Metabolic Response to trauma

What constitutes Trauma?

  1. Injury
  2. Major Surgery
  3. Infection
  4. Major Burns
  5. Ischemia
  6. Autoimmune response

Homeostatic control in trauma

Severe InjuryMetabolic responseProvides local and systemic environmentFacilitates healing

Metabolic response intensity and duration   Degree of tissue injury, severity of pain and complications that arise

Earlier it was thought that everyone has to go through these events, but by proper fluid, pain and nutritional management this can be avoided.

So how does metabolic response maintain homeostasis?

  1. Metabolic response tries to conserve fluid.
  2. Increase local blood flow and tissue perfusion.
  3. Provides adequate utilizable energy to injured tissue.

Mechanism of Metabolic Response-what stimulates it?

Pain

Injured tissueAfferent nerve fibersStimulation of sympathetic nervous systemStimulation of pituitary endocrine axisRelease of hormones

 

Volume loss

Body can compensate 500ml loss easily

 Greater than 500ml lossPlasma osmolality changesSympathetic afferent nerve stimulationIncreased catecholamines concentrationsRelease of ADH and aldosterone

 

Anesthesia

  1. General anesthesia has little effect on inflammatory response.
  2. Depolarising Muscle relaxants like Succinylcholine increases muscle metabolism which increases creatinine kinase and muscle breakdown.
  3. Hypotensive anesthesia mimics blood loss and stimulates metabolic response.

 

Inflammatory response

Local inflammationLocally acting paracrine and autocrine factorsRelease of cytokines in the circulation

 

Endotoxaemia

Severe injuryGut mucosal barrier damaged due to shockBacterial wall products–endotoxins exposed outside gut in circulationInflammatory response

 

Pathology of Metabolic response- what are the changes it causes?

Inflammatory reaction/ MODS/SIRS

Inflammatory responseRelease of vasoactive amines-IL6, IBb1,cytokinesFever, Tachycardia, Catabolic response

Sympathetic and neuro-endocrine response

 

 

Acute phase protein reaction

TraumaLiverNegative APP- Albumin, prealbumin and transferrin, when levels reduceDifferential oncotic pressure across capillariesWall damageFluid retentionARDS, sepsis

Coagulation response

Acute phase proteinsFibrinogenIncreased coagulationThrombotic episodes

 

Immune system activation

Stimulation of macrophages and neutrophilsSuppression of lymphocytesDamage to host cellsIncreased infections and tumor recurrence

 

Body composition changes

Mobilization of fat, glycogen, proteins for energyStimulation of IL1, IL6Increased body temperatureMetabolic rate increases 12% to every 1 degree Celsius rise in body temperature

 

Negative nitrogen balance leading to muscle loss.

 

Postop fatigue– in first month in 1/3rd of patients after major surgery.

 

Determinants of magnitude of metabolic response

  1. Magnitude of trauma
  2. Inter-individual variation mostly genetically influenced
  3. Diabetes
  4. Pain
  5. Ischemia reperfusion injuries—more blood more inflammatory cells
  6. Endotoxic
  7. Sepsis in GI surgery
  8. Pre-existent nutritional status
  9. Post-op complications
  10. Concurrent diseases- RA, IBS
  11. Smoking, nicotine up regulates pro-inflammatory cytokine production.

Modifying metabolic response

Reducing the stimulus

  1. Handle with care
  2. Gentle
  3. Soft tissue handling
  4. Reduce loss
  5. Avoid contamination with gut contents
  6. Careful suturing without strangulation

Nutritional support

  1. Enteral nutrition support stimulates gut functions and thereby reducing translocation of bacterial products.
  2. Glutamine is a major fuel which improves muscle protein synthesis and abolishes catabolic response.

Carbohydrates-

  1. Atleast 100gms/day needed to prevent ketosis.
  2. Intake during stress should be between 30-40% of total calories.
  3. Glucose intake should not exceed 5mg/kg/min

Fats-

  1. Provides 20-35% of total calories.
  2. Maximum recommendation for intravenous lipid infusion: 1-1.5 g/kg/day
  3. Monitor triglyceride levels to ensure adequate lipid clearance.

Proteins-

  1. Comprises 20-30% of total calories during metabolic recovery.
  2. Requirements ranges from 1.2-2 g/kg/day

Anaesthetic modifications

Epidural anesthesia reduces neuroendocrine, hyperglycemic and catabolic responses.

Selective digestive decontamination

  1. Done in major surgeries like cardiopulmonary bypass.
  2. Reducing the endotoxin and cytokine levels.

NSAIDs

  1. Reduces prostaglandin secretion.
  2. Reduces body temperature.
  3. Reduces metabolic rate.
  4. Reduces magnitude of APP response.
  5. Reduces inflammatory response overall.

Steroids

Given per or perioperatively reduces IL6, IL8 and TNFa production and thereby reducing the inflammatory response.

 

 

 

 

 

Leave a Reply

Your email address will not be published. Required fields are marked *