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
