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Anurag Goel ST5 Royal Preston Hospital. Slide 2 What is It? Potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial refeeding (whether enterally or parenterally) The hallmark biochemical feature of re feeding syndrome is hypophosphataemia JPEN J Parenter Enteral Nutr 1990;14:90-7 Slide 3 Discovery of RFS Observed & described after WWII Victims of starvation experienced cardiac and/or neurologic dysfunction After being reintroduced to food Neurologic signs & symptoms developed later Slide 4 How common is RFS? True incidence is unknown Study 1 of 10,197 patients, incidence of hypophosphatemia = 43 % Malnutrition one of strongest risk factors Parenteral patients = 100% incidence of hypophosphatemia (if no PO4 in PN) ; 18% with PO4 containing PN 2. 1. Mineral & Electrolyte Metabolism 1990;16:365-8 2. Nutr Hosp 2006;21:657-60. Slide 5 Understanding Starvation Glucose is normally the main fuel. Starvation - Shifts to protein & fat Insulin (due to availability of glucose) Catabolism of protein loss of cellular & muscle mass atrophy of vital organs & internal organs Respiratory & cardiac function due to muscular wasting & fluid/electrolyte imbalances Body is now surviving by slowly consuming itself Slide 6 Starvation The serum concentrations of electrolytes may appear normal in the starved state!! (Due to alterations in renal excretion rates of electroytes.) Slide 7 Slide 8 Effects of Refeeding on the Cardiovascular System Increases in heart rate, blood pressure, oxygen consumption, cardiac output expansion of plasma volume Response is dependent on amount of calories, protein and sodium given The malnourished heart can easily be given a metabolic demand that is too high for it to supply Slide 9 Effects of Refeeding on the Cardiovascular System Congestive Heart Failure is a common complication of refeeding Cardiac output cant increase enough to meet the needs from the increased plasma volume, increased oxygen consumption and increases in blood pressure and heart rate Slide 10 Effects of Refeeding on the Respiratory System Excess carbon dioxide production and increased oxygen consumption from giving too much glucose and overfeeding A person with malnutrition-induced respiratory muscle wasting can get short of breath Cant sustain an increased ventilatory drive Pulmonary edema due to increased water load Slide 11 Effects of Refeeding on the Gastrointestinal System Activity of the brush border enzymes and pancreatic enzyme secretion return to normal with refeeding Requires a period of readaptation to food to minimize GI complaints Diarrhea, nausea and vomiting Slide 12 Main Pathophysiologic Features Disturbances of body-fluid distribution Abnormal glucose & lipid metabolisms Thiamine deficiency Hypophosphatemia Hypomagnesemia Hypokalemia Slide 13 Hypophosphatemia Phosphorus is predominantly intracellular Impaired cellular-energy pathways Adenosine triphosphate (ATP) 2,3-diphosphoglycerate (2,3 DPG) Impaired skeletal-muscle function Including weakness & myopathy Seizures & perturbed mental state Impaired blood clotting processes & hemolysis also can occur Slide 14 Hypomagnesemia cofactor in most enzyme systems, including oxidative phosphorylation and ATP production. also necessary for the structural integrity of DNA, RNA, and ribosomes. Mild cases: often asymptomatic Severe cases: Cardiac arrhythmias Abdominal discomfort Anorexia Tremors, seizures, & confusion Weakness Slide 15 Hypokalemia major intracellular cation. Serum levels may remain normal in starvation! Features: Cardiac arrhythmias Hypotension Cardiac arrest Weakness Paralysis Confusion Respiratory Depression Slide 16 Thiamin Deficiency Functions as a cofactor in intermediary carbohydrate metabolism (TCA cycle) Amount needed depends on carbohydrate ingested. Mental confusion, ataxia, muscle weakness, edema, muscle wasting, tachycardia and cardiomegaly Wernickes encephalopathy can be precipitated by carbohydrate feeding in thiamine-deficient patients Slide 17 Slide 18 Who is at risk? Some risk: People who have eaten little or nothing for more than 5 days REMEMBER: Even an overweight or obese patient can be malnourished & a victim for RFS NICE guidelines (2006) Slide 19 Who is at risk? High Risk Either patient has 1 or more: BMI 15% in past 3-6 mo Little/no nutritional intake for 10 days Low levels of potassium, phosphate, or magnesium before feeding Or patient has 2 or more: BMI 10% in past 3-6 mo Little/no nutritional intake for >5 days History of alcohol misuse or drugs NICE guidelines (2006) Slide 20 Patients at high risk: Anorexia nervosa Chronic alcoholism Oncology patients Postoperative patients Elderly Uncontrolled diabetes mellitus GI fistulas Chronic malnutrition: Marasmus Prolonged fasting or low energy diet Morbid obesity with weight loss Long term antacid users Long term diuretic users Slide 21 Managing refeeding syndrome Identifying patients who are at risk. Prevent Refeeding syndrome. Once refeeding starts: Replace K, PO4, Mg even if normal (not if levels high) Potassium: 2-4 mmol/kg/day Phosphate: 0.3-0.6 mmol/kg/day Magnesium: Oral 0.4 mmol/kg/d OR i.v. 0.2mmol/kg/d PS : Prefeeding replacement is not required even if electrolytes abnormal !! Slide 22 Managing refeeding syndrome Identifying patients who are at risk. Prevent Refeeding syndrome. Prefeeding replacement is not required if electrolytes abnormal Replace K, PO4, Mg even if normal (not if levels high) Potassium: 2-4 mmol/kg/day Phosphate: 0.3-0.6 mmol/kg/day Magnesium: Oral 0.4 mmol/kg/d OR i.v. 0.2mmol/kg/d MANTAINANCE Slide 23 Slide 24 Slide 25 Managing refeeding syndrome Feed cautiously 10kcal/kg for first 2 days, 5kcal/kg in extreme cases Increase slowly (over 4 - 7 days) No more than 150 to 200 gm of glucose 1.2-1.5 gm of protein per kg actual bodyweight 20-30% of calories from fat PS: Weight Gain is NOT the goal in first 2 weeks. Slide 26 Hypo-phosphataemia verses initial feed rate P = 0.008 Feed-rate kcal / kg Slide 27 Managing refeeding syndrome Pabrinex (high dose thiamine) and balanced multivitamin/mineral supplement ORAL: Thiamine 200 300 mgs + Vit B Co Strong 1-2 tabs TDS X 10 days IV: Pabrinex OD X 10 Days. first dose being administered at least 30 minutes before starting feeding. Slide 28 Electrolytes in Refeeding: phosphate Oral One tablet = 16.1mmolPO4, 20.4mmol Na, 3.1mmol K) i.v. (phosphate polyfuser) 500ml = 50mmol PO4, 81mmol Na, 9.5mmol K+) Mild PO 4 (0.6-0.85 mmol/l) Phosphate Sandoz (16mmol each) - 2 tds 15mmol PO4 Polyfusor (150ml) over 12hrs peripherally Moderate PO 4 (0.3-0.6 mmol/l) Phosphate Sandoz (16mmol each) - 2 tds Preferred route - i.v. 25mmol PO4 Polyfusor (250ml) over 12hrs peripherally Severe PO 4 ( Summary Points Characterized by hypophosphatemia Patients at high risk: undernourished, little or no energy intake for > 10 days Start refeeding at low levels Correction of electrolyte & fluid imbalances before feeding is not necessary (do not delay feeding) Slide 39 Questions