title: Lung diffusion capacity for nitric oxide and carbon monoxide is impaired similarly following short-term graded exercise.
abstract: Study aimed to determine whether short-term graded exercise affects single-breath lung diffusion capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) similarly, and whether the DLNO/DLCO ratios during rest are altered post-exercise compared to pre-exercise. Eleven healthy subjects (age=29+/-6 years; weight=76.6+/-13.2 kg; height=177.9+/-13.2 cm; and maximal oxygen uptake or V(.-)(O(2max) = 52.7 +/- 9.3 ml kg(-1) min(-1))performed simultaneous single-breath DLNO and DLCO measurements at rest (inspired NO concentration=43.2+/-4.1 ppm, inspired CO concentration=0.30%) 15 min before and 2h after a graded exercise test to exhaustion (exercise duration=593+/-135 s). Resting DLNO and DLCO was similarly reduced 2h post-exercise (DLNO=-7.8+/-3.5%, DLCO=-10.3+/-6.9%, and P<0.05) due to reductions in pulmonary capillary blood volume (-11.3+/-9.0%, P<0.05) and membrane diffusing capacity for CO (-7.8+/-3.5%; P<0.05). The change in DLCO was reflected by the change in DLNO post-exercise such that 68% of the variance in the change in DLCO was accounted for by the variance in the change in DLNO (P<0.05). The DLNO/DLCO ratio was not altered post-exercise (5.87+/-0.37) compared to pre-exercise (5.70+/-0.34). We conclude that the decrease in single-breath DLNO and DLCO from pre- to post-exercise is similar, the magnitude of the change in DLCO closely reflects that of the change in DLNO, and single-breath DLNO/DLCO ratios are independent of the timing of measurement suggesting that using NO and CO transfer gases are valid in looking at short-term changes in lung diffusional conductance.
authors.affiliation: Department of Anesthesia, McGill University Health Center, 1650 Cedar Avenue, Room D10-144, Montreal, Que., Canada H3G 1A4. gerald.zavorsky@mcgill.ca
authors.forename: Gerald S
authors.initials: GS
authors.lastname: Zavorsky
authors.forename: Larry C
authors.initials: LC
authors.lastname: Lands
mesh_terms: D000328:Adult; D002248:Carbon Monoxide / Q000008:administration & dosage / Q000378:metabolism*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000008:administration & dosage / Q000378:metabolism*; D010101:Oxygen Consumption; D005082:Physical Exertion / Q000502:physiology*; D011653:Pulmonary Diffusing Capacity / Q000502:physiology*
chemical_list: D009569:Nitric Oxide; D002248:Carbon Monoxide