Posture changes the deposition pattern of an inhaled aerosol

Quint, M.J., Fleming, J., Bolt, L., Williams, J., Postle, A.D. and Conway, J.H. (2002) Posture changes the deposition pattern of an inhaled aerosol. American Journal of Respiratory and Critical Care Medicine, 8 (165 Supplement).

Abstract

Rationale: A complete understanding of the mechanisms underlying the regional deposition of an inhaled aerosol is not as yet available. The role of particle size and respiratory manoeuvre are appreciated but the impact that posture may have is not. This study aimed to evaluate the effect of changes in posture on regional deposition of an inhaled aerosol.
Methods: Randomised, cross-over trial with three limbs. Ten, healthy male (22-38 yr) subjects were enrolled. Each individual inhaled a nebulised suspension of radiolabelled human serum albumin (HSA) on three separate occasions in three different positions (sitting, lying and right side lying). The aerosol was delivered in a controlled manner using a closed nebuliser circuit incorporating a pneumotachograph. Gamma scintigraphy was used to assess the regional deposition of the radio-aerosol.
Results: A comparison of the activity between the right and left lung demonstrated marked changes in deposition. With the subject in right side lying there was a marked increase in the deposition in the dependant (i.e. right) lung. This was significant (p=0.001).
Conclusion: Changes in body posture result in changes in the deposition pattern of an inhaled aerosol. This may have clinical implications.

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