Term
| What are the main indications for TPN? |
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Definition
Non-functional GI Tract - SBS, intractable vomitting for 5+ days, severe diarrhea in infants, IBD, obstruction or pseudo obstruction
Cancer - Acute GI toxicity from chemo, radiation, BMT. EN indicated when po not expected for >1 week, start therapy when oncology therapy starts. SNS not indic. for well or mildly malnourished patients where po intake is expected. PN is unlikely to benefit patients with advanced unresponsive malignancy (3 months or less left), maintain with hydration only
Pancreatitis - Enteral route usually adequate, post pyloric feeding may reduce chance of exacerbating conditions, PN is indicated if feeding leads to increased abd. pain, ascites, or increased fistula output. Mod-severe pancreatitis when po intake not expect. for 5-7days
Others - Severe malnutrition, critical care, disease specific failure (liver, pulmonary, renal), Pre-op malnutrtion starting 7 days prior to surgery, eating disorders, excessive vomiting while prego, premies, inborn errors in children. |
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Term
| What is SNS? Where/how should it be administered? |
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Definition
SNS = Specialized Nutrition Support
Short term - Peripheral PN
Long term - Central PN
If GI function returns, go to PO, if it doesn't, go to Central PN
Central - Tip of catheter just prior to right atrium, fast blood flow dilutes high osmolar sol.
Peripheral - Slow blood flow, low concentration solution, not good for >3-5 days
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Term
| What are practice points to know before administering a TPN? |
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Definition
Clinical Factors:
- Age
- ABW vs. IBW
- Disease state and degree of metabolic stress
- Renal Function - affects fluids, electrolyte and protein requirement
- Liver Function affects Na and H2O req., and tolerance of protein
Respiratory function - high dex. concentrations lead to inc. CO2, bad for these patients
Pancreatic function - Affects glucose and lipids
GI losses - Need to know how much fluid/electrolytes we lose
- Goal and duration of therapy
- Route of admin. |
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Term
| What does the standard TPN contain? |
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Definition
- Fluid
- Protein
- Energy in the form of carbs and fat
- Electrolytes
- Micronutrients like trace elements and vitamins |
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Term
| What are the different kinds of protein in a TPN? |
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Definition
Protein (Nitrogen)
- Mixed AA's
- BCAA enriched/lower aromatic AA (stress, liver)
- Electrolyte free/low electrolyte, increased EAA and histidine (renal)
- Pediatric (taurine, glutamate, aspartate, phenylalanine, glycine, methionine) |
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Term
| What are the standard energy requirements for a TPN? |
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Definition
nEnergy
nCarbohydrate -dextrose
nFat:
LCT (soybean/safflower)
LCT/MCT (structured or mixed)
SCFA
Omega 3 fatty acids |
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Term
| What are the fluid requirements for a standard TPN? |
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Definition
- 25-35 ml/kg/day
- Also can be est. as....1500 ml for the first 20kg, but 20ml/kg for the weight > 20kg
- Fluid must compensate abnormal losses as well.
Fluids for age groups:
30-35 ml/kg/day for 18-54
30 ml/kg/day for 55-65
25 ml/kg/day for >65 |
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Term
| In terms of energy requirements (daily kcal), what do we need to know to calculate this for a patient? |
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Definition
Mild to moderate stress - 25 kcal/kg/day
Severe stress - 25-30 kcal/kg/day
BMR must be calculated
Body Weight (kg) BMR kcal/day
n 40 1050
n 50 1200
n 60 1400
n 70 1550
n 80 1700
+20% bed bound, +30% bed bound but mobile, +40% mobile in ward, + up to 1000kcal/day if depleted
In solutions, look at % of main ingredient. Dextrose is 3.4kcal/g, protein is 4, and fat is 9.7. This will help you determ,ine the CALORIFIC value.
Fat should constitute 10-40% of nonprotein kcal, no more than 60%; standard dose is 1g/kg/day, max of 2.5g/kg/day. Given over 24h part of TPN or 10h separately. For 10% lipid, max infusion of 125ml/hr, for 20% lipid it's 60ml/hr. If serum TG's are >400, then lipids aren't being cleared and we need to adjust this. |
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Term
| Normal Albumin is 4.0g/dl, by how much will serum calcium rise with a fall in 1g/dl in Albumin? |
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Definition
| For each 1g/dl fall in serum Albumin, serum calcium will increase by 0.8g/dl |
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Term
| What are possible mechanical complications of TPN's? |
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Definition
Arterial Injury - Puncture of subclavian or carotid artery during cather insertion
Pneumothorax - Puncture of pleura/lung during cather insertion
Air Embolism - >5ml getting into venous circulation coudl be fatal
Catheter Embolism - Part of catheter breaks off and enters venous circulation
Venous thrombosis - Clot forming inside/outside catheter, need to protect with LMWH, warfarin, monitor INR, etc.
Chylothorax - Injury to thoracic duct during catheter insertion - accumulation of lymph in pleural space
Brachial Plexus injury - damage to nerve during insertion, catheter malposition, extravasation of hypertonic solutions. |
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Term
| In administering the TPN, how do we prevent over-feeding, and guarantee the correct amount of fat, protein, dextrose, and fluids? |
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Definition
- Over three days, go 50% total dex, 75% of total dex, 100% of total dex, as tolerated of course
- Calories --> mild or mod. stress 25kcal/kg severe 25-30kcal/kg
- Protein is 10-15% of daily kcal. Mild-mod stress = 0.8-1.2kcal/kg/day. Severe stress = 1-1.5kcal/kg/day
Dextrose - Constitutes 50-60% of total calories. To calculate.....
(Total kcal x % dex)/3.4 = Grams of dextrose
- Fat ~ 30% of daily kcal, or 0.5-1g/kg/day, fat emulsion has 2kcal/ml (fyi)
Same principle
(total daily kcal x %fat in diet)/10 (kcal/g) = Grams of fat
- Fluid is 25-35ml/kg/day, unless over 65yo, in which it is 25ml/kg |
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Term
| What are the normal electrolyte requirements in a TPN? How do we correct acid-base problems? |
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Definition
nUsual requirements PLUS abnormal losses
nSodium 50-150meq/day
nPotassium 50-150 meq/day
nCalcium 10-20 meq/day
nMagnesium 10-20meq/day
nPhosphorus 800-1200mg/day
(1meq NaPO4=23mg phos, 1meq KPO4 =21mg phos)
nChloride-need to add more chloride when the patient is alkalotic-pH > 7.4
nAcetate-need to add more acetate salts when the patient is acidotic- pH< 7.4
**Remember to correct serum Calcium!!** |
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Term
| How do we monitor patients on TPN's? |
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Definition
nGlucose finger stick q6h x 4 days
nBaseline labs: CBC with differential, prealbumin
CMP (Na, K,Cl,Gluc,BUN, albumin, LFT’s Ca, CR Total protein),TG, Mg,P, prothrombin time, weight, input/output
Day 2-4: BMP (Na,K,Cl,HCO3,Gluc, BUN, Cr), P, weight, I&O’s
nWhen stable: twice per week: prealbumin CMP, TG, Mg, P,weight |
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