1. Metabolic Response to Stress, Injury or Surgery
Metabolism of substrates and micronutrients is altered by starvation and trauma. During periods of starvation, metabolic processes slow down to conserve energy and adapt to calorie deprivation. After trauma, the body’s hormonal situation changes, increasing the demand for energy, proteins, and micronutrients. If nutritional requirements are not recognized and met during starvation or trauma, there may be a loss of body mass, body protein, and impairment or loss of body functions.

2. Objectives The effects of trauma /Surgery on metabolism
Consequences of the metabolic response
Determination of calorie and protein requirements during metabolic stress
Lesson objectives are:
Explain the differences between metabolic responses to starvation and trauma.
Explain the effect of trauma on metabolic rate and substrate utilization.
Determine calorie and protein requirements during metabolic stress.
This session will also review macronutrients during metabolic stress, highlighting the role of conditionally-essential nutrients in specific situations.

3. Metabolism......?
All chemical reactions involved in maintaining the living state of the cells and the organism
Metabolism is closely linked to nutrition and the availability of nutrients i.e Nutrition is the key to metabolism.Food provides a variety of substances that are essential for the building and repair of body tissues, and for the efficient functioning of the body

4. Metabolism of substrates and micronutrients is altered by trauma.
After trauma, the body’s hormonal situation changes, increasing the demand for energy, proteins and micronutrients.
If nutritional requirements are not recognized and met during starvation or trauma, there may be a loss of body mass, body protein, and impairment or loss of body functions.

5. Increased growth hormone release stimulates protein synthesis

6. Mediating the Response
The Endocrine System
Pituitary Gland (↑ GH, ↑ ACTH,)
Adrenal Gland (↑ Cortisol, Aldosterone)
Pancreatic (↑Glucagon,  Insulin)
Others (Renin, Angiotensin,  Sex hormones,  T4)
The net effect of the endocrine response to surgery is an increased secretion of catabolic hormones
Lesson objectives are:
Explain the differences between metabolic responses to starvation and trauma.
Explain the effect of trauma on metabolic rate and substrate utilization.
Determine calorie and protein requirements during metabolic stress.
This session will also review macronutrients during metabolic stress, highlighting the role of conditionally-essential nutrients in specific situations.

7. Mediating the Response
Afferent Neuronal impulses from the site of injury  Hypothalamus
Efferents to sympathetic Nervous system  Adrenal Medulla↑ catecholamines (tachycardia, hypertension)
Lesson objectives are:
Explain the differences between metabolic responses to starvation and trauma.
Explain the effect of trauma on metabolic rate and substrate utilization.
Determine calorie and protein requirements during metabolic stress.
This session will also review macronutrients during metabolic stress, highlighting the role of conditionally-essential nutrients in specific situations.

8. Mediating the Response
The endothelium, activated leucocytes and fibroblasts produce Cytokines (IL /INF)
These act on their target cells to produce different proteins
Lesson objectives are:
Explain the differences between metabolic responses to starvation and trauma.
Explain the effect of trauma on metabolic rate and substrate utilization.
Determine calorie and protein requirements during metabolic stress.
This session will also review macronutrients during metabolic stress, highlighting the role of conditionally-essential nutrients in specific situations.

9. Mediating the Response
The Acute Inflammatory Response
Cellular activation
Inflammatory mediators (TNF, IL1, etc)
Lesson objectives are:
Explain the differences between metabolic responses to starvation and trauma.
Explain the effect of trauma on metabolic rate and substrate utilization.
Determine calorie and protein requirements during metabolic stress.
This session will also review macronutrients during metabolic stress, highlighting the role of conditionally-essential nutrients in specific situations.

10. Consequences of the Response
Mobilization of substrates
Lesson objectives are:
Explain the differences between metabolic responses to starvation and trauma.
Explain the effect of trauma on metabolic rate and substrate utilization.
Determine calorie and protein requirements during metabolic stress.
This session will also review macronutrients during metabolic stress, highlighting the role of conditionally-essential nutrients in specific situations.

11. Trauma/surgery causes major alterations in energy and protein metabolism.
The response to trauma can be divided into the ebb phase and the flow phase.
The ebb phase occurs immediately after trauma and lasts from hours followed by the flow phase.After this, comes the anabolism phase and finally, the fatty-replacement phase.

12. Phases – Physiological response
Injury
EBB
FLOW
RECOVERY
Hours
Days
Weeks
SHOCK
CATABOLISM
ANABO LISM
BREAKING DOWN ENERGY STORES
BUILDING UP USED ENERGY

13. Metabolic Response to Trauma: Ebb Phase
Characterized by hypovolemic shock
Priority is to maintain life/homeostasis
 Cardiac output
 Oxygen consumption
 Blood pressure
 Tissue perfusion
 Body temperature
 Metabolic rate
The ebb phase is characterized by hypovolemic shock. Cardiac output, oxygen consumption and blood pressure all decrease, thereby reducing tissue perfusion. These mechanisms are usually associated with hemorrhage. Body temperature drops. The reduction in metabolic rate may be a protective mechanism during this period of hemodynamic instability.
Cuthbertson DP, et al. Adv Clin Chem 1969;12:1-55 Welborn MB. In: Rombeau JL, Rolandelli RH, eds. Enteral and Tube Feeding. 3rd ed. Philadelphia, PA: WB Saunders; 1997.
Cuthbertson DP, et al. Adv Clin Chem 1969;12:1-55 Welborn MB. In: Rombeau JL, Rolandelli RH, eds. Enteral and Tube Feeding. 3rd ed. 1997

14. The ebb phase is characterized by hypovolemic shock.
Cardiac output, oxygen consumption and blood pressure all decrease, thereby reducing tissue perfusion.
These mechanisms are usually associated with hemorrhage.
Body temperature drops.
The reduction in metabolic rate may be a protective mechanism during this period of hemodynamic instability.

15. Metabolic Response to Trauma: Flow Phase
 Catecholamines
 Glucocorticoids
 Glucagon
Release of cytokines, lipid mediators
Acute phase protein production
The ebb phase is characterized by hypovolemic shock. Cardiac output, oxygen consumption and blood pressure all decrease, thereby reducing tissue perfusion. These mechanisms are usually associated with hemorrhage. Body temperature drops. The reduction in metabolic rate may be a protective mechanism during this period of hemodynamic instability.
Cuthbertson DP, et al. Adv Clin Chem 1969;12:1-55 Welborn MB. In: Rombeau JL, Rolandelli RH, eds. Enteral and Tube Feeding. 3rd ed. Philadelphia, PA: WB Saunders; 1997.
Cuthbertson DP, et al. Adv Clin Chem 1969;12:1-55 Welborn MB. In: Rombeau JL, Rolandelli RH, eds. Enteral and Tube Feeding. 3rd ed. 1997

16. Key catabolic elements of flow phase
Hypermetabolism
Alterations in skeletal muscle
protein
Alterations in Liver proteins
Insulin resistance

17. Metabolic Response to Trauma
Fatty Acids
Glucose
Amino Acids
Fatty Deposits
Liver & Muscle (glycogen)
Muscle (amino acids)
Endocrine Response
Endocrine response in the form of increased catecholamines, glucocorticoids and glycogen, leads to mobilization of tissue energy reserves. These calorie sources include fatty acids and glycerol from lipid reserves, glucose from hepatic glycogen (muscle glycogen can only provide glucose for the involved muscle) and gluconeogenic precursors (eg, amino acids) from muscle.

18. These calorie sources include
Endocrine response in the form of increased catecholamines, glucocorticoids and glycogen, leads to mobilization of tissue energy reserves.
These calorie sources include
fatty acids and glycerol from lipid reserves,
glucose from hepatic glycogen (muscle glycogen can only provide glucose for the involved muscle) and gluconeogenic precursors (eg, amino acids) from muscle.

19. The response to trauma includes a breakdown of muscle tissue.
This mechanism provides amino acids for gluconeogenesis and for synthesis of proteins involved in immunologic response and tissue repair.
However, this process can lead to a loss of body mass, most notably body protein.

20. Prolonged metabolic stress without provision of adequate calories and protein leads to impaired body functions and ultimately malnutrition.

21. Metabolic Response to Trauma28 24 20 16 12 8 4
Nitrogen Excretion (g/day)
This slide illustrates nitrogen losses in relation to trauma. With respect to protein, the greater the trauma, the greater the effect on the nitrogen balance. Similar to metabolic rate, patients experience nitrogen losses according to the severity and duration of the trauma.
The normal range is indicated by the shaded area. The amount of protein requirement relative to calories increases in patients with metabolic stress.
Long CL, et al. JPEN 1979;3:
Days
Long CL, et al. JPEN 1979;3:

22. Previous slide illustrates nitrogen losses in relation to trauma.
With respect to protein, the greater the trauma, the greater the effect on the nitrogen balance.
Similar to metabolic rate, patients experience nitrogen losses according to the severity and duration of the trauma.

23. Severity of Trauma: Effects on Nitrogen Losses and Metabolic Rate
Basal Metabolic Rate
Cirugía
mayor
Cirug í a
electiva
Infecci ó n
Sepsis
grave
Quemadura
moderada a grave
Nitrogen Loss in Urine
Major
Surgery
Elective
Infection
Severe
Moderate to Severe
Burn
This graph illustrates that severity of injury correlates to increasing urinary nitrogen loss and increasing energy needs. Elective surgery being least traumatic and the lowest nitrogen loss in urine, whereas burn results in an increase in basal metabolic rate and urinary loss of nitrogen.
Adapted from Long CL, et al. JPEN 1979;3:
Adapted from Long CL, et al. JPEN 1979;3:

24. The graph illustrates that severity of injury correlates to increasing urinary nitrogen loss and increasing energy needs.
Elective surgery being least traumatic and the lowest nitrogen loss in urine, whereas burn results in an increase in basal metabolic rate and urinary loss of nitrogen.

25. Estimation of energy requirements
There are a wide variety of methods for estimating energy requirements.
Common methods include indirect calorimetry and the Harris-Benedict Equation.

26. Indirect calorimetry is based on calculating heat production by measuring oxygen consumed and carbon dioxide produced, through analysis of exhaled gas or use of pulmonary catheters.

27. The Harris-Benedict Equation calculates basal energy requirements for healthy people
It has also been applied to sick patients through the use of correction factors for stress and activity.
The simplest estimate of adequate energy intake for patients in metabolic stress is the “rule of thumb” of kcal/kg body weight per day.

28. Determining Calorie Requirements
Indirect calorimetry
Harris-Benedict x stress factor x activity factor
25-30 kcal/kg body weight /day
There are a wide variety of methods for estimating energy requirements. Common methods include indirect calorimetry and the Harris-Benedict Equation.
Indirect calorimetry is based on calculating heat production by measuring oxygen consumed and carbon dioxide produced, through analysis of exhaled gas or use of pulmonary catheters.
The Harris-Benedict Equation calculates basal energy requirements for healthy people, but has also been applied to sick patients through the use of correction factors for stress and activity.
The simplest estimate of adequate energy intake for patients in metabolic stress is the “rule of thumb” of kcal/kg body weight per day.

29. Metabolic Response to Starvation and Trauma: Nutritional Requirements
Example:
Energy requirements for patient with cancer in bed
= BEE x 1.10 x 1.2
Injury
Minor surgery
Long bone fracture
Cancer
Peritonitis/sepsis
Severe infection/multiple trauma
Multi-organ failure syndrome
Burns
Stress Factor
1.00 – 1.10
1.15 – 1.30
1.10 – 1.30
1.20 – 1.40
1.20 – 2.00
When the Harris-Benedict Equation is used to calculate energy requirements, estimated basal energy expenditure is multiplied by a stress factor. As shown in this slide, the stress factor for a long bone fracture is , resulting in a metabolic rate increase of 15%-30%. Burns have a greater impact on energy requirements, increasing basal energy expenditure by 20%-100%.
In addition, activity factor of 1.2 or 1.3 must be multiplied to determine the energy requirement.
ADA: Manual of Clinical Dietetics. 5th ed. Chicago: American Dietetic Association; Long CL, et al. JPEN 1979;3:
Activity
Confined to bed
Out of bed
Activity Factor
1.2
1.3
ADA: Manual Of Clinical Dietetics. 5th ed. Chicago: American Dietetic Association; 1996
Long CL, et al. JPEN 1979;3:

30. Macronutrients requirements during Stress
Carbohydrate
At least 100 g/day needed to prevent ketosis
Carbohydrate intake during stress should be between 30%-40% of total calories
Glucose intake should not exceed 5 mg/kg/min
Delivery of appropriate substrates or macronutients is essential. Patients require at least 100g of glucose per day during metabolic stress to prevent ketosis. During hypermetabolic stress, a carbohydrate level of 30%-40% of total calories is recommended. Glucose intake should not exceed 5 mg/kg/min.
Barton RG. Nutr Clin Pract 1994;9:
ASPEN Board of Directors. JPEN 2002;26 Suppl 1:22SA.
Barton RG. Nutr Clin Pract 1994;9:
ASPEN Board of Directors. JPEN 2002; 26 Suppl 1:22SA

31. Macronutrientes during Stress
Fat
Should provide 20%-35% of total calories
Maximum recommendation for intravenous lipid infusion: g/kg/day
Monitor triglyceride level to ensure adequate lipid clearance
Dietary fat should provide between 20-35% of total calories. Maximum recommended infusion rate when administering intravenous lipids is g/kg/day. Serum triglyceride levels in stressed patients should be monitored to ensure adequate lipid clearance.
Barton RG. Nutr Clin Pract 1994;9:
ASPEN Board of Directors. JPEN 2002;26 Suppl 1:22SA
Barton RG. Nutr Clin Pract 1994;9:
ASPEN Board of Directors. JPEN 2002;26 Suppl 1:22SA

32. Macronutrientes during Stress
Dietary fat should provide between 20-35% of total calories. Maximum recommended infusion rate when administering intravenous lipids is g/kg/day. Serum triglyceride levels in stressed patients should be monitored to ensure adequate lipid clearance.

33. Macronutrients during Stress
Protein
Requirements range from g/kg/day during stress
Comprise 20%-30% of total calories during stress
Protein requirements increase during metabolic stress and are estimated at between g/kg/day, or approximately 20% to 30% of the total calorie intake during stress.
Barton RG. Nutr Clin Pract 1994;9:
ASPEN Board of Directors. JPEN 2002;26 Suppl 1:22SA
Barton RG. Nutr Clin Pract 1994;9:
ASPEN Board of Directors. JPEN 2002;26 Suppl 1:22SA

34. Protein requirements increase during metabolic stress and are estimated at between g/kg/day, or approximately 20% to 30% of the total calorie intake during stress.

35. Determining Protein Requirements for Hospitalized Patients
Stress Level
Calorie:Nitrogen Ratio
Percent Potein / Total Calories
Protein / kg Body Weight
No Stress
Moderate Stress
Severe Stress
> 150:1 :1
< 100:1
< 15% protein
15-20% protein
> 20% protein
Calorie-to-nitrogen ratios can be used to prevent lean body mass from being utilized as a source of energy. Therefore, in the non-stressed patient, less protein is necessary to maintain muscle as compared to the severely stressed patient.
Nitrogen balance can be affected by the biological value of the protein as well as by growth, caloric balance, sepsis, surgery, activity (bed rest and lack of muscle use can promote nitrogen excretion), and by renal function.
0.8 g/kg/day
g/kg/day
g/kg/day

36. Calorie-to-nitrogen ratios can be used to prevent lean body mass from being utilized as a source of energy. Therefore, in the non-stressed patient, less protein is necessary to maintain muscle as compared to the severely stressed patient.

37. Micronutrients
Micronutrients, trace element, vitamin, and mineral requirements of metabolically stressed patients seem to be elevated above the levels for normal healthy people.
There are no specific dosage guidelines for micronutrients and trace elements, but there are plausible theories supporting their increased intake.
The following slide lists some of these nutrients along with the rationale for their inclusion.

38. Key Vitamins and Minerals
Vitamin A
Vitamin C
B Vitamins
Pyridoxine
Zinc
Vitamin E
Folic Acid, Iron, B12
Wound healing and tissue repair
Collagen synthesis, wound healing
Metabolism, carbohydrate utilization
Essential for protein synthesis
Wound healing, immune function, protein synthesis
Antioxidant
Required for synthesis and replacement of red blood cells
Micronutrient, trace element, vitamin, and mineral requirements of metabolically stressed patients seem to be elevated above the levels for normal healthy people.
There are no specific dosage guidelines for micronutrients and trace elements, but there are plausible theories supporting their increased intake.
This slide lists some of these nutrients along with the rationale for their inclusion.

39. Role of Glutamine in Metabolic Stress
Considered “conditionally essential” for critical patients
Depleted after trauma
Provides fuel for the cells of the immune system and GI tract
Helps maintain or restore intestinal mucosal integrity
Glutamine is one of the few nutrients included in the category of conditionally-essential amino acids.
Glutamine is the body’s most abundant amino acid and is involved in many physiological functions. Plasma glutamine levels decrease drastically following trauma.
It has been hypothesized that this drop occurs because glutamine is a preferred substrate for cells of the gastrointestinal cells and white blood cells. Glutamine helps maintain or restore intestinal mucosal integrity.
Smith RJ, et al. JPEN 1990;14(4 Suppl):94S-99S.
Pastores SM, et al. Nutrition 1994;10:
Calder PC. Clin Nutr 1994;13:2-8.
Furst P. Eur J Clin Nutr 1994;48:
Standen J, Bihari D. Curr Opin Clin Nutr Metab Care 2000;3:
Smith RJ, et al. JPEN 1990;14(4 Suppl):94S-99S; Pastores SM, et al. Nutrition 1994;10: Calder PC. Clin Nutr 1994;13:2-8; Furst P. Eur J Clin Nutr 1994;48:
Standen J, Bihari D. Curr Opin Clin Nutr Metab Care 2000;3:

40. Glutamine is one of the few nutrients included in the category of conditionally-essential amino acids.
Glutamine is the body’s most abundant amino acid and is involved in many physiological functions. Plasma glutamine levels decrease drastically following trauma.
It has been hypothesized that this drop occurs because glutamine is a preferred substrate for cells of the gastrointestinal cells and white blood cells. Glutamine helps maintain or restore intestinal mucosal integrity.

41. Arginine is also considered a conditionally essential amino acid.