THE USABILITY OF HARRIS-BENEDICT AND CURRERI EQUATIONS IN NUTRITIONAL MANAGEMENT OF THERMAL INJURIES

Annals of Burns and Fire Disasters - vol. XVIII - n. 3 - September 2005

THE USABILITY OF HARRIS-BENEDICT AND CURRERI EQUATIONS IN NUTRITIONAL MANAGEMENT OF THERMAL INJURIES

Spodaryk M.1 Kobylarz K.1,2

1 Polish-American Children’s Hospital, Collegium Medicum, Jagiellonian University, Cracow, Poland
2 Department of Anaesthesiology and Intensive Care Medicine, Collegium Medicum, Jagiellonian University, Poland

SUMMARY. This part of the paper presents an analysis of ways of meeting the energy requirements of burn patients, the amount of which is calculated on the basis of commonly employed mathematical equations. It is however demonstrated that these equations are unusable in particular clinical situations.

Part one


Introduction

Thermal injuries are associated with the need to supply patients with much more energy than required in other clinical situations.1-3 Nutritional action and its effect on wound healing are increasingly often described in articles dealing with the comprehensive management of severe burns. The authors of such articles usually present an incomplete description of protocols intended to satisfy patients’ metabolic needs, diet selection, and gastrointestinal access routes, as well as methods of diet administration.3-6 In the majority of publications, nutritional intervention procedures are limited to an account of the amount of energy supplied, which is calculated on the basis of the Harris-Benedict or Curreri equations, or to a definition of a high-protein/high-energy diet.3,4,7,8 Such an understanding of the problem does not allow for reproduction of the nutritional treatment protocol; it is also impossible to analyse the effectiveness of medical management and the true role of nutrition in wound healing.

As we know, the response of the body to a thermal injury is an increased metabolic rate, increased oxygen consumption, and elevated body temperature. The release of catecholamines, glucagons, and adrenal cortex hormones stimulates gluconeogenesis, glycogenolysis, and lipolysis, which triggers an increase of serum glucose and free fatty acid levels, resulting in impaired tolerance of energy carriers and thus hindering nutritional treatment.

The maximum daily glucose supply in adult patients is 7 g/kg of body mass, while in septic patients and individuals who have been injured (including a thermal injury) it should not exceed 3 g/kg of body mass - this determines an infusion rate of not more than 6-8 mg/kg/min in children and 3 mg/kg/min in adults.11-13 When the dose determined by the supply of 7-10 mg/kg of body mass/min (in children) and 3 mg/kg of body mass/min (in adults) is exceeded, hyperglycaemia follows, with glycosuria and metabolic acidosis. Administration of insulin in order to improve glucose tolerance and decrease glycaemia does not have the desired clinical effect, owing to tissue resistance to the hormone. It seems that insulin resistance, a phenomenon so characteristic of post-injury states, results from the hyperglycaemia-triggering effect of glucagon and catecholamines.5,6,12,13 The need to decrease fat emulsion doses to 20-30% of the total energy supply at an infusion rate not exceeding 150 mg/kg of body mass/hour limits the practical possibility of providing the energy supply that would follow from the commonly accepted mathematical equations.


Harris-Benedict equation

Males BEE = 66.47 + (13.75 x W) + [(5.0 x H) - (6.75 x A)]

Females BEE = 665.1 + (9.65 x W) + [(1.86 x H) - (4.668 x A)]

TEE = BEE x AF x IF x TF

TEE = total energy expenditure; BEE = basal energy expenditure

AF - activity factor: bed-ridden patient 1.2

active but bed-ridden patient 1.35

ambulatory patient 1.3

IF - injury factor: TBSA < 20% 1.5

TBSA 20-50% 1.8

TBSA > 50% 2.1

TF - thermal factor: 38 oC 1.1

39 oC 1.2

40 oC 1.3

41 oC 1.4



Curreri equation

TEE = (25 kcal x kg) + (40 kcal x % TBSA)


Simulated calculations of energy requirements in burned patients make it possible to determine the true value of the Harris-Benedict and Curreri equations in nutritional treatment


Simulation 1

Patient 1. Age, 30 yr; gender, male; body mass, 70 kg; height, 175 cm; burns involving 50% TBSA; body temperature, 39 oC

Question - Is the energy dose calculated based on commonly employed equations the same and can the above equations be alternatively employed?

Calculation of energy requirements in burned patients

  • Curreri equation: (25 kcal x kg) + (40 kcal x % TBSA)

    energy = (25 x 70) + (40 x 50) + 1750 + 2000 = 3750 (kcal)

  • Harris-Benedict equation:

    BEE = 66.47 + (13.75 x W) + [(5.0 x H) - (6.75 x A)]

    TEE = BEE x AF x IF x TF

    Energy: TEE = BEE x 1.2 x 1.8 x 1.2

    BEE = 66.47 + (13.75 x 70) + [(5.0 x 175) - (6.75 x 30)]

    BEE = 66.47 + 962.5 + [875 - 202.5]

    BEE = 66.47 + 962.5 + 672.5

    BEE = 1701.47

    TEE = 1701.47 x 1.2(AF) x 1.8(IF) x 1.2(TF)

    TEE = 4410.2 (kcal)

Conclusion 1

Curreri equation ¤ Harris-Benedict equation

Answer - The analysed equations employed in a patient with the same vital parameters and burn wound yield significantly different results and thus cannot be used alternatively.


Simulation 2

Question - Can the Curreri equation be employed in children with severe burns?

Patient 2. Age, 6 yr; body mass 20 kg; burn wound involving 50% TBSA

Energy = (25 x 20) + (40 x 50) = 500 + 2000 = 2500 (kcal)


2500 kcal

70% energy from glucose 30% energy from fat

1750 kcal 750 kcal

glucose: 1 g = 3.4 kcal fat: 1 g = 9.0 kcal

1750: 3.4 = 514.7 (g glucose) 750: 9.0 = 83.3 (g fat)

514.7 g: 20 kg: 1440 min 83.3 g: 20 kg: 24 h = 0.0179 (g/kg/min) = 0.174 (g/kg/h)

17.9 mg/kg/min 174 mg/kg/h


Conclusion 2

The Curreri equation cannot be employed to calculate energy requirements in children, since the supply of the resultant energy dose is impossible.

Answer - If nutritional treatment is provided according to the above result, the patient receives too much glucose and fat emulsions.


Simulation 3

Question - Can the Harris-Benedict equation be employed in severely burned adults?

Patient 1. Age, 30 yr; gender, male; body mass, 70 kg; height, 175 cm; burns involving 50% TBSA; body temperature, 39 oC

Energy calculated according to the Harris-Benedict equation: TEE = 4410.2 (kcal)


4410.2 kcal

70% glucose 30% fat

3087.14 kcal 1323.06 kcal

glucose: 1 g = 3.4 kcal fat: 1 g = 9.0 kcal

3087.14: 3.4 = 907.98 (g glucose) 1323.06: 9.0 = 147.0 (g fat)

908 g: 70 kg: 1440 min = 147.0 g: 70 kg: 24 h = 0.009 (g/kg/min) = 0.088 (g/kg/h.)

9.0 mg/kg/min 88 mg/kg/h


Conclusion 3

The Harris-Benedict equation cannot be employed in practice in calculations of energy requirements in severely burned adults.

Answer - The supply of such an amount of energy would lead to administering too much glucose to the patient, in excess of tolerance.

Discussion

An analysis of the above results of the simulated calculations leads to the following general conclusions:

  1. Calculating the energy dose on the basis of the Harris-Benedict or Curreri equations yields significantly variable results for the same parameters that are used to describe the patient and the wound. Thus, these equations should not be employed alternatively.
  2. In the majority of severely burned patients, it is objectively impossible to administer the amount of energy calculated on the basis of the above equations without provoking glucose and fat overdose.
  3. Tissue resistance to insulin that results from glucagon and catecholamine activity does not trigger a hypoglycaemic effect.

Nutritional treatment that determines the process of wound healing in burn disease is a difficult problem to implement. Attempts have been made to introduce high-energy solutions to combat hypermetabolism in the early phase of burn disease. Yet, as demonstrated by the simulated calculations, increasing the amount of energy supplied beyond the limits of metabolic tolerance resulting from the patient’s reaction to thermal injury inevitably leads to metabolic complications in nutritional treatment and hinders the course of therapy. Thus, what remains to be done is to pose the question of how we should understand reports describing nutritional interventions that are based on the mathematical equations cited in the literature on the subject and why the majority of publications do not present detailed protocols of nutritional treatment along with its negative side effects. It would appear that what we are dealing with here is the copying of methods that are not always understood or not necessarily used in clinical practice. How then are we to solve the issue of the appropriate calculation of energy supply? The answer is difficult, but it appears that the greatest benefit for the patient is achieved when we calculate an energy value based on the ratio of non-protein calories to grams of nitrogen, where the key element of reasoning is the amount of amino acids administered.

The optimum value of the above ratio is 150-200:1 for children and 120-150:1 for adults.


RESUME. Les Auteurs présentent une analyse des modalités de satisfaire les exigences énergétiques des patients brûlés, dont la quantité est calculée sur la base de certaines équations mathématiques communément utilisées. Cependant, ils démontrent que ces équations, dans certaines situations cliniques, ne peuvent pas être employées.


Bibliography

  1. Badetti C., Cynober L., Bernini V., Garabedian M., Manelli J.C.: Nutrition proteins and muscular catabolism in severely burnt patients. Comparative effects of small peptides or free amino acids. Ann. Fr. Anesth. Reanim., 13: 654-62, 1994.
  2. “The Merck Manual of Diagnosis and Therapy”, 14th ed., R. Berkow, Merck & Co., Inc., Rahway NJ, 1982.
  3. Bisgwa F., Pitzler D., Partecke B.D.: Initial management of severely burned patient from the surgical viewpoint. Unfallchirurg., 98: 180-3, 1995.
  4. Cabral L., Riobom F., Diogo C., Teles L., Cruzeiro C.: Toxic epidermal necrolysis - Lyell’s syndrome. Annals Burns and Fire Disasters, 17: 90-102, 2004.
  5. Koller J., Kvalteni K.: Early enteral nutrition in severe burns. Acta Chir. Plast., 36: 57-60, 1994.
  6. Warner B.W., Bower R.H.: Complications of therapy. In: “Nutritional Support in Critical Care”, 131-46, ed. Lang C.E., Aspen Publications, Aspen Inc., Rockville, Maryland, 1987.
  7. Marvaki C., Joannovich I., Kiritsi E., Iordanou P., Iconomou T.: The effectiveness of early enteral nutrition in burn patients. Annals Burns and Fire Disasters, 14: 192-6, 2001.
  8. El-Gallal A.R.S., Yousef S.M.: Our experience in the nutritional support of burn patients. Annals Burns and Fire Disasters, 15: 79-82, 2002.
  9. Cunningham J.J.: Factors contributing to increased energy expenditure in thermal injury: A review of studies employing indirect calorimetry. JPEN, 14: 649-56, 1990.
  10. Hennenberger A., Partecke B.D.: Therapy of the severely burned child from the paediatric intensive care viewpoint. Unfallchirurg., 98: 193-7, 1995.
  11. Heyland D.K., MacDonald S., Keefe L., Drover J.W.: Total parenteral nutrition in the critically ill patient. A meta-analysis.JAMA, 280: 2013-9, 1998.
  12. Spodaryk M.: Burn disease: Problems in nutritional support and their solutions. Abstract Book, Global Challenges in Paediatric Burn Care, Hong Kong, 2002.
  13. Spodaryk M., Puchal´a J.: Early total parenteral nutrition employing TPN v. 1,2 PATIsoft software in the treatment of children with massive burns. Surg. Childh. Intern., 2: 96-8, 1997.

Part two

STRATEGY OF NUTRITIONAL INTERVENTION IN SEVERE THERMAL INJURIES - MANAGEMENT ALGORITHM


SUMMARY. This part of the paper presents nutritional support in the comprehensive management of severe burns.

A body reacts to a thermal injury by increased metabolism: oxygen consumption increases, as well as body temperature, and the organism releases catecholamines, glucagons, and adrenal cortex hormones. The increased gluconeogenesis, glycogenolysis, and lipolysis trigger elevated serum glucose and free fatty acid levels, which leads to deteriorated tolerance of exogenous energy carriers.1-3 The maximum daily glucose supply in adult patients amounts to 7 g/kg of body mass, while in septic and post-injury states, including burns, the amount should not exceed 3 g/kg of body mass.1-3 When the dose of 7-10 mg/kg of body mass/min (in children) and 3 mg/kg of body mass/min (in adults) is exceeded, the patients usually present hyperglycaemia and metabolic acidosis. The tissue resistance to insulin that is associated with glucagon and catecholamine activity fails to induce hypoglycaemia following insulin administration, thus not allowing an increase in the glucose dosage.1,3 Another hindrance in nutritional treatment lies in abnormalities in visceral circulation, as also in disturbances of GI motility. A decelerated gastric emptying and peristaltic wave most likely result from side effects of analgesic drugs (opioids). H2 blockers employed to prevent bleeding from stress ulcers, as well as the delayed initiation of enteral feeding, both contribute to increasing dysfunction of the GI tract, additionally favouring bacterial translocation and overgrowth.

Assuming that both prolonged starving and an increased amount of energy achieved through carbohydrate or fat supply in excess of the normal tolerance threshold are disadvantageous for the patient from the viewpoint of nutritional treatment, we arrive at a full range of real problems in nutritional interventions in patients with burn disease.1 The metabolic effects of a thermal injury and the impossibility of supplying, in practice, the amount of energy calculated using the Harris-Benedict and Curreri equations impose a search for other solutions.

The strategy of nutritional support should be based on four principles:

  • early introduction of parenteral nutrition
  • continuation of parenteral nutrition for 24 h a day, without any intermission when the patient is in the operating room
  • early introduction of appropriate enteral artificial formulas
  • a shift from an artificial formula to a normal diet when burn wound healing is complete

Strategy of nutritional support

0-24 h after thermal injury

  1. Management of burn shock, following the principles of fluid resuscitation and pain management
  2. Preliminary procedures, necessary for initiating nutritional support:
    • central vein access
    • radiological monitoring of venous catheter tip placement
    • insertion of nasogastric tube, drainage of gastric contents

Having stabilized the patient, one may commence nutritional support per se. The choice of the nutrient administration route depends on the possibility of using existing GI tract motility function.


More than 24 h after injury

  • collect blood for biochemistry: blood ions, total protein, BUN, creatinine, AspAT, AlAT, TGL, ammonia and pH status, blood and urine glucose
  • introduction of parenteral nutrition immediately following burn shock control

The composition of parenteral nutrition fluid must be complete - the fluid contains amino acids, glucose, electrolytes, minerals, and trace elements calculated for the patient’s current requirements. In the first days of therapy, no vitamins need to be supplied. The solution has to be infused over 24 h. Supplementary fluid therapy - if needed owing to the patient’s clinical status - requires a separate venous access (e.g. a peripheral vein).

  • meeting 50% of the daily amino acid (protein) requirement

The daily dose of amino acids depends on the patient’s age, body mass, and metabolic requirements. Protein loss through the damaged skin does not affect the planned supply, since it is supplemented by infusions of albumin and blood products. One should bear in mind that amino acids administered intravenously are not used as a source of energy, but rather as a substrate for protein synthesis, thus facilitating wound healing.

  • calculation of energy dose based on the ratio of non-protein calories to grams of nitrogen (optimal value for children, 150-200:1; for adults, 120-150:1)

alpha = non-protein calories:grams of nitrogen after transformation:


non-protein calories = alpha x (g amino acids:6.25) (where non-protein calories = total amount of calories originating from glucose and fat;

g nitrogen = g amino acids:6.25;

6.25 = coefficient corresponding to amount of g proteins containing 1 g nitrogen)

Deep analgesia and sedation of the patient, in addition to sparing the respiratory muscles through prolonged ventilatory support, lead to decreased energy consumption, which makes it possible to limit energy administration. An early introduction of fat emulsion is associated with a reduction in the amount of glucose supplied to the patient, which excludes the necessity of insulin administration in individuals with abnormal carbohydrate tolerance.

  • administration of fat emulsions at a rate of 20-30% of the calculated energy from non-protein sources
  • the requirement for electrolytes and minerals varies and is defined based on lab results

The entire solution is prepared in agreement with the “All in one” principle - in a single nutrition bag.

  1. Introduction of another nasal tube to the jejunum in a gastroscopic procedure
  2. Continued gastric decompression through the nasogastric tube
  3. Introduction of enteral feeding

    The possibility of using the GI tract in nutritional treatment is mostly dependent on its motility. Gastric content retention is not an appropriate parameter in evaluating GI motility, especially in victims of injuries. Considerable gastric retention with effective GI motility is a well-known fact. That is why an appropriate solution is to supply the nutrients directly to the small intestine below the level of the Treitz ligament. Initially, the elementary diet should be diluted with water at a ratio of 1:1; infusion starts at a rate of 5-10 ml/h, with infusion gradually increasing over the subsequent days. On reaching a level of three-quarters of the target dietary volume, the concentration level is increased by reducing the volume of water added. This method of nutrition is contraindicated in the event of bleeding, perforation, or obstruction of the GI tract.

  4. Monitoring of patients and nutritional support

    The above tests may be performed more frequently if the clinical status of the patient requires such lab management.

    Thus, apart from analgesia, fluid therapy, and surgical wound debridement, nutritional support is an integral element of the comprehensive management of burn disease.

    -




    RESUME. Les Auteurs présentent ici le support nutritionnel dans la gestion compréhensive des grands brûlés.


    Bibliography

    1. Spodaryk M.: Burn disease: Problems in nutritional support and their solutions. Abstract Book, p. 22, ECPB Congress, Hong Kong, Nov. 2002.
    2. Spodaryk M., Puchal´a J.: Early total parenteral nutrition employing TPN v.1,2 PATIsoft software in the treatment of children with massive burns. Surg. Childh. Intern., 2: 96-8, 1997.
    3. “The Merck Manual of Diagnosis and Therapy”, 14th ed., R. Berkow, Merck & Co., Inc., Rahway NJ, 1982.

    This paper was received on 14 December 2004.
    Address correspondence to: Micolaj Spodaryk, MD, PhD, Polish-American Children’s Hospital, Collegium Medicum, Jagiellonian University, 265 Wielicka St., 30-663 Cracow, Poland. E-mail: mikobyla@cyf-kr.edu.pl

     

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