Metabolic response to trauma/ critical illness Flashcards
What are the various factors that can contribute to hyper-metabolic response
1) Sepsis
2) Fractures
3) Stress
4) Trauma
5) Burns
6) Major surgery
What are hormonal mediators of stress response?
1) Aldosterone
2) Anti-diuretic Hormone (ADH)
3) ACTH
4) Catecholamines
What is the role of aldosterone?
Causes renal retention
What is the role of ADH?
stimulates renal tubular water absorption
What is the role of ACTH?
Acts on aderenal cortex to release cortisol (glucocorticoids). (stimulates lipolysis and mobilized amino acids from skeletal muscles)
What hormones are the flow phase characterized by?
High levels of insulin predominant
Patients with type I diabetes may have episodes of _____ following an illness or injury
Ketoacidosis
What are the metabolic changes following a wound or trauma?
- Phagocytic release of mediators
- Rapid loss of fluid and electrolytes
- Hemorrhage
,Regarding metabolic changes following trauma rapid loss of fluid and electrolytes and hemorrhages lead to what?
Hypovolemia
Regarding metabolic changes following trauma, hypovolemia leads to what?
Secretion of: Catecholamines Aldosterone ADH Glucocorticoids
Regarding metabolic changes following trauma, release of catecholamines ect. is associated with what?
Increased proteolysis and lipolysis
What are the inflammatory mediators of stress response?
Cytokines
Complement
Eicosanoids
PAF
What are the general roles of the catecholamines, epinephrine and norepinephrine?
stimulate hepatic glycogenolysis, fat mobilization, gluconeogenesis
Where are catecholamines released from?
Adrenal medulla
Which cytokines are released by phagocytes in response to tissue damage, infection, inflammation?
Interleukins,
tumor necrosis factor (TNF),
eicosanoids
What are the roles of cytokines in response to tissue damage, infection, inflammation?
Promote wound healing,
increase blood supply,
Localize wound
Increase white cell counts and fascilitate migration
Responsible for fever (inc metabolic rate)
Stimulates acute phase protein synthesis
What 2 eicosanoids are important mediators of inflammation?
PGE2
PGF2-alpha
What is the Ebb phase also known as?
Unresuscitated Phase
What is the Flow phase also known as?
Adrenergic - corticoid
What is the Anabolic phase also known as?
Recovery/ convalescent phase
Nitrogen balance is _______ in the anabolic phase.
Positive
What is the nitrogen balance in the Ebb and Flow phase?
Negative
What characterizes the Ebb phase?
- Hypovolemia
- Shock
- Tissue hypoxia
Why do many patients have lactic acidosis in the Ebb Phase?
- Glucose is oxidized anaerobically to form lactate
- Low blood flow (impaired transport to liver - disrupt Cori cycle)
- May also be seen in flow phase
How is the metabolic rate in patients in the Ebb phase?
Decreased
How are the insulin levels in the Ebb Phase?
Normal to Low
Mostly low
Characteristically, how are the insulin levels in the Flow Phase?
High due to insulin resistance
How are the cardiac output, body temperature, and energy expenditures in the flow phase?
Increased
In the flow phase, there is an increase in circulating levels of what?
Catecholamines
Insulin
Glucagon/cortisol
inflammatory cytokines
Total body catabolism begins in what phase post trauma?
Flow phase
During the flow phase, catabolized muscle protein provides amino acids for the liver to synthesis of what?
Acute phase proteins
What are the acute phase proteins synthesized in the liver in the flow phase?
C-reactive protein
Alpha1-antitrypsin
Which amino acids are utilized for maintenance of immune function in the Flow phase?
Glutamine
Besides synthesis of acute phase proteins and maintenance of immune function, what else are amino acids used for during the flow phase?
Gluconeogensis precursors
-maintain blood glucose levels
Epinephrine and cortisol stimulated increased levels of what during the flow phase?
Lipolysis
- circulating free fatty acids
What hormone is characteristic in the flow phase?
Insulin
Which hormones contribute to insulin resistance in the flow phase?
Catecholamines
Cortisol
Cytokines
Regarding Carbohydrate metbolism, what is predominant in the flow phase?
Glucose productions
Hyperglycemia
The metabolic rate is proportional to what in the flow phase?
Extent and severity of injury
Why is there hyperglycemia during the ebb phase?
- Epinephrine & Glucorticoids stimulate glycogenolysis and gluconeogenesis
- Low insulin levels
What may patients with type I diabetes have episodes of following an injury/infection
Ketoacidosis
Why do patients with type I diabetes may have episodes of ketoacidosis following an injury/infection?
Patient does not respond to the normal doses of insulin due to the occurrence of insulin resistance
What is the definition of insulin resistance?
Any requirement of insulin during critical illness is greater than 200 Units/day
During the flow phase, what is the wound & hypoxic tissues convert most of the glucose to?
Lactacte (anaerobic glycolysis)
Once lactate is made in anaerobic glycolysis in the flow phase, where does it go?
Liver - Cori cycle
What are he energy providers for the brain in both flow phase and prolonged starvation?
Flow Phase: Glucose
Starvation: Glucose + Ketone bodies
Compare GLUT 4 activity in the flow phase and starvation.
Flow: low due to insulin resistance
Starvation: Low due to low levels of insulin
Why do patients with major trauma rapidly deplete their fat sotres?
Epinephrine/norepinephrine, glucocorticoids activate Hormone-Sensitive lipase causing high rate of TAG mobilization and oxidation.
Why is ketogenesis not observed in patients with major trauma?
- High insulin levels
- Peripheral tissues use free fatty acids or ketone bodies rapidly
Ketogenesis is __________ to severity of injury
inversely proportional
Protein catabolism is ______ to severity of illness.
proportional
Both critical illness and starvation are states of negative nitrogen balance, but protein depletion is_________ in critical illness.
More severe
How do you evaluate degree of muscle proteolysis?
Urine Urea Nitrogen (UUN) excretion in gms per day
What system in skeletal muscle cells is activated by stress/illness?
Ubiquitin-Proteasome system
Proteolysis of skeletal muscle during the flow phase is used for what?
- Hepatic gluconeogensis
- maintenance of immune system
Which two amino acids are the major type released during proteolysis after trauma?
Glutamine
Alanine
Acute phase proteins are synthesized by the liver in response to inflammation and are commonly used to monitor what?
Progress and prognosis of inflammation.
The degree of rise of the acute phase proteins is proportional to?
The severity of injury.
Extensive protein depletion after trauma results in what?
- Impaired wound healing
- Decreased immune response
- Breakdown of gut-mucosal barrier
- Decreased mobility/respiratory effort
- Increased predisposition to infection and hypermetabolism (vicious cycle)
How much body protein must be depleted for fatality to generally occur?
greater than 20-30%
In the anabolic/recovery phase, there is what?
Positive nitrogen balance and build up of tissue protein.
During the flow phase, what is characteristic regarding urea excretion in the urine?
Increased
What are the goals of nutritional management post trauma?
- Minimalize catabolism
- Meet protein, energy and micronutrient needs
- Establish and maintain fluid and electrolyte balance
- Plan nutrition therapy (oral, enteral, and/or parental nutrition)
What is the goal of nutritional support in regards to protein supplementation?
May not result in +N balance, but may slow down protein loss and increase protein synthesis.
Which amino acids are supplemented for enhancement of immune function?
Glutamine
Arginine
Which nutritional support preserves intestinal mucosal integrity better?
Enteral nutrition
better than perenteral
What is a prerequisite for enteral nutrition?
Functional GI tract
