E-Journal Club – December 2018

We have continued to hold our monthly nutrition support journal club here at UVA, but I have been delayed in writing up the summaries due to clinical and teaching responsibilities. I plan to get back on schedule, thus will jump right into the article summary:

Gonzalez-Granda A, Schollenberger A, Haap M, et al. Optimization of Nutrition Therapy with the Use of Calorimetry to Determine and Control Energy Needs in Mechanically Ventilated Critically Ill Patients: The ONCA Study, a Randomized, Prospective Pilot Study. J Parenter Enteral Nutr. 2018 Sep 25. doi: 10.1002/jpen.1450. [Epub ahead of print]

This was single-center, randomized, unblinded, pilot study of 40 medical ICU patients that investigated use of indirect calorimetry (IC) for establishment of nutrition support goals compared to 25 kcals/kg (standard care).

The IC group had several indirect calorimetry measurements during the study (up to 3/patient) with most patients receiving 1 IC measurement/ week. Nutrition therapy was modified and controlled by the study personnel in IC group, while nutrition therapy in the standard care group (SC) was the responsibility of the “ward staff”. Protein goal in both groups was set at 1.2 gm/kg preadmission weight/day. Energy goals were gradually increased each day from day 1 through day 4 (25%, 50%, 75%, 100%).

The primary outcome of the study was the change in phase-angle as determined by bioelectrical impedance analysis (BIA). Increased phase angle usually reflects an increase in body cell mass relative to fat-free mass, an increase in fat-free mass relative to body weight, or improved hydration of the fat-free mass. BIA was measured as early as possible after ICU admission (first day after ICU admission, or at least within the first 48 hours) and every 3 days (± 1 day) thereafter until ICU discharge.

Secondary outcomes were changes in body cell mass (BCM) and the ratio of extracellular mass (ECM) to BCM (ECM/BCM), as determined by BIA, as well as changes in the Acute Physiology and Chronic Health Evaluation II (APACHE II) and the sequential organ failure assessment (SOFA) scores, mortality, and length of stay in the ICU and at the hospital.

Inclusion criteria:

Adult medical ICU patients expected to stay longer than 2 days in the ICU and receiving mechanical ventilation for at least 3 days with indication for enteral nutrition (EN) or parenteral nutrition (PN).

Exclusion criteria:

Patients who could not receive indirect calorimetry, BIA, had no indication for nutrition support, or no informed consent was possible.

Initially, 76 patients were enrolled and randomized, but 36 patients (18 in each group, > 47% of all patients randomized) withdrew informed consent. There were no marked differences in baseline characteristics between the groups. Most patients received exclusive EN (n = 26) but some patients received supplemental PN as needed (n = 12) or exclusive PN (n = 2) when EN was not possible.

The mean goal energy goal of the IC group was 20.4 kcals/kg and the mean actual the actual energy delivery was 98% of goal (20.0 kcals/kg). The mean actual nutrition provided to the SC group was only 79% of goal, so the actual average calorie delivery was very similar to the IC group (19.75 kcals/kg). Although protein goals were similar between the 2 groups (90 gm IC versus 85 gm SC), the IC group received substantially more protein than the SC group (78 gm/day IC versus 59 gm/day SC).

There was no difference in phase-angle between the groups at baseline, or at discharge. The phase-angle was numerically increased, but did not change significantly from baseline to discharge in the IC group (3.20° ± 1.07° to 3.34° ± 1.42°). In the SC group, there was a trend towards a decreased phase-angle from admission to discharge (3.31° ± 1.34° to 2.95° ± 1.15°, P = .077).

There was no significant change in the ECM/BCM index in either group. The BCM decreased in both groups, whereas the ECM tended to decrease in the IC group. The length of ICU stay (P < .05) and the length of hospital stay (P = .07) were lower in the IC group than the SC group.

“…an individualized optimization of nutrient supply on the basis of measuring energy need by using IC and controlling protein delivery on a regular basis might improve nutrition status, as assessed by PhA, as well as clinical outcomes….. individual nutrition therapy, including the use of IC and BIA by well‐trained staff, is recommended to improve nutrition support and outcomes in critically ill patients.

This study is remarkably similar to some other investigations of IC that we have reviewed in the past that purported to find clinical benefits of indirect calorimetry, but ultimately, the amount of calories received by the 2 groups was essentially the same. Only the protein provision was substantially different between the 2 groups, which had nothing to do with indirect calorimetry. It is important to remember that the 2 groups of this study were not treated the same, the SC group had the nutrition managed by the “ward staff” and the IC group had the nutrition managed by the research staff. In the end, the major differences between the groups were in protein delivery and individual attention to nutrition management.

While it might be tempting to suggest that based on the results of this study, protein delivery and attention to nutrition delivery may improve patient outcome, it is very important to remember that this was a pilot study with a very small numbers of patients who completed the study – far, far too few to be able to study patient outcomes.

1. This study provided no meaningful information regarding the clinical role of indirect calorimetry in nutrition management of critically ill adults.
2. Be very wary of speakers that would reference this study to suggest that indirect calorimetry improves clinical outcome of critically ill patients.
3. This study was far too small to reliably rule out effects related to chance differences between the groups.

Other News on the UVAHS GI Nutrition Website: (www.ginutrition.virginia.edu):

Latest PG Article:

April: Enteral Nutrition Part III: Jejunal Enteral Feeding: The Tail is Wagging the Dog(ma)

Upcoming Webinars:

May 23: Nutrition in Liver Disease—Joe Krenitsky, MS, RDN

Joe Krenitsky MS, RDN

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