Parenteral Nutrition Flashcards
Nutritionally at risk
1 month >5% UBW loss
6 month >10% UBW or >20% IBW loss
% IBW
Weight/IBW x 100
% of ideal body weight
% UBW
% usual body wight
Current weight/usual weight x 100
% of recent weight
Usual weight -current weight/usual weight x100
When should actual weight be used?
If the patient is underweight or normal weight
For severely underweight use actual weight initially and then increase requirements to an upper limit if 35 kcal/kg/day
When should adjusted body weight be used?
In overweight patients so as not to overestimate nutritional requirements
Adjusted weight
(Adj-IBW/2)+IBW
Parenteral nutrition
Administered outside the digestive tract intravenously
Enteral nutrition
Oral or tube feedings into the digestive tract
When to use parenteral nutrition
If the GI tract is not working
If the GI tract is not used
It can atrophy
Gut bacteria can translocate to the circulatory system when GI tract atrophies
Nutrition types
Enteral
Peripheral parenteral nutrition
Total parenteral nutrition
Peripheral parenteral nutrition (PPN)
AKA peripheral venous nutrition
PPN advantages
Avoid central catheter-related complications
Avoid hyperosmolar complications
PPN Disadvantages
Thrombophlebitis
Frequent vein rotation
Caloric intake is limited
Fluid restriction is NOT possible
Why it’s caloric intake limited in PPN
Because the hypertonic solutions would cause an intolerable rush of fluid into the small veins via osmotic shift leading to thrombosis
PPN infusion
Catheter in upper arm
Up to 1800-2500 kcal and 90g protein supported
Only supported for a short period at high levels
TPN
AKA central parenteral nutrition
Hyperal
TPN advantages
Long term catheter maintenance
Maximum caloric intake
Fluid restriction is possible
TPN disadvantages
Mechanical complications of catheter placement
Potential hyperosmolar complications
Infectious complications
Parenteral nutrition composition
Dextrose—3.4 kcal/gm
Protein—4 kcal/gm
Fat—10 kcal/gm
Electrolytes
Trace elements
Vitamins
Water—35 mL/kg/day
Other ingredients
Composition of 10% amino acid products
Nitrogen content
Essential AA
BCAA
AAA
Actual content amounts vary depending on the specific product
What does aminosyn II have more of than Travasol
BCAA
Classification of fatty acids
Carbon chain length
Number of double bonds
Carbon chain length
SCFA: 2-4 C
MCT: 6-12 C
LCT: 14-24 C
Number of double bonds
Saturated: 0
Monounsaturated: 1
Polyunsaturated: 2+
US Commercially available IV lipid products
Linoleic acid (Omega-6)—49-65.8%
Linolenic acid (Omega-3)—4.2-9%
How are lipids administered?
Via Y tube of piggybacked
Does not have to be mixed with amino acids and dextrose
Electrolyte requirements
Na: 1-2 mEq/kg
K: 1-2 mEq/kg
Phos: 20-40 mmol/day
Ca (gluconate): 10-15 mEq/day
Mg(SO4): 8-20 mEq/day
Vitamins
Administered daily, now contain vitamin K
Multiple entity product
Trace elements
Zn, Cr, Se, Cu, Mn
Single or multiple entity products
For osteomyelitis or diarrhea losses
Increased Zn
For severe hepatic cholestasis
Decrease Cu and Mn intake
Other components of PN
Albumin
Heparin
Insulin
Vein protectors
Hydrocortisone 15 mg
Heparin 1500 units
Nitroglycerin patch 0.1 mg/hr
H2 antagonists and PN
Given in patients with GI stress ulcer for prophylaxis
Famotidine common, stable 72 hours
Ranitidine may also be added, stable 24 hours
Fluid status monitoring
Signs and symptoms of fluid overload/dehydration
Measuring daily weight
Measuring daily input/output
When should PN be used
patients who cannot/will not eat for >7 days
Can be used for up to 1 week
Central PN is necessary when GI tract is not accessible/functional for > 2 weeks
Optimal provision of nutrition
max glucose: 5 mg/kg/min
Infuse 30% or less of total daily calories as fat to avoid immune dysfunction
Protein delivery in stressed patients with normal function is 1.5-2 g/kg/day
Mifflin-St Jeor Equation
Men: BMR=10W + 6.25H - 5A+5
Women: BMR=10W + 6.25H - 5A - 161
Revised Harris-Benedict Equation
For men: BMR=13.397W + 4.799H + 5.677A + 88.362
For men: BMR = 9.247W + 3.098H + 4.330A + 447.593
Katch McArdie Formula
BMR = 370 + 21.6 (1-F)W
F= body fat percentage
Micronutrients
Na/K: 1-2 mEq/kg
Phosphate: 20-40 mmol/day
Magnesium: 8-24 mEq/day
Calcium: 10-15 mEq/day
Chloride 60-100 mEq/day
Acetate: 60-100 mEq/day
What should not be made for TPN
Kevorkian because it’s deadly
Osmolarity compatibility
osmotic pressure is proportional to the total number of particles in solution
nonelectrolyte: 1 mmol = 1 mOsmol
electrolyte: 1 mmol NaCl = 2 mOsmol assuming complete dissosciation
Osmolarity of separate ions
mOsmol/L = W substance (g/L)/MW(g) x 1000
Osmolarity of whole electrolyte
mOsmol/L = W substance (g/L)/MW(g) x number of species x 1000
Osmolality
mmol/kg of solvent
PN solution osmolarity
<600-900 mOsm/L
Hazardous preciptiation
Phosphates + calcium ions in solution form a less soluble compound leading to precipitation
Factors of ensuring the solubility of Ca and P in PN formulations (additives)
Lower final pH to get the more soluble compound
–higher dextrose
–add cysteine HCl
–lower final concentration of lipids
Increase the amino acid concentration
Rate of growth in admixtures may be variable
Keep concentrations below the solubility curve
Factors of ensuring the solubility of Ca and P in PN formulations (technique)
Agitate after each ingredient
Added Phos early and CaGluc nearly last
using a 0.2 micron filter
Never use CaCl2
Factors favoring Ca / P solubility
Ca<10 mEq/L and PO4 <30 mMol/L
decreased T
IV lipid emulsion stability
Contain chylomicron-like oil droplets of neutral TGs with a surrounding layer of phospholipids
Droplet size ~0.5 microns and negative surface size
Charge prevents aggregation and maintains emulsion stability
Broken/cracked emulsion
Cracked TNA occurs when oil globules on the surface coalesce or fuse to form larger oil droplets
Appears as an amber oil layer or streaks
Irreversible
