lecture 4 Flashcards
Parenteral Nutrition (PN)
Advanced form of MNT
– Prescribing PN independently is not an entry-level competency
– Entry-level competencies (ICDEP)
• Calculate PN regimen requirements (ICDEP, 3.02q)
• Design PN feeding regimens (ICDEP, 3.02r)
• Identify necessary changes to nutrition care plans (3.04c)
PN: “Ingredients”
1.Protein
2.CHO- Dextrose
3.Fat (lipid emulsions)
4.Electrolyte
5.Multivitamin
6.Trace Elements
Extras: medication, ex. insulin
Indications for parenteral nutrition
• A form of nutrition therapy for those:
- Non-functional GI Tract
- Unable to meet nutritional requirement via po and/or EN
- Inadequate PO and/or EN or NPO status for prolongued period i.e. 5-7 days
• Can be used to provide all requirements or “top-up”
– Total parenteral nutrition (TPN)
– Supplemental PN
Non-Functional GI Tract
• Significant malabsorption – i.e. Short bowel syndrome, persistent diarrhea • Bowel obstruction • Prolonged ileus • GI ischemia • Intractable vomiting – Hyperemesis gravidarum • GI fistula • GI bleed
Populations PN Commonly Used
Acute exacerbations of Crohn’s • GI fistulas • Short bowel syndrome • Acute pancreatitis • Critically ill • Cancer patients
Contraindications to PN
- Functioning GI tract- if it works, use it
- Anticipated Duration/need less than 7 days- not always obvious
- Prognosis in which goals of care do not warrant agressive nutrition support
- not a black and white scenario, for example people with more than 3 months to live
Routes of PN Infusion
• Central (CPN) – Infused through a large diameter vein • Subclavian, internal jugular
• Peripheral
– Infused through a
small diameter vein
• Anticubital
CPN (central vs. peripheral) vs PPN Choice Dependent Upon
- aNTICIPATED DURATION OF THERAPY
- Osmolarity
- Energy requirement
- Fluid Tolerance
- Cnetral line contraindication
PPN (peripheral parenteral nutrition)- Indications
Short-term periods of PN
– Up to 14 days
- Patient reasonably nourished
- Have peripheral vein access (sometimes malnourished patients have bad vein access)
• Catheterization of a central vein is
contraindicated or not possible
PPN - Contraindications
Maximum solution osmolarity =
• Large calorie, nutrient or electrolyte needs (can cause blood clots, inflammation, infection- irritates vein)
– Maximum solution osmolarity = _900mOsm/L__________
• Fluid restriction (would need the soluation to be more concentrated)
• Need for prolonged PN (>2 weeks)
• Renal or liver compromise
• Severe metabolic stress
• Poor peripheral vein access
PPN - Complications
• Phlebitis – Inflammation of a vein (caused by concentrated solution, too loong of a period) • Thrombosis • Pain • Infection
PPN – Advantages vs Central PN
• Venous access “relatively” easy vs central line insertion
• Decreased complications and infectious risk associated with
central lines
• BUT… IV sites usually changed often to maintain patency of the
vein
Central PN: Sites for Access
PN delivered to a large-diameter vein – i.e. superior vena cava adjacent to right atrium • Several different types of catheters – PICC (peripherally inserted central catheter) – CVC (central venous catheter) – Tunnelled – Implantable ports – See RQHR Table 4.1 p.70 & Chapter 5 Nelms
Indications for Central PN (vs PPN)
• Requiring PN > 14 days
• Can accommodate a hyperosmolar solution
– Required to provide adequate nutrition
– The central vein can tolerate a hypertonic solution because the high
blood flow and volume of blood present rapidly dilutes the
hypertonic solution so that it doesn’t damage the blood vessel.
• Easier to maintain than peripheral access
Macronutrient Components of PN: Protein
• Protein: essential for anabolic processes
– Nitrogen balance must be maintained to minimize breakdown of protein for
gluconeogenesis
• Form in PN:
– Cyrstalline amino acids (essential and non-essential)
• Commercially available concentrations range from 3.5 - 20%
– Several different products (Nelms Table 5.5)
– TravasolTM (3.5%, 4.25%, 5.5%, 8.5%, 10%)
– i.e. 5.5% = 55 g protein per 1 L solution
• 4 kcal/g protein when oxidized for energy
Macronutrient Components of PN: Protein
• Protein: essential for anabolic processes
– Nitrogen balance must be maintained to minimize breakdown of protein for
gluconeogenesis
• Form in PN:
– Cyrstalline amino acids (essential and non-essential)
• Commercially available concentrations range from 3.5 - 20%
– Several different products (Nelms Table 5.5)
– TravasolTM (3.5%, 4.25%, 5.5%, 8.5%, 10%)
– i.e. 5.5% = 55 g protein per 1 L solution
• 4 kcal/g protein when oxidized for energy
• Amino acid products typically assumed to be 16% nitrogen
– 1 g Nitrogen = 6.25_________
• Useful when determining nitrogen balance in some clinical
scenarios
– Nitrogen balance = (protein intake g/d ÷ 6.25) - (UUN g/d + 4 g/d)
• UUN = urinary urea nitrogen
• Requires 24h urine collection
Macronutrient Components of PN: Carbohydrate
• Primary source of energy
• Dextrose monohydrate: 3.4______ kcal/g
• Available concentrations: 2.5% – 70%
– i.e. 10% solution = 100 g CHO per 1L solution
– Maximum concentration for PPN: 10% dextrose
• > 10% delivered peripherally will result in thrombophlebitis
Macronutrient Components of PN: Carbohydrate
• Maximum oxidative rate: 4-5______ mg/kg/min
– Excessive administration:
• Hyperglycemia
• Hepatic abnormalities (i.e. fatty liver, cholestasis)
• Excess CO2 production / ventilatory drive
• Overfeeding
• Minimum (amount of CHO) required for protein sparing (not to degrade muscles): 1____ mg/kg/min
Macronutrient Components of PN: Lipid
• Dual role of lipid
– Source of (non-protein) energy (1 g lipid = 9 kcal)
– Source of essential fatty acids (prevent EFA deficiency)
• Linoleic & alpha-linolenic
• PN lipid emulsions available in following concentrations:
– 10% (1.1 kcal/mL)
– 20% (2.0 kcal/mL)
– 30% (3.0 kcal/mL)
Different types of lipid emulsions
1st generation – IntralipidTM • Soybean oil • Egg yolk phospholipid (emulsifier) • Glycerol (ensures emulsion in isotonic) – High in n-6 fatty acids • Pro-inflammatory • Associated with hypertrigylceridemia, liver disease etc.
• 2nd generation – Balanced blends of n-3, n-6, n-9 PUFA’s • LCT + MCT mixtures • Fish oil emulsions • Olive oil based lipid emulsions – Anti-inflammatory properties – Associated with: • Reduced PN-associated liver disease • Improved outcomes septic patients 22/11/17 9 Glucose 10-40% Na, K, Ca, P Amino acids Na, K, Mg Lipid emulsions Trace elements Vitamins Modern PN – All-in-One Admixtures No significant differences Apparent insignificant differences Special solutions (glutamine) - many types of emulsions (LCT, MCT/ LCT, omega-3- FA, structured) - Special solutions (omega-3- FA) No major differences Minor differences (iron, manganese) Lipid emulsions nowadays Long - chain triglycerides (LCT) LCT+MCT mixtures Fish oil emulsions Olive oil based lipid emulsions SMOF-emulsion Basics in clinical nutrition, ESPEN 2004. Fürst P. J. Nutr. 128: 789-796, 1998. Wirtitsch M. Et al
2nd Generation Lipid Emulsions: SHR
• ClinOleic® –20% soybean oil –80% olive oil • SMOFlipid® –30% soybean oil (S) –30%MCT (M) –25% olive oil (O) –15% fish oil (F)
- Minimum amount of fat to prevent EFA deficiency
* Typical adult dosing:
8-10% of energy requirements
– 500 mL Intralipid® weekly
• Hypertriglyceridemia à restrict amount
• Typical adult dosing:
– 25-30% of energy requirements
– Maximum 1-1.5_____ g/kg/d non-ICU patients; ICU patients 1______ g/kg/d
– Infusion rate should not exceed 0.11_____ g/kg/h
Nutrient Admixtures
• 3-in-1 / Total Nutrient Admixture (TNA) solution
– Incorporates all PN components (aa, dextrose, lipid, electrolytes,
vitamins, trace elements) in form of an emulsion
• 2-in-1 solution
– Incorporate all constituents except lipids (can be hung separately)
PN Additives
• Additives – Electrolytes – Vitamins – Trace Elements • American Medical Association originally released recommendations for vitamins and trace elements (1979) – ASPEN recommended modifications in 2012 • Refer to SHR order sets & RQHR handbook • Adjusting doses is NOT entry level – Restricted activity
