Adult Parenteral Nutrition Flashcards
Enteral advantages
- less cost
- more complete nutrient profile
- fewer complications
Parenteral advantages
- easier admin
- better patient acceptance
- more reliable delivery
Contraindications for parenteral nutrition
- functioning and accessible GI tract
- treatment <7 days anticipated NPO status w/o severe malnutrition
- prognosis that does not warrant aggressive nutrition support
- risk exceeds benefits
- inability to obtain venous access
Indications for parenteral nutrition
- nonfunctioning GI tract
- inability to tolerate oral feedings
- patient failed enteral nutrition
- prognosis warrants aggressive nutrition therapy
T/f benefits should be weight against risks for every potential nutrition candidate
True
Conditions warranting use of parenteral nutrition
- preoperative (severely malnourished, NPO >10 days)
- lower GI obstruction
- high output GI fistula (>500ml/day)
- acute IBD
- short bowel syndrome
- severe acute pancreatitis
- critical care
- cancer
Parenteral nutrition definition
- process of supplying nutrients via IV route
- components in elemental form
What is parenteral nutrition also known as?
- TPN (total parenteral nutrition)
- hyperalimentation
Goal of parenteral nutrition
Formulate a safe, clinically appropriate end product
PN protein, CHO and fat
AA
Dextrose
Lipid emulsion
PN formula considerations
- central vs peripheral IV access
- osmolality
- fluid volume needed
- concentration of dextrose, AA and lipids
- addition of MVI, TE
- pH of solution
- stability
- compatibility of nutrient components to meet nutritional needs
- microbial growth potential of admixture
Central line advantage
- more calories can be delivered
- longer duration of therapy (>10 days to years)
Limitations of central line
- obtaining central access
- more catheter maintenance
- more metabolic complications
Peripheral vein uses
- short term therapy (7-10 days)
Peripheral vein advantages
- easy to obtain access
Limitations of peripheral vein
- large electrolyte needs (K strong vascular irritant)
- nutrient provided (lipids majority)
- patient tolerance to larger fluid volumes
- medication compatibilities
- osmolarity <900mOsm
TPN vs PPN
- TPN: glucose concentration 15-25%, PPN 5-10%
- Osmolarity TPN: >1300-1800, PPN: <900
- TPN: large diameter vein (central), PPN: peripheral vein
- TPN: more concentrated; PPN: large fluid volumes
When a _____ solution is introduced into a small vein with a low blood flow, fluid from the surrounding tissue moves into the vein due to ______
Hypertonic
Osmosis
The high concentration in a small vein leads to ______
Phlebitis (pain, irritation, inflammation of vein)
Osmolarity limits in peripheral line
600-900 mOsm/L
Osmolarity limits in central line
> 1800 mOsm/L
Increased osmolarity limits in central line allows for increased concentrations of _____ and ______ to be delivered
Dextrose
AA
AA PN osmolarity
100 mOsm/1% final concentration/L
Dextrose PN osmolarity
50 mOsm/1% final concentraiton/L
Estimating PN osmolarity of dextrose
G dextrose/L x 5
% dextrose of solution x 50
Estimating PN osmolarity of protein
G protein/L x 10
% AA of solution x 100
Primary energy substrate in PN
Carbohydrate
Kcal/g of dextrose monohdyrate
3.4 kcal/g
% concentration range of dextrose monohydrate
5-70%
Kcal/g of glycerol
4.3 kcal/g
Glycerol in PN
Pre-manufactured PPN solutions typically
Naturally occurring sugar alcohol
Potential adverse effects of carbohydrates in PN
- increased minute ventilation
- increased CO2 production
- increased O2 consumption
- increased RQ
- hepatic steatosis
- hyperglycemia
Source for nitrogen in PN
Protein
Kcal/g of protein
4 kcal/gm
% concentration of protein
3-15%
Standard amino acids
Mixture of essential and non-essential AA
Condition specific or modified protein
- renal and liver failure formulations
- costly
- not commonly used
Potential adverse effects of protein in PN
- increased renal solute load
- azotemia
20% lipid emulsion kcal/ml
2 kcal/mL
Potential adverse effects of fat in PN
- egg allergy
- hypertriglyceridemia
- decreased cell mediated immunity in immunosuppressed
- elevated LFTs
MVI-13
- limited stability once added to TPN
- contains vitamin K
Trace elements in PN
- Zn, Cu, Mn, Cr, Se
- essential to normal metabolism and growth
Conditions that require adding trace elements individually
- decreased excretion with biliary disease
- deficiency states may develop with increased metabolic requirements or increased losses
Electrolytes uses in PN
- essential nutrients that perform critical physiologic functions and maintain homeostasis
Stability of TPN solution is dependent upon compatibility of each _____ and other components of admixture
Electrolytes
______ forms of electrolytes can affect acid/base balance
Salt forms (acetate vs chloride)
Electrolyte needs dependent upon
- renal function
- acid/base balance
- GI losses
- medications
T/F electrolytes must be individualized
True
Important electrolytes to add to PN
Na, K, P, Mg, Ca
Which form of calcium is preferred for PN?
Gluconate
Why is bicarbonate not used in TPN?
Precipitation of Ca and Mg
Why is acetate commonly used in TPN?
Readily converted endogenously to bicarbonate
How is acid/base balance maintained in TPN?
Acetate and chloride salts
Acetate/chloride in metabolic acidosis
Maximize acetate
Minimize Cl
Drug shortages and TPN
- occur for variety of components (lipids, AA, electrolytes, MVI)
- communicate availability
- prescription may need to be modified
- if patient risk for deficiency, monitor labs closely
Fluid in TPN
- sterile water added to adjust total volume of fluid needed to meet prescribed 24 hour fluid intake
T/F individual fluid needs do not need to be considered in every TPN prescription
False! Must be considered
What considerations must be taken with fluids and TPN?
- other IVF
- IV drugs
- blood products being prescribed
With fluid levels what do you monitor?
BUN
Creatinine
T/f the order of admixing can affect overall stability of final product
True
Stability issues of TPN
- impacted by order components added (esp calcium, P)
- max cal and P product is 50 (40-45 preferred to prevent precipitation)
- concentration of AA affects pH
- temp
- adequate mixing/agitation
2 in 1 admixture
Piggyback
-dextrose, AA, electrolytes infused separately from lipids
3 in 1 admixture
Total nutrient admixture (TNA)
- lipid emulsion admixed with dextrose, AA and electrolytes
Advantages of TNA
- decreased nursing time
- decreased risk of touch contamination, possibly decreased infection risk
- ease of admin for home TPN patients
- better lipid utilization
Better lipid utilization of TNA
- continuous, slow infusion
- short infusions under 10 hours associated with reticuloendothelial system impairment
Disadvantages of TNA
- stability (decreased by lipid)
- compatibility (decreased amounts of nutrients when lipid present)
- impaired visual inspection (opaque limits precipitation visualization)
- filtration
- TNA may be safely filtered with 1.2um filter (removes large organisms, but not common bacterial contaminants)
FDA requires disclosure of _____ content of PN components as all of them contain it
Al
Where is aluminum highly found?
AA solutions
Phosphate salts
Ca gluconate
TE
Implications of aluminum
Metabolic bone disease
Neurologic dysfunction
Microcytic anemia
At risk populations of aluminum
- neonates
- those with renal dysfunction
- those on long term PN
Symptoms of toxicity of manganese
- HA
- tremor
- parkinson like gait dysfunction
At risk population of manganese toxicity
Cholestatic liver disease
Parenteral nutrition monitoring
- labs
- weight
- I/Os
- vital signs
- Meds
- changes in medical condition
- determine readiness to transition to enteral nutrition
What labs should you monitor in PN
- serum electrolytes
- blood glucose
- triglycerides
- LFTs
TG >250 in PN
Consider reducing lipid infusion
TG >400 PN
Hold lipids
Glucose abnormalities of PN
- hyperglycemia (limit glucose)
- hypoglycemia (occurs with sudden discontinuation)
What should you check with glucose abnormalities of PN?
Assess for new or resolving stress, new or discontinued meds or dextrose containing IVF
When can hepatic steatosis occur in PN?
- may occur 1-2 weeks after starting
When can cholestasis occur in PN?
- may occur 2-6 weeks after starting
Cholestasis indicated by
Progressive increase in total bilirubin and alkaline phosphatase
Cholestasis occurs due to
Lack of intestinal nutrients to stimulate hepatic bile flow, causing disruption or blockage
Hepatic steatosis indicated by
Elevated LFTs
Hepatic steatosis due to
Overfeeding of dextrose and lipids
May be due to carnitine or choline deficiency
GI atrophy due to
Lack of enteral stimulation associated with
- villus hypoplasia
- colonic mucosal atrophy
- decreased gastric function
- impaired GI immunity
- bacterial overgrowth
- bacterial translocation
How to prevent GI atrophy in PN?
Initiate trophic enteral feeding
Acid base disorders in PN due to
- increased renal or GI loss of bicarbonate
- renal failure
- ketoacidosis
- lactic acidosis
- excessive chloride administration
Vascular access issues in PN
- pneumothorax
- arterial puncture
- infection
What are some complications of PN support?
- glucose abnormalities
- metabolic bone disease
- hepatic steatosis
- cholestasis
- GI atorphy
- Acid base disorders
- vascular access issues
Reducing risk of refeeding syndrome
- identify patients at risk
- correct electrolyte abnormalities BEFORE initiation of nutrition support
- limit volume initially
- limit dextrose to 150mg/day initially
- may need to supplement thiamine
- GO slow: permissive underfeeding
Refeeding syndrome major concern of causing
Cardiorespiratory failure
Refeeding syndrome can cause
- thiamine deficiency
- hypophosphatemia
- hypokalemia
- salt and water retention
- hypomagnesemia
- excessive demands of malnourished heart
Permissive underfeeding
- approx 2/3 of needs
- temporary
Perfmissive underfeeding used for
- refeeding syndrome
- hyperglycemia
- organ failure
- need for significant fluid restriction
Defense against PN complications
- appropriate patient selection
- do not overfeed
- monitor fluid/electrolyte/vitamin/mineral status
- monitor organ function, changes in patient medical status
- aseptic technique for insertion and site care of IV catheters
