1. Nutritional considerations when commencing TPN
Mary Peck, Dietitian

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

3. 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

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

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

6. Calculation of BMR Use equations based on gender, age and weight.
Henry/Oxford (2005) equations currently used.
F M
W W+545
W W+593
W W+567
W W+481
Mrs A BMR: 10.2x50+572=1082kcals

7. 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

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

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

10. 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)

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

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

13. 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)

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

15. 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.

16. 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

17. 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

18. 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.

19. 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

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