The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

COMPARISON OF A TRADITIONAL OPEN CIRCUIT TECHNIQUE TO THE SENSORMEDIC VMAX SYSTEM FOR DETERMINING REE:

Carl D. Mottram, RRT RPFT; Kenneth C. Beck, Ph.D.; Naomi Kothenbeutel; DeeAnn Pease CPFT; Mayo Clinic, Rochester, MN 55905

Introduction: Indirect calorimetry is a method of determining caloric energy requirements (Resting Energy Expenditure, REE) in patients to allow for nutritional assessment and management. Our out-patient laboratory uses a traditional open circuit method involving direct expired gas collection into a Tissot spirometer and gas analysis using a mass spectrometer. This study was performed to compare the Sensormedics Vmax 229 canopy system with this traditional methodology. Methods: Twenty consecutive patients (16 female 4 male, age 22-66, mean BMI 41, range 19-77) scheduled for an REE study were tested on both systems sequentially, randomizing which test was performed first. Patients were instructed to fast after midnight, and to avoid strenuous activity shortly before the test. Both systems were calibrated on each study day. Patients rested in the supine position for 35 minutes and data collected over the last 10 minutes were averaged. Results:

VO2 KCALS/24 Hr RQ

Tissot SM Tissot SM Tissot SM

Mean 278 273 1918 1931 0.80 0.86

SD 114 109 770 732 0.05 0.06

R^{2} 0.98 0.98 0.36

T-Test p = 0.10 p = 0.56 p < .0001

VCO2

Tissot SM

Mean 219 232

SD 80 80

R^{2} 0.96

T-Test p = .002

Conclusion: Our results indicate that the Sensormedic Vmax system was highly comparable to our traditional method in measurement of VO2 and Kcals/24 Hr. but that there was a statistically significant difference in the RQ and VCO2 values measured. The between difference the Sensormedic Vmax and the Tissot measurement of these variables were biased exclusively high.

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

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