Patent ID: 9700235
Date: 2017-07-11
CPC Classifications: A61B

Claim:
1. A peak expiratory flow rate measuring apparatus (PFM), comprising; at least one measurement channel comprising at least one first flow entrance; at least one bypass flow channel comprising a proximal end, a distal end, at least one second flow entrance at the proximal end, at least one exit at the distal end, at least one inner wall, at least one outer wall, and wherein at least a portion of said at least one bypass flow channel has a variable cross-sectional area; and at least one guide wall, having a proximal portion adjacent to said second flow entrance and said outer wall, and a distal portion adjacent to said first flow entrance and said inner wall, said guide wall being disposed between the inner wall and the outer wall, and angled toward the measurement channel to direct a flow toward the measurement channel, wherein the cross-sectional area of the bypass flow channel adjacent to the second flow entrance and distal to the guide wall is larger than a cross sectional area of the at least one second flow entrance, such that an expansion chamber is formed in the bypass flow channel, and the bypass flow channel tapers from a distal end of the expansion chamber to the distal end of the bypass flow channel, to form a reducing flow channel.