Fluidic spirometer

Claim 2

A fluidic spirometer comprising an expendable mouthpiece transducer means for generating a variable pneumatic pressure signal proportional to the airflow rate therethrough, said transducer means including an output passage, means connected to said output passage of said mouthpiece transducer means for preventing the air flowing therethrough from entering a nonexpendable portion of the spirometer to thereby prevent contamination thereof, a fluidic integrator having no moving mechanical parts, said integrator including an input in communication with said preventing means and an output, said output of said integrator being a pneumatic pressure signal proportional to the volume of air flowing through said mouthpiece transducer means, and readout means connected to said output of said integrator for indicating the volume of air flowing through said mouthpiece transducer means over a period of time.

Claim 3

The fluidic spirometer set forth in claim 1 wherein said expendable mouthpiece transducer means comprises a tubular member having a first end adapted for breathing therethrough and a second end open to the atmosphere.

Claim 4

The fluidic spirometer set forth in claim 2 wherein said expendable mouthpiece transducer means comprises an outer tube, and a plurality of small diameter tubes disposed within said outer tube to obtain laminar flow of the air breathed therethrough.

Claim 5

The fluidic spirometer set forth in claim 3 wherein said plurality of small diameter tubes are each of equal length and of slightly shorter length than said outer tube, at least one aperture passing through the wall of said outer tube in the region removed from said plurality of small diameter tubes but closely adjacent thereto, and means in communication with the aperture through said outer tube for transmitting the airflow rate generated pressure signal from said mouthpiece transducer means to said preventing means.

Claim 6

The fluidic spirometer set forth in claim 4 wherein second ends of said plurality of small diameter tubes are disposed in close proximity to the second end of said outer tube and, the aperture through the wall of said outer tube is located closely adjacent the first ends of said small diameter tubes and in the region near the first end of said outer tube.

Claim 7

The fluidic spirometer set forth in claim 5 wherein said outer tube and said plurality of small diameter tubes are fabricated of paper.

Claim 8

The fluidic spirometer set forth in claim 5 wherein said outer tube is of approximately 10-inch length, 1-inch outer diameter and 0.040-inch wall thickness, and said plurality of small diameter tubes are each of 9-inch length, 0.05-inch inner diameter and 0.010-inch wall thickness.

Claim 9

The fluidic spirometer set forth in claim 4 and further comprising a manifold body including a first cylindrical member enclosing said outer tube along a portion of the length thereof which includes the aperture therethrough.

Claim 10

The fluidic spirometer set forth in claim 8 wherein said manifold body further including a tubular passage member extending radially outward from said first cylindrical member and provided with means for quickly disconnecting said signal-transmitting means from said manifold body, said-signal-transmitting means comprising a flexible tubing having a first end adapted for quick connection and disconnection with the tubular passage member of said manifold body, and said mouthpiece transducer means and said manifold body forming a unitary body which is expendable and quickly connected and disconnected from the nonexpendable portion of the spirometer resulting in a short time interval per patient for the measurement of lung capacity.

Claim 11

The fluidic spirometer set forth in clAim 8 wherein said manifold body further including a tubular passage member extending radially outward from said first cylindrical member, the outer end of said tubular passage member connected to said signal-transmitting means, and said manifold body further including a cylindrical guide member for quickly directing said expendable mouthpiece transducer means into and out of said first cylindrical member resulting in a short time interval per patient for the measurement of lung capacity.

Claim 12

The fluidic spirometer set forth in claim 1 and further comprising means connected to the output of said integrator for reducing the pressure thereat to substantially zero to provide an initial condition of zero setting on said readout means prior to beginning measurement of a patient''s lung capacity.

Claim 13

The fluidic spirometer set forth in claim 1 wherein said readout means comprises a first pressure gage.

Claim 14

The fluidic spirometer set forth in claim 4 wherein said readout means comprises first, second and third pressure gages connected in parallel to the output of said integrator, and timing means in communication with said preventing means for controlling the operation of said first gage for a short time interval, controlling the operation of said second gage over a longer time interval, and controlling the operation of said third gage over a still longer time interval corresponding to the total breathing test period whereby said third gage records the total lung capacity.

Claim 15

The fluidic spirometer set forth in claim 13 wherein the time interval of operation of said first, second and third gages if 1, 3 and 10 seconds, respectively, said spirometer further comprising first high gain proportional type fluid amplifier means for amplifying the air flow rate generated pressure signal, said first amplifier means having no moving mechanical parts and having an input in communication with said preventing means and an output connected to an actuating member in said timing means for initiating operation thereof upon the first flow of air being breathed through said mouthpiece transducer.

Claim 16

The fluidic spirometer set forth in claim 14 and further comprising second high gain proportional type fluid amplifier means having no moving mechanical parts and having an input connected to said preventing means and the output in communication with the input of said integrator for permitting lower gain operation thereof.

Claim 17

The fluidic spirometer set forth in claim 15 wherein said second amplifier means output is also connected to the input of said first amplifier means whereby said second amplifier means functions as a preamplifier.

Claim 18

The fluidic spirometer set forth in claim 15 wherein said second amplifier means comprising at least one stage of proportional type fluid amplifier, an input network including first and second restrictors having second ends thereof respectively connected to first and second control inputs of the first stage amplifier, the first end of said first restrictor connected to an output end of said signal transmitting means, the first end of said second restrictor connected to a vent, said preventing means comprising third and fourth restrictors connected in series from the first end of said first restrictor to the first end of said second restrictor, said second amplifier means further comprising a power fluid input connection to each stage of the fluid amplifiers, the juncture of said third and fourth restrictors connected to a power fluid source supplying the power fluid inputs of said second amplifier means to thereby develop a constant pressure at the juncture of said first and third restrictors of magnitude exceeding the maximum signal pressure generated in said mouthpiece transducer.

Claim 19

The fluidic spirometer set forth in claim 17 wherein said second amplifier means further comprising a negative feedback network including fifth and sixth restrictOrs having first ends thereof respectively connected to first and second outputs of the last stage amplifier and second ends respectively connected to said first and second control inputs of said first stage amplifier, said fifth and sixth restrictors being of the variable fluid resistance type and connected for ganged operation in the same direction of varying resistance to provide a gain adjustment for calibrating said readout means.

Claim 20

The fluidic spirometer set forth in claim 15 and further comprising seventh and eighth restrictors having first ends thereof respectively connected to first and second outputs of said second amplifier means, and second ends respectively connected to first and second inputs of said integrator, said seventh and eighth restrictors being of the variable fluid resistance type and connected for ganged operation in opposite directions of varying resistance to provide a bias adjustment for zero setting of said integrator.