Ruff F
Scand J Respir Dis Suppl. 1974;85:190-200.
Closing volume and closing capacity increased linearly with age. In the seated position, the closing volume exceeded the expiratory reserve volume in subjects older than about 65 years, while in the supine position, as the expiratory reserve volume is markedly reduced, this occurred at about 44 years. Above these two "critical ages", ventilation to the dependent parts of the lungs is reduced during the normal tidal volume breathing. Thus, in seated subjects older than 65 years and in supine individuals older than 44 years there is significant impairment of ventilation distribution to the dependent lung zones, which necessiarly causes impaired gas exchange within the lungs.
闭合气量和闭合容量随年龄呈线性增加。在坐位时，约65岁以上的受试者闭合气量超过补呼气量，而在仰卧位时，由于补呼气量明显减少，这种情况发生在约44岁时。在这两个“临界年龄”以上，在正常潮气量呼吸时，肺下垂部位的通气减少。因此，65岁以上的坐位受试者和44岁以上的仰卧位个体，肺下垂区域的通气分布有明显受损，这必然导致肺内气体交换受损。
