theoretical nutrition and patient assessment t r wilson
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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
Morbidity Mortality0
10
20
30
40
50
60
70
80
Well NoursihedMalnourished
Perc
enta
ge P
atien
ts
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– 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 NeedsAssessment Provision Monitoring
Normally Nourished Ward Staff Catering Admission weightWeekly Weight
Under Nourished(BMI < 20)
(Weight loss >10%)
Ward StaffDieticians
Catering+/- Sip Feeds
Admission weightWeekly WeightIntake RecordsBiochemistry
Partial Intestinal Failure
(Functioning Gut)
Ward StaffDieticians+/- NST
Enteral Feed+/- Sip Feeds+/- CateringVia NG/NJ/PEG
Admission weightWeekly WeightIntake RecordsBiochemistryClinical (≥2x/week)
Intestinal Failure(Gut not
functioning)
NST Parenteral Nutrition+/- Enteral FeedVia 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 Metabolism and Physiology
Altered Body Composition
Loss of Reserve
Brittle Metabolism
Loss Homeostasis
InfectionTraumaSmall bowel overgrowth
Excess Energy/ProteinAbnormal LossesSpecific Deficiency
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– 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– 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
Starvation
AA
Micronutrients
Enzyme
Co Enzyme
(e.g. Thiamine, Riboflavin, Pyridine, Iron, Zinc, Copper)Catabolism
AA
PN
PROTEIN
Refeeding
AA AA
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
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