Nutrition

Owen McIntyre

DEFINITIONS
•Basal metabolic rate
•Amount of energy liberated by catabolism of food per unit time under standardized conditions, ie relaxed, room temp, 12-14 hours post-prandial
•Corrected for age, sex and surface area
•Normal adult male= 197 Kj/m2/hr; 40Kcal/m2/hr

DEFINITIONS
•Calorie
•1 calorie=energy reqired to heat 1gram of water by 1o C
•1 Cal=1Kcal
1 kg of water by 1o C
•1 kcal= 4.18 kjoules
•Joule
•SI unit of energy
•1 joule=energy expended in moving a resistive force of 1 newton a distance of 1 metre

DEFINITIONS
•Nitrogen Balance
•1 gram of nitrogen=6.2 grams of protein
=30 grams of muscle
•Normal losses=0.15-0.2g/kg/day
•ITU losses can be> 0.5g/kg/day
•Mainly in urinary urea
•Approx 4g/day in skin/hair/faeces
•Also: proteinuria, GIT fistula
•Measured by 24 hour urea collection with corrections for other losses

DEFINITIONS
•Malnutrition
•Multiple nutrient deficiencies
•Common in hospital patients
•Impaired healing
•Reduced immune system function
•Reduced muscle mass/poor mobility and weaning
•Anaemia
•Electrolyte disturbances
•Starvation
•Carbs- hepatic and muscle glycogen = 24-48 hrs
•Protein- from skeletal muscle = 10-12 days
•Fat- from adipose tissue = 20-25 days

DEFINITIONS
•Catabolism
•Form of accelerated starvation with glycogenolysis, lipolysis and proteolysis/gluconeogenisis
•Malnutrition is a predisposing factor
•Assoc with severe illness, sepsis, burns, trauma and stress response to surgery
Common mechanism: catabolic hormones
insulin resistance
increased metabolic rate
increased oxygen demand

NORMAL DAILY REQUIREMENTS
•Energy: 30- 40 kcal/kg
carbs= 50% (4kcal/g)
lipids= 35% (9kcal/g)
protein= 15% (4kcal/g)
•Water: 30- 40 ml/kg
1000ml of water for 1000kcal expended
•Nitrogen: 0.2 g/kg=1.5 g/kg
•Fat: 2 g/kg
•Glucose: 2 g/kg

NORMAL DAILY REQUIREMENTS
•Na+ 1mmol/kg
•K+ 1
•Cl- 1.5
•Mg+ 0.1-0.2
•Ca+ 0.1-0.2
•Phos 0.2-0.5

NUTRITIONAL ASSESSMENT
•Careful history and exam
•Objective tests
•Subjective global assessment
•Experimental
•All difficult in ITU setting
•Nutritional Risk Screening
•Impaired nutritional status
•Severity of disease

QUESTIONS?
•What routes are available for nutritional support?

•List the pros and cons for each route

•List the contraindications for each

•List the complications of each

ENTERAL FEEDS
•Polymeric
•Normal gut function
•Nitrogen source is protein
•Energy from triglycerides and glucose polymers
•Elemental
•GI failure,pancreatic insufficiency, often NJ
•Nitrogen from amino acids or oligopeptides
•Energy from short glucose polymers, no lipid
•Specialist, Disease specific

PARENTERAL FEEDS
•Nitrogen from L-amino acids
•Energy from glucose-50% lipid emulsion-50%
•Electrolytes
•Trace elements and minerals
•Bespoke

MONITORING
•Fluid balance, calorie intake, ?weight
•Urea and electrolytes, phosphate
•Blood glucose
•FBC
•LFTs, Ca and Mg
•Plasma triglycerides

FINAL POINTS
•Glutamine
•Significantly reduce mortality and ITU stay?
•Prevents gut atrophy, direct fuel for enterocytes and lymphoid tissue
•Conditionally essential in critical illness
•Re-feeding Syndrome
•Previously malnourished
•Low K+, Mg+, Phosphate