Simulation System for a Rebreathing Technique To Measure Multiple Cardiopulmonary Function Parameters

Abstract

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 (Q.c). Methods A test gas mixture containing 0.3% methane, 0.3% CO, 0.8% acetylene, 30% O2, 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% O2 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, Q.c, 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). Conclusion 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.

Bioengineering of Pulmonary Epithelium With Preservation of the Vascular Niche

“…Using high-resolution computer tomography at two inflation pressures and the deformation analysis, the same group showed that the remaining lobes had non-uniform regional mechanical strains. Two growth phases were identified: (i) an initial rapid proliferative phase, characterized by air space and blood volume increases, and (ii) a progressive remodeling phase, characterized by tissue relaxation and increased lung compliance persisting over several months (Hsia et al, 2008;Yilmaz et al, 2009).…”