Abstrict A peak expiratory flow meter device for indicating airway obstruction
in a patient. The device includes an elongated channel arranged
perpendicularly to a mouthpiece, at the end of which an adjustable
orifice is disposed. A float moves within the channel in response
to expiration from the patient. A removable pin is provided with
the channel for accommodating various ranges of expiration, and
for the same general reason, rotatable discs are provided to partially
cover the orifice.
Claims What is claimed is:
1. A peak expiratory flow metering device for measuring airway
obstruction in a patient indicating the necessity of more definitive
testing comprising a mouthpiece, an elongated channel substantially
perpendicular to said mouthpiece, an orifice member disposed substantially
inline with said mouthpiece and defining a first orifice therein,
a float located within said channel and for motion within said channel,
said channel and orifice member in flow communication with said
mouthpiece whereby said motion occurs in response to expiration
from said patient, a plurality of channel openings defined by said
channel at various points along said channel, means for preventing
downward motion of said float within said channel including a removable
pin positionable within said channel openings and means for selectively
lessening said first orifice.
2. The invention according to claim 1 wherein said means for selectively
lessening comprises a removable occluding disc for said first orifice.
3. The invention according to claim 2 wherein said means for selectively
lessening further comprises a removable disc defining a second orifice
smaller than said first orifice for lessening the effective orifice
of said member.
4. The invention according to claim 1 wherein said float is a metal
ball.
5. The invention according to claim 4 wherein said channel defines
a constant diameter race in which said ball moves.
6. The invention according to claim 1 wherein said channel defines
a channel opening which is constantly wider as the channel elongates
further from said mouthpiece.
7. The invention according to claim 1 wherein said mouthpiece includes
means for attaching a disposable mouthpiece cover.
8. The invention according to claim 1 wherein said mouthpiece and
channel intersect in a primary orifice which includes means for
preventing entrance of said float therein.
9. The invention according to claim 8 wherein said channel includes
means for preventing removal of said float from the end of said
channel furthest from said mouthpiece.
Description This invention relates generally to expiration flow rate measuring
devices and more particularly to such devices which may be self-administered
and which are adjustable in their range of measurement.
Peak expiratory flow rate is a good general indicator of the presence
or absence of airway obstruction. Such a rate measurement is also
determinative of responsiveness to bronchodilators and it is known
that airway obstruction associated with lung disease is measurable
long before symptoms may appear.
The measurement of peak expiratory flow rate could therefore be
an effective medical tool if it could offer a quick, effective screening
technique for presumably normal subjects away from the hospital
and physician's office. Furthermore, such a device would be particularly
useful in factories and as part of health survey programs on a regular
basis.
Furthermore, in connection with lung disease, it is particularly
important to determine the effectiveness of a prescribed drug without
the necessity for hospitalization or constant visits to a physician'
s office. Expiratory flow rate is also indicative of the severity
of an asthmatic attack.
Attempts at measuring devices such as the present invention have
been made, but suffer from the disadvantages of cumbersome construction,
lack of a compact design, complexity of operation effectively prohibiting
home use and lack of sufficient accuracy.
Accordingly, a primary object of the present invention is to provide
a compact, lightweight construction, peak expiratory flow meter
which is simple to operate and yet efficient and accurate in its
measurement.
A further object of the present invention is to provide a peak
expiratory flow meter which may be adjusted in its range of measurement
and accommodated for varying patient ages and conditions.
These and other objects of the present invention are accomplished
in a peak expiratory flow meter according to the present invention
which features a mouthpiece, an elongated channel substantially
perpendicular to the mouthpiece and an orifice member disposed substantially
in-line with the mouthpiece. The orifice member defines a first
orifice at its end furthest from the mouthpiece, and the orifice
is adjustable by means of a pair of discs, separately rotatable
to either occlude the first orifice or lessen its effective opening.
A float moves within the elongated channel in response to expiration
from the patient and a removable pin prevents downward motion of
the float within the channel, depending upon the range of expiration
expected from the patient. The float in a preferred embodiment is
a metal ball moving within a central race defined by the channel,
and the channel is constantly wider as it elongates further from
the mouthpiece in order to make it more difficult to move the float.
The mouthpiece includes means for accommodating a disposable mouthpiece
cover, thereby enabling use by more than one person, since the patient
inspires air from outside the device before exhaling therethrough.
Other objects, features and advantages of the present invention
will be apparent by reference to the following more detailed description
of a preferred, but nonetheless illustrative, embodiment of the
present invention with reference also to the accompanying drawings,
wherein:
FIG. 1 is an isometric representation of a peak expiratory flow
meter according to the present invention showing particularly the
device in use and adjustment capability of the orifice thereof;
FIG. 2 is a side, sectional view of the present invention, taken
along the line 2--2 of FIG. 1 and showing particularly the construction
thereof and the use of range adjusting pin for the channel thereof;
FIG. 3 is a front sectional view of the present invention taken
along the line 3--3 of FIG. 2 and showing particularly the channel
construction thereof;
FIG. 4 is a sectional view of the channel, taken along the line
4--4 of FIG. 3; and
FIG. 5 is a partial view similar to that of FIG. 3 but showing
the use of a defined range within the channel of the device.
Referring to the drawings, a peak expiratory flow meter is shown
to include a mouthpiece 10 and an elongated channel, generally
designated 12 disposed substantially perpendicularly to the mouthpiece,
and an orifice member 14 disposed substantially in-line with mouthpiece
10. The mouthpiece 10 is constructed to define a mouthpiece opening
16 and a stepped outer surface 18. The stepped outer surface is
structured to accommodate a disposable mouthpiece cover 20., so
that different patients are able to use the same device. The mouthpiece
cover 20 may be paper or plastic or any suitable material and the
expiratory meter itself is preferably of plastic or glass.
The orifice member 14 (FIG. 2) includes an upper member 22 into
which is inserted a disc pin 24 for holding a pair of rotatable
discs 26 28 at the end of the orifice member. Disc 28 is an occluding
disc which may be rotated by means of pin 24 to a position shown
by ghost lines 30. In this position, the orifice of the device is
determined by orifice 32 defined by second orifice disc 26. Likewise,
with both occluding disc 28 and second orifice disc 26 rotated by
means of pin 24 to a position shown by ghost lines 34 32 the orifice
of the device will be determined by first orifice 36 as shown in
FIG. 2.
The channel 12 includes an elongated base structure 38 defining
a channel opening 40 which is constantly wider (FIG. 3) as the channel
elongates further from mouthpiece 10. Still further, channel opening
40 includes a constant diameter race 42 extending the length of
the channel to accommodate and control motion of a float 44 (FIG.
3), whose motion is controlled by operation of the device. The float
44 may be in the form of a metal ball or any other material useable
in the preferred construction. Channel 12 still further defines
a plurality of channel openings 46a, 46b, 46c, 46d, 46e, as shown
in FIG. 2. Such channel openings are designed to engage removable
pin 48 which, as shown in FIG. 2 is provided to prevent downward
motion of float 44 depending upon the range of the device selected
by the user. Channel 12 also includes a bottom stop 50 and a top
stop 52 which respectively prohibit entrance of float 44 to primary
orifice 54 defined at the intersection of mouthpiece 10 and channel
12 and to prevent removal of float 44 from the end of channel 12
furthest from the mouthpiece.
Channel 12 has its base structure 38 shown in two mating halves
38' and 38" (FIG. 4), but it may be formed in a unitary mold
or by any other convenient manufacturing process.
In order to more fully describe the present invention, a description
of its operation and use will now be provided.
Defining the position of orifice discs 26 28 as shown in FIG.
2 as "total occulsion", rotation of disc 28 to its ghost
line position of FIG. 2 as "partial occlusion" and rotation
of both orifice discs 26 28 to their ghost line positions of FIG.
2 as "open", the following table represents a typical
flow chart for guiding use of the device:
Table 1 ______________________________________ Peak Flow Index
Gradation (Peak expiratory flow-liters/min) ______________________________________
Low range (65-175) Orifice caliber: total occlusion Position of
metal ball: PEF Position #1 65 Position #2 125 Position #3 175 Medium
range (175-325) Orifice caliber: partial occlusion Position of metal
ball: Position #1 175 Position #2 250 Position #3 325 High range
(325-525) Orifice caliber: open Position of metal ball: Position
#1 325 Position #2 425 Position #3 525 and above ______________________________________
Also, the following charts represent spirometry in males, females
and children to guide initial position of the orifice discs and
pin 48:
Table 2 ______________________________________ Spirometry in Normal
Males (Peak expiratory flow-liters/min) (approximate values) Height
(inches) Age 60" 65" 70" 75" 80" ______________________________________
20 554 602 649 693 740 30 532 577 622 664 710 40 509 552 596 636
680 50 486 527 569 607 649 60 463 502 542 578 618 70 440 477 515
550 587 ______________________________________
Table 3 ______________________________________ Spirometry in Normal
Females (Peak expiratory flow-liters/min) (approximate values) Height
(inches) Age 55" 60" 65" 70" 75" ______________________________________
20 390 423 460 496 529 30 380 413 448 483 516 40 370 402 436 470
502 50 360 391 424 457 488 60 350 380 412 445 475 70 340 369 400
432 461 ______________________________________
Table 4 ______________________________________ Spirometry in Normal
Children and Adolescents (Peak expiratory flow-liters/min) (approximate
values) Height (inches) Males Females ______________________________________
43" 147 147 44" 160 160 45" 173 173 46" 187
187 47" 200 200 48" 214 214 49" 227 227 50"
240 240 51" 254 254 52" 267 267 53" 280 280 54"
293 293 55" 307 307 56" 320 320 57" 334 334 58"
347 347 59" 360 360 60" 373 373 61" 387 387 62"
400 400 63" 413 413 64" 427 427 65" 440 440 66"
454 454 67" 467 467 ______________________________________
Using the above predicted values, peak flow index in normal subjects
according to their sex, age and height, may be determined. Before
the patient 60 exhales into the device, the orifice caliber may
be positioned, and the float positioned by means of pin 48. For
example, if the patient is a 40 year old male, 5'10" in height,
the predicted normal peak airflow will be 596 liters per minute.
Accordingly, Table 1 is consulted to show the degree of occulsion
and position of the flow such that both discs 26 and 28 will be
rotated to nonoperating position or an orifice caliber designated
"open". The float 44 will be located at "position
#3", or the highest of the three ranges, shown in FIG. 3 wherein
the extent of travel of float 44 is between the solid float position
shown and the position 44' shown in ghost lines. This range is determined
by position of pin 48 as shown in FIG. 3. Accordingly, stop 52
will prevent removal of float 44 from the device.
Referring to FIG. 5 if the patient's condition and other factors
had indicated "position #1", the range of travel would
be between the position indicated by float 44 as shown and float
44" depicted by the ghost lines in FIG. 5. Stop 50 would prevent
entrance of float 44 to primary orifice 54.
To obtain "position #1", the positioning pin 48 is simply
removed from the device. To obtain "position #2", pin
48 is temporarily removed, and the device inverted so that the float
44 rolls to the top of the channel. The positioning pin 48 is then
reinserted to maintain float 44 above a median position of the device.
To obtain "position #3", pin 48 is temporarily removed
and float 44 moved to the top of the channel by inverting the device.
Pin 48 is then placed in the position shown at 48 in FIG. 3. Of
course, a plurality of other positions are also obtainable by use
of the various openings 46a-e shown in FIG. 2.
Also, in use of the device, the patient should receive clear instructions
and be encouraged to make a maximum expiratory effort so that he
exhales a single, short, powerful blast. Practice by the patient
would both relax him and indicate whether or not readjustment of
the device is necessary. For instance, if the patient fails in a
practice attempt to move the ball at all, a lowering of pin 48 or
a rotation into operating position of one or both of discs 26 28
or another combination of adjustments would be indicated.
Accordingly, a simple, efficient and structurally sound device
and accurate indication of peak expiratory flow is obtained by use
of the present invention to determine the necessity for more definitive
testing by other means. The device may be used without a hospital
or physician's office environment and its simple design and operation
provides a lasting quality for intended use. |