PN Complications
PN Calculations: Monitoring & Complications
Learning Objectives
List the common complications associated with PN.
List the components that are commonly monitored to assess tolerance to PN.
Describe the MNT (Medical Nutritional Therapy) interventions that can be used to prevent & treat:
Hyperglycemia.
Electrolyte, vitamin & mineral alterations.
Describe what "runs" are & what standard doses are typically given when runs are needed.
Adjust a PN order form based on provided data.
Preventing Complications From the Start
Steps to follow:
Determine nutrition prescription including:
Total kilocalories (kcals).
Protein requirements.
Fluid needs.
Determine how many grams are needed of:
Carbohydrates.
Protein.
Fat.
Calculate glucose goal (in mg/kg/minute).
Determine “stock” solution for each of the macronutrients.
Evaluate clinical status to decide if alterations are needed in the additives based on:
Check lab results for trends (increases/decreases).
Anticipate and head off potential problems by adjusting additives.
For potassium: Check if potassium is present in the MIV (Macronutrient Intravenous).
If potassium and phosphate are low prior to starting PN, administer a potassium phosphate run via IV (10 - 20 mEq).
If magnesium levels are low, give a magnesium run IV: 1 - 2 grams.
Administer 100 mg of thiamine IV for 4 - 5 days for malnourished patients.
Recap: Writing the Orders
Dextrose:
Day #1: Start with 150-200 grams of dextrose; increase on day #2 if glucose levels are < 200.
Order protein and lipid in goal grams/day.
Check for refeeding syndrome:
Replace potassium, phosphorus, and magnesium.
Administer 100 mg thiamine IV for 4 - 5 days in malnourished patients.
Order your additives:
Electrolytes.
Vitamins, minerals (calcium, phosphorus, magnesium) & trace minerals.
Other additives like insulin, as needed.
Glycemic Control
The objective is to maintain glucose levels as hyperglycemia is the most common complication associated with PN.
To minimize hyperglycemia:
Start PN with 150 - 200 grams dextrose.
Only increase PN if glucose < 200 mg/dL.
Carbohydrate administration should be restricted to 4 - 7 mg/kg/min in general; and 4 - 6 mg/kg/min for hospitalized patients.
Check fingersticks every < 6 hours.
Treat hyperglycemia with sliding scale insulin coverage (regular) or insulin drip.
Note: this option should be indicated on the PN order form by checking the appropriate box.
Initiating Coverage for Insulin
Check the box on the PN order form to initiate insulin coverage based on the following:
Ensure to specify how much insulin the patient will receive for each glucose level > 140 mg/dL.
TNA Day 1: Calculations Based on Patient Weight
Weight used for calculations: kg
All additives based on the amount per day:
Dextrose: 200 grams
Amino acids: 131 grams
Lipids: 65 grams
Sodium Chloride: 100 mEq
Sodium Acetate: 60 mEq
Sodium Phosphate: 0 mEq
Potassium Chloride: 60 mEq
Potassium Phosphate: 20 mEq
Potassium Acetate: 0 mEq
Magnesium Sulfate: 10 mEq
Calcium Gluconate: 10 mEq
MVI (Adult): 10 mL
Trace Elements: 1 mL
Regular Insulin: units
Famotidine: mg
Thiamine: mg
Folic Acid: mg
Zinc sulfate: mg
Starting PN – Completing Orders
Day 1:
Start PN at 30 mL/hour for 8 hours.
After 8 hours, if fingerstick blood sugar (FSBS) < 200 mg/dL, increase PN to:
60 mL/hour.
Decrease MIV rate to 70 mL/hour.
Continue to monitor; if FSBS < 200 mg/dL after further 8 hours:
Increase PN to goal rate of 100 mL/hour and decrease MIV rate to 40 mL/hour.
After another 8 hours if FSBS <200 mg/dL, increase PN to goal rate of 115 mL/hour and discontinue MIV.
Total volume PN = 2760 mL/day (ensure this meets fluid volume & goals).
Date for the lab draw: (next day).
Check TPN-A labs: CBC with Differential, BMP, Pre-albumin, Magnesium, Phosphorus, Calcium, Triglycerides, PT/INR (only on the 7th day of infusion or change in clinical status).
Check TPN-B labs: BMP, Magnesium, Phosphorus, Calcium, Albumin (always check B labs on day #2; check A again 1 week later).
Conduct daily weight monitoring.
Monitor daily intake and output.
Administer necessary additions like IV runs of K, phosphorus, or magnesium (e.g. 20 mEq of potassium phosphate & 2 grams of magnesium IV).
Acute Inpatient PN Monitoring
Parameters to monitor with frequency:
Glucose: Initially daily.
Electrolytes: Initially daily.
Phosphorus, Magnesium, BUN, Creatinine, Calcium: Initially check every day; then weekly.
Triglycerides: Initially daily.
Fluids/Intake & Output: Daily.
Temperature: Daily.
Total Bilirubin, Liver Function Tests: Baseline, then weekly.
Inpatient Monitoring PN Parameters
Parameters to monitor:
Body Weight: Initially check daily, then weekly.
Hemoglobin, Hematocrit: Check weekly.
Catheter Site: Initially check daily, then weekly.
White Blood Cell Count: Initially check daily, then weekly.
Clinical Status: Daily monitoring.
Electrolytes: PN Initiation & Follow-Up
Key electrolyte assessments:
Potassium: Hypokalemia may result from excessive GI losses, metabolic alkalosis, and refeeding syndrome.
Phosphorus & Magnesium levels: Must be monitored.
Hyperkalemia: Can occur due to renal failure, metabolic acidosis, potassium administration or hyperglycemia.
Sodium levels: Often reflect fluid distribution versus actual sodium status.
Adjust chloride and bicarbonate to help maintain acid-base balance. Always check pH level.
Determining Additives
Additives to consider:
Electrolytes (Sodium, Potassium, Chloride, Bicarbonate).
Begin with standard provision of 1 - 2 mEq/kg.
Use standard facility templates for starting doses.
Adjust based on lab results and clinical status.
Provide IV runs to replete potassium, phosphorus, and magnesium levels when they fall below the normal range (e.g., Kphos in 10-20 mEq increments over 6 hours, and magnesium 1-2 grams).
Multi-vitamins (MVI) and trace elements must be included in standards.
Adjust calcium and magnesium based on individual clinical situations and lab results, always reassessing additives based on observed trends in patient status.
MNT Plan
Overview of Goals:
Aim to increase PN to provide adequate nutrition.
Assess whether to:
Increase PN rate.
Increase grams of dextrose to nutritional goals.
Add insulin to PN for glycemic control.
Modify any additives based on trends.
TNA Day 2: Calculations Based on Patient Weight
Weight used for calculations: kg
All additives based on the amount per day:
Dextrose: 445 grams
Amino Acids: 131 grams
Lipids: 65 grams
Sodium Chloride: 100 mEq
Sodium Acetate: 60 mEq
Sodium Phosphate: 0 mEq
Potassium Chloride: 60 mEq
Potassium Phosphate: 20 mEq
Potassium Acetate: 0 mEq
Magnesium Sulfate: 10 mEq
Calcium Gluconate: 10 mEq
MVI (Adult): 10 mL
Trace Elements: 1 mL
Regular Insulin: units
Famotidine: mg
Thiamine: mg
Folic Acid: mg
Zinc Sulfate: mg
Vitamin C: mg
MNT Plan Continued
Next-day Reassessment Goals:
Review glucose levels from lab results or fingersticks.
Review WBCs and temperature.
Evaluate any changes in clinical status.
Assess the response to the addition of insulin in PN.
Reassess all relevant labs and check for potential refeeding syndrome.
Conduct daily weight and intake/output evaluations.
Monitoring PN: Potential Changes for PN Day 5
For Day 4 Evaluations:
Weight utilized: kg
Daily Additives to monitor:**
Dextrose: 445 grams
Amino Acids: 131 grams
Lipids: 65 grams
Sodium Chloride: 100 mEq
Sodium Acetate: 60 mEq
Sodium Phosphate: 0 mEq
Potassium Chloride: 60 mEq
Potassium Phosphate: 20 mEq
Potassium Acetate: 0 mEq
Magnesium Sulfate: 10 mEq
Calcium Gluconate: 10 mEq
MVI (Adult): 10 mL
Trace Elements: 1 mL
Regular Insulin: 0 units
Famotidine: mg
Thiamine: mg
Folic Acid: mg
Zinc Sulfate: mg
Vitamin C: mg
MNT Plan: Additional Goals
Objectives to Promote PN Tolerance:
Consider decreasing dextrose grams in PN.
Assess the need to add insulin to PN.
Evaluate if more lipid should be added to PN.
IV "Runs"
Definition and Purpose:
IV runs are solutions administered directly into the vein to promote the repletion of necessary electrolytes.
These solutions come from the pharmacy and are administered separately from PN.
Examples of runs include:
Magnesium runs: dose can vary from 1 - 4 grams administered over 6 hours.
Potassium phosphate (Kphos) runs: administered in mEq based on specific runs, with typical dosages ranging from 10 - 20 mEq per run over 4 - 6 hours.
Adjusting the Order Form for TNA Day 5
Weight used for calculations: kg
All additives based on the amount per day:
Dextrose: 445 grams
Amino Acids: 131 grams
Lipids: 65 grams
Sodium Chloride: 100 mEq
Sodium Acetate: 60 mEq
Sodium Phosphate: 0 mEq
Potassium Chloride: 60 mEq
Potassium Phosphate: 35 mEq
Potassium Acetate: 15 mEq
Magnesium Sulfate: 12 mEq
Calcium Gluconate: 10 mEq
MVI (Adult): 10 mL
Trace Elements: 1 mL
Regular Insulin: 10 units
Famotidine: mg
Thiamine: mg
Folic Acid: mg
Zinc Sulfate: mg
Vitamin C: mg
Recap: Completing the PN Order Form
Recap of steps:
Determine nutrition prescription consisting of: kcals, protein, and fluids.
Calculate grams needed of carbohydrates, protein, and fat; compute the mg/kg/min goals.
Establish stock solutions for each of the macronutrients.
Evaluate clinical status to determine potential alterations in additives based on lab results, monitoring trends.
Update/additives as needed to mitigate potential problems:
If potassium and phosphate are low before starting PN, administer a Kphos run via IV (10-20 mEq).
If magnesium is low, give a magnesium run IV of 1-2 grams.
Provide 100 mg of thiamine IV x 4-5 days for malnourished patients.
Determine if insulin is necessary in PN to control hyperglycemia.
Common Complications
Infectious complications:
Catheter-related infections.
Bloodstream infections leading to sepsis.
Metabolic complications:
Electrolyte disorders (e.g., hypophosphatemia, hypomagnesemia).
Vitamin deficiencies (e.g., thiamine deficiency).
Hyperglycemia and elevated triglycerides.
GI consequences:
Altered immune function.
Impaired GI mucosa integrity and possibly altered mucosal enzyme content.
Changes in GI microflora.
Dysregulated tight junctions leading to compromised GI integrity, aberrant cell signaling, and increased cytokine levels (potentially contributing to fatty liver).
Poor gallbladder contraction leading to bile sludge and gallstone formation.
Monitoring PN
Frequency of Monitoring:
PN should be monitored daily.
Daily monitoring includes:
Weight & intake/output (I/Os).
Laboratory assessments for electrolytes, glucose, renal function, and refeeding labs & triglycerides.
Fingerstick assessments for glucose tolerance & necessity of insulin coverage.
Assessment of catheter sites for signs of infection, i.e., redness and inflammation.
Evaluation of PN effectiveness in meeting nutrient needs and overall patient tolerance.