Respiratory mechanics after 180 days space mission (EUROMIR'95)

Abstract

The present study reports data on respiratory function of lung and chest wall following the 180 days long European — Russian EuroMir '95 space mission. Data reported refer to two subjects studied before the mission, on day 9 and 175 in flight and on days 1, 10, 12, 27 and 120 after return. In-flight vital capacity (VC) and expiratory reserve volume (ERV) were similar to those in supine posture, namely ~ 5% and ~ 30% less than in sitting posture. On day 1 after return, VC was reduced by ~30 % in both postures. This reflected a decrease in ERV (~0.5 L) and in IC (inspiratory capacity, ~ 1.7 L) that could be attributed to a marked weakening of the respiratory muscles. Regain of normal preflight values barely occurred 120 days after return. Post-flight pressure-volume curves of the lung, chest wall and total respiratory system are equal to preflight ones. The pressure-volume curve of the lung in supine posture is displaced to the right relative to sitting posture and shows a lower compliance. As far as the lung in-flight condition resembles that occurring in supine posture, this implies a lower compliance, a greater amount of blood in the pulmonary microvascular bed, a more homogeneous lung perfusion and therefore a greater microvascular filtration rate towards lung interstitium.