METABOLIC RESPONSE TO INJURY and its surgical implication in perioperative care

metabolic responses to injury and its surgical implications

1. METABOLIC RESPONSE TO INJURY

2. Metabolic response Systemic reaction to trauma/surgery Involves neuroendocrine, immune, and metabolic pathways Goal: survival & repair

3. Metabolic response Injury /surgery Local tissue inflammation systemic changes affecting organ function Surgical stress response 1. hormones 2. inflammation related cytokines 3. neural circuits

4. Surgical stress response alterations of body metabolism ,wound healing ,immunity collectively called metabolic response aim is to limit damage and initiate repair process

5. Metabolic response to injury Catabolic phase anabolic response Conserves circulating volume and energy sources tissue repair

6. Phases of Response Ebb Phase (0–48 hrs) ↓ Cardiac output, ↓ metabolism Hypothermia, lactic acidosis Mediators: catecholamines, cortisol 2. Flow Phase ↑ Cardiac output, hypermetabolism Fever, oedema, insulin resistance Driven by cytokines (IL-1, IL-6, TNF α) 3. Anabolic Phase Recovery stage Protein synthesis > breakdown Tissue repair & weight gain

7. Mediators Neuroendocrine ↑ Cortisol, adrenaline, glucagon Suppression of thyroid, GH–IGF axis Cytokines IL-1, IL-6, TNF α → fever, proteolysis, acute-phase proteins DAMPs/Alarmins Trigger SIRS → risk of MODS

8. Key Features Catabolism & muscle wasting (↑ proteolysis) Stress hyperglycemia (insulin resistance) Protein shifts: ↓ albumin, ↑ acute-phase proteins Fat mobilization: lipolysis Fluid retention: ADH & aldosterone → Na⁺, H₂O retention

9. Factors Prolonging Response Hypothermia Sepsis & infection Starvation Poor analgesia Secondary insults (e.g., haemorrhage, reperfusion injury)

10. Clinical Significance Adaptive if short-lived Harmful if prolonged → catabolism, sepsis, MODS Perioperative goals : Maintain normothermia Adequate analgesia Early enteral nutrition Prevent & treat sepsis

11. CONCLUSION Complex interplay of hormones + cytokines + immune mediators Short-term: protective Long-term: detrimental Surgical care aims to attenuate stress response and enhance recovery

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