2. Introduction
• The neuro endocrine /stress/ metabolic response is used to
maintain homeostasis
• Surgery/Injury evokes a series of hormonal and metabolic
changes commonly referred to as the stress response.
• These changes are important in:
− Preserving oxygen delivery,
– Mobilizing substrates,
– Limiting tissue damage,
– Destroying infectious organisms,
– Activating repair processes,
• The response is proportional to the degree of Injury or
surgical trauma.
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7. Most important Stimuli
• Pain: From trauma site
– Afferent fibers to hypothalamus
• Hypovolemia
– Baro-receptors
– Sympathetic activation
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The classical neuroendocrine pathways of the stress
response consist of afferent nociceptive neurones, the
spinal cord, thalamus, hypothalamus and pituitary
9. Other stimuli
– Tissue hypoxia or hypoxemia-(sensed by Chemo
receptors and message is sent to the CNS)
– Emotional arousal-(Autonomic nervous system)
– Infection-(Initiates systemic inflammatory
response)
– Changes in ambient and core temperature
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13. • Purpose of neuroendocrine changes following injury
The constellation of neuroendocrine changes following injury
acts to:
■ Provide essential substrates for survival
■ Postpone anabolism
■ Optimise host defence
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14. Adrenal response: Sympathetic
• Catecholamines released from the adrenal medulla by direct
sympathetic stimulation, results in tachycardia and HTN.
• It also alters the metabolism of glucose, fats and proteins.
• Sympathetic stimulation Renin released from renal
afferent arterioles triggers conversion of Angiotensin
I to II Aldostrone
– Increases the reabsorption of Na, water and Cl-
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16. Goals of Endocrine changes
• Cardiovascular stabilization in the presence of hypovolemia which
is brought about by baroreflex increase in sympathetic nervous
activity
• Maintain blood pressure through continuous peripheral
vasoconstriction
• Water and salt conservation
• The above three are prominent features in the early phase of the
neuroendocrine response
• Provision of ready energy to the muscles, heart and brain, RBC and
WBC
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17. Hormonal regulation of Metabolism
• Three mechanisms
-increase substrate availability
-alter the membrane transport properties of cells for a
given substrate
-alter the activity or synthesis of key regulatory enzymes
that are necessary for reactions to proceed
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18. Hormonal changes
Cortisol
-Increases in a few minutes
-Negative feed back fails
Effects
-Skeletal muscle breakdown
-Impaired glucose utilization
-Lipolysis
-Mineralo-corticoid effect
-Anti inflammatory [high dose]
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19. Catecholamines
• 3-4 fold increase after trauma and remain high for 24 to 48
hours
• Has got metabolic, immunomodulatory, and vasoactive effect
• Catabolic hormones
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20. Growth hormone
• Has mixed anabolic/catabolic
• Has got minor role in Surgery
• Effects-Glycogenolysis
-Lipolysis
-Inhibits glucose uptake
-Prevents muscle break down
-Enhances protein synthesis
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21. Prolactin and ADH
• The physiological effects of increased Prolactin during surgery are unknown
• ADH is an important anti diuretic, vasopressor and enhances haemostasis
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During surgery prolactin increase but after surgery it decrease so its better not to operate on a women while
lactating because there is decreased breast milk production
22. Glucagon
• Glucagon release:
– Promotes gluconeogenesis
– stimulates the breakdown of glycogen in the liver and
muscle
– increases glucose and lactate concentrations
– mobilization of free fatty acids (FFAs) from available
lipid stores.
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23. Aldosterone
• Mineralocorticoid released by Adrenal cortex in response to
stimulation by ACTH, angiotensin II, hypovolemia,
hyperkalemia
• Acts on distal convoluted tubules of the kidneys
-retention of Na, H2O, Cl
-eliminates K and H
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24. Insulin
• Anabolic Hormone
• It Promotes glucose utilization, glycogen synthesis and
Lipolysis is inhibited and muscle protein loss reduced
• ‘Insulin resistance’ by target cells occurs during catabolic
phase because of a defect in the insulin receptor/intracellular
signalling pathway.
• Thus, the peri-operative period is characterized by a state of
functional insulin deficiency
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25. Other hormones
• Circulating concentrations of T4 and T3 are inversely correlated with
sympathetic activity.
• After surgery there is a reduction in thyroid hormone production, which
returns to normal over a few days.
• Testosterone and estrogen concentrations are decreased for several
days…………..leading to decreased sexual drive
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27. • Avoidable factors that compound the response to
injury
■ Continuing haemorrhage
■ Hypothermia
■ Tissue oedema
■ Tissue underperfusion
■ Starvation
■ Immobility
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28. Metabolic response: Carbohydrates
• Hyperglycaemia is a major feature caused by increased glucose production and
reduction in glucose utilization.
• This is facilitated by catecholamines and Cortisol, which promote glycogenolysis and
gluconeogenesis and glucose infusions and blood products.
• The usual mechanisms of regulation are ineffective because of failure of insulin
secretion followed by insulin resistance.
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29. Metabolic response: Proteins
• Enhanced catabolism is the response we
expect in severe injury.
• Protein catabolism is stimulated by
increased cortisol and cytokine
concentrations.
• After major abdominal surgery, up to 0.5
kg/day of lean body mass may be lost.
• Acute phase proteins are increased but
albumin production is reduced.
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Protein[cardiac] usually last to remain
31. • Skeletal muscle wasting
■ Provides amino acids for protein synthesis in central
organs/tissues
■ Is mediated at a molecular level mainly by activation of the
ubiquitin–proteasome pathway
■ Can result in immobility and contribute to hypostatic
pneumonia and death if prolonged and excessive
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32. Metabolic response: Lipids
• Increased catecholamine, cortisol and glucagon secretion, in
combination with insulin deficiency, promotes lipolysis and
ketone body production.
• Triglycerides are metabolized to fatty acids and glycerol; the
latter is a gluconeogenic substrate.
• High glucagon and low insulin concentrations also promote
oxidation of FFAs to acyl CoA.
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33. Salt and water metabolism
• ADH secretion results in water retention, concentrated urine, and potassium loss
and this may continue for 3–5 days after surgery.
• Renin is secreted from the juxta-glomerular cells of the kidney secondary to
sympathetic afferent activation.
• It converts angiotensin to angiotensin I, which in turn is changed to angiotensin II by
alveolar cells
• Angiotensin II releases aldosterone from the adrenal cortex promoting sodium and
water retention from the distal convoluted tubule
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34. Effect of Metabolic Changes
• Severe injury ends up in marked tissue wastage and weight loss
which is partly due to semi starvation and partly to the
extreme catabolism which occurs in the immediate post injury
period.
• The intensity and duration of catabolic period depends on
-the severity of the injury
-complications like sepsis
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35. Phases of Metabolic Changes in Surgery/Injury
• Catabolic phase
-Hyperglycemia
-insulin resistance
-increased lipolysis serves as energy source
-increased urinary nitrogen excretion probably due to
exceeded rate of degradation to that of synthesis
-primarily muscle protein loss leading to tissue wastage, weight loss,
and chachexia
-continues till volume deficit is corrected, pain has been eliminated,
infection has been controlled, and complete oxygenation has been
restored
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36. Metabolic changes: Recovery
• Anabolic phase
• Insulin is the key hormone
• Reparative phase
• Slow but progressive reaccumulation of protein
• Re-accumulation of body fat
• May take longer time than catabolic phase
– Several weeks to months
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Severe burn has increased response while elective surgery elect less response
6 hrs golden hours in surgery
In people that live in high altitude where the co2 tension is high , the carotid bodies are continuously stimulated as a result it hypertrophy forming carotid sinus tumor
To maintain homeostasis
Weight loss significant : 5% in 1 month or 10 % in 6 month
The adrenal glands have a rich arterial supply from three main groups of inflow vessels ( figure 5 and figure 6 ) [ 8,12 ]:
Superior suprarenal arteries – The superior suprarenal arteries are derived from the inferior phrenic arteries, which pass just superior and medial to the adrenal glands. Each inferior phrenic artery gives off a series of branches to the ipsilateral adrenal gland before it supplies the diaphragm.
Middle suprarenal artery – The middle suprarenal artery is derived from the aorta.
The inferior suprarenal renal arteries – The inferior suprarenal arteries are derived from the adjacent renal artery.
- each adrenal gland has a single draining vein
Islets cells found at the tail of pancrease.
- But high dose insulin is given after surgery.
The main labile energy reserve in the body is fat, and the main labile protein reserve is skeletal muscle.
First few days after surgery , urine output lowers
