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Clinical Nutrition and Dietetics: Stress Response to Surgery - Coggle…

- - - - Net nitrogen excretion during trauma/ net breakdown of protein: rise in nitrogen excretion then drops. Most significant and delayed in major burn, major trauma/surgery with illness, major uncomplicated surgery then starvation (drops below 10g/day)
        
        uncomplicated injury (50-80 g N lost), ileus/malabsoprtion (150g N lost), severe injury (300-500g N lost). For every g N lost, around 26-35g muscle tissue= need to reduce surgery complications. Severe burns/ surgery around 9kg muscle lost.
      - In sepsis or injury, burns= 2/3 fold increase in AA from muscle (alanine and glutamine) which needed for APR proteins, leucocytes and proteins for wound healing and to turn into glucose for glucose dependent tissues
      - Muscle wasting in multi-organ failure- as stay increase, decrease in muscle depth
      - Chnages in Nitrogen
      - Normal individuals- maintain nitrogen balance at 0.75g/kg (0.12gN)
        
        Severe injury or sepsis (trauma/surgery)- 1.6g/kg (0.25gN) to reduce -ve balance but no further benefit after 0.2g N per kg so don't overfeed giving burden to liver.
        
        1.2g-1.5g/kg (PENG) for trauma or burns. Once no longer catabolic, will respond respond to N intake progressively
    - - Stress/trauma -> triggers 'fight or flight' -> digestion stopped -> glycogen stores depleted as glucose released into body -> hypothalamus triggers SNS which increases catecholamines secretion and stimulates renin secretion from kidneys (adolsterone release from kidneys and salt retention) ADH from kidneys so watee rretention after surgery also
        
        post-operative ileus chnaces increased if eat before surgery as surgery stops digestion
        
        Neuroendocrine pathway
        
        Rise in catecholamines secretion = MR increased by 15% (increased NEFA/TAG cycling, glucose products, lactate produced by glucose in wound and taken to liver to be converted to glucose / cory cycle,
        
        Growth hormones = stimulate protein synthesis/ inhibit breakdown. GH mediates action through IGF1.
        
        Hormones released from pituitary like cortisol (max. reached within 4/6 hours)= promotes protein breakdown+ GNG in liver, glycogenolysis, glucose stopped from entering cells resulting in hyperglycaemia , promotes lipolysis, anti-inflammatory
        
        Surgery= insulin drop during surgery and anaesthesia, glucagon transient increase but not major cause of hyperglycaemia, insulin resistance related to magnitude of surgery e.g. major surgery / open surgery under anaesthetic for long time vs smaller laparoscopic. Thyroid hormones increase following surgery but return to normal after 2/3 days
        
        ('Flow' phase) After surgery, RMR will rise then fall between 10-20 day mark and highest in major burn, then major trauma/surgery with illness and then major uncomplicated surgery
        
        ADH and aldosterone on kidney causing salt/ water retention
    - - IL-1, TNF, IL-6 production high = metabolic effect (fever),
      - cytokines and acute-phase proteins released after surgery
      - Acute phase proteins in inflammatory state increase/ decrease around 25%. E.g. CRP (positive effect, rises) but Albumin (negative effect, lowers)
      - Glutamine and alanine released by muscle and provide energy for gut, immune cells and GNG and help produce APR proteins in liver
      - Changes in liver protein synthesis, all up or down by 25% to try and heal body and protect tissue= CRP (removes antigens from host, activates immune response), Alpha 1 and 2 inhibiting iimmun response
      - Nutritional implications of inflammation: fever resulting in increased EE, increase in APP and this synthesis will cause protein breakdown to supply the amino acids. Zn, glycine, serine, cysteine changes. zinc drops as delivered to liver and immune cells. Free radical production with vits E, c, B2 glycine, sulphur aa (cysteine), selenium. Vit E to maintain cell membranes as break down free radical rxns which would unsaturated PUFAs in membranes. Iron is potent free radical catalyst (ferritin increase but transferrin decreases in inflammatory response as free iron can cause damage). Glutamine is fuel for immune cells.
    - - Essential and most abudant AA, produced by muscle and transports N around body. Levels drop around 50% during trauma/surgery
      - May help reduce bacterial translocation, preserve tissues and metabolic function in stress , antioxidant, anti-inflammatory
      - Mixed evidence for effectiveness of additional feeding during trauma or stress:
        
        Increased mortality found in one study due to infection complications from IV feeding