Rate-based enteral nutrition delivery has long been the standard in most ICUs, especially with the use of enteral feed pumps that allow for a constant rate to be set and forgot about amongst all the other activity in the ICU. What often happens, however, is enteral feeds are held for procedures, gastric intolerance, or medication administration. Once the tube feeds are restarted, they’re simply started at the same rate as before, without thought to how many calories the patient has missed.
Enter volume-based enteral feeds. These rely on a daily target volume, and any interruption can be “made up” by increasing the rate for a fixed amount of time after the feeds are paused, usually up to a maximum rate set by protocol or physician. While slightly more complicated, the theory is that volume-based feeding will lead to less days of under-delivered calories and protein, therefore leading to faster recovery and less loss of muscle mass.
Speaking of muscle mass, the ASPEN and ESPEN guidelines suggest high protein delivery for ICU patients of 1.2-2 g/kg/day, even though there is little evidence to support this recommendation. A randomized trial to assess both would sure be nice.
The much-anticipated FEED trial (Targeted Full Energy and Protein Delivery in Critically Ill Patients: A Pilot Randomized Controlled Trial) was recently published in the Journal of Parenteral and Enteral Nutrition, which sought to determine if volume-based, high protein enteral nutrition was associated with greater energy and protein delivery, and what effect this had on outcomes.
The FEED trial was a randomized, non-blinded trial that enrolled patients > 18 years of age, mechanically ventilated for at least 48 hours and expected to remain ventilated for at least another day. Patients were excluded if they had a contraindication to enteral feeding, death was imminent, if they were unable to ambulate >10m prior to hospital admission, pregnant, or if the intervention was not in the patient’s best interest according to their physician. Sixty patients total were required to detect a difference of 15 g/day of protein delivery, assuming a baseline of 50 g/day.
Patients in the intervention group received a high-protein formula (Nutrison Protein Plus, 63g protein and 1250 kcal per liter), had a daily volume target and hourly rate with a goal of 25 kcal/kg/day and 1.5 g/kg/day of protein. Nurses were to assess the volume of feeds delivered at 1600 each day and could increase the rate up to 150 mL/hr over the remaining eight hours to make up any difference. Patients in the standard care group received Nutrison 1.0 kcal (40g protein and 1000 kcal per liter). Actual body weight was used unless the patient was above a BMI of 32 kg/m2, in which case an adjusted body weight was used.
Protein delivery was increased by about 37 g/day, or about 0.45 g/kg/day, and increased energy delivery (2.8 kcal/kg). Feeding intolerance and diarrhea were similar between both groups. Muscle mass loss, as measured by quadriceps muscle layer thickness (QMLT) was less in the intervention group, and the proportion of patients considered malnourished at ICU discharge was less in the intervention group (6.9% vs. 27.6%, p=0.04).
This study excels in several areas. While the nature of the intervention did not allow for blinding, the use of randomization to keep both groups relatively similar is excellent. Because both protein delivery and energy delivery was changed in the intervention group, it’s difficult to know if the outcomes are due to the different formulation or the delivery method. Regardless, this is a great step forward for a patient population that often has difficulties reaching enteral nutrition targets. Given the lack of downsides mentioned in the study, providers should consider adopting volume-based enteral nutrition delivery at their institution wherever feasible.