Simulation system for a rebreathing technique to measure multiple cardiopulmonary function parameters.
BACKGROUND
We developed a simple method for simulating a rebreathing maneuver to test the accuracy of the apparatus for simultaneous measurement of lung volume, diffusing capacity of the lung for carbon monoxide (Dlco), diffusing capacity of the lung for nitric oxide (Dlno), and pulmonary blood flow (Qc).


METHODS
A test gas mixture containing 0.3% methane, 0.3% CO, 0.8% acetylene, 30% O(2), and 40 ppm nitric oxide in balance of nitrogen was sequentially diluted with a rebreathing gas mixture containing 0.3% acetylene, 0.3% methane, and 21% O(2) in balance of nitrogen in order to simulate the in vivo end-tidal disappearance of the test gas mixture. Simulation of one rebreathing maneuver consisted of at least four serial dilution steps with a performance time of < 5 min. Using this technique, we estimated functional residual capacity, Qc, Dlco, and Dlno at various flow rates and dilution ratios (0.95 to 4.04 L, 3.54 to 6.83 L/min, 7.27 to 15.12 mL/min/mm Hg, and 6.51 to 12.00 mL/min/mm Hg, respectively) and verified simulation results against nominal values. The same apparatus also could simulate a single-breath procedure.


RESULTS
Compared to nominal values, errors in measured values by rebreathing and single-breath Dlco simulation remained < 5% and 7%, respectively. Slopes of the correlations were close to 1.0 (within +/- 5% and +/- 6.4% in rebreathing and single-breath Dlco simulation studies, respectively).


CONCLUSIONS
The results demonstrate the feasibility of this simulation method for standardizing the experimental measurements obtained by rebreathing and single-breath techniques. Incorporation of these simulation steps enhances the noninvasive assessment of cardiopulmonary function.
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX. Electronic address: cuneyt.yilmaz@utsouthwestern.edu.
Cuneyt
C
Yilmaz
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX.
William W
WW
Chance
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX.
Robert L
RL
Johnson
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX.
Connie C W
CCW
Hsia
D001944:Breath Tests / Q000295:instrumentation / Q000379:methods*; D002248:Carbon Monoxide / Q000097:blood; D002302:Cardiac Output; D004867:Equipment Design; D005240:Feasibility Studies; D006321:Heart / Q000502:physiology*; D006801:Humans; D008168:Lung / Q000502:physiology*; D008176:Lung Volume Measurements; D009569:Nitric Oxide; D011653:Pulmonary Diffusing Capacity / Q000502:physiology
D009569:Nitric Oxide; D002248:Carbon Monoxide