonic secretory function and colonic motility.

METHODS

Using a rat model chronically implanted with intracerebroventricular (ICV) and cecal catheters, we validated the correlation between colonic secretion and colonic motor functions, as well as the role of ICV injection volume.

RESULTS

Compared to saline controls (5 μL/rat), ICV acyl ghrelin at 1 nmol/5 μL enhanced the total fecal weight, accelerated the colonic transit time, and increased the fecal pellet output during the first hour post-injection, while ICV des-acyl ghrelin at 1 nmol/5 μL only accelerated the colonic transit time. These stimulatory effects on colonic motility and/or secretion from acyl ghrelin and des-acyl ghrelin disappeared when the ICV injection volume increased to 10 μL compared with saline controls (10 μL/rat). Additionally, the ICV injection of 10 μL of saline significantly shortened the colonic transit time compared with the ICV injection of 5 μL of saline. The total fecal weight during the first hour post-injection correlated with the colonic transit time and fecal pellet output after the ICV injection of acyl ghrelin (1 nmol/5 μL), whereas the total fecal weight during the first hour post-injection correlated with the fecal pellet output but not the colonic transit time after the ICV injection of des-acyl ghrelin (1 nmol/5 μL).

CONCLUSION

Colonic secretion does not always correlate with colonic motility in response to different colonic stimulations. Acyl ghrelin stimulates colonic secretion.

The efficacy and safety of prokinetic agents in critically ill patients receiving enteral nutrition: a systematic review and meta-analysis of randomized trials

Background

Intolerance to enteral nutrition is common in critically ill adults, and may result in significant morbidity including ileus, abdominal distension, vomiting and potential aspiration events. Prokinetic agents are prescribed to improve gastric emptying. However, the efficacy and safety of these agents in critically ill patients is not well-defined. Therefore, we conducted a systematic review and meta-analysis to determine the efficacy and safety of prokinetic agents in critically ill patients.

Methods

We searched MEDLINE, EMBASE, and Cochrane Library from inception up to January 2016. Eligible studies included randomized controlled trials (RCTs) of critically ill adults assigned to receive a prokinetic agent or placebo, and that reported relevant clinical outcomes. Two independent reviewers screened potentially eligible articles, selected eligible studies, and abstracted pertinent data. We calculated pooled relative risk (RR) for dichotomous outcomes and mean difference for continuous outcomes, with the corresponding 95 % confidence interval (CI). We assessed risk of bias using Cochrane risk of bias tool, and the quality of evidence using grading of recommendations assessment, development, and evaluation (GRADE) methodology.

Results

Thirteen RCTs (enrolling 1341 patients) met our inclusion criteria. Prokinetic agents significantly reduced feeding intolerance (RR 0.73, 95 % CI 0.55, 0.97; P = 0.03; moderate certainty), which translated to 17.3 % (95 % CI 5, 26.8 %) absolute reduction in feeding intolerance. Prokinetics also reduced the risk of developing high gastric residual volumes (RR 0.69; 95 % CI 0.52, 0.91; P = 0.009; moderate quality) and increased the success of post-pyloric feeding tube placement (RR 1.60, 95 % CI 1.17, 2.21; P = 0.004; moderate quality). There was no significant improvement in the risk of vomiting, diarrhea, intensive care unit (ICU) length of stay or mortality. Prokinetic agents also did not significantly increase the rate of diarrhea.

Conclusion

There is moderate-quality evidence that prokinetic agents reduce feeding intolerance in critically ill patients compared to placebo or no intervention. However, the impact on other clinical outcomes such as pneumonia, mortality, and ICU length of stay is unclear.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1441-z) contains supplementary material, which is available to authorized users.

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.

The use of cricoid pressure during rapid sequence induction in trauma patients – UK and European practice compared

Introduction

There is ongoing debate and conflicting evidence surrounding the place of cricoid pressure (CP) as part of a rapid sequence induction (RSI) of anaesthesia. This study investigated the current use of CP during trauma RSI and compared reported practice in the UK with the rest of Europe.

Methods

An anonymised, web-based survey was sent to all clinicians registered as European Trauma Course instructors.

Results

CP use was reported by 83.1% of UK respondents and 39.4% from the rest of Europe, with an overall reported use of 49.8%. Anaesthetists use CP less commonly (35.6%) than clinicians from other specialties (63.6%). The most common reason given for not using CP (76.7%) was a perceived lack of evidence of effectiveness.

Conclusion

Generally the use of CP appears to be in decline with only half of all clinicians reporting to use it; however it remains much more commonly used in the UK than the rest of Europe.