Comparison of oxygen consumption measurements
1991; Lippincott Williams & Wilkins; Volume: 19; Issue: 11 Linguagem: Inglês
10.1097/00003246-199111000-00017
ISSN1530-0293
AutoresMARKN SMITHIES, B. Royston, Koshi Makita, Krysia Konieczko, J.F. Nunn,
Tópico(s)Hemodynamic Monitoring and Therapy
ResumoObjective To compare measurement of oxygen consumption (o2) by spirometry and the reversed Fick method. Design Within-patient comparison using simultaneous measurements by the two methods, one previously calibrated on a metabolic simulator. Patients Twenty sets of observations on eight patients (57 to 83 yrs) requiring mechanical ventilation in a critical care unit. Interventions None during or immediately before the measurements. Measurements and Main Results Duplicate pairs of measurements of o2 were made with a previously validated spirometric technique and the reversed Fick method (t[Cao2 – Co2]), where t is cardiac output, Cao2 is arterial oxygen content, and Co2 is mixed venous oxygen content. The coefficient of variation of the difference between duplicate measurements by the former technique was only 2.53% compared with 10.4% for the latter. The mean o2 measurement by the spirometric method was 285.7 ± 40.7 (SD) mL/min standard temperature and pressure, dry (STPD) and for the reversed Fick method, the mean o2 measurement was 249.3 ± 38.5 mL/min STPD. The mean difference was 36.4 ± 28.5 mL/min STPD (p <.001). Conclusions The repeatability of the spirometric method was four times better than the reversed Fick method. The latter gave a significantly lower value that probably, in part, reflects the o2 of the lung, which is included in the spirometric method but not in the reversed Fickmeasurement.
Referência(s)