M.C. Borges, E. Ferraz, J. Terra-Filho and E.O. Vianna. Protective effect of bronchial challenge with hypertonic saline on nocturnal asthma. Braz J Med Biol Res, March 2008; Volume 41: 209-214.
Figure 2. Variation of forced expiratory volume in 1 s (FEV1) on the control and study days. FEV1 is reported in liters from 16:00 to 4:00 h for 12 asthmatic subjects on 2 days. On the control day (dotted line) the asthmatics inhaled isotonic saline and on the study day (solid line) they underwent hypertonic saline challenges at 16:00 and 18:00 h. No medications were taken between 16:00 and 4:00 h.