Ventilatory capacity meters

摘要

A peak flow meter has a body (2) forming a chamber (16) along which a piston (12) can be moved against the force of a spring (14) by a subject exhaling through an inlet into the chamber. A slot (24) runs along a side of the chamber to allow the air to escape and a pointer (26) is movable along the slot by the piston to indicate its maximum displacement. Deflection means (40) at the chamber inlet concentrates the flow through the chamber (16) towards the side at which the slot (24) is located. By the use of such deflection means it is possible to measure reliably relatively small peak exhalation rates.