Does the timing and route of nutritional support have an effect on survival and disability in head-injured patients?

After a moderate or severe head injury, patients use more energy as their body's metabolism is working at a greater rate. This increases the body's nutritional requirements which may lead to malnutrition and other complications.

Patients are often unable to meet the increased requirements by oral feeding alone, even if oral feeding is possible, therefore other methods are required. However, the method and timing of nutritional support can differ. Some can be started immediately following head injury but others may be delayed until the digestive system is found to be functioning.

Enteral nutrition is provided by inserting a feeding tube via the nose or mouth, into the stomach or small intestine. The feeding tube delivers a liquid formula containing the required nutrients. Total parenteral nutrition (TPN) provides an alternative to conventional enteral feeding. Parenteral nutrition means feeding someone via their blood stream (intravenously). Total parenteral nutrition (TPN) means that a patient is only fed intravenously. This method may carry risks of infectious complications.

It is unclear whether the timing and route of the administration of nutrition has an effect on mortality and morbidity of head-injured patients. The authors of this a systematic review searched for all high quality trials to determine the best timing (early or delayed), and route (enteral or parental) of nutritional support following head injury.

The authors identified 11 eligible trials that investigated the timing and route of nutritional support in head-injured patients. These trials included a total of 534 patients. However, of the many of the trials had methodological weaknesses.

The authors found that early feeding may be associated with fewer infections and a trend towards better outcomes in terms of survival and disability. However, the trials were small so any improvements detected were on a small scale. Also the focus of many of the trials was on nutritional outcomes, and many did not report the effect on death and disability. The authors were unable to obtain data for death and disability for all of the included trials so they feel there may be a possibility of bias. Further trials of nutritional support following head injury are required. These trials should report death and disability as well nutritional outcomes. They should also be large enough to detect clinically important treatment effects.

Authors' conclusions: 

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

Read the full abstract...
Background: 

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

Objectives: 

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

Search strategy: 

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

Selection criteria: 

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

Data collection and analysis: 

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

Main results: 

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

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