Position affects distribution of ventilation in the lungs of older people: an experimental study.

Question: What is the effect of sitting and side-lying on the distribution of ventilation during tidal breathing in healthy older people?

Design: Randomised, within-participant, experimental study.

Participants: Ten healthy people more than 65 years old.

Intervention: Tidal breathing during sitting and right side-lying.

Outcome Measures: Distribution of ventilation as a percentage of total counts using Technetium-99m Technegas lung ventilation imaging.

Results: In sitting, the ratio of the distribution of ventilation to apical: middle: basal regions was 1: 3.5: 3.3 in the right lung, and 1: 2.9: 2.3 in the left lung. In right side-lying, 32% (95% CI 22 to 43) more ventilation was distributed to the right lung than to the left lung. The ratio of the distribution of ventilation to apical: middle: basal regions was 1: 2.8: 2.2 in the right lung, and 1: 2.4: 1.9 in the left lung.

Conclusions: In both sitting and right side-lying, ventilation was distributed more to the middle than to the basal region, which may be related to age-associated changes in the respiratory system.