Abstrict A portable peak flow meter for monitoring the expiratory flow rate
of a user includes an on-line metering unit having a combination
cover and handle. The metering unit, which has opposed mouthpiece
and exit ends, is of generally rectangular construction. A pair
of opposed and hinged cover elements are pivotly mounted to the
side walls of the metering unit, and pivot from a first position
in which they embrace and cover the mouthpiece, to a second position
perpendicular to the length of the metering unit in which they serve
as a handle. The cover elements both maintain the mouthpiece in
a sanitary condition when the unit is not in use and allows the
unit to be held in a manner where the user's hand is distanced from
the meter, thus preventing interference with operation of the unit.
Claims We claim:
1. A breath flow meter comprising a hollow meter body; flow measurement
means mounted in said body for measuring and displaying the flow
rate of breath passing through said meter body; a mouthpiece at
a first end of said body and a breath outlet in said body displaced
from said first end; a cover coacting pivot means for pivotally
mounting said cover to said body, and means for selectively maintaining
said cover in a chosen one of two alternative orientations wherein
a first orientation encloses said mouthpiece and a second orientation
extends said cover from said body as a handle.
2. The apparatus of claim 1 wherein said meter body comprises
a plurality of passageways therethrough between said mouthpiece
and said breath outlet.
3. The apparatus of claim 2 wherein said flow measurement means
is located in one of said passageways.
4. The apparatus of claim 3 further comprising means within said
body for diversion of the breath among each of said passageways.
5. The apparatus of claim 1 wherein said measurement means includes
indicator means adapted to retain a measurement of peak flow through
said body.
6. A breath flow meter comprising an elongated hollow meter body
having first and second ends and opposed side walls; flow measurement
means for measuring and displaying flow rate of breath passing through
the meter body mounted in said body; a mouthpiece at said first
end; and first and second hinged, mating cover elements, at least
one of said cover elements having means for pivotally mounting said
cover elements to said body to selectively enclose or expose said
mouthpiece.
7. The apparatus of claim 6 wherein said means for pivotally mounting
said at least one of said cover elements comprises an axle post
projecting from each of said opposed side walls, and a pair of opposed
arms mounted to said first cover element, each of said arms including
means for accepting said axle posts projecting from each of said
opposed side walls.
8. The apparatus of claim 7 further comprising a self-hinge joining
said cover elements.
9. The apparatus of claim 7 wherein said cover elements comprise
fastening means to removably fasten them together to enclose said
mouthpiece.
10. The apparatus of claim 9 wherein said fastening means for
said cover elements comprise means for removably fastening said
cover elements together to serve as a handle for said apparatus
when said mouthpiece is exposed.
11. The apparatus of claim 7 wherein said means for pivotably
mounting said cover elements includes means for removably fastening
said cover elements together to serve as a handle for said apparatus
while said mouthpiece is exposed.
12. The apparatus of claim 11 wherein said handle extends at an
approximately right angle from said body.
13. A breath flow meter comprising an elongated hollow meter body
having first and second ends and opposed side walls and being divided
into a plurality of longitudinally-extending, flow-accepting passageways
therein, said passageways having a common entrance port at said
body first end; flow measurement means for measuring and displaying
flow rate of breath passing through the meter body mounted within
one of said passageways; a mouthpiece located at said body first
end; a pair of cover elements; and pivot means for pivotally joining
said cover elements to each other and to said body to allow said
cover elements to alternatively enclose said mouthpiece and serve
as a handle for the flow meter.
14. The apparatus of claim 13 wherein said measurement means comprise
a spring-biased piston mounted for longitudinal travel in one of
said passageways; a longitudinal slot in said meter body, and an
indicator extending outwardly through said slot from said one of
said passageways.
Description The present invention relates to an expiratory flow rate measuring
and monitoring device, and particularly to such a device which may
be easily transported upon the person.
BACKGROUND OF THE INVENTION
It is well established that the measure of peak expiratory flow
rate is a good indication of the condition of the airways of the
body. Thus, such measurement is helpful, for example, in the management
of asthma.
Asthma is recognized as a chronic disease which can manifest itself
in bronchial inflammation of which the patient may be unaware, and
has the ability to result in an acute attack under a variety of
circumstances, resulting in the partial or complete obstruction
of the breathing of the individual. Because of its chronic nature,
asthma patients must be continuously on guard to become aware of
symptoms which might forebode an attack. The use of effective anti-asthma
drugs can substantially limit or eliminate such attacks, but need
to be dispensed with care to prevent both over- and under-dosing.
An effective method for managing asthma is testing the respiratory
function. Such testing may typically be performed by the patient
himself by use of a portable peak expiratory flow meter. Such devices
measure the peak expiratory flow rate, that is, the maximum rate
of air flow which can be exhaled under various circumstances and
at various times throughout the day. This permits the patient to
monitor the respiratory function and receive warning of changes
in respiratory function which may indicate an impending asthma attack.
Typically, such peak flow meters, even when characterized as "portable"
are of relatively large size, and are not conducive to inconspicuous
transport or use by the patient. The peak flow meter depicted in
Alvino, U.S. Pat. No. 4944306 for example, utilizes a vertically-extending
indicator tube affixed to a horizontal mouthpiece/exit port. While
providing accurate peak flow rate measurement over a range of expiratory
flows, such an apparatus is relatively large and cumbersome, and
is not easily transported on the person. Such constructions limit
the effectiveness and usefulness of such devices by impeding the
ability of the patient to keep such a peak flow meter with him at
all times so that respiratory rate can be monitored whenever required.
It is thus a purpose of the present invention to provide a peak
flow meter of improved construction which results in a compact unit
being able to be carried on the person.
Yet another purpose of the present invention is to provide a peak
flow meter having the capacity to be folded into a compact unit
for transit and being able to be unfolded into a use position.
Still another purpose of the present invention is to provide such
a device in which the mouthpiece of the unit is protected from the
environment when not in use, thus improving the sanitation and safety
of the unit.
Yet a further purpose of the present invention is to provide such
a device in a manner which may be efficiently and economically manufactured.
BRIEF DESCRIPTION OF THE INVENTION
In accordance with the foregoing and other purposes and objects,
the present invention is directed to an improved portable peak flow
meter which utilizes a direct, in-line flow path for the expired
air. The airflow is divided into a plurality of streams, the first
of which activates a peak flow indicator means. The remaining air
streams bypass the indicator. In this manner, the indicator mechanism
deals with a relatively small volume of air and thus may be made
more sensitive to changes in peak flow rate
The flow meter is of generally rectangular configuration, with
a mouthpiece at a first end and an exhaust at the opposed second
end. It includes a pair of joined "clamshell" cover elements
which cover the mouthpiece portion of the unit when not in use,
open to expose the mouthpiece, and pivot downwardly to an in-use
position approximately perpendicular to the major axis of the flow
meter where they provide an operating handle for the unit. In the
"handle" position the user's left hand is maintained away
from the body of the unit, thus insuring uninterrupted flow and
non-interference with meter operation. After use the handle elements
may again be pivoted to close about the mouthpiece, allowing the
unit to be stored for subsequent use. The handle elements may preferably
be joined by an integral "living" hinge for manufacturing
nd eerformance efficiencies.
BRIEF DESCRIPTION OF THE DRAWINGS
A fuller understanding of the present invention will be accomplished
upon consideration of the following detailed description of a preferred,
but nonetheless illustrative embodiment of the present invention
when reviewed in association with the annexed drawings, wherein:
FIG. 1 is a perspective view of the present invention presented
in the closed position with the handle elements covering the mouthpiece;
FIG. 2 is a perspective view showing the handle elements in a transitory
position between the closed and open operating positions;
FIG. 3 is perspective view showing the invention in the fully open,
operative position;
FIG. 4 is a top plan view in section taken along line 4--4 of FIG.
1 detailing the interior of the invention;
FIG. 5 is a side elevation view in section taken along 5--5 of
FIG. 4;
FIG. 6 is an end elevation view in section taken along line 6--6
of FIG. 4;
FIG. 7 is an end elevation view looking in from the right end of
the unit as shown in FIG. 3;
FIG. 8 is a detail elevation view in section taken along line 8--8
of FIG. 5 illustrating the indicator mechanism of the invention;
and
FIGS. 9A and 9B are detailed end and side elevation views, respectively,
of the interconnection arms which join the covers to the body.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring initially to FIGS. 1 through 3 the portable peak flow
meter 10 of the present invention consists of a main body 12 in
the general form of a hollow rectangular prism, coupled to a mouthpiece
14 at a first end and having an exhaust at the opposed second end
16. A flow rate indicator 18 extends through a slot in the upper
surface 20 of the body, which is provided with indicia 22 calibrated
to indicate the flow rate shown by the indicator. A pair of cover
elements 24 26 hinged together at 28 are pivotly attached to
the sides of the body at 30. In a first position, shown in FIG.
1 the cover pieces enclose the mouthpiece 14 while in the operating
position as shown in FIG. 3 the cover elements 24 26 extend downwardly
from the body 12 in a generally perpendicular manner and provide
an operating handle for the unit.
With reference to FIGS. 4 through 6 the body 12 may be formed
of upper and lower portions 32 34 best seen in FIG. 5 which may
be joined together along a horizontal seam in an appropriate manner
to provide the body chamber. Interlocking elements may be provided
to allow the portions to be joined together without the need for
adhesive. As may be seen in FIG. 4 both upper and lower body portions
include the opposed side walls 36 38 which, in conjunction with
top 40 on portion 32 and bottom 42 on portion 34 define a rectangular
chamber through which the expired air passes.
Mounted within the chamber are interior walls 44 46 each of which
has portions formed as a part of upper body and lower body portions
32 34. The interior walls divide the chamber into three generally
parallel passageways 54 56 and 58 having a common entrance port
area at the right-hand end of the body. The inner walls 44 46 include,
at their proximal ends, respective arcuate portions 48 50 the
inwardly-directed ends of which define a narrow entrance aperture
52 into the central chamber 54. The arcuate portions 48 50 also
serve to smoothly divert the incoming air flow not aligned with
the entrance aperture 52 to the opposed lateral passageways 56 and
58 defined by the side walls 36 38 and the respective adjacent
inner walls 44 46.
Mouthpiece 14 adjoins the first end of the body 12 and includes
a first portion 60 adapted and dimensioned to be held by the lips
of the user, coupled to flared portion 62 which mates at its distal
end with the first end of the body 12. As shown, the body 12 may
be provided with a peripheral shoulder 64 which mates with a similar
opposed shoulder 66 on the mouthpiece to connect the body and mouthpiece
together. Both the body and mouthpiece may be formed of any appropriate
material, such as styrene plastic. The mouthpiece may be permanently
joined to the body or may be removable.
Mounted within central passageway 54 is piston 68 which the expiratory
flow impinges against t provide measurement of its flow rate. As
seen in FIGS. 4 and 5 piston 68 includes piston plate 70 positioned
transversely to the passageway 54 and which provides a flow barrier
across the passageway. The plate is mounted to collar 72 which
has a bore therethrough through which support rod 74 extends, permitting
travel of the piston along the length of the chamber. Support rod
74 is mounted at is ends in notched support blocks 76 78 each
of which is formed in two parts, as elements of the upper and lower
body portions 32 34 as may be seen in FIG. 5. Spring 80 has its
first end affixed to the piston 68 and its second end affixed to
the support block 76 at the entrance to passageway 54 to provide
an appropriate restoring force against the force developed by the
expirtory air against the piston plate 70.
In order to provide a visual indication of the maximum displacement
of the piston 68 as a result of expiratory flow, the top 40 of the
meter body is provided with a longitudinal slot 82 extending for
a length corresponding to the travel of the piston from its rest
position to a displaced position resulting from the maximum contemplated
expiratory flow rate to be encountered.
As may be seen in FIGS. 6 and 8 the slot 82 may include a lower
neck portion 84 having parallel sides adjoining an upper, generally
semicircular portion 86. Extending through the slot is the indicator
18 seen in FIG. 8 which includes a neck section 90 rectangular
in cross-section adapted to be embraced by the neck section of the
slot. The neck 90 supports at its upper end an indicator head 92
embraced by the hemispherical portion 86 of the slot, the head bearing
on its top surface a transversely directed, generally rectangular
pointer means 94 which, during travel, aligns with the indicia 22
seen in FIG. 3 to indicate the flow rate. Extending downwardly from
the neck 90 is a widened base portion 96 terminating in hemispherical
end 98. The hemispherical end 98 rests upon support rod 74 and is
engaged by the piston plate 70 whereby the indicator is moved leftwardly
as shown in FIGS. 4 and 5 in accordance with the maximum expiratory
flow rate developed by the user. As the flow rate decreases, the
piston returns to the right, the indicator remaining in its .position
of maximum displacement from its initial, rightmost rest position
to indicate the maximum flow. Frictional forces between the indicator
and the top wall and/or the support rod 74 retain the indicator
in position upon retraction of the piston. Spring means 88 encircling
portion 96 provides an expansion force between the hemispheric
end 98 top wall 40 and support rod to enhance the frictional contact
to insure that the indicator does not inadvertently change position.
The cover pieces 24 26 provide protection for the mouthpiece 14
of the device when not in use and, when pivoted to the position
as shown in FIG. 3 both expose the mouthpiece for use and serve
as an operating handle for the unit. As seen in FIGS. 1-3 first
cover piece 24 includes a bottom panel 100 surrounded by upstanding
end wall 102 and opposed side walls 104 106. A pair of arms 108
are formed as extensions to the side walls 104 106 each arm including
a generally semicircular shoulder portion 110 of reduced thickness
fully surrounding transverse bore 112 as detailed in FIGS. 9A and
9B. Posts 114 extend from the body side walls 36 38 and serve
as axles through the bores 112 allowing the handle unit to pivot
thereabout. The portion of the post 114 extending beyond the bore
may be widened or otherwise deformed to prevent removal of the handle.
The second cover piece 26 is of generally similar construction,
including top panel 100', end wall 102' and side walls 104', 106'.
Its arm portions 108' are each provided with a semicircular recess
116 on the inner face thereof to accept the semicircular shoulder
110 of the arm 108 and further includes semicircular transverse
bore 118 to accommodate the posts 114.
The semicircular shoulders 110 of the arms 108 may further include
a latch shoulder 120 which engages with a complimentary shoulder
122 formed into the surface of the semicircular recess 116 in the
arms 108', such that the cover elements may interengage and lock,
both in the closed position as shown in FIG. 1 as well as in the
open and operative position as shown in FIG. 3. The cover portions
24 26 may be formed from a unitary piece of material, typically
polypropylene, and are joined at the tops of their end walls 102
102' by integral self-hinge element 28. It is to be further appreciated
that the distance "d" between the ends 124 124' of the
bottom and top panels 100 100', respectively, and the center of
the transverse bores 112 118 in the respective arms 108 108' is
equal to the height above the bottom 42 of the body for the axis
of posts 114 such that in the open position, as shown in FIG. 3
the handle assumes the perpendicular position, whereby the body
10 is generally retained in position by the ends 124 124' of the
cover panels.
The peak flow meter is normally disposed in the closed condition
shown in FIG. 1 with the cover pieces 24 26 engaged with each
other about the mouthpiece of the unit. In such a condition, the
unit may be placed in the pocket, in a handbag or attache case,
or the like, with the mouthpiece being covered and protected from
inadvertent contact with surrounding objects. When it becomes necessary
to operate the device, the cover elements are separated and pivoted
about the body, re-engaging in the perpendicular position as shown
in FIG. 3. The piston is in the rest position as depicted in FIG.
4. The indicator is gently slid to the right such that the hemispheric
protrusion 98 is in gentle contact with the piston. The user then
places the mouthpiece in his or her mouth and exhales through the
unit in the manner taught by the prescribing professional. The expiratory
breadth enters the body of the unit, a substantial portion thereof
being diverted by the curved end portions 48 50 of the inner walls
44 and 46 to pass the piston through the lateral passageways 56
58. A portion of the air enters the central air passageway 54 where
it impinges against the piston plate 70 driving the piston plate
to the left as shown in phantom in FIG. 4 against the restoring
force of the spring 80. Slot 82 allows for dissipation of the breadth
portion impinging against the piston without substantial diminution
of the force generated thereby.
Maximum travel of the piston corresponds to the maximum flow rate
and resultant force. As the flow rate decreases and terminates,
the piston returns to the rest position. During piston travel, however,
the indicator 18 is driven to the left, remaining in the position
corresponding to the maximum flow rate. This maximum flow rate can
be read off the indicia 22 on the top surface of the unit, the flow
rate to be used for reporting or medication dispensation by the
patient as instructed. The indicator then may be reset to the rightmost
position, the handles being separated from the operative position
to be refolded about the mouthpiece of the unit to permit storage.
In general, for a central passageway of cross-sectional area of
1.125 inches.times.0.52 inches and having an entranceway of 0.375
inches by 0.52 inches, a spring formed of 0.008 inches diameter
type 302 stainless steel having a spring constant of 0.0134 lb./inch
has been found to allow measurement across the range of flow rates
typically experienced with a piston travel of about 3.8 inches.
It is to be recognized that modifications and adaptations of the
present invention as set forth herein are possible without departing
from the spirit or scope of the invention. |