The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

CONTINUOUS INDIRECT CALORIMETRY COMPARED WITH INTERMITTENT INDIRECT CALORIMETRY IN THE CRITICALLY ILL PATIENT.

Jennifer R. Burns. MAEd. RRT, Assistant Professor of Medicine, Director of Clinical Education, The University of Alabama at Birmingham, Birmingham, AL.

Background: Changes in body composition that affect body weight and metabolic active tissue make it difficult for clinicians to evaluate the critically ill patient for nutritional support. Allard and associates in 1993 showed that improper support of a patient nutritionally, whether that be overfeeding or underfeeding. may adversely affect that patient's ICU outcome. Patients who do not respond as expected to estimated evaluation may be better assessed using a method known as indirect calorimetry (Allard, 1993). There are essentially two methods of indirect calorimetry, a continuous method and an intermittent method. This study was designed to evaluate [Vdot]O_{2} (oxygen consumption), [Vdot]CO_{2} (carbon dioxide production), and REE (resting energy expenditure) via both methods of indirect calorimetry to determine if an intermittent spot check for [Vdot]O_{2}, [Vdot]CO_{2}, and REE would accurately determine a patient's nutritional needs. Method: Patients were recruited from UAB's MICU (medical intensive care unit) and monitored continuously for 24 hours. The Nellcor Puritan Bennett (NPB) 7250 metabolic monitor in conjunction with the NPB 7200 ventilator were used to study each patient in the MICU. Sixteen patients were recruited, 9 males and 7 females ranging in age from 19 to 88 years of age. APACHE II scores were determined from each patient upon entrance into the study. An external computer was then attached to the monitor and set to gather data every 10 minutes for a period of 24 hours. The computer was programmed to place an asterisk at 2:00am, which is considered to be a time in the patients day most reflective of REE. Results: A paired t-test analysis was performed on the data. The researcher found no significant difference in the two methods of indirect calorimetry with respect to [Vdot]O_{2}, [Vdot]CO_{2}, and REE in these critically ill patients. Experience: The researcher has completed two years of intensive care therapy as a registered respiratpry therapist, two years of research experience with a concentration on mechanical ventilation in a university hospital, and has three years of educational experience. Conclusions: From the study performed, the researcher found that there is no significant difference in the two methods of indirect calorimetry. The typical intermittent spot check does accurately predict a patient's [Vdot]O_{2}, [Vdot]CO_{2}, and REE. The twenty minute spot checks were within 10% of the 24-hour values. This is important for clinicians to understand, so that they are reassured that the method currently being used is adequate for critically ill patient populations.

The 44th International Respiratory Congress Abstracts-On-DiskĀ®, November 7 - 10, 1998, Atlanta, Georgia.

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