Burn injuries trigger a complex cascade of metabolic alterations, including hypermetabolism and hypercatabolism. Adequate nutrition is crucial for burn patients to support the healing process, prevent complications, and minimize lean body mass loss. This article provides a comprehensive overview of nutritional needs, assessment methods, and support strategies for burn patients in both hospital and home settings.
The Hypermetabolic Response to Burn Injury
Severe burns cause extensive physical trauma, leading to a hypermetabolic state where the body's energy requirements are significantly increased. The basal metabolic rate of a burn patient may be twice their normal rate, resulting in severe weight and lean mass loss. This hypermetabolic response increases the risk of infection and delays wound healing. The nutritional requirement for burn patients is more extensive. The sustained healing can trigger a cascading effect that leads to the need for more calories.
Why Nutrition Matters
Without proper nutrition, burn patients are more prone to infections and weight loss. Adequate nutrition can reduce the damaging loss of lean body mass, stored energy, and protein. Meeting caloric needs and achieving a positive nitrogen balance are short-term goals of nutrition support, with long-term goals of minimizing lean body mass loss and maximizing wound healing.
Consequences of Inadequate Nutrition
A 2011 report published by The Surgical Clinics of North America highlights the severe impact of body mass loss:
- 10% loss: Severe impact on the immune system
- 20% loss: Decreased wound healing
- 30% loss: Severe infections
- 40% loss: Potential for death
Burn patients can lose as much as one-quarter of their body weight in the first three weeks if nutrition is not properly managed.
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Nutritional Assessment
The nutrition assessment of a burn patient includes obtaining pre-injury weight, height, medical history, biochemical data, medications, and physical examination data. A visible assessment prior to fluid resuscitation can be used to determine if temporal wasting or other signs of malnutrition are present. Recent weight loss and a timeline for any poor oral intake prior to injury should be determined when the patient can answer questions or if family members are present to provide this information.
Determining Dry Weight
The usual dry weight must be determined in order to properly use assessment calculations, as patients may be extremely hypervolemic. The usual dry weight can be determined using the medical record, admission weight minus any intravenous fluids provided prior to admission if it is a recent burn, an identification card (driver’s license/identification card), or a report per the patient or family.
Estimating Energy Needs
An accurate estimation of energy needs is crucial for avoiding underfeeding or overfeeding. The Milner equation is often used to determine the resting energy expenditure for patients with a ~ ≥20% TBSA burn, utilizing an activity factor of 1.4 in an effort to maintain weight, along with anabolic agents and physical therapy to maximize lean body mass retention and strength retention.
Monitoring Nutritional Intake
The calorie intake from enteral nutrition, parenteral nutrition, intravenous fluids, and oral intake is monitored from admission to healing. A calorie surplus (over 120% of goal) is avoided, as overfeeding can lead to ventilator dependence due to increased carbon dioxide production. The target enteral nutrition rate should be achieved within 48 h of admission, and 80-120% of the kcal goal should be met every day starting on hospital day 3, along with the achievement of a positive nitrogen balance.
Body Composition Analysis
Body composition analysis via DEXA is a valuable tool for assessing nutritional adequacy and monitoring changes over time in burn patients. Visceral proteins (prealbumin, transferrin, and retinol binding protein) are not measured, as they are not good indicators of nutrition status.
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Macronutrient Requirements
Carbohydrates
Carbohydrates are the primary source of energy for burn patients. The body will turn the carbohydrates into glucose. Burn wounds use glucose for energy. In fact, they can't use any other source. A higher carbohydrate and lower fat intake was found to lower the incidence of pneumonia and wound infection, decrease hospital LOS per percentage of TBSA burn, lower rates of PaO2/FiO2 < 200, and shorten the time to wound healing per percentage of TBSA burn in two individual RCTs evaluating a low-fat (≤15%) and high-carbohydrate (≥60%) intake.
Protein
Patients need a lot of protein while healing because the body will lose protein through the burn wounds and muscles will break down trying to produce extra energy for the healing process. Protein losses in burn patients are significantly elevated through both urinary losses and wound exudate, with a higher protein uptake in the wound beds due to utilization with wound healing. At least 1.5-2 g protein/kg per day is recommended. Alternatively, 25% of calories from protein can be used as the initial protein goal. Nitrogen balance studies can be conducted to better evaluate losses.
Fat
We also include fat in the diet to provide essential fatty acids and extra calories. But normally no more than 30% of the calories will come from fat. Adequate fat intake is important for preventing essential fatty acid deficiency; however, only 1-4% of total energy intake as fat is sufficient
Micronutrient Requirements
Burn patients utilize additional vitamin C due to increased oxidative stress and tissue damage. Individual patient assessments should guide the need for specific micronutrient supplementation.
Vitamins
- Vitamin C: Enhances collagen synthesis, aids in wound healing, and improves immune function.
- Vitamin E: May improve wound healing.
- Vitamin A: Plays a crucial role in wound healing, immune function, and epithelial cell differentiation. Supplementation can help promote re-epithelialization and reduce the risk of infections.
- Vitamin D: Low levels are common in burn patients. Deficiency is associated with lower bone mineral density, increased prevalence of long bone fractures, low scar elasticity, and decreased skin barrier function.
- Thiamine: Supplementation can aid in decreased lactate levels.
- Vitamin B12 and Folate: Supplemented if deficiencies are found, based on evaluations of methylmolonic acid and homocysteine levels.
Minerals
- Zinc: Deficiency is common and can impair wound healing and immune function. Supplementation is associated with improved wound healing rates, reduced infection rates, and enhanced immune response.
- Copper: Deficiency can occur with high doses of zinc. Copper deficiency results in poor wound healing, anemia, and neutropenia.
- Selenium: Burn injuries result in decreased selenium levels, and supplementation may have a beneficial effect on wound healing and infection rates.
- Iron: Plays a role in wound healing as a cofactor in collagen synthesis.
Electrolytes
If a patient is malnourished, extreme electrolyte disturbances are expected. However, phosphorus also significantly drops in well-nourished, hypermetabolic patients during nutrition initiation and must also be closely monitored and aggressively repleted. Due to this, intravenous sodium phosphate is started at 30 mmol every 6 h with the initiation of enteral nutrition. When unable to obtain phosphorus over 2 mg/dL, potassium over 3 mmol/L, and magnesium over 1 mg/dL, enteral nutrition is held or temporarily decreased until these levels are under control.
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Methods of Nutrition Support
Enteral Nutrition (EN)
Enteral nutrition (EN) is the preferred route of nutrition, as it aids in maintaining gut integrity, preserving immune function, and reducing the risk of infection. The initial goal for a burn patient is to start enteral nutrition as soon as clinically appropriate, within the first 24 h of admission. We use an enteral formulation with high protein and high carbohydrate provisions. Low-fat and high-carbohydrate formulas were found to improve healing and other outcomes in burn patients.
Initiating and Advancing Enteral Nutrition
Since the guidelines recommend waiting to start enteral nutrition until hemodynamic stability is achieved, albeit with no definition of hemodynamic stability, we clinically defined hemodynamic stability as lactate beginning to normalize (<3 mmol/L) and epinephrine or norepinephrine infusions under 0.15 mcg/kg/min and await these criteria before initiating enteral nutrition. Bowel sounds, stool output, and flatus are not used to determine if enteral nutrition can be initiated, as they are not good signs of bowel function. Enteral nutrition is initiated at 20 mL/h and increased by 20 mL/h every 4 h as tolerated, until the goal rate is achieved.
Adjustments for Procedures
Post-pyloric enteral nutrition can be held at the time of transport to surgery in patients with protected airways. Otherwise, enteral nutrition formulas can be held six hours prior to surgery. Clear liquids (e.g., clear supplement drinks or a maltodextrin mixture) can be continued orally, in the stomach, or post-pyloric until two hours before surgery. Toast or cereal (not with milk) can be allowed up to six hours before surgery. When there is a nasogastric/orogastric tube, the stomach is suctioned out in both the intensive care unit room prior to leaving for surgery and in the operating room prior to starting surgery to aid in preventing aspiration. Enteral nutrition can be resumed at the pre-surgical rate when the patient is hemodynamically stable after surgery.
Considerations for Medications
Enteral nutrition is not held for vasopressin or dobutamine. Enteral nutrition is held for epinephrine or norepinephrine at 0.15 mcg/kg/min. A catch-up rate is ordered to allow the nursing staff to automatically account for any time enteral nutrition is missed: the current enteral nutrition goal rate is increased by one-third for 3 h for every one hour of enteral nutrition missed.
Parenteral Nutrition
If a patient is not able to take in enough nutrition by mouth, he or she will likely need to be fed through a tube. If tube feeding is needed, a nasogastric tube (NG tube) is inserted into the nose and slid into the stomach. Depending on your child’s condition, the medical team may have a PICC (Peripherally Inserted Central Catheter) put in. A PICC is a plastic tube that is inserted into a large vein to give intravenous (IV) therapy (nutrition or medicine). Through the PICC line, liquid nutrition called TPN (Total Parenteral Nutrition) will be given.
Oral Diet
Patients should follow the diet plan. It's very important that they do everything they can to get proper nutrition. Encourage high calorie and high protein foods. There are many drinks available to add protein and calories to your diet. Milk is the easiest and least expensive option. Even though you may not have much of an appetite, we encourage patients to follow a diet high in calories and protein. Any patient who cannot meet their nutritional needs with PO intake.
Sustaining Nutrition at Home
Once a burn patient is home, it is critical to remember that their body needs fewer calories than when hospitalized. That can be a difficult adjustment to make, as well. While in the hospital, survivors eat large meals, so their appetite will be big. Once home, you must focus more on a balanced diet and avoid empty calories, processed foods, and sugar. Instead, provide lean meats, whole grains, and fruits and vegetables. The level of healing will help you determine how to focus on nutrition. For instance, survivors will need more protein if the burn wounds are still open. This is because the body breaks protein down into amino acids that serve as building blocks for new tissue.
Tips for Eating Right
The key is to find what foods help burns heal and follow the healthcare team's recommendations. Consider some tips to help you balance a burn patient's nutrition once they leave the hospital.
- High-Protein Diet: Every meal and snack should include protein to help wounds heal and build muscle.
- Include Carbohydrates: Carbohydrates provide glucose that supports healing and prevent the body from breaking down muscle.
- Reduce Meal Sizes and Calorie Intake: Focus on nutrition more than quantity.
- Keep Snacks On Hand: Fruit is an excellent option for energy and fiber. Avoid sugary drinks and candy.
- Stay Hydrated: Drink lots of water throughout the day.
- Make Meals Colorful: Experiment with different herbs and spices to find their favorites.
- Carefully Examine Hunger: Be mindful of emotional eating.
Nutrition for Children
While your child is healing, it is especially important for him to get good nutrition. Your child’s body needs extra energy while trying to heal. Your child will need to keep a daily record of what he or she eats and drinks. Food and liquids taken in by mouth (oral intake) will be recorded on a paper labeled ‘Calorie Counts’ that will be placed on the door to your child’s room each day. Recording how much your child goes to the bathroom helps the medical team know if he or she is eating and drinking enough. If your child is in diapers, do not throw the diapers away when you change them. It is important to keep the used diapers in the bathroom for staff to weigh them. If your child is potty trained, there will be a measuring device in the toilet for urine. Boys can use a urinal.
Conclusion
Nutrition plays a vital role in the recovery of burn patients. Understanding the hypermetabolic response to burn injury, accurately assessing nutritional needs, and implementing appropriate nutrition support strategies are essential for promoting wound healing, preventing complications, and improving patient outcomes. Whether in the hospital or at home, a well-balanced diet with adequate macronutrients and micronutrients is crucial for supporting the healing process and helping burn patients regain their strength and vitality.