The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

USE OF CONTINUOUS INDIRECT CALORIMETRY IN MECHANICALLY VENTILATED PATIENTS WITH CATABOLIC ACUTE RENAL FAILURE ON CONTINUOUS RENAL REPLACEMENT THERAPY

Petrea Monson MS, RD, Maria T. Pascual RN, MPH, F. Wayne Johnson RCP, Ravindra L. Mehta M.D., UCSD Medical Center, 200 West Arbor Drive, San Diego, CA, 92103-8375

Introduction: The provision of adequate calories is an essential component of nutrition support in patients with catabolic acute renal failure (ARF). Recent advances in continuous renal replacement therapies (CRRT): continuous arteriovenous hemodiafiltration (CAVHDF) and continuous venovenuous hemodiafiltration (CVVHDF) have allowed for the delivery of full nutrition support in these patients, yet tools available to assess energy expenditure (EE) in mechanically ventilated patients with ARF have been limited. Predictions of EE using the Harris Benedict Equation (HBE) with applicable stress factors (HBE+F) under-and overestimate EE. A technique to accurately measure 24-hour EE, continuous indirect calorimetry (CIC), is now available with the use of the Nellcor Puritan Bennett 7250 metabolic monitor (NPB7250MM) (Nellcor Puritan Bennett, Carlsbad, CA) which integrates into the Nellcor Puritan Bennett 7200ae Ventilator (NPB7200ae). The purpose of the study is to compare EE differences between CIC and HBE+F during CRRT. Methods: CIC was performed over 38 days for a total of 810 hours in 4 patients treated with CRRT (3F, 1M, Ages 34-37) to determine daily values for oxygen consumption (VO_{2}), carbon dioxide production (VCO_{2}), respiratory quotient (RQ), and EE, Daily delivery of non-protein calories via parenteral, enteral, and dialysate sources was recorded. Results: Predicted EE using HBE+F matched measured EE-CIC ± 5% on 10/38 days while HBE+F EE under-and overestimated EE-CIC on 21/38 and 7/38 days, respectively. The range by which HBE+F EE under-and over predicted EE-CIC was ± 40%. Daily calorie delivery based on HBE+F exceeded EE-CIC by 15% due to increases in dextrose-containing intravenous solutions which contributed 7% of total calories delivered.

Mean SD

Calories Delivered/d 2377 740

EE-CIC (calories/d) 2097 506

HBE+F (calories/d) 2224 376

Conclusions: Use of CIC as a routine component of nutritional assessment assists in the accurate determination of 24 hour EE. Use of CIC should therefore permit optimal calorie delivery while preventing overfeeding in ARF patients on CRRT.

Reference: OF-96-109

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