Our trainees for October were greeted with damp and unseasonably cool weather (for Charlottesville), but fair weather soon prevailed and everyone was able to enjoy C’ville starting to show its Fall colors. Our trainees for October traveled from Minneapolis, MN; Downers Grove, IL; Williamsburg, VA and Kuwait.
Our journal club this month deals with the sometimes contentious subject of meeting goal nutrition (or not) in the adult ICU patient.
Weijs PJ, Stapel SN, de Groot SD, et al. Optimal protein and energy nutrition decreases mortality in mechanically ventilated, critically ill patients: a prospective observational cohort study. JPEN 2012 Jan;36(1):60-8.
This was a single-center, observational study of 886 sequential mixed medical-surgical adult patients in a tertiary care university hospital that were expected to require “long-term” intensive care. All patients were fed with the same algorithm with a calorie goal of resting energy expenditure X 10% and a protein goal of 1.2-1.5gm/kg.
The cumulative energy and protein intakes were calculated for all patients while they were receiving mechanical ventilation. Patients were categorized into 4 groups according to whether energy and protein targets were reached (or not reached):
· Neither protein nor energy target reached (NT),
· Both protein and energy target reached (PET),
· Only energy target reached (ET),
· Only protein target reached (PT).
The outcomes monitored were length of ICU and hospital stay, length of ventilation, mortality in the ICU, at 28 days, and in the hospital.
Inclusion and Exclusion Criteria were:
Patients were evaluated on day 3-5 (time of first indirect calorimetry) and those who were expected to require at least 5-7 additional days of nutrition support were included. Other inclusion criteria were indirect calorimetry measurement performed, age over 18 years, and first admission to the ICU with indirect calorimetry measurement.
Exclusion criteria were FiO2 > 0.6, air leaks through cuffs and/or chest drains, and unavailable metabolic monitor and/or personnel.
Major Results reported by authors:
The calorie intake for the NT, ET, and PET groups, was 75% ± 15%, 96% ± 5%, and 99% ± 5% of target, and protein intake was 72% ± 20%, 89% ± 10%, and 112% ± 12% of target, respectively. The length of ICU, total hospital stay (days) and number of ventilator days were significantly shorter in the NT group compared to the ET and PET groups (P < 0.05). There were no statistically significant differences in mortality in the ICU, at 28-days, and hospital stay between the three target groups (P > 0.05).
The hazard ratio using a regression analysis with length of hospital stay as the time variable; ICU, 28-day, and hospital mortality as outcome variables; and with PET achieved (yes/no) or ET achieved (yes/no) as independent variables, suggested a significantly decreased 28 day and hospital mortality in the group receiving energy and protein goals (PET) compared to those not reaching either goal. Hazard ratios models that were adjusted for sex, age, BMI, APACHE II score, diagnosis category, and hyperglycemic index, time to energy target and use of parenteral nutrition did not substantially change the results compared to the unadjusted hazard ratio model.
Successfully reaching a predefined energy target and protein target cumulative over the whole period of mechanical ventilation—with energy provision guided by indirect calorimetry and with protein provision guided by at least 1.2 g/kg of preadmission body weight—is associated with a decrease in 28-day mortality as much as 50%. Reaching only the energy targets does not appear to be sufficient.
We are in need of randomized controlled trials to demonstrate the real value of protein and energy nutrition in mechanically ventilated, critically ill patients as well as predefined subgroups.
First and foremost it must be remembered that this is an observational study, which can only describe associations, and should never be used to suggest cause and effect. There is just no way to statistically control for all of the factors associated with survival in an ICU, and it is quite possible that those same patients not doing well (and more likely to die), are also not going to receive full feedings in the ICU. We are in full agreement with the author’s final conclusion that there is a need to do randomized studies to determine if meeting calorie and protein goals will improve patient outcome in the ICU.
The importance of the hazard ratio analysis is unclear, especially when there was no significant difference in the ICU survival between the groups, and significantly increased length of mechanical ventilation, ICU stay and hospital stay in the group that received full calories and protein (compared to not reaching goal). It seems odd that the unadjusted hazard analysis reported statistically improved hospital survival for the PET group when there was actually an 8.2% greater hospital mortality (not statistically significant) in the PET group compared to the NT group.
On a practical note, the difference in the amount of nutrition provided to the groups was very modest – approximately 300 calories and 20 gm of protein/day between the NT and PET groups. Odd that this amount of nutrition could affect outcomes, while in a large (1000 patient) multicenter randomized study(1) (see our February 2012 e-journal club) a difference of 900 calories/day did not affect outcomes.
Our Take Home Message (s)
There is a need for randomized controlled trials to determine when to begin feeding, and the amount of nutrition which will result in the best outcomes for mechanically ventilated, critically ill patients.
1) The National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network. Initial Trophic vs. Full Enteral Feeding in Patients with Acute Lung Injury: The EDEN Randomized Trial. 2012;307(8):795-803.
Other News on the UVAHS GI Nutrition Website:(www.ginutrition.virginia.edu):
--Tuesday, November 13: Nutritional Anabolics--Joe Krenitsky, MS, RD
--Tuesday, December 11: Information Mastery: Evidence-Based Medicine in the Real World--David Slawson, MD
--Tuesday, January 15: Outpatient PEGs & the “Stat RD Consult--Carol Parrish, MS, RD
Check out What’s New:
--“Nutrition Support Blog”
Latest Practical Gastroenterology article:
Joe Krenitsky MS, RD
Carol Rees Parrish MS, RD
PS – Please feel free to forward on to friends and colleagues.