Non-invasive cardiac output measurement using a fast mixing box to measure carbon dioxide elimination.
This study investigated the accuracy of a new technique for measuring cardiac output using the derivative Fick principle based on the ratio of change in the partial pressures of end-tidal and mixed expired carbon dioxide produced by short periods of partial rebreathing. A prospective clinical study involving 24 patients following cardiopulmonary bypass for coronary artery bypass grafting or valvular surgery was undertaken in the intensive care unit of a university-affiliated hospital. Haemodynamic measurements were performed after admission to the intensive care unit. Cardiac output was measured simultaneously by bolus pulmonary artery thermodilution and by a non-invasive carbon dioxide partial rebreathing technique. Cardiac output measurement using the new technique demonstrated a significant but consistent underestimate, with a bias of -0.60 +/- 0.87 l/min. This new adaptation of the partial rebreathing technique is reliable in measuring cardiac output in postoperative patients. Reasons for the consistent discrepancy between thermodilution and partial rebreathing techniques are discussed.
Intensive Care Unit, Monash Medical Centre, Clayton, Victoria, Australia.
C J
CJ
Killick
W G
WG
Parkin
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002245:Carbon Dioxide / Q000378:metabolism*; D002302:Cardiac Output / Q000502:physiology*; D004867:Equipment Design; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology; D013815:Thermodilution; D055815:Young Adult
D002245:Carbon Dioxide