III. PUTTING IT ALL TOGETHER.Nutrition intervention is best done using published guidelines. Clinical management guidelines linked to performance-improvement pro- cesses are useful to prevent errors, initiate nutrition interventions, and guide safe ther- apy. Periodic updates of all protocols should be performed. Utilizing specialized nutrition teams and a registered dietitian skilled in NI are recommended.
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76 The Trauma Manual: Trauma and Acute Care Surgery Specific NI includes the following categories:
1. Oral intake at will 2. Controlled starvation 3. Enteral nutrition 4. Parenteral nutrition 5. Oral nutrition supplements
Inevitably, NI will fall into one or more of these categories. The option chosen will depend on a careful evaluation of the benefits and risks of a given choice, as well as a comparison with alternative interventional options. The physician should consider the following factors in determining how to make this decision.
A. Oral intake at will.Most adult human beings are able to maintain adequate nutri- tion intake, constantly meeting demands of water, electrolytes, vitamins, micro and macronutrients through volitional intake, and physiologic cues of thirst and hunger.
Oral intake is the simplest and most natural way to provide adequate nutrition.
Trauma and critical illness dramatically interfere with the capacity of the patient to maintain normal oral intake. Critically ill and injured patients with altered mental status may be at risk of vomiting and aspiration, have poor splanchnic perfusion or recent GI surgery putting them at risk for complications if allowed oral intake.
In addition, disease frequently causes a significant degree of anorexia. Furthermore, access to food may be limited in the hospital. These problems obligate the surgeon to intervene. Careful evaluation of the nutritional history on arrival of the patient, followed by adequate monitoring of caloric/protein intake and a well-constructed plan of NI, is essential.
Oral intake at will should be allowed if possible and daily assessment of intake is desirable. Incorporating the patient and family into discussions of NI is often feasible and may be beneficial for the psychological well-being of the patient; empowering the patient to maintain some degree of control of his/her own care may bring significant benefits.
B.Controlled starvation.The decision to prevent oral intake occurs frequently in hospitalized patients. Virtually any member of the health care team can stop or pre- vent a patient from obtaining adequate oral intake. Orders for “NPO” or “clear flu- ids” are frequently inappropriate or unnecessary and may be detrimental for patient care.
Short-term “starvation” in the hospital is allowable on otherwise healthy human beings as it can be tolerated for short periods with no apparent ill effects.
During starvation, complex biologic mechanisms are induced that allow protection and sparing of resources and stores. For example, increased utilization of lipid occurs when glycogen stores are depleted, protein turnover is significantly decreased, and energy expenditure is significantly reduced. As a result of these metabolic adaptive changes, healthy individuals can maintain normal organ function for weeks or even months at a time. Eventually, these protective mechanisms fail if starvation is pro- longed and malnutrition with organ dysfunction occurs.
In critical illness, protective mechanisms observed during starvation become ineffective and malnutrition occurs faster. Increased gut permeability and dysmotility in the traumatized patient can occur with starvation beyond 24 hours. Caloric and protein deficits build rapidly increasing morbidity and mortality. Every effort should be made to minimize starvation in the trauma patient.
C. Enteral nutrition (EN).Most trauma patients are able to tolerate oral or enteral intake within the first 24 hours following the injury.The most important limiting factor for early EN is the presence of shock and poor gut perfusion.Early EN is associated with easier tolerance to a diet and decreased infection rates. Enteral nutrition increases wound healing and decreases length of stay. Early enteral nutrition may decrease mortality and has become the standard of nutrition interventions in the critically ill and trauma patient.
1.Although it is clear that early EN is beneficial, the amount that needs to be deliv- ered early is still debated. Proponents of early aggressive EN to meet caloric goals (increasing volume of delivery), suggest that mortality is proportional to the “caloric debt” accumulated early in the course of disease; opponents refute
Chapter 8 rNutritional Intervention 77 these observations and suggest that the risks of aggressive EN outweighs the benefits. Yet others suggest starting early EN along with supplemental use of TPN. In view of this controversy, the guidelines published by the Society of Crit- ical Care Medicine and the American Society of Parenteral and Enteral Nutri- tion (SCCM/ASPEN) compromise by stating that a reasonable goal is to provide 50% and 65% of caloric goals by the end of the first week in the intensive care unit.
2.Enteral nutrition does have complications, including those stemming from the placement of a feeding tube, gastrostomy, or jejunostomy. Diarrhea occurs in up to 30% of patients and enteral feeding may also lead to vomiting and aspiration.
A major, although rare complication of EN, is that of bowel necrosis, which is observed when aggressive volumes of EN are delivered, especially in the presence of poor bowel perfusion and shock. Careful evaluation of the risks and benefits of early EN, along with increased supervision of the patient are necessary in the hemodynamically unstable patient.
3.Tube placement and confirmation is important. The tip of the nasoenteral feeding tube can be left in the stomach or advanced into the duodenum or jejunum. Naso- jejunal tube feeds appear better tolerated than nasogastric tube feeds and may be associated with less aspiration. In a recent report, up to 2% of the nasoenteral feeding tubes were misplaced within the tracheobronchial tree. Confirmation of a correct position within the stomach by using an abdominal x-ray or chest x-ray is highly recommended before usage. “Tube migration” into the small bowel from the stomach usually occurs quickly, can be enhanced with bedside fluoroscopic manipulation.
D. Total parenteral nutrition (TPN).The advent of TPN in 1968 allowed the pro- vision of complete nutritional support delivered by a central venous catheter. TPN has undoubtedly saved innumerable patients from a certain death when the gastroin- testinal tract is not available. TPN indications include:
1.Severely malnourished patient who cannot eat and will be undergoing elective surgery. In this patient population, TPN decreases complications.
2.Patients with short gut syndrome.
3.Patients where enteral nutrition has failed for at least 1 week.
TPN is not indicated when the gastrointestinal tract is functional or during short periods of starvation.Recent work performed by Casear and others, in over 4,000 patients, demonstrated that “supplemental TPN” in patients who were starved or in patients where enteral nutrition failed to meet caloric goals during the first week, showed that supplemental TPN was associated with poor outcomes including increased days on ventilator, increased incidence of infections, increased days on dialysis, and a trend toward decreased mortality. Blood sugars were also moderately elevated in the TPN group.
TPN requires close attention for ordering (composition, additives, rate) line placement, and monitoring. Nutrition teams should work with the primary surgical and critical care team in all cases and standardized guidelines for insertion site care and laboratory monitoring are available. In addition, this nutritional sup- port team and pharmacists skilled in the use of parental nutrition should tailor the macro- and micronutrients delivered based on the patient’s goals and needs. Careful monitoring for side effects, complications, and efficacy is required.
E. Oral nutrition supplements.There is a growing variety of nutritional supple- ments, which can be categorized into three basic categories:
1.Nutritionally complete oral nutritional supplements (ONS). These supplements are intended to provide all the nutrients necessary for an otherwise normal indi- vidual. Complete ONS can come with higher protein concentrations and are advocated for the trauma patient with significant wounds. Data suggests a pos- sible beneficial effect including decreased infections with the use of high-protein ONS in patients undergoing surgery for hip fractures.
2.Fortified nutritional supplements. These supplements supply specific nutrients and are given for specific conditions in a patient who may otherwise have a normal dietary intake. These supplements are not to be used as the sole source of nutrition.
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An example is improved wound healing with the use of supplemental arginine, vitamin C, or vitamin E in patients with chronic wounds.
3.Specialized ONS. These supplements are considered ONS and are designed to be used for patients with special needs. Examples of specialized ONS include those prescribed for patients with diabetes or chronic renal failure.