Energy expenditure and gas exchange measurements in postoperative patients

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Abstract
To compare a method of measuring energy expenditure and gas exchange using the Pick principle with the standard indirect calorimetry technique. Prospective study of a consecutive sample of postoperative patients. Oxygen consumption (JOURNAL/ccme/04.02/00003246-199209000-00014/ENTITY_OV0312/v/2017-07-20T220822Z/r/image-pngo2), CO2 production (JOURNAL/ccme/04.02/00003246-199209000-00014/ENTITY_OV0312/v/2017-07-20T220822Z/r/image-pngco2), respiratory quotient, and energy expenditure were derived from measurements of variables, including oxygen content and cardiac output. Energy expenditure and gas exchange were measured simultaneously by continuous indirect calorimetry over a 60-min period. Surgical ICU in a university hospital. Twenty-six consecutive patients (45 to 80 yrs) who underwent sustained surgical trauma. Excluded from the study entry were patients with time-related fluctuations of hemodynamic variables, poor cooperation, patients who required supplemental oxygen, or mechanical ventilation. None. While the measurements of JOURNAL/ccme/04.02/00003246-199209000-00014/ENTITY_OV0312/v/2017-07-20T220822Z/r/image-pngo2 and JOURNAL/ccme/04.02/00003246-199209000-00014/ENTITY_OV0312/v/2017-07-20T220822Z/r/image-pngco2 by calorimetry and thermodilution were significantly correlated with one another (for JOURNAL/ccme/04.02/00003246-199209000-00014/ENTITY_OV0312/v/2017-07-20T220822Z/r/image-pngo2, r2 =.93, p ConclusionsIn postoperative patients, while JOURNAL/ccme/04.02/00003246-199209000-00014/ENTITY_OV0312/v/2017-07-20T220822Z/r/image-pngo2 and energy expenditure measurements by thermodilution are easy to perform and accurate for clinical purposes, JOURNAL/ccme/04.02/00003246-199209000-00014/ENTITY_OV0312/v/2017-07-20T220822Z/r/image-pngco2 and respiratory quotient measurements are too imprecise and inaccurate to serve any useful function. Therefore, in those clinical situations in which an evaluation of respiratory quotient and substrate utilization may be useful for purposes of metabolic care of the surgical patient, precise measurements of gas exchange with indirect calorimetry are mandatory. (Crit Care Med 1992; 20:1273–1283)