Effect of water immersion as a model of weightlessness on lung closing volume
Tikhonov, M.A.; Kondakov, A.V.; Asyamolova, N.M.; Volkov, M.Yu
Kosmicheskaia Biologiia i Aviakosmicheskaia Meditsina 17(1): 37-40
1983
ISSN/ISBN: 0321-5040 PMID: 6843068 Document Number: 218068
The effect of 7-day water immersion combined at night with head-down (6.degree.) tilting on the volumes of lung expiratory closing was examined in 6 healthy male test subjects, aged 25-35. During immersion they showed, along with a stable reduction of the lung vital and functional residual capacity (by 4.2 and 14.8.degree., respectively), an increase in the fraction parameters of the expiratory closing volumes. The increase in the closing volume (up to 40.degree.) (P < 0.05) was particularly distinct on immersion day 2. Subsequent changes indicated gradual recovery of the closing volumes and a decline in regional nonuniformity of lung ventilation. The variations in the closing volumes may be attributed to an increase in the intrapulmonary blood volume at the early stage of adaptation to immersion and to a decrease in the nonuniformity of the ventilation-perfusion ratios.