Nutritional considerations when commencing TPN Mary Peck, Dietitian

Nutritional considerations when commencing TPN Assessment of nutritional requirements Assessment of re-feeding risk Safe introduction of TPN

Case study Mrs A Wt 50kg, ht 150cm, BMI 22 Small bowel resection with anastomosis 10days ago. Now has septic picture, ?anastomotic leak. Minimal diet since surgery. Pt currently in bed or sitting in a chair. Bloods: creat 50, urea 5, Na 139, k3.9, PO4 1.0, mg 0.73, CRP 190

Assessment of nutritional requirements Energy (fat and glucose} Nitrogen Electrolytes Micronutrients Fluid

Energy The components of energy expenditure are: Basal metabolic rate (BMR) Disease state/stress Activity level

Calculation of BMR Use equations based on gender, age and weight. Henry/Oxford (2005) equations currently used. F M 18-30 13.1W+558 16.0W+545 30-60 9.74W+694 14.2W+593 60-70 10.2W+572 13.0W+567 70+ 10W+577 13.7W+481 Mrs A BMR: 10.2x50+572=1082kcals

Weight Weight can be deceptive Oedema: minimal 1.0kg,moderate 5.0kg, severe 10.0kg Ascites: minimal 2.2kg, moderate 6.0kg, severe 14.0kg

Adjusting for stress Adjust BMR to account for stress Examples: Infection 25-45% Surgery (uncomplicated ) 5-20% Surgery (complicated) 25-45% Mrs A (BMR 1082kcals)25% infection= 270kcals

Activity Adjust BMR to account for activity level Sedated and ventilated 0% Bed bound immobile 10% Bed bound mobile/sitting 15-20% Mobile on ward 25% Mrs A (BMR 1082kcals): 20% activity= 216kcals

Energy requirements of case study Mrs A, 62yrs, wt 50kg, CRP 190, sitting in chair BMR: 10.2x50+572=1082kcals 25%infection: 270kcals 20% activity: 216kcals Total energy requirements 1568kcals (1600kcals)

Calculation of nitrogen requirements Normal requirements 0.17g/kg/day (0.14-0.2) Hypermetabolic 5-25% 0.2 (0.17-0.25) 25-50% 0.25 (0.2-0.3) >50% 0.3 (0.25-0,35) Mrs A: 50x0.25=12.5g nitrogen per day

Electrolyte requirements Na: 1mmol/kg K: 1mmol/kg: (2-4mmols/kg in re-feeding) Mg: 0.1-0.2mmol/kg: (0.2mmol/kg in re-feeding) P04: 0.5-0.7mmol/kg: no specific re-feeding guideline, but will need to give maximum P04 limit in small TPN bags Ca: 0.1-0.15mmol/kg

Daily fluid requirements 18-60 yrs: 35ml/kg >60yrs : 30ml/kg Re-feeding: consider prescribing: 20-25mls/kg. (NICE-Intravenous fluid therapy in adults in hospital, 2013)

Mrs A requirements Mrs A: 62yrs, 50kg, BMI 22 Energy: 1600 kcals Nitrogen: 12g Na: 50 mmols K: 50 mmols P04: 25-35 mmols Mg: 5-10 mmols Ca: 5-7.5 mmols Fluid approx 1500ml

Assessment of re-feeding risk (NICE) At risk Little or no intake > 5 days Introduce feeding at maximum of 50% requirements for the first 2 days. Monitor biochemistry Meet full requirements for electrolytes and micronutrients.

High re-feeding risk (NICE) Starved state plus any of the following: BMI<16 Unintentional weight loss >15% within the last 3-6 months Little or no nutrition >10days Low levels K, Mg or P04 prior to feeding Starved state plus 2 of the following: BMI<18.5 Unintentional weight loss >10% within the last 3-6 months. Very little or no nutrition for >5 days History of alcohol abuse

Management of high re-feeding risk (NICE) Start nutrition at 10kcals/kg/day Build up over 4-7days Monitor K, Mg, P04, supplement if necessary 1 pair pabrinex o.d for 10 days

Mrs A: re-feeding risk High risk since minimal nutrition for 10 days. K, Mg, P04 currently normal, but likely to drop Pabrinex: 1pair od for 10days Start feeding at 10kcals/kg: 500kcalsday Increase nutrition over minimum of 4 days.

Mrs A: increase in TPN Requirements: 1600kcals, 12gN Day 1: smof 4 (500kals, 4gN) Day 2: smof 4 (500kals, 4gN) Day 3 :smof 8 (1100kcals, 8gN) Day 4: smof 12 (1600kcals, 12gN) Full complement of electrolytes and micronutrients

Summary Nutritional assessment to determine requirements. Assess re-feeding risk before starting nutrition. Increase nutrition cautiously as per NICE (2006 CG32) on re-feeding.