Parenteral and Enternal Nutrition - Lecture 2 Flashcards
Parenteral nutrition
the process of supplying nutrients via an intravenous delivery system (i.e. protein, carbohydrates, fat, electrolytes, vitamins, minerals)
synonyms: TPN, PN, TNA, 3-in-1
PN indications
anticipated prolonged NPO course (>7 days)
inability to absorb nutrients via the gut, such as secondary to: small bowel or colonic ileus, extensive small bowel resection, malabsorptive states, intractabl vomiting/diarrhea
enterocutaneous fistulas
inflammatory bowel disease
hyperemesis gravidum
bone marrow transplantation (mucositis)
Routes of administration
peripheral
central
Peripheral PN
dextrose and amino acid solutions are hypertonic: not well tolerated via a peripheral vein
restrict final dextrose concentration to 5-10% or total osmolarity to < 900 mOsm/L
addition of other substances to solution may enhance vein tolerance
Peripheral PN requires
large volumes of fluid: may not be the best choice for HF or AKI/CKD pts
limited in calories: secondary to the osmolality AND fluid
short term access (<7-10 days): does this pt need PN at all?
pharmacy/MD error? (always double-check to confirm peripheral route was intentional)
Central PN advantages
allows administration of hypertonic solutions
more calories can be delivered
Central PN disadvantages
risk of infection: appropriate central line care is key to prevention
central line is not a benign procedure: pneumothorax, air embolus, thrombus
Central venous access
central venous catheter (CVC) insertion sites: subclavian (SC) - under clavicle, internal jugular (IJ) - in neck, femoral - in groin
short term: percutaneously inserted
long term: PICC (peripherally inserted central catheter), tunneled, implanted port
Meeting energy requirements
protein calories
non-protein calories (NPC): carbohydrates, fats
Meeting protein requirements
one gram protein = 4 kcal - many hospitals actually order protein in gm/day
standard amino acid products: travasol, freamine III, aminosyn II
Carbohydrates (dextrose)
max concentration available: D70% (D70W)
one gram dextrose = 3.4 kcal
limitations: a final dextrose concentration > 10% (adults) and >12.5% (peds) should not be infused into a peripheral vein due to vein irritation
max carb utilization: 4-5 mg/kg/min (double check)
IV fat (lipid) emulsion - intralipid
provides a concentrated source of calories:
1 gram lipids = ~ 10 kcal
prevents essential fatty acid deficiency
intralipid 10% consists of: soybean oil, glycerin (check for allergies), egg yolk phospholipid (check for allergies), water for injection
IV fat (lipid) emulsion - SMOFlipid
SMOFlipid consists of:
soybean oil - omega-6 essential fatty acid
medium-chain triglycerides - rapidly available energy source
olive oil - omega-9 monounsaturated fatty acid
fish oil (check for allergies) - omega-3
SMOFlipid compared to pure soybean oil products
improved liver function (lower ALT/AST concentrations)
lower increase in TG levels from baseline
SMOFlipid compared to non-omega-3 PN
less pro-inflammatory
less negative impact on liver function
reduced risk of infection
decreased length of hospital stay
Additional lipid considerations
max intake - do not exceed: 60% of caloric intake as lipid; generally 1-1.5 gm/kg/day of lipids in adults - max of 2.5 gm/kg/day of lipids in adults if tolerating; 4 gm/mg/day of lipids in infants/peds
propofol is a 10% lipid solution; provides 1.1 kcal/mL
IV fat emulsion - administration
IV fat emulsion 10% and 20% are isomolar (isotonic) with serum: may infuse via peripheral vein; piggyback into PN; admix into dextrose/amino acid solution to decrease osmolarity
IV fat emulsion 30%: must be incorporated into total nutrient admixture (3-in-1)
IV fat emulsion - infectious complications
IV lipids provide an environment suitable for pathogen growth:
hang-time of IV fat emulsion by itself should be limited to 12 hrs after opening of manufacturer packaging; if added as TNA (3-in-1) safety is increased to 24 hrs
Administration of PN - total nutrient admixture (custom TPN)
dextrose, AA, and lipids in one bag
3-in-1 = TPN (total parenteral nutrition)
Administration of PN - conventional administration (custom TPN)
dextrose and AA in one bag
lipid 2-3 times a week as a separate IVPB
Administration of PN - premix solution for injection (standard TPN)
available with or w/o electrolytes
no lipids
In line filters
reduces infusion of particulates, microprecipitates, microorganisms, pyrogens, and air
1.2 micron filter can be used for all total nutrietn admixtures (TNAs) or 3-in-1 (w/ lipids)
0.22 micron filter only used for 2-in-1 formulations (no lipids)
Premix PN solutions (clinimix/clinimix E)
standard TPN - not able to customize these products
amino acid in dextrose - with or w/o electrolytes
lipid compatible
peripheral and central line preparations
contains: amino acids + dextrose (+/- Na, K, Mag, Ca, acetate, Cl, Phos)
Clinimix/Clinimix E dosing
standard PN order, must assess renal function: CrCl < 50 - standard PN formula, NO electrolytes; CrCl>/= 50 - standard PN formula WITH electrolytes
PN initiation and discontinuation guidelines
start at ~25% of goal and achieve the final rate within 24 hrs
initiation: check blood glucose Q4-6 hrs, before each increase in rate; if BG < 200, continue at same rate x 4 hrs and recheck, if repeat BG > 200, consider insulin therapy
cessation: decrease rate by half q2hrs until rate < 50mL/hr, then discontinue
Cycling PN (for pts going home on PN)
infusion over ~12-18hrs/day
transitioning to EN or PO intake
pts who desire time free from the infusion pump (home PN pts)
rate of infusion generally cut back (tapered) during the first/last hour of infusion to prevent dysglycemias
no specific guidelines for cycling PN (max ~200mL/hr)
Additives
electrolytes
vitamins
trace elements
Electrolytes
calcium, magnesium, phosphorous, sodium, potassium, chloride, acetate
Calcium standard daily range
10-20 mEq
Magnesium standard daily range
8-24 mEq
Phosphorous standard daily range
15-45 mMol
Sodium standard daily range
1-2 mEq/kg
Potassium standard daily range
0.5-1 mEq/kg to start
Chloride and acetate standard daily range
as needed to maintain acid-base balance
chloride ~2/3
acetate ~1/3
Electrolyte considerations
in pts with renal disease: caution should be used with potassium, phosphate, and magnesium (b/c these are renally cleared)
acid-base balance obtained through balance of acetate and chloride
avoid calcium + phosphorous precipitation: avoid Ca (mg/L) x phos (mMol/L) > 150
Vitamins
thiamin, riboflavin, niacin, folic acid, panthotenic acid, pyridoxine, cyanocobalamin, biotin, ascorbic acid, A, D, E, K
adult and pediatric (>40 kg): 10 mL/day of injectable adult multivitamin-12
pediatric (3 kg-40 kg): 2 mL/day of injectable pediatric multivitamin
Trace element adjustments
liver dysfunction (chronic liver disease or LFTs > 2x ULN): discontinue trace elements, supplement individually: zinc 5 mg (1mL), selenium 60 mcg (1mL)
renal disease (CKD/ESRD on hemodialysis): consider checking serum levels if use expected beyond 14 days, use selenium and chromium with caution, different rules for CRRT
Iron
give IV iron separately
addition of iron to PN is not recommended: can destabilize IV fat emulsion in 3-in-1 formulations, may contribute to infectious complications
Medications in PN
for the most part, the addition of meds to PN formulations is not advised; may use famotidine (H2 blocker) may be utilized for GERD or stress ulcer prophylaxis
PPIs NOT compatible with PN
Insulin in PN
regular insulin only!
common regimen: 0.1 units/gram of dextrose
if BG > 150 mg/dL: 0.15 units/gram dextrose
if BG > 300 mg/dL: do not initiate PN until < 200 mg/dL
max amount: 0.3 units/gram dextrose
5-10 units stick to the bag
Converting phos mMol to mEq
average = 1 mMol phos = 1.4 mEq phos
Positive ions
sodium and potassium
Negative ions
chloride, acetate, and phos
Chloride:acetate balance
total positive and negative ion balance must equal zero
consider acid/base status and CMP
additional losses can contribute
titrate based on response
PN complications
mechanical
infectious
metabolic
Mechanical complications
catheter related: clotting of line, displacement
Infectious complications
catheter-related sepsis, solution contamination, bacterial translocation
Bacterial translocation
time-dependent passage of bacteria or endotoxins from GI tract to extra-intestinal sites
enteric organisms cause systemic infections: pneumonia, central line infections, abcesses, multi-organ dysfunction syndrome
infectious morbidity and mortality
Metabolic complications
electrolyte imbalances, fluid imbalance, hyper- and hypoglycemia, liver function abnormalities: steatosis (fatty liver), intrahepatic chloestasis, cholelithiasis
PN baseline monitoring
baseline: CMP, Mg, phos ionized Ca; hepativ function panel; prealbumin/CRP; PT/INR
Q6-4H: finger sticks for glucose, residuals, distention, vomiting, aspiration
Ongoing PN monitoring - daily
vital signs, intake/output, CMP, feeding tube placement and patency, may decrease frequency when stable
Ongoing PN monitoring - twice weekly
weight, CBC, Mg, phos, Ca, prealbumin/CRP, ICU setting –> increase to daily
Ongoing PN monitoring - weekly
albumin, transferrin, nitrogen balance, liver function tests, triglycerides, PT/INR, respiratory quotient/indirect calorimetry
Additional complications
refeeding syndrome
essential fatty acid deficiency
Refeeding syndrome
constellation of fluid, micronutrient, electrolyte, and vitamin imbalances
occurs within first few days of feeding a starved pt
potentially life threatening
Clinical finding of refeeding syndrome
hypophosphatemia (most likely to experience! controls muscle contractions, stop breathing), hypomagnesemia, hypokalemia (3 you’re most likely to see)
respiratory distress
paresthesias
tetany
cardiac arrhytmias
hemolytic anemia
Risk factors for refeeding
rapid feeding, excessive dextrose infusion
low BMI
excessive weight loss
insufficient caloric intake
low levels of K, phos, or Mag prior to feeding
high risk comorbidities: alcoholism, anorexia nervosa, marasmus
Prevention of refeeding syndrome
replete electrolytes before initiating feeds
initiation recommendations (day #1): limit carbs (dextrose) to 100-150 gm, limit fluids to 800mL/day, provide adequate amounts of electrolytes, provide approx 50% of total caloric needs
advance calories/dextrose by 20-33% of goal every 1-2 days as tolerated
give thiamine 100 mg daily x5-7days
Essential fatty acid requirements
estimated to be 4-10% of daily caloreis
EFAs include linoleic and linolenic acids
Essential fatty acid deficiency MOA
continuous infusion of hypertonic dextrose will increase circulating insulin levels
inhibits lipolysis and fatty acid mobilization
EFAD clinical onset and symptoms
clinical onset: several weeks on fat-free PN regimen (10-14 days)
sx: dry scaly skin, brittle hair, lack of luster
Prevention of EFAD
recommended minimum requirement is to provide approx. 4% of caloric intake as lipids
prevention: provide at least 500 mL of 10% fat emulsion over at least 3-5hrs twice weekly OR provide at least 250 mL of 20% fat emulsion over at least 5-9hrs twice weekly
