Steady-state measurement of NO and CO lung diffusing capacity on moderate exercise in men

Abstract

Using a rapidly responding nitric oxide (NO) analyzer, we measured the steady-state NO diffusing capacity (DL(NO)) from end-tidal NO. The diffusing capacity of the alveolar capillary membrane and pulmonary capillary blood volume were calculated from the steady-state diffusing capacity for CO (measured simultaneously) and the specific transfer conductance of blood per milliliter for NO and for CO. Nine men were studied bicycling at an average O(2) consumption of 1.3 +/- 0.2 l/min (mean +/- SD). DL(NO) was 202.7 +/- 71.2 ml. min(-1). Torr(-1) and steady-state diffusing capacity for CO, calculated from end-tidal (assumed alveolar) CO(2), mixed expired CO(2), and mixed expired CO, was 46.9 +/- 12.8 ml. min(-1). Torr(-1). NO dead space = (VT x FE(NO) - VT x FA(NO))/(FI(NO) - FA(NO)) = 209 +/- 88 ml, where VT is tidal volume and FE(NO), FI(NO), and FA(NO) are mixed exhaled, inhaled, and alveolar NO concentrations, respectively. We used the Bohr equation to estimate CO(2) dead space from mixed exhaled and end-tidal (assumed alveolar) CO(2) = 430 +/- 136 ml. Predicted anatomic dead space = 199 +/- 22 ml. Membrane diffusing capacity was 333 and 166 ml. min(-1). Torr(-1) for NO and CO, respectively, and pulmonary capillary blood volume was 140 ml. Inhalation of repeated breaths of NO over 80 s did not alter DL(NO) at the concentrations used.

Reverse Engineering of Oxygen Transport in the Lung: Adaptation to Changing Demands and Resources through Space-Filling Networks

“…For (“moderate exercise”), we take the linear regression relation between oxygen current and volumetric flow rates in the trachea reported by Newstead [18] to calculate the oxygen current, and found it to be 1360 ml/min when the volumetric flow rate is 30400 ml/min. Borland et al [19] measured the membrane diffusing capacity att an oxygen current of 1300 ml/min, which is very close to 1360 ml/min. We therefore associate Borland's oxygen current and membrane diffusing capacity with z cd  = 19.…”

Short-term hypoxic exposure at rest and during exercise reduces lung water in healthy humans

“…being negligible by the fourth to fifth breath. Moreover, Borland et al (11), and more recently Zavorsky and Murias (68), have specifically examined this concept and have found that inhalation of NO for over 1 min does not alter D M or Vc.…”

Impaired lung diffusing capacity for nitric oxide and alveolar-capillary membrane conductance results in oxygen desaturation during exercise in patients with cystic fibrosis

“…Gas diffusion can be assessed by the measurement of diffusion capacity of the lungs for carbon monoxide (DLCO) which is dependent on both alveolar-capillary membrane conductance (D M ) and pulmonary capillary volume (V C ). Using simultaneous measurement of DLCO with the diffusion capacity of the lungs for nitric oxide (DLNO), these components of DLCO can be partitioned out [22][23][24][25]. Although the combined assessment of DLCO and DLNO provides important information about gas diffusion, DLNO independently provides a direct measure of D M .…”