Energy-Dense versus Routine Enteral Nutrition in the Critically Ill
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In mechanically ventilated critically ill patients, the delivery of energy-dense enteral nutrition did not improve 90-day survival or other clinical outcomes compared to routine enteral nutrition.
Key Findings
Study Design
Study Limitations
Clinical Significance
The TARGET trial definitively demonstrated that aggressively increasing caloric delivery using an energy-dense enteral formulation does not confer a survival or recovery advantage in mechanically ventilated critically ill adults. As the largest blinded trial of ICU nutrition to date, it supports the current consensus that standard enteral feeding strategies—or even permissive underfeeding—are perfectly adequate and safe, steering clinicians away from the historic practice of chasing high caloric goals early in critical illness.
Historical Context
For decades, critical care nutrition was driven by the assumption that matching the high energy expenditure of critical illness would prevent catabolism and improve outcomes. However, a series of prior trials (such as EDEN in 2012 and PermiT in 2015) suggested that trophic or permissive underfeeding was not inferior to full feeding. The TARGET trial was designed to address the persistent controversy regarding optimal caloric targets by delivering a purely caloric intervention—keeping volume and protein constant—in a double-blind fashion, ultimately confirming the lack of benefit for augmented caloric delivery.
Guided Discussion
High-yield insights from every perspective
Why might critical illness alter a patient's metabolic demand, and what is the physiologic rationale behind providing early enteral nutrition rather than parenteral nutrition in these patients?
Key Response
Critical illness induces a hypercatabolic state driven by counter-regulatory hormones and cytokines. Early enteral nutrition helps maintain gut mucosal integrity, prevents bacterial translocation, and supports the gut-associated lymphoid tissue (GALT), which is why it is preferred over parenteral nutrition despite the intuitive appeal of delivering higher calories intravenously.
Given the TARGET trial found no survival benefit to energy-dense formulas, how does this influence your daily practice regarding feeding targets and monitoring for complications like refeeding syndrome in a newly intubated patient?
Key Response
The lack of benefit from energy-dense feeds supports using standard 1.0 kcal/ml formulas, which are generally better tolerated and reduce the risk of overfeeding. Residents must recognize that pushing high calories early can precipitate refeeding syndrome (hypophosphatemia, hypokalemia, hypomagnesemia) or cause hyperglycemia and increased CO2 production, making standard feeds a safer default.
How do the findings of the TARGET trial align with previous major nutrition trials in the ICU, such as EDEN, PERMIT, or EPaNIC, regarding the timing and dosing of caloric delivery in the acute phase of critical illness?
Key Response
TARGET adds to a consistent body of literature (EDEN showed trophic feeds were equal to full feeds early; EPaNIC showed late PN was better than early PN; PERMIT showed permissive underfeeding of calories was non-inferior). The synthesis suggests that aggressive early caloric loading does not improve outcomes and may cause harm, as the acute phase of critical illness is characterized by endogenous energy production that exogenous calories cannot suppress.
If achieving 100 percent of calculated caloric goals during the acute phase of critical illness does not improve survival or functional outcomes, should we shift our paradigm from 'feeding to meet targets' to focusing on specific macronutrients, such as protein delivery, or tailored recovery-phase nutrition?
Key Response
Attendings need to lead the paradigm shift away from dogmatic early caloric targets. The trial highlights that mere energy delivery in the acute phase is futile or potentially harmful. The teaching point is to pivot focus toward avoiding overfeeding acutely, perhaps prioritizing protein delivery to attenuate muscle wasting, and intensifying nutritional rehabilitation during the post-ICU recovery phase when anabolic pathways are restored.
Scholarly Review
Critical appraisal through the lens of expert reviewers and guideline development
The TARGET trial used a double-blind design with identically packaged 1.5 kcal/ml and 1.0 kcal/ml formulas. What are the methodological advantages and potential unblinding risks of this design, and how might differing gastric residual volume protocols affect the actual volume of formula delivered?
Key Response
Blinding enteral formulas eliminates caregiver bias regarding feeding intolerance management. However, energy-dense formulas can delay gastric emptying, potentially increasing gastric residual volumes (GRVs) and prompting nurses to hold feeds, leading to unblinding or disproportionate volume interruption. Evaluating how the protocol standardized GRV thresholds is critical to ensuring the intended caloric separation was achieved without confounding by differential interruption.
In evaluating the TARGET trial for publication, how should the peer review process scrutinize the choice of the primary outcome (90-day all-cause mortality) versus functional or patient-centered outcomes, given that nutritional interventions may primarily affect morbidity, muscle mass, or rehabilitation rather than acute mortality?
Key Response
A seasoned reviewer would flag that while 90-day mortality is objective, it may be insensitive to nutritional interventions. Nutrition might not save a patient from overwhelming sepsis but could improve ICU-acquired weakness, days alive and out of hospital, or physical function at 6 months. Reviewers must critically appraise whether the lack of mortality benefit masks unmeasured functional benefits or harms.
Based on the TARGET trial results, should current SCCM/ASPEN guidelines be updated to explicitly recommend against the routine use of energy-dense enteral formulas to achieve early caloric targets in unselected mechanically ventilated patients, and what level of evidence does this trial provide?
Key Response
SCCM/ASPEN guidelines previously emphasized starting early EN but had varying recommendations on caloric targets, often suggesting 70-80 percent of calculated needs. TARGET provides high-quality (Level 1) evidence that aggressive early caloric delivery via energy-dense formulas offers no benefit. The guidelines should reflect a strong recommendation against using 1.5 kcal/ml formulas purely to force early caloric goals, emphasizing standard feeds to minimize intolerance and metabolic complications.
Clinical Landscape
Noteworthy Related Trials
EPaNIC Trial
Tested
Late initiation of parenteral nutrition to supplement enteral feeding
Population
Critically ill adults with a high risk of malnutrition
Comparator
Early initiation of parenteral nutrition within 48 hours
Endpoint
Time to discharge alive from the ICU
EDEN Trial
Tested
Trophic enteral feeding for up to 6 days
Population
Critically ill adults with acute lung injury
Comparator
Full enteral feeding
Endpoint
Ventilator-free days to day 28
PermiT Trial
Tested
Permissive underfeeding at 40 to 60 percent of calculated caloric requirements
Population
Critically ill adults receiving enteral nutrition
Comparator
Standard enteral feeding at 70 to 100 percent of calculated requirements
Endpoint
90-day mortality
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