Surgical Nutrition

Outline Introduction Review of physiology Nutritional Assessment Nutritional Support Enteral Parenteral Conclusion

Introduction Surgical nutrition is important in Well nourished and mildly malnourished patients who cannot take oral food for more than one week post operatively to avoid prolonged starvation. Severely malnourished patients undergoing general surgery procedures. All critically ill patients (Sepsis patients, Multiple Injury patients, Burn patients, etc). Patients whom you predict cannot use their gut for prolonged period of time (Short gut syndrome, EC fistula, etc).

Critical issues Nutritional screening Nutritional assessment ABCD Nutritional requirements Nutritional support

Review of Physiology There are two broad classes of nutrients: Those that provide energy Carbohydrates, fats and proteins Those that are incorporated in tissue synthesis Proteins, vitamins, electrolytes, trace elements and water Carbohydrates 30-60% Stores depleted in 48hrs after starvation but within 24 hrs of stress Proteins Not stored; 2.5% daily turnover 2-4g/day is depleted in starvation but 30-50g/d after severe stress Lipids 25-40% of total calories Depleted in prolonged starvation and stress

The Cori cycle

ENERGY/NUTRIENT REQUIREMENT Energy requirement is increased in catabolic state. Neonates/infants require about 3X energy requirements in adults. The basal requirements are: Energy J/kg 125-146 Proteins [g] 0.7-1.0 Carbohydrates [g] 4.2-6 Fat [g] 1.5-2 Water [ml] 30-35 [45 -50] Electrolytes Vitamins

ESTIMATION OF ENERGY REQUIREMENT Harris-Benedict equation estimates BEE at rest. Men 66 + (13.7x weight) + (5x height) –(6.8 x age). Women 65 + (9.6 x weight) + (1.7 x height) – (4.7 x age) Most require 25-35 kcal/kg/day. Stress increases these values. Requirements are increased by activity, surgery, trauma, fever, infection, burns, head injury, renal failure. Decreased by sedation, paralysis, B blocker

Human catabolism Short term starvation Prolonged starvation During the first 48-72 hrs increased use of fat stores, and most tissues except RBCs, WBCs, and renal medulla oxidize lipid stores. Brain has an obligate glucose requirement, over 3-5 days uses fatty acids for energy. Reserves can maintain this demand for 12hrs but this can elongated by gluconeogenesis from lactate, glycerol and amino acids. Prolonged starvation Hepatic and renal gluconeogenesis drops Brain cells use ketone bodies for energy.

Human catabolism [stress] Protein Proteolysis and synthesis [energy and acute phase reactant proteins by the liver]; negative nitrogen balance Nitrogen loss: 5-8 gm/d normally 2-4 gm/d after several days of unstressed starvation 30-50 gm/d under severe stress (multiple trauma, sepsis, burns) Lipids Lipolysis Carbohydrates Glycogenolysis and gluconeogenesis Insulin resistance This response is stimulated by: Hormones ACTH, GH, glucagon Catecholamines Cytokines associated with acute stress response

Nutritional assessment – ‘ABCD’ Anthropometric measurement Length/ height; Weight/BMI; MUAC/skin fold thickness Weight [<10%BW, <80% Ideal, 5% in 1month] Biochemical findings Serum protein [<30g/l] FBC [PCV-anemia; Lymphocyte count <1500/mm3] Immune competence [delayed hypersensitive reaction, antigen tests] Clinical findings History-weight loss, persistent nausea, anorexia, vomiting, diarrhoea, malaise, dysphagia Signs: fluffy hair, pallor, skin rash, cheilosis, glossitis, neuropathy, dementia, muscle wasting, edema, Ascites Dietary recall How often, how much, how well Indirect calorimetry Oxygen consumption, determination of respiratory quotient Measurement of nitrogen balance Measurements of immunologic function

Nutritional requirement Calculate total energy requirement [use equation] Distribute thus: Carbohydrates 50% Fats 35% Proteins 15% Calculate nitrogen requirement -1.25g/kg BW Trace elements Electrolytes Vitamins Fluid 3L Determine route Enteral Parenteral

Nutritional support Aims Routes To provide energy, protein, trace elements and vitamins; To supply fluids and electrolytes Routes Enteral Oro-enteric Naso-enteric [NGT-NDT-NJT] Needle catheter jejunostomy Percutaneous endoscopic Gastrostomy/Jejunostomy Parenteral Peripheral /Central Supplementary/Total Temporary/permanent

Indications for nutritional support This should consider the following: The patient's premorbid state (healthy or otherwise) Poor nutritional status (current oral intake meeting <50% of total energy needs) Significant weight loss (initial body weight less than usual body weight by 10% or more or a decrease in inpatient weight by more than 10% of the admission weight The duration of starvation (>7 days' inanition)

Indications for nutritional support An anticipated duration of artificial nutrition (particularly total parenteral nutrition [TPN]) of longer than 7 days The degree of the anticipated insult, surgical or otherwise A serum albumin value less than 3.0 g/dL measured in the absence of an inflammatory state A transferrin level of less than 200 mg/dL Anergy to injected antigens

Nutrition in surgery: routes

Enteral Advantages Options Routes Complications Cheap, more physiological, more efficacious in traumatized and burns patient Options Blenderised Chemically defined Special purpose formulation Modular Routes Oro-enteral Nasoenteral Needle Catheter Jejunostomy Percutaneous endoscopic gastrostomy/jejunostomy PEG/PEJ Complications Tube –displacement, dislodge, blockage; bowel perforation, reflux and aspiration pneumonia Feed-high osmolar feed cause severe diarrhoea

Indications for enteral feeding PEM with inadequate oral intake Dysphagia except for fluids Prolonged return to normal dietary intake after trauma/ surgery Inflammatory Bowel Disease (IBD) Distal, low output enterocutaneous fistulas To enhance adaptation after massive enterectomy

Contraindications Mesenteric ischemia Small Bowel obstruction Sepsis Pancreatitis Fistula proximal small intestinal SBS Severe diarrhoea

Complications of enteral feeding Pneumothorax Oesophageal stricture, perforation Fatal arrhythmias Relating to the feeding regimen Feed intolerance (diarrhoea, vomiting) Hyperglycaemia Enteric infection Relating to the feeding tube Malposition Dislodgement / migration Aspiration, sinusitis Peritonitis Fistula formation Intestinal obstruction Tube fracture/ blockage Oesophageal and gastric mucosal erosions

Parenteral Sources Formulations Carbohydrate-based Fat-based Intralipid 10% Intralipid 20% Vamin 9 glucose Synthamin 14

Indications When nutritional support is appropriate but effective enteral nutrition is not possible Proximal intestinal fistula IBD (especially in the perioperative period) Massive intestinal resection (<100cm of small bowel remains) Ileus Severe pancreatitis Acute burns Hepatic failure (acute decompensation on cirrhosis

Standard TPN Standard Glucose 250g 4200J Protein 500ml 4200J Amino acids 14g Na 100mmol K 100mmol Cl 191mmol Mg 19mmol Folic acid Water

TPN Access Protocol Peripheral Central ‘Daily dose method’ Calculate energy required Calculate VOLUME requirements/24h. Determine PROTEIN requirements g/kg/d. Calculate daily CALORIES kcal/kg/d. Determine % to be given as protein, CHO, fats. Add electrolytes, trace elements. Co-administer Lipids to prevent fatty acid deficiency.

Monitoring Daily Clinical evaluation, input-output chart, weight, urinalysis, blood glucose 48-hrly EUC, blood pH, Clotting profile Weekly LFTs, Serum Ca, FBC

TPN Advantages Successful outcome Improved survival Wound healing Resistance to infection Immunity is improved Synthesis of blood elements RBC, plasma proteins Successful outcome GI fistula Bowel failure Burns Persistent ileus Pancreatic pseudocyst/ascites/fistulae

Advantages of TPN Can be used for longer periods with hyperosmolar fluids at larger volumes Survival rate is improved and morbidity reduced. Weight loss and tissue breakdown are minimized Wound healing is enhanced Resistance to infection and general immunity are improved Formation of RBCs and plasma proteins is maintained

Complications of TPN Procedure Feed Needle malposition Air embolism Fat embolism CCF Pulmonary embolism Septicaemia Feed Acute reactions to fats and amino acids Hyperosmolarity-related complications Metabolic acidosis Hyperglycemia Rebound hypoglycemia Anaemia Zinc deficiency Jaundice Altered biochemical profile Refeeding syndrome

Conclusion Nutritional supplementation reduces the risk of complications if given to severely malnourished patients undergoing major surgical procedures and in patients with severe sepsis, trauma and burns. One of the most important therapeutic modalities of the 20th century has been nutritional support, in particular, IV feeding. The ability to intervene in and correct nutritional deprivation states that cause significant mortality in patients is germane hence it should not counted as a luxury.