Bedside Calculation of Energy Expenditure Does Not Guarantee Adequate Caloric Prescription in Long-Term Mechanically Ventilated Critically Ill Patients: A Quality Control Study

Abstract

Nutrition is essential in critically ill patients, but translating caloric prescriptions into adequate caloric intake remains challenging. Caloric prescriptions (P), effective intake (I), and caloric needs (N), calculated with modified Harris-Benedict formulas, were recorded during seven consecutive days in ventilated patients. Adequacy of prescription was estimated by P/N ratio. I/P ratio assessed accuracy of translating a prescription into administered feeding. I/N ratio compared delivered calories with theoretical caloric needs. Fifty patients were prospectively studied in a mixed medicosurgical ICU in a teaching hospital. Basal and total energy expenditure were, respectively, 1361 ± 171 kcal/d and 1649 ± 233 kcal/d. P and I attained 1536 ± 602 kcal/d and 1424 ± 572 kcal/d, respectively. 24.6% prescriptions were accurate, and 24.3% calories were correctly administered. Excessive calories were prescribed in 35.4% of patients, 27.4% being overfed. Caloric needs were underestimated in 40% prescriptions, with 48.3% patients underfed. Calculating caloric requirements by a modified standard formula covered energy needs in only 25% of long-term mechanically ventilated patients, leaving many over- or underfed. Nutritional imbalance mainly resulted from incorrect prescription. Failure of “simple” calculations to direct caloric prescription in these patients suggests systematic use of more reliable methods, for example, indirect calorimetry.

Volume‐Based Enteral Nutrition Support Regimen Improves Caloric Delivery but May Not Affect Clinical Outcomes in Critically Ill Patients

“…Discrepancies between prescribed EN goals and actual delivery of EN in the critically ill patient are common 3 . In fact, multiple studies show that patients in North America routinely receive between 51.3% and 59% of goal calories 4 .…”

Nutrition support in the critically ill

“…The proportion of patients who were over, under and correctly fed during the first 7 days of ICU stay (adapted with permission[13]). …”

Nutritional and Metabolic Alterations during Continuous Renal Replacement Therapy

“…The final aim should be to optimize the nutritional status of the patient and to reduce the so-called ‘dialytrauma' induced by CRRT [37]. Daily recommended energy requirements during CRRT fluctuate between 25 and 35 kcal/kg (60-70% carbohydrates and 30-40% lipids) and between 1.5 and 1.8 g/kg protein [1,2,3].…”

“…), differences are tiny as long as the dose is the same amongst the various modalities. The only differences are concerning electrolytes although the recent work of the group of Bellomo did show that CVVHD or CVVHDF was not superior to CVVH if the same dose was applied even regarding electrolytes clearance [36,37,38]. It is really the dose that would make the major difference regarding nutrition guidelines [36].…”