Measurements are obtained preferably in the sitting position. Although body
posture has no significant influence on the result of the measurement in healthy subjects
[53], and even in convalescent neonates [54], in COPD patients changes in body posture
may significantly impact on the obtained result. Leaning forward for example may result
in higher inspiratory pressures [55], while measurements obtained in the recumbent
position may lead to lower pressures [56].