Currently accepted techniques utilize the plateau concentration of nitric oxide (NO) at a constant exhalation flow rate to characterize NO exchange, which cannot sufficiently distinguish airway and alveolar sources. Using nonlinear least squares regression and a two-compartment model, we recently described a new technique (Tsoukias et al. J Appl Physiol 91: 477-487, 2001), which utilizes a preexpiratory breath hold followed by a decreasing flow rate maneuver, to estimate three flow-independent NO parameters: maximum flux of NO from the airways (JNO,max, pl/s), diffusing capacity of NO in the airways (DNO,air, pl·s-1·ppb-1), and steady-state alveolar concentration (Calv,ss, ppb). In healthy adults (n = 10), the optimal breath-hold time was 20 s, and the mean (95% intramaneuver, intrasubject, and intrapopulation confidence interval) JNO,max, DNO,air, and Calv,ss are 640 (26, 20, and 15%) pl/s, 4.2 (168, 87, and 37%) pl·s-1·ppb-1, and 2.5 (81, 59, and 21%) ppb, respectively. JNO,max can be estimated with the greatest certainty, and the variability of all the parameters within the population of healthy adults is significant. There is no correlation between the flow-independent NO parameters and forced vital capacity or the ratio of forced expiratory volume in 1 s to forced vital capacity. With the use of these parameters, the two-compartment model can accurately predict experimentally measured plateau NO concentrations at a constant flow rate. We conclude that this new technique is simple to perform and can simultaneously characterize airway and alveolar NO exchange in healthy adults with the use of a single breathing maneuver.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of Applied Physiology|
|State||Published - Nov 10 2001|
- Diffusing capacity
ASJC Scopus subject areas
- Physiology (medical)