Nutrition Support in Traumatic Brain Injury

In any form of acquired brain injury, your first concerns are stabilizing the patient and preventing further neuronal injury/limiting secondary brain damage. In patients with traumatic brain injury (TBI) many metabolic alterations can occur such as hypermetabolism, hypercatabolism, and glucose intolerance (Wang et al., 2013). The management of such alterations hinges on nutritional support.

Nutritional support is recognized as an “important adjunctive therapy" (Wang et al., 2013) for targeting primary, secondary and long-term effects of TBI. Various prevention strategies have been identified which may reduce mortality, improve outcomes and decrease infectious (i.e., pneumonia/other respiratory tract infections; CNS infection; bloodstream infection/sepsis; urinary tract infection) and feeding-related  complications (i.e., feeding intolerance; aspiration; diarrhea; vomiting; constipation; abdominal distention) (Wang et al., 2013). These include the use of enteral nutrition (EN) and parenteral nutrition (PN) feedings, the use of nasogastric or non-nasogastric EN feedings, and early initiation of feedings. The use of probiotics as well as arginine, glutamine, nucleotides and omega-3 fatty acids also have been investigated.

Decisions regarding choice and delivery of nutrition support in TBI remain controversial - both routes of nutrient administration are effective in improving nutritional status and promoting positive outcomes in post-head injury hypermetabolic states, and both approaches show specific advantages and disadvantages. In any case there are certain parameters that will help determine which will be preferred. Parameters that determine the optimal route of administration include gut functionality, duration of NPO status, symptoms of malabsorption and current energy intake compared to goal energy intake. Patients with severe head injuries should receive early enteral feeding when feasible and when the gastrointestinal tract is functional.

EN is generally the preferred route of nutrition support for patients with TBI; this is due to less risk of infection/noninfectious complications, decreased length of stay and reduced hospital costs. EN supports cell and organ function, gut mass and barrier function; also reduces risk of hyperglycemia or hyperosmolarity (Wang et al., 2013). There are, of course, disadvantages regarding this approach. Such disadvantages include the concern of inadequate delivery of nutrients, obstructions of feeding tubes, GI intolerance to tube feedings, and interruptions in feedings (Vincent et al., 2012; Wang et al., 2013). Delivery of enteral feedings and occurrence of feeding intolerances and interruptions can be the difference between improved clinical outcomes and in-hospital malnutrition. When EN is no longer a feasible option, or is no longer tolerated (<50% of their goal rate by day 7 post-injury) PN should be introduced (Wang et al., 2013).

PN feedings, which are indicated for patients with impaired gastric function, is likely to be beneficial for TBI patients. For TBI parenterally fed patients, PN has the benefit of allowing more nutrient bioavailability and delivering nutrients over shorter time periods without the complications brought about by EN (Wang et al., 2013). For moderately to severe head injured patients, PN might be the optimum route of feeding; however, this route “should not be misunderstood as opposition to the suggestion that EN is preferable whenever possible with functional gastrointestinal tracts” (Zaloga, 2006).

Though PN can be an alternative approach of nutritional support when enteral feeding is not feasible or when a risk of malnutrition is present, it is filled with complications especially when PN is not gradually introduced. Consequently rapid refeeding can lead to the condition known as refeeding syndrome (hypophosphatemia). Refeeding syndrome occurs when aggressive PN particularly carbohydrate (dextrose) is delivered to a patient in a nutritionally compromised state. The sudden administration of dextrose stimulates the release of insulin, which promotes rapid glucose, phosphorous, potassium and magnesium uptake into the cells. The net result: a shift in electrolyte (serum concentration of phosphorous, potassium and magnesium decrease) and fluid balance (insulin secretion associated with high carbohydrate load leads to sodium and fluid retention). This marked shift in electrolyte and fluid balance can potentially be fatal. One potential consequence from fluid retention may be an increase in cardiac workload. Increased cardiac workload due to fluid retention may further increase heart rate and oxygen consumption leading to acute cardiac failure. Increased extracellular fluid volume also can lead to pulmonary edema.

Various studies have demonstrated that non-nasogastric (NNG) feeding has a positive impact on reducing mortality rate and decreasing ventilator days in TBI patients (Escribano et al., 2010; Grahm et al., 1989; Kostadima et al., 2005; Minard et al. 2000). The use of NNG feeding in TBI patients in the ICU setting also promotes EN tolerance, helps avoid overfeeding and prevents aspiration pneumonia (Wang et al., 2103). Supplementation with immune-enhanced formulae post-injury appear to reduce infectious complications; however, more studies are warranted to determine its effect on mortality and functional outcome.

References
Acosta-Escribano, J., Fernandez-Vivas, M., Grau Carmona, T., Catturla-Such, J., Garcia-Martinez, M., et al. (2010). Gastric versus transpyloric feeding in severe traumatic brain injury: a prospective, randomized trial. Intensive Care Medicine 36(9), 1532-1539.  

Grahm, T., Zadrozny, D., & Harrington, T. (1989). The benefits of early jejunal hyperalimentation in the head-injured patient. Neurosurgery 25(5), 729-735.

Kostadima, E., Kaditis, A., Alexopoulous, E., Zakynthinos, E., & Sfyras, D. (2005). Early gastrostomy reduces the rate of ventilator-associated pneumonia in stroke or head injury patients. The European Respiratory Journal 26(1), 106-111.

Minard, G., Kudsk, K., Melton, S, Patton, J., & Tolley E. (2000). Early versus delayed feeding with an immune-enhancing diet in patients with severe head injuries. JPEN Journal of Parenteral and Enteral Nutrition 24(3), 145-149.

Wang, X., Dong, Y., Han, X., Qi, X., Huang, C., & Hou, L. (2013). Nutritional support for patients sustaining traumatic brain injury: a systematic review and meta-analysis of prospective studies. PLoS ONE 8(3), e58838.

Zaloga, G. (2006). Parenteral nutrition in adult in patients with functioning gastrointestinal tracts: assessment of outcomes. Lancet 367(9516), 1101-1111.

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