The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts

EFFECT OF MECHANICAL DEADSPACE ON OXYGEN CONSUMPTION AND ENERGY EXPENDITURE WHEN USING INDIRECT CALORIMETRY.

Akio Kinoshita, Shigeki Fujitani; Tokyo Bay Urayasu Ichikawa Medical Center, Urayasu, Japan

Background Nutrition management is one of the important factors in Intensive Care Units. We often use calculations, such as the Harris-Benedict method, for calorie counting; however, it is known that using indirect calorimetry is more accurate. Indirect calorimetry is installed on the Engstrom Carestation (GE Healthcare) and it computes oxygen consumption (VO2) and energy expenditure (EE) using the Weir calculation. It is not known whether VO2 and EE are possibly affected and not accurate in cases of increasing deadspace. Therefore, we studied whether VO2 and EE are affected in cases of increasing mechanical deadspace. Methods We measured VO2 and EE on seven healthy subjects, without additional mechanical deadspace (non-increased DS), who were ventilated noninvasively, then we added 25 mL of mechanical deadspace and measured VO2 and EE again (increased DS). Result VO2 and EE tended to decrease with increased DS. The results are VO2 272 ± 37 mL/min and EE 1824 ± 260 kcal in non-increased DS, and VO2 244 ± 38 mL/min and EE 1600 ± 261 kcal in increased DS. With increased DS, the average VO2 is 28 mL/min lower and EE is 224 kcal lower than non-increased DS. Conclusion This study demonstrates that the measured VO2 and EE using the Engstrom Carestation decrease as mechanical deadspace is added. This may be due to a change of concentration of oxygen due to the increased deadspace. Sponsored Research - None