Opinion ID: 209426
Heading Depth: 3
Heading Rank: 1

Heading: Claim Construction of “fluid characteristic”

Text: Respironics argues that “fluid characteristic” in the claims of the ’575 and ’517 patents should not be limited to just “flow rate,” because the specification also discloses 2008-1164, -1193 24 “volume” as a fluid characteristic. See ’575 patent col.23 ll.65-67 (“said fluid characteristic is one of a rate of said flow of gas within said patient interface and a volume of gas to be exhaled”) (emphases added). We agree that the claim construction should be modified to include volume. Although volume can be calculated from flow rate, such a calculation would require additional steps to be performed: measuring time and then multiplying time by average flow rate (or integrating a time-varying flow rate). Aside from volume, however, Respironics points to no other fluid characteristic disclosed in the specification. Nor do we see any. Thus, properly construed, “fluid characteristic” means “flow rate or volume.”