US 5,137,026 A · Personal spirometer

Abstract

A self-contained portable spirometer includes a housing and an air tube with an orifice. Within the housing there is a transducer and microprocessor-based circuitry for generating standard exhaled air performance measurements such as forced expiration volume and peak expiratory flow rate, commonly referred to as FEV.sub.1 and PFER. These measurements are displayed on a screen disposed on the housing. Since the air tube has a non-linear response, two amplifier stages with different amplification are coupled between the transducer and the microprocessor. The microprocessor monitors the flow rate through the tube and selects the signal from either one or the other amplification stage depending on the flow through the tube. The microprocessor also monitors the flow to determine when no air is blown through the tube. In this latter case, the computer shuts the power to the analog circuitry to conserve power.

Claims12

Dependent claims

A portion spirometer comprising:

an air tube coupled to said housing and including a substantially linear air passage with a reduced diameter orifice for generating a turbulence in the air passage;
pressure sensing means for sensing a differential pressure across said orifice when a person exhales through said air tube;
filter means disposed at an interface between said tube and said pressure sensing means for protecting said pressure sensing means, said filter means being made of a material permeable to gases and impermeable to liquids;
electronic circuitry means disposed in said housing and coupled to said pressure sensing means for generating electric input signals corresponding to said differential pressure, said electronic circuitry means including calculating means for calculating performance signals from said electric input signals;
and
display means for displaying said performance signals.

3 more elements

Dependencies are inferred from the claim text.

Personal spirometer

Life of this patent

Personal spirometer

Life of this patent

Abstract

Claims12