Nutritional management of the critically ill neurologic patient

The Brain–Gut Axis in Traumatic Brain Injury: Implications for Nutrition Support

Purpose of Review

Early enteral nutrition improves outcomes following traumatic brain injury (TBI). This can prove difficult due to TBI-induced feeding intolerance secondary to disruption of the brain-gut axis, a network composed of central nervous system (CNS) input, autonomic signaling, and immunologic regulation that controls gut and CNS homeostasis. Here, we discuss the pathophysiology of brain–gut axis dysregulation and outline nutrition strategies in patients with TBI.

Recent Findings

Feeding intolerance following TBI is multifactorial; complex signaling between the CNS, sympathetic nervous system, parasympathetic nervous system, and enteric nervous system that controls gut homeostasis is disrupted within hours post-injury. This has profound effects on the immune system and gut microbiome, further complicating post-TBI recovery. Despite this disruption, calorie and protein requirements increase considerably following TBI, and early nutritional supplementation improves survival following TBI. Enteral nutrition has proven more efficacious than parenteral nutrition in TBI patients and should be initiated within 48 hours following admission. Immune-fortified nutrition reduces CNS and gut inflammation and may improve outcomes in TBI patients.

Summary

Although autonomic dysregulation of the brain–gut axis results in feeding intolerance following TBI, early enteral nutrition is of paramount importance. Enteral nutrition reduces post-TBI inflammation and enhances immunologic and gut function. When feasible, enteral nutrition should be initiated within 48 hours following injury.

Nutrition Therapy, Glucose Control, and Brain Metabolism in Traumatic Brain Injury: A Multimodal Monitoring Approach

The goal of neurocritical care in patients with traumatic brain injury (TBI) is to prevent secondary brain damage. Pathophysiological mechanisms lead to loss of body mass, negative nitrogen balance, dysglycemia, and cerebral metabolic dysfunction. All of these complications have been shown to impact outcomes. Therapeutic options are available that prevent or mitigate their negative impact. Nutrition therapy, glucose control, and multimodality monitoring with cerebral microdialysis (CMD) can be applied as an integrated approach to optimize systemic immune and organ function as well as adequate substrate delivery to the brain. CMD allows real-time bedside monitoring of aspects of brain energy metabolism, by measuring specific metabolites in the extracellular fluid of brain tissue. Sequential monitoring of brain glucose and lactate/pyruvate ratio may reveal pathologic processes that lead to imbalances in supply and demand. Early recognition of these patterns may help individualize cerebral perfusion targets and systemic glucose control following TBI. In this direction, recent consensus statements have provided guidelines and recommendations for CMD applications in neurocritical care. In this review, we summarize data from clinical research on patients with severe TBI focused on a multimodal approach to evaluate aspects of nutrition therapy, such as timing and route; aspects of systemic glucose management, such as intensive vs. moderate control; and finally, aspects of cerebral metabolism. Research and clinical applications of CMD to better understand the interplay between substrate supply, glycemic variations, insulin therapy, and their effects on the brain metabolic profile were also reviewed. Novel mechanistic hypotheses in the interpretation of brain biomarkers were also discussed. Finally, we offer an integrated approach that includes nutritional and brain metabolic monitoring to manage severe TBI patients.

Selected pharmacokinetic issues of the use of antiepileptic drugs and parenteral nutrition in critically ill patients

OBJECTIVES

To conduct a systematic review for the evidence supporting or disproving the reality of parenteral nutrition- antiepileptic drugs interaction, especially with respect to the plasma protein-binding of the drug.

METHODS

The articles related to the topic were identified through Medline and PubMed search (1968-Feburary 2010) for English language on the interaction between parenteral nutrition and antiepileptic drugs; the search terms used were anti-epileptic drugs, parenteral nutrition, and/or interaction, and/or in vitro. The search looked for prospective randomized and nonrandomized controlled studies; prospective nonrandomized uncontrolled studies; retrospective studies; case reports; and in vitro studies. Full text of the articles were then traced from the Universiti Sains Malaysia (USM) library subscribed databases, including Wiley-Blackwell Library, Cochrane Library, EBSCOHost, OVID, ScienceDirect, SAGE Premier, Scopus, SpringerLINK, and Wiley InterScience. The articles from journals not listed by USM library were traced through inter library loan.

RESULTS

There were interactions between parenteral nutrition and drugs, including antiepileptics. Several guidelines were designed for the management of illnesses such as traumatic brain injuries or cancer patients, involving the use of parenteral nutrition and antiepileptics. Moreover, many studies demonstrated the in vitro and in vivo parenteral nutrition -drugs interactions, especially with antiepileptics.

CONCLUSIONS

There was no evidence supporting the existence of parenteral nutrition-antiepileptic drugs interaction. The issue has not been studied in formal researches, but several case reports and anecdotes demonstrate this drug-nutrition interaction. However, alteration in the drug-free fraction result from parenteral nutrition-drug (i.e. antiepileptics) interactions may necessitate scrupulous reassessment of drug dosages in patients receiving these therapies. This reassessment may be particularly imperative in certain clinical situations characterized by hypoalbuminemia (e.g., burn patients).

Nutritional support in head injury

Nutritional support is imperative to the recovery of head-injury patients. Hypermetabolism and hypercatabolism place this patient population at increased risk for weight loss, muscle wasting, and malnutrition. Nutrition management may be further complicated by alterations in gastrointestinal motility. Resting energy expenditure should be measured using indirect calorimetry and protein status measured using urine urea nitrogen. Providing early enteral nutrition within 72 hours of injury may decrease infection rates and overall complications. Establishing standards of practice and nutrition protocols will assure patients receive optimal nutrition assessment and intervention in a timely manner.

Protein-energy malnutrition increases activation of the transcription factor, nuclear factor kappaB, in the gerbil hippocampus following global ischemia

Protein-energy malnutrition (PEM) exacerbates functional impairment caused by brain ischemia. This is correlated with reactive gliosis, which suggests an increased inflammatory response. The objective of the current study was to investigate if PEM increases hippocampal activation of nuclear factor kappaB (NFkappaB), a transcription factor that amplifies the inflammatory response involved in ischemic brain injury. Mongolian gerbils (11-12 weeks old) were randomly assigned to control diet (12.5% protein) or protein-deficient diet (2%) for 4 weeks. The 2% protein group had a 15% decrease in voluntary food intake (P<.001; unpaired t test), resulting in PEM. Body weight after 4 weeks was 20% lower in the PEM group (P<.001). Gerbils were then exposed to sham surgery or global ischemia induced by 5-min bilateral common carotid artery occlusion. PEM independently increased hippocampal NFkappaB activation detected by electrophoretic mobility shift assay at 6 h after surgery (P=.014; 2-factor ANOVA). Ischemia did not significantly affect NFkappaB activation nor was there interaction between diet and ischemia. Serum glucose and cortisol concentrations at 6 h postischemia were unaltered by diet or ischemia. A second experiment using gerbils of the same age and feeding paradigm demonstrated that PEM also increases hippocampal NFkappaB activation in the absence of surgery. These findings suggest that PEM, which exists in 16% of elderly patients at admission for stroke, may worsen outcome by increasing activation of NFkappaB. Since PEM increased NFkappaB activation independent of ischemia or surgery, the data also have implications for the inflammatory response of the many individuals affected globally by PEM.

Implementing clinical guidelines for nutrition in a neurosurgical intensive care unit

Patients in neurosurgical intensive care have individual needs concerning nutrition because of their conditions. An important therapeutic goal is to prevent the development of malnutrition as it contributes to an increase in mortality and enhances the risk of complications in these patients. The health-care team has a mutual responsibility for this, although it is a complex task and a correct assessment of patients' nutritional needs is vital. Multidisciplinary clinical guidelines focused on nutrition might help the health-care staff in decision-making and allowing individualized treatment for patients. The aim of this study was to evaluate the implementation and use of such a guideline. The results show that the guideline is used in varying degrees by the health-care team. Areas that focused on more practical aspects of nutritional support seemed to have a unified approach, whereas areas on nutritional assessment and routine nutrition orders demonstrated both a lack of knowledge and unclear role responsibilities. The results reveal how different professional groups in health care perceive the implementation of a clinical guideline. Some areas need further clarification, there needs to be continuing development of nutritional guidelines, and education of staff is needed in order to enhance the nutritional care of patients.

Case study of hip fracture in an older person

PURPOSE

To discuss proximal femoral (hip) fractures as the leading cause of hospitalization for injuries among older persons, using a case example that illustrates not only the orthopedic injury but also how an older person's chronic problems complicate the acute event.

DATA SOURCES

Extensive review of scientific literature on the conditions discussed, supplemented by the case study.

CONCLUSIONS

Hip fractures in older adults can present multiple challenges to care when complicated by preexisting or coexisting conditions. This case of an older man with a hip fracture emphasizes the resuscitation priorities for the patient found after a "long lie" and the impact of chronic alcoholism and malnutrition, which lead to serious complications.

IMPLICATIONS FOR PRACTICE

Careful physical and psychosocial assessment is important for determining the presenting problem and comorbid conditions. Priorities for postoperative management of hip fracture and its complications guide the nurse practitioner through the successful return of the patient to the community.

Prospective randomized trial to assess caloric and protein needs of critically Ill, anuric, ventilated patients requiring continuous renal replacement therapy

OBJECTIVES

We measured the energy and protein needs in 50 sequential, critically ill, ventilated patients requiring continuous renal replacement therapy (CRRT) for renal failure by using indirect calorimetry and three sequential isocaloric protein-feeding regimes of 1.5, 2.0, and 2.5 g. kg(-1). d(-1). We also assessed the compliance of actual feeding with target feeding and correlated the predictive energy requirements of the formulae with the actual energy expenditure (EE) measured by indirect calorimetry. We also determined whether these feeding regimes affected patient outcome.

METHODS

The energy and protein needs of 50 consecutive, critically ill patients (31 male; age 53.3 +/- 17.4 y; Acute Physiology and Chronic Health Evaluation (APACHE II) score: 26.0 +/- 8.0; Acute Physiology and Chronic Health Evaluation score predicted risk of death: 50.0 +/- 25.0%) were assessed by using indirect calorimetry and ultrafiltrate nitrogen loss. Entry into this study was on commencement of CRRT. To eliminate any beneficial effect from the passage of time on nitrogen balance, 10 of the 50 patients were randomized to receive 2.0 g. kg(-1). d(-1) throughout the study, and the others received an escalating isocaloric feeding regime (1.5, 2.0, and 2.5 g. kg(-1). d(-1)) at 48-h intervals. Enteral feeding was preferred, but if this was not tolerated or unable to meet target, it was supplemented or replaced by a continuous infusion of total parenteral nutrition. Energy was given to meet caloric requirements as predicted by the Schofield equation corrected by stress factors or based on the metabolic cart readings of EE and was kept constant for all patients throughout the trial. Patients were stabilized on each feeding regime for at least 24 h before samples of dialysate were taken for nitrogen analysis at 8-h intervals on the second day. CRRT was performed by using a blood pump with a blood flow of 100 to 175 mL/min. Dialysate was pumped in and out counter-currently to the blood flow at 2 L/h. A biocompatible polyacrylonitrile hemofilter was used in all cases.

RESULTS

EE was 2153 +/- 380 cal/d and increased by 56 +/- 24 cal/d (P < 0.0001) throughout the 6-d study period to 2431 +/- 498 cal/d. At study entry, the mean predicted (Schofield) caloric requirement was 2101 +/- 410. Patients received 99% of the predicted energy requirements. However, the mean EE was 11% higher at 2336 +/- 482 calories. This difference was not uniform. If the predicted caloric requirement was less than 2500, the EE exceeded the predicted by an average of 19%. If the predicted caloric requirement was greater than 2500, the EE on average was 6% less than predicted. This relation was significant (P = 0.025) and has not been described previously. Nitrogen balance was inversely related to EE (P = 0.05), positively related to protein intake (P = 0.0075), and more likely to be attained with protein intakes larger than 2 g. kg(-1). d(-1) (P = 0.0001). Nitrogen balance became positive in trial patients over time but were negative in control patients over time (P = 0.0001). Nitrogen balance was directly associated with hospital outcome (P = 0.03) and intensive care unit outcome (P = 0.02). For every 1-g/d increase in nitrogen balance, the probability of survival increased by 21% (P = 0.03; odds ratio, 1.211; 95% confidence limits, 1.017,1.443). Further, although enterally and parenterally fed patients had lower mortalities than predicted, the presence of enteral feeding, even after adjusting for predicted risk of death, had a statistically significant benefit to patient outcome (P = 0.04).

CONCLUSIONS

This study found that a metabolic cart can improve the accuracy of energy provision and that a protein intake of 2.5 g. kg(-1). d(-1) in these patients increases the likelihood of achieving a positive nitrogen balance and improving survival. Enteral feeding is preferable, but if this is not possible or does not achieve the target, then it should be supplemented by parenteral feeding.

Nutritional considerations in the surgical patient

The nutritional status of the patient is integral to the care of the patient. Nutritional assessment and management begins with the initial patient contact and continues into the postoperative period.

Effects of continuous versus bolus infusion of enteral nutrition in critical patients

PURPOSE

Enteral alimentation is the preferred modality of support in critical patients who have acceptable digestive function and are unable to eat orally, but the advantages of continuous versus intermittent administration are surrounded by controversy. With the purpose of identifying the benefits and complications of each technique, a prospective controlled study with matched subjects was conducted.

PATIENTS AND METHODS

Twenty-eight consecutive candidates for enteral feeding were divided into 2 groups (n = 14 each) that were matched for diagnosis and APACHE II score. A commercial immune-stimulating polymeric diet was administered via nasogastric tube by electronic pump in the proportion of 25 kcal/kg/day, either as a 1-hour bolus every 3 hours (Group I), or continuously for 24 hours (Group II), over a 3-day period. Anthropometrics, biochemical measurements, recording of administered drugs and other therapies, thorax X-ray, measurement of abdominal circumference, monitoring of gastric residue, and clinical and nutritional assessments were performed at least once daily. The principal measured outcomes of this protocol were frequency of abdominal distention and pulmonary aspiration, and efficacy in supplying the desired amount of nutrients.

RESULTS

Nearly half of the total population (46.4%) exhibited high gastric residues on at least 1 occasion, but only 1 confirmed episode of pulmonary aspiration occurred (3.6%). Both groups displayed a moderate number of complications, without differences. Food input during the first day was greater in Group II (approximately 20% difference), but by the third day, both groups displayed similarly small deficits in total furnished volume of about 10%, when compared with the prescribed diet.

CONCLUSIONS

Both administration modalities permitted practical and effective administration of the diet with frequent registered abnormalities but few clinically significant problems. The two groups were similar in this regard, without statistical differences, probably because of meticulous technique, careful monitoring, strict patient matching, and conservative amounts of diet employed in both situations. Further studies with additional populations, diagnostic groups, and dietetic prescriptions should be performed in order to elucidate the differences between these commonly used feeding modalities.

Direct percutaneous endoscopic jejunostomy with small bowel enteroscopy and fluoroscopy

BACKGROUND

Approaches to the creation of a percutaneous jejunostomy (PEJ) include enteroscopy with jejunal transillumination, fluoroscopy with small bowel distension and tract dilation, and jejunal enteral tube placement through a percutaneous endoscopic gastrostomy. Although all have been successful, the combination of enteroscopy and fluoroscopy may improve visualization and the success of PEJ placement. This is a description of such a technique and its successful use in 7 patients.

METHODS

The procedure was performed with the patient under conscious sedation in a manner similar to standard PEG placement. The proximal jejunum was visualized and a standard snare was passed though the enteroscope and was opened. A needle and guidewire were directed percutaneously though the snare by using fluoroscopic guidance. Under direct endoscopic visualization the snare was closed around the guidewire. A standard 20F push-type "gastrostomy" tube was passed over the guidewire and through the mouth and the dome seated in the jejunum. A bumper was passed externally over the tube and tightened at the skin.

RESULTS

PEJ placement was successful in all 7 patients. The average length of the procedure was 40 minutes (range 22-64 minutes). There were no major complications. Mean follow-up was 124 days (range 28-308 days). Feeding tubes remained functional until removal (2), death (1), or surgical removal for an unrelated reason (1). Three tubes are still in use.

CONCLUSIONS

Percutaneous endoscopic jejunostomy tube placement can be performed successfully with enteroscopy and fluoroscopy. This technique is safe and efficient and provides distal enteral nutritional support for patients in whom PEG cannot be used.

The nutritional management of patients with head injuries

Severe head injuries tend to be associated with hypermetabolism and hypercatabolism resulting in negative nitrogen balances which may exceed 30 grams day-1. Enteral feeding should begin as soon as the patient is hemodynamically stable, attempting to reach a non-protein caloric intake of at least 30-35 kcal kg-1 day-1 and a protein intake of 2.0-2.5 g kg-1 day-1 as soon as possible. With severe head injuries (Glasgow Coma Scale < 8), there is an increased tendency for gastric feeding to regurgitate into the upper airway. Keeping the patient upright and checking residuals is important in such patients. Jejunal feedings are less apt to be aspirated. If it is apparent that the gastro-intestinal tract cannot be used to reach the nutritional goals within three days, total parental nutrition is begun within 24-48 h so as to reach these nutrition goals by either one or both routes by the third or fourth day. Blood glucose levels exceeding 150-200 mg dl-1 tend to increase the severity of the neurologic problems and efforts should be made to prevent hyperglycemia by carefully regulating the glucose and insulin intake. Indirect calorimetry to determine the respiratory quotient and resting energy expenditure should be determined twice weekly. To determine N2 balance, urinary urea nitrogen should be measured in 24-h specimens. These tests should be performed once or twice weekly until it is clear that the nutrition is adequate.

Acute care management of severe traumatic brain injuries

Preservation or restoration of optimal neurologic function following traumatic brain injury (TBI) requires timely and aggressive therapeutic interventions. Effective diagnostic tools, together with an armamentarium of treatment modalities, have augmented the treatment strategies utilized today. In addition, the Guidelinesfor the Management of Severe Head Injury have established a standardized approach for the TBI patient. This article will provide current information regarding the resuscitation priorities, appropriate interventions, and pharmacological agents used in the treatment required by the complex nature of TBI. Also, a review of the occurrences associated with TBI will be discussed.

Spontaneous transpyloric migration of a ballooned nasojejunal tube: a randomized controlled trial

BACKGROUND

Spontaneous transpyloric migration of a simple nasojejunal tube (NJT) can be expected in only one-third of insertions. Guidance of the tube by radiologic or endoscopic maneuvers is usually required. We believed that locating a 5-mL balloon near the tip of an NJT on which natural peristalsis could act would improve the rate of spontaneous transpyloric migration and facilitate small bowel propagation.

METHODS

Thirty healthy volunteers were randomly assigned to have an inflated or noninflated, ballooned NJT fashioned from a modified 9F Hickman line catheter inserted. The pH of aspirates was measured hourly and the final location of the tube assessed by gastrografin contrast abdominal x-ray (AXR) at the end of 6 hours, at which time the tube was removed.

RESULTS

After 6 hours, spontaneous transpyloric migration occurred in 86.6% of the ballooned and 66.6% of the nonballooned tubes. The final disposition of the ballooned tubes was: stomach, 2 (13.3%); duodenum, 1 (6.7%); and small bowel, 12 (80%). The final disposition of the nonballooned tubes was: stomach, 5 (33%), NS; duodenum, 9 (60%), p < .05; and small bowel, 1 (6.7%), p < .05.

CONCLUSIONS

Ballooned NJT have a higher rate of spontaneous transpyloric migration and are significantly more likely to achieve an optimal small bowel location.

Routine intragastric feeding following traumatic brain injury is safe and well tolerated

BACKGROUND

Delayed gastric emptying following traumatic brain injury (TBI) has led some to advocate jejunal feeding. Our purpose was to review our experience with percutaneous endoscopic gastrostomy (PEG) and intragastric feeding in TBI patients to assess safety and effectiveness.

METHODS

All patients on a TBI clinical pathway at our institution were targeted for early PEG. After PEG, standard enteral nutrition was initiated. Abdominal examination and gastric residual volumes were used to assess tolerance.

RESULTS

There were 118 patients with moderate to severe TBI. The average age was 36 years. Mean Injury Severity Score (ISS) was 25. Enteral access was obtained and intragastric feeding was initiated on day 3. 6. Intragastric feeding was tolerated without complication in 111 of 114 (97%) patients. Five patients aspirated, but had no evidence of intolerance prior to the event.

CONCLUSIONS

PEG provided reliable enteral access in moderate to severe TBI patients. Intragastric feeding was well tolerated with a low complication rate (4%).