What are the guidelines for using Total Parenteral Nutrition (TPN) in pregnant individuals who require nutritional support?

Total Parenteral Nutrition in Pregnancy

TPN should be initiated in pregnant patients when oral or enteral nutrition is inadequate or impossible, particularly in cases of severe malnutrition that threatens maternal and fetal outcomes, but only after attempting enteral nutrition first when the gastrointestinal tract is functional. 1

Primary Indications for TPN During Pregnancy

TPN is indicated in pregnancy for specific conditions where adequate nutrition cannot be achieved through oral or enteral routes:

• Severe inflammatory bowel disease with active disease, obstruction, or high-output fistulas preventing adequate enteral intake 1
• Bowel obstruction not amenable to feeding tube placement beyond the obstruction 1
• Severe gastrointestinal dysmotility making enteral feeding impossible 1
• High-output intestinal fistulas or surgical anastomotic breakdown 1
• Patient intolerance of enteral nutrition when oral maintenance is impossible and gut access for enteral feeding is unavailable 1
• Hyperemesis gravidarum refractory to conventional treatment, though enteral options like PEG tubes should be considered first 2, 3
• Crohn's disease with inability to tolerate enteral feedings during pregnancy 3

Hierarchical Approach to Nutritional Support

Always attempt enteral nutrition first when the gastrointestinal tract is functional 1. The proper sequence is:

1. Nutritional counseling and oral intake optimization 1
2. Oral nutritional supplements 1
3. Enteral tube feeding (including PEG placement if needed) 1, 2
4. Parenteral nutrition as the final option 1

Timing of TPN Initiation

• Initiate TPN within 24-48 hours when patients are not expected to resume adequate oral nutrition within 3 days 1
• Delayed initiation leads to cumulative negative energy balance associated with increasing complications 1

Nutritional Composition Requirements

Energy Targets

• Provide 1.3 times resting energy expenditure (REE) to support both maternal and fetal needs 1
• Alternatively, target approximately 25 kcal/kg/day, increasing to target over 2-3 days 1
• Base energy targets on measured energy expenditure when possible 1

Macronutrient Distribution

• Glucose: minimum 2 g/kg/day, providing 50-60% of non-protein energy requirements 1
• Amino acids: 1.2-1.5 g/kg/day 1
• Lipid emulsions: use formulations with lower n-6 unsaturated fatty acid content than traditional pure soybean oil emulsions 1

Micronutrients

• Provide daily micronutrients from the first day of PN, including water-soluble vitamins and trace elements 1

Critical Safety Considerations

Catheter Selection and Management

• Single-lumen Hickman catheters are strongly preferred for long-term TPN (>6 months or home parenteral nutrition), with sepsis rates of 0-5% compared to 10-20% with multi-lumen catheters 1, 4
• Position catheter tip at the superior vena cava-right atrium junction for optimal function 1, 4
• If multi-lumen catheters must be used, dedicate one lumen exclusively to PN administration 1, 4
• Avoid blood sampling from the TPN line when possible 1, 4

Infection Prevention

• Maintain strict aseptic technique during catheter access and dressing changes 1, 4
• Use the catheter only for TPN administration, not for blood transfusion or other medications 4

Administration Safety

• Use an infusion pump (preferably portable/ambulatory) for controlled delivery to prevent rapid administration complications from hypertonicity and glucose/potassium content 1, 4

Metabolic Monitoring

• Maintain strict glucose control, avoiding hyperglycemia (glucose >10 mmol/L), as this contributes to death and infectious complications in critically ill patients 1
• Avoid overfeeding, which is as deleterious as underfeeding 1

Special Considerations in Pregnancy

• TPN should only be administered by a qualified, knowledgeable team very familiar with the techniques 1, 5
• Patients with inflammatory bowel diseases have an independent risk factor for venous thromboembolism, requiring heightened vigilance 1
• The relatively high rate of premature delivery associated with patients requiring TPN during pregnancy requires the presence of an intensive care nursery in the institution 5
• Successful outcomes have been reported in patients requiring continuous TPN from conception through labor and delivery, including those with short bowel syndrome 6

Common Pitfalls to Avoid

• Do not bypass enteral nutrition attempts when the GI tract is functional—enteral feeding is always preferred and safer 1, 2
• Do not use multi-lumen catheters unless absolutely necessary, as infection rates are significantly higher 1, 4
• Do not overfeed—calculate requirements carefully and increase gradually 1
• Do not delay initiation once the decision is made, as cumulative negative energy balance increases complications 1