Device for breathing measurement

DETAILED DESCRIPTION 1.
A device for monitoring a patient's ability to exhale comprising a hollow body part, a piston member having first and second sides, said piston member being moveably mounted in said hollow body part, a mouthpiece mounted to said hollow body part and communicating with the interior of the hollow body part on the first side of the piston member for admitting exhaled air to said first side of the piston member, said piston member being moveable between a first position adjacent the point at which the mouthpiece is mounted to said hollow body part and a second position spaced from said point and determined by the patient's rate of exhalation into said mouthpiece, resilient loading means in the hollow body part and in contact with said piston member for opposing movement of the piston member in the hollow body part away from said mouthpiece by pressure of exhaled air on said first side of the piston member, venting means in said hollow body part for permitting the discharge of part of the exhaled air from the interior of the hollow body part, said venting means being in communication with the interior of the hollow body part on the second side of said piston member when piston member is in said first position and venting the exhaled air to atmosphere only after the piston member passes said venting means as said piston member moves to said second position, said venting means comprising a plurality of individual vents, individual removable seals in said vents for controlling the amount of exhaled air permitted to be discharged from the hollow body part, the amount of exhaled air discharged from said hollow body part being increased by removal of one or more of said individual seals, and means for indicating the extent of travel of the piston member during an exhalation.
2.
A device according to claim 1 further comprising a slot in the hollow body part, the slot running generally in the direction of movement of the piston member and the indicating means being mounted in said slot and moveable therein by the piston member