Are there any reasons to withhold Total Parenteral Nutrition (TPN) if initiation is delayed?

From the Guidelines

There is no compelling reason to withhold Total Parenteral Nutrition (TPN) if initiation is delayed, as recent evidence suggests that late initiation of PN may actually lead to improved clinical outcomes, including increased proportion of patients discharged alive and earlier from ICU and hospital, as well as reduced infectious complications 1.

Key Considerations

• The metabolic response to critical illness is complex and involves distinct phases, including the 'ebb' or early shock phase, the 'flow' or catabolic phase, and the anabolic recovery phase 1.
• Recent randomised controlled trials (RCTs) have found no benefit or harm with early nutrition delivery, and some have even observed harm with aggressive nutrition in the early stages of critical illness 1.
• The EPaNIC trial, the largest nutrition trial in critical illness, found that late initiation of PN (started on day 8 of the ICU stay) led to improved clinical outcomes, including increased proportion of patients discharged alive and earlier from ICU and hospital, as well as reduced infectious complications 1.

Clinical Implications

• Healthcare providers should proceed with TPN administration as soon as possible, rather than skipping the feeding entirely, to ensure consistent nutritional support for patients requiring parenteral nutrition.
• If the delay is substantial, the healthcare team may need to adjust the rate or volume of the current feeding to avoid overlap with subsequent feedings and maintain metabolic stability.
• The primary concern with TPN is maintaining steady nutritional intake and avoiding rapid fluctuations in glucose levels, which could lead to metabolic complications, as supported by the findings of the TARGET trial 1.

From the Research

Reasons to Withhold Total Parenteral Nutrition (TPN)

There are several factors to consider when deciding whether to withhold TPN, including:

• Patient-specific factors, such as functional status, nutritional status, and ability to safely administer nutrition 2
• Disease-specific considerations, such as the type and severity of the disease, and the potential for future treatments 2, 3
• The presence of gut failure or intolerance to enteral nutrition, which may necessitate the use of TPN 4, 3
• The risk of complications associated with TPN, such as overfeeding, sepsis, and vascular access complications 4, 3

Delayed Initiation of TPN

If initiation of TPN is delayed, it is essential to consider the potential consequences, including:

• Malnutrition and its associated complications, such as impaired wound healing and increased risk of infection 5
• The potential for gut atrophy and decreased gut function, which may make it more challenging to transition to enteral nutrition in the future 4
• The need for careful assessment and monitoring of the patient's nutritional status and overall health to determine the best course of action 2, 3

Alternatives to TPN

In some cases, alternatives to TPN may be considered, such as:

• Enteral nutrition, which is generally preferred due to its ability to promote gut function and prevent translocation of intestinal bacteria 4
• Peripheral parenteral nutrition, which may be used as a complement to enteral nutrition or as an alternative to TPN in certain clinical situations 6