Theoretical Nutrition and Patient Assessment T R Wilson

WHY IS Nutrition important?

Prevalence Malnutrition in Hospital 30% Overtly malnourished 8% Severely malnourished Screen all hospital admissions Weigh (BMI) Ask if they have lost weight Ask when they last ate properly MUST SCORING

Malnutrition and Surgical Complications Percentage Patients

Assessing patients

Who is at risk nutritional problems? Hospital patients (1/3) Prolonged ITU stay Prolonged fasting Cancer patients Crohn's Disease Post (and Pre) bariatric surgery Elderly Chronic alcoholic abuse Anorexia Nervosa

MUST Score Screening tool 3 elements Score from 0 to 6 BMI >20 = 0 18.5-20 = 1 <18.5 = 2 % Weight loss last 3-6 months <5% = 0 5-10% = 1 >10% = 2 Acute disease effect Acute illness, no nutritional intake ≥ 5 Days = 2 Score from 0 to 6 2 or more is high risk → dietician input

Assessment Nutritional Status Where has patient come from? Long term history of nutritional problem Risk factors History of weight loss History of inadequate intake Where is patient currently? On going / current pathologies (cancer?) Sepsis Hydration/electrolyte status What you can do? – Where are you going? What is likely course of their pathology What is their likely nutritional intake in next 48 hours / week / longer?

Meeting Nutritional Needs Assessment Provision Monitoring Normally Nourished Ward Staff Catering Admission weight Weekly Weight Under Nourished (BMI < 20) (Weight loss >10%) Dieticians +/- Sip Feeds Intake Records Biochemistry Partial Intestinal Failure (Functioning Gut) +/- NST Enteral Feed +/- Catering Via NG/NJ/PEG Clinical (≥2x/week) Intestinal Failure (Gut not functioning) NST Parenteral Nutrition +/- Enteral Feed Via CVP line Daily Assessment (Clinical, fluid balance, biochem) Weight 2x/week

PATHOPHYSIOLOGY (What goes wrong and how to fix it safely)

Reductive Adaptation of Malnutrition Reduced Intake Reduced Mass Reduced Work Altered Body Composition Altered Metabolism and Physiology Loss of Reserve Brittle Metabolism Excess Energy/Protein Abnormal Losses Specific Deficiency Infection Trauma Small bowel overgrowth Loss Homeostasis

Basal Metabolic Demand Mechanical Work Cardiac Output/Ventilation/Movement Turnover Substances Amino acids / Protein Glucose / Glycogen Fatty acids / TAG Transport across membranes Substrates / Products Electrolytes (Na/K pumps) 10% 20% 70% (67%)

Electrolyte Shifts Down regulation of Na/K pumps Leaking of K, Mg, PO4 out of cells → High serum K/Mg/PO4 → Renal excretion → Decreased body levels Leaking of Na into cells → Low serum Na → Renal conservation → Increased body levels Na Fluid follows Na → General fluid retention → Oedema → Fluid shift into cells

Nutritional Oedema Impaired membrane function Salt and water retention Down regulation Na/K pumps Free radical damage Salt and water retention Impaired renal function Potassium/phosphate depletion Acid-base imbalance Hypoalbuminaemia Decreased synthesis (minor long term) Third space loss (SIRS, Sepsis, Membrane damage)

Problems of Na, Cl and Fluid excess Left ventricular failure Oedema Skin breakdown Hyperchloraemic acidosis Ileus Anastomotic and wound dehiscence ↑ PN requirement ↑ Length of Stay ↑ Death

Loss Homeostasis Increased Toxins / Free radicals Reduced protection Infection / Trauma Iron (from RBC breakdown) Small bowel overgrowth Reduced protection Vitamins: B1, B2, B6, C, E, niacin, β carotene Elements: Cu, Se, Zn, Mn Other: Glutamine, Glycine, Cystine Electrolyte and fluid shifts Decreased body stores – e.g. glycogen

Micronutrients Starvation PN AA AA AA AA PROTEIN Refeeding Catabolism Enzyme Co Enzyme AA AA AA AA Catabolism (e.g. Thiamine, Riboflavin, Pyridine, Iron, Zinc, Copper) PROTEIN

Sepsis and malnutrition Malnourished → immunosuppression May not mount typical immune response Normal bloods Hypothermia rather than temperature Refeeding / over feeding → further immunosuppression BEWARE THE DEADLY TRIAD Low BMI Hypoglycaemia Hypothermia

Problems of over feeding / over enthusiastic early nutritional support Excess Nitrogen delivery May produce toxic amino-acids Drive ammonia and urea production High renal solute load → contribute to Na retention Metabolic instability Insulin resistance and hyperglycaemia Liver dysfunction/diversion Immunosuppression Re-feeding syndrome

Refeeding Syndrome (definition) Potentially lethal Occurs in malnourished patients undergoing re-feeding Can occur with any route of feeding Results in severe electrolyte and fluid shifts Associated with metabolic abnormalities (Nearly 1% all hospital patients)

Refeeding Pathophysiology Starvation Protein catabolism Gluconeogensis ↑ Insulin resistance ↓ soluble B vit levels Down regulation cellular pumps Extracellular leakage K/PO4/Mg Excretion of K/PO4/Mg Intracellular Na retention Renal Na conservation Refeeding On going aa metabolism ↑glucose metabolism ↑Insulin ↑ Thiamine utilisation Reactivation cellular pumps Intracellular uptake Na/PO4/Mg Low serum levels

Specific refeeding problems Electrolyte disturbance Weakness, seizures, arrhythmias, tetany, paraesthesia Heart failure / pulmonary oedema Infection (CRP and WCC may not rise) Hyper/hypoglycaemia Risk of brain damage / Wernicke's

Avoiding all refeeding syndromes Start at appropriate low rate 5 Kcal/Kg/Day in extreme cases 10 Kcal/Kg/Day in severe cases Half requirements 20/Day for less severe re-feeding risk Gradually increase over 4-7 days Replace electrolytes aggressively Vitamin supplementation (Thiamine) Monitor observations