Ch 14: Overview of PN Flashcards
If administered inappropriately, PN can result in:
- Venous thrombosis (blood clots; e.g., DVT)
- Suppurative thrombophlebitis (presence of venous thrombosis, inflammation, and bacteremia)
- Extravasation (leakage of fluid in the tissues around the IV site – PN fluid is a vesicant (a fluid that irritates tissue))
mOsm/to calculate osmolarity:
Dex, AA, lytes
- Dextrose: 5 mOsm/g
- AA: 10 mOsm/g
- Electrolytes: 1 mOsm/mEq of individual electrolyte additive
TPN characteristics
- Glucose content: 150-600g per day
- Hyperosmolar solution → delivered into a large-diameter vein (superior vena cava) via CVC
- Rate of blood flow rapidly dilutes hypertonic PN to body fluids
- Preferred in patients requiring a fluid restriction as it can be concentrated
- Long term indefinite duration
- Preferred in patients requiring > 7-14 days of PN
Max osmolarity of PPN
900 mOsm/L
Content of PPN:
- Dextrose: 150-300 g/day (5-10% concentration)
- AA: 50-100 g/day (3% concentration)
Why is PPN Used for short periods?
How long a time?
- Up to 2 weeks
- Due to few suitable peripheral veins and limited patient tolerance
- May be limited by venous access
*
PPN Contraindications
- Significant malnutrition
- Severe metabolic stress
- Large nutrient or electrolyte needs (K is a strong vascular irritant)
- Fluid restriction
- Need for prolonged PN (>2 weeks)
- Renal or liver compromise
Midline catheters recommended for PPN
Midline catheters recommended for PPN >6 days d/t catheter length and lower probability of dislodging vs other peripheral cannulas
Do Midlines reduce the risk of thrombophlebitis?
does not reduce the risk of thrombophlebitis
Permissive underfeeding
Provide 80% of EEN until pt’s condition improves
* Minimizes complications of PN delivery
* Critical illness
Hypocaloric feeding
Meet protein requirements, provide less energy
* Used in EN/PN for obese patients
* Minimizes metabolic complications of PN while improving nitrogen balance
* Used with BMI >30
* Critically ill or other hospitalized patients
Supplemental PN
Purpose to avoid energy deficits during no nutrition or undernutrition
* Used when EN is insufficient to meet energy needs
Indications for PN
- Contraindication to EN or access
- Impaired absorption or loss of nutrients
- Mechanical bowel obstruction
- Need for bowel rest
- Motility disorders
- Inability to achieve or maintain enteral access
Criteria for PN
Delay in those with severe metabolic instability
* Address electrolyte abnormalities
* Address hypovolemia, shock, hypoxia
Is CVC available?
Duration of therapy exceeds 5-7 days
Criteria for PN in:
Well nourished stable adult
Wait 7 days
Criteria for PN in:
Nutritionally-at-risk
Wait 3-5 days
Criteria for PN in:
Baseline moderate or severe malnutrition
as soon as feasible
Conditions where PN should be used with caution:
- Hyperglycemia (>300 mg/dL)
- Azotemia (BUN >100 mg/dL)
- Hyperosmolality (serum osmo >350 mOsm/kg)
- Hypernatremia (>150 mEq/L)
- Hypokalemia (K <3 mEq/L)
- Hyperchloremic metabolic acidosis (Cl >115 mEq/L)
- Hypophosphatemia (Phos <2 mg/dL)
- Hypochloremic metabolic acidosis (Cl <85 mEq/L)
PN & IBD
PN has not been shown to improve outcomes as primary management
* Bowel rest not necessary to achieve remission in Crohn’s
PN & SB fistulas
PN noted improvement in mortality rates and spontaneous surgical closures
* Exception: when fistula arises from bowel with active Crohn’s
PN & pancreatitis
Unlikely to benefit mild, acute, or chronic relapsing pancreatitis when <1 week
PN & pancreatitis
Recommendations
- 25-35 kcal/kg
- Adequate glycemic control
- Glutamine administration (0.3g/kg alanyl-glutamine dipeptide) to minimize effects of NPO status on gut integrity
Why is GI/bowel rest + PN no longer indicated in pancreatitis? Why should PN be avoided (unless EN is not feasible)?
d/t ileus, SBO, inability to place feeding tube
What baseline state have studies shown have the highest risk of adverse postsurgical outcomes?
low visceral protein stores (specifically Alb) at baseline
Perioperative PN reserved for severe malnutrition at baseline where risk > benefits of surgery 2/2
high risk for post-op complications
Max benefits seen in >7-10 days
2011 evidence - cancer/surgical patients
EN comparable to PN in malnourished cancer patients undergoing surgery
Does ASPEN/SCCM recommend EN or PN as preferential feeding route?
ASPEN/SCCM recommend EN > PN as preferential route
* Greatest benefit seen in first 24-48 hours after admission to ICU
When should PN should be a last resort in patients with normal nutrition status?
cannot initiate EN > 7 days
PN indications in critical illness
- hemodynamically stable patients
- paralytic ileus
- acute GI bleed
- complete bowel obstruction
PN & GI malignancies
Review of PN literature has reported improved outcomes in patients with upper GI malignancies when PN is initiated 7 days before surgery
PN during chemo/XRT associated with:
- increased infection complications
- no improvement in clinical response, survival, or toxicity to chemo
ASPEN guidelines: PN & cancer
- thorough nutrition assessment
- use PN only in malnourished patients unable to ingest/absorb adequate nutrients for >7-14 days
Is EN or PN preferred in hematopoietic cell transplant and why?
EN preferred in hematopoietic cell transplant 2/2 better glycemic control vs PN
Is standard formula immune-enhancing formula appropriate in cancer patients?
Data supports use of immune-enhancing EN
Home PN considerations
- Patient/caregiver capabilities
- Safety of home environment for PN
Medicare & home PN requirements for reimbursement:
- Document GI tract is non-functional (“artificial gut”)
- Condition is permanent (>/= 90 days therapy needed)
- Documented evidence of inability to tolerate EN
Medical conditions requiring caution with home PN initiation:
- DM
- CHF
- Pulmonary disease
- Severe malnutrition
- Hyperemesis gravidarum
Electrolyte d/o requiring caution with home PN initiation:
- Hypernatremia
- Hypokalemia
- Hyperchloremic metabolic acidosis
- Hypophosphatemia
- Hypochloremic metabolic alkalosis
PN associated with complications and patient harm include:
- Infections related to introduction of IV catheter and their manipulations
- Administration of viable growth medium
- Metabolic complications from overfeeding or refeeding
- Problems caused by other errors during prescription, transcription, or preparation
Successful use of PN requires:
adequate system to order, transcribe, prepare (compound), dispense, and administer
PN should only be advanced when the following criteria are met:
- Stable blood pressure, pulse, respiration rates – can be adversely affected by PN
- Normal K, Phos, BG
Prevent rebound hypoglycemia with d/c of PN
taper over 1-2 hours
What to do if PN needs to be emergently stopped
replace with D10W at same rate, or at least 50 ml/hr
Current water-soluble vitamin daily parenteral doses are 2 to 2.5 times greater than the Recommended Dietary Allowance (RDA) or Adequate Intake (AI) because of
ASPEN self assessment - PN
increased requirements due to
* malnutrition
* baseline vitamin deficiencies
* increased urinary excretion of water-soluble vitamins when used intravenously.
