Biomedical Engineering Reference
In-Depth Information
Fig. 6.1 AIM CIs in relation to parent full-resolution systems ( Courtesy Copley Scientifi c Ltd,
MSP Corp., Astra Zeneca and Westech Instrument Services Ltd )
have been reviewed in Chap. 4 . Most of these considerations have already been
explored with all types of abbreviated CIs, and outcomes of such experimental
studies are reviewed in Chap. 10 . This chapter should therefore be consulted before
choosing an AIM-based approach.
Whether a sponsor selects their own size ranges or uses one or more of the ranges
recommended in Sect. 6.3 , the chosen size ranges need to be not only justifi ed but
also qualifi ed against the only widely accepted gold standard , i.e., full-resolution CI
data for the given product. This exercise will form a sound basis for future use of the
chosen system by the sponsor and any potential troubleshooting or investigations of
deviations. It may also alert the sponsor to underappreciated or overlooked factors
infl uencing accuracy and precision of CI measurements.
The issue of which “parent” full-resolution CI to choose as the reference appara-
tus against which to validate measurements made by the chosen AIM-based system
will in many cases be obvious (Fig. 6.1 ). For example, the designs of the fast-
screening Andersen impactor (FSA) and the fi ne particle dose-abbreviated system
(FPD-AVCI) are based on those of the nonviable and viable forms of the ACI,
respectively (see Fig. 10.28 and associated explanatory text in Chap. 10 for a com-
parison between the two types of Andersen impactor). Likewise, the full-resolution
NGI would be the obvious choice as reference CI, if modifying this system into an
abbreviated apparatus. However, some abbreviated CIs, in particular the fast-
screening impactor (FSI), have no obvious parent full-resolution impactor, as they
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