[Estimation of static lung volumes by nitrogen washout method. Single breath of oxygen]

Total lung capacity (TLC) and residual volume (RV) estimations were obtained from single-breath nitrogen washouts in 96 male and 77 female healthy never-smokers with normal spirometry from a non-polluted rural area in north-east France. TLC depended on height (both sexes) and diminished slightly with age in males, with the body-mass index (kg/m2) in females. RV increased with age in both sexes and with weight in males. The RV/TLC ratio was related only to age. When compared with values obtained using multiple-breath helium dilution, our results yielded lower predicted values. The test depends heavily on the subject's co-operation, and errors are frequent if a standard procedure is not observed. This method cannot thus be recommended for routine use in patients with respiratory diseases.