U.S. patent number 3,596,515 [Application Number 04/685,928] was granted by the patent office on 1971-08-03 for drop flow sensor and resilient clamp therefor.
This patent grant is currently assigned to Ivac Corporation. Invention is credited to Richard A. Cramer.
United States Patent |
3,596,515 |
Cramer |
August 3, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
DROP FLOW SENSOR AND RESILIENT CLAMP THEREFOR
Abstract
Apparatus for monitoring drop flow in the drip chamber of an
intravenous set and including a sensor housing containing a
reference light source located a fixed distance from a photocell to
define a fixed optical sensing gap therebetween, with a reference
light beam normally impinging upon the photocell. The housing can
be selectively clamped upon the drip chamber with the drip chamber
positioned within the sensing gap to intercept the reference beam.
A falling drop of fluid within the drip chamber interrupts the
reference beam, and the variation in the electrical response of the
photocell is communicated to an indicator to indicate the presence
of a drop. A spring-biased sleeve clamps the housing onto any size
drip chamber without altering the size of the sensing gap. The
clamping sleeve is provided with rods which extend radially outward
from opposite sides of the sleeve and, in conjunction with one end
of the housing, define a syringe-type grip for positioning the
sleeve.
Inventors: |
Cramer; Richard A. (La Jolla,
CA) |
Assignee: |
Ivac Corporation (La Jolla,
CA)
|
Family
ID: |
24754241 |
Appl.
No.: |
04/685,928 |
Filed: |
November 27, 1967 |
Current U.S.
Class: |
73/861.41 |
Current CPC
Class: |
A61M
5/1689 (20130101); G01P 13/0086 (20130101); G06M
1/101 (20130101) |
Current International
Class: |
A61M
5/168 (20060101); G01P 13/00 (20060101); G06M
1/10 (20060101); G06M 1/00 (20060101); G01p
005/00 () |
Field of
Search: |
;73/194
;250/43.5,218,222 ;340/239 ;356/39,41 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gill; James J.
Claims
I claim:
1. A sensing device adapted to be mounted on the drip chamber of an
intravenous set, said sensing device comprising:
a generally oblong housing having a sensing gap therein, said gap
being adapted to receive said drip chamber;
a light source positioned in a first end of said housing, the light
from said light source being formed into a narrow reference beam
directed through said sensing gap and any drip chamber contained
therein;
photosensitive means positioned in a second end of said housing
said photosensitive means being in the path of said reference
beam;
a hollow conduit communicating with said first end and said second
end of said housing and establishing the spacing therebetween;
means within said conduit for electrically interconnecting said
light source and said photosensitive means;
clamping means for detachably clamping said device to said drip
chamber, said clamping means comprising a sleeve disposed around
one of said first and second ends of said housing in sliding
relationship therewith, said sleeve being resiliently urged across
said gap, and at least one grip rod extending from said sleeve,
said grip rod forming a syringe-type grip in conjunction with an
external face of said one of said first and second ends of said
housing; and
means for electrically connecting said photosensitive means to an
indicating means.
2. The sensing device of claim 1, wherein said photosensitive means
is spaced a fixed distance from said light source, said clamping
means serving to detachably clamp said device to said drip chamber
without altering the spacing between said light source and said
photosensitive means.
3. sensing apparatus for sensing drop flow in a fluid conduit,
comprising:
a light source;
photosensitive means;
housing means for supporting said light source and said
photosensitive means in fixed spatial relationship relative to each
other, whereby said light source and said photosensitive means are
spaced apart by a predetermined distance defining a sensing
gap;
means for defining a reference light beam from said light source,
said reference beam being directed across said sensing gap to
impinge upon said photosensitive means; and
resiliently urges clamping means adjacent said sensing gap for
retaining a fluid conduit within said gap in the path of said
reference beam, said clamping means including a spring biased
sleeve surrounding at least a part of said housing means, and at
least one grip rod extending from said sleeve to define a syringe
like grip with one end of said housing means, said clamping means
enabling retention of different size conduits within said sensing
gap without altering the size of said gap.
4. Sensing apparatus as set forth in claim 3, and further including
means cooperatively associated with said light source and said
clamping means for positioning a conduit closer to said light
source than to said photosensitive means. pg,16
5. Sensing apparatus as set forth in claim 3, said housing means
including:
a first substantially tubular housing for said light source;
and
a second substantially tubular housing for said photosensitive
means.
6. Sensing apparatus as set forth in claim 5, wherein said spring
biased sleeve surrounds and is concentric with at least one of said
substantially tubular housings.
7. Sensing apparatus as set forth in claim 6, wherein said sleeve
surrounds only said second housing.
8. Sensing apparatus as set forth in claim 6, wherein said means
for defining said reference beam includes means for defining at
least one columnating aperture within at least one of said
housings.
9. Sensing apparatus as set forth in claim 6, including a pair of
grip rods extending outwardly from said sleeve on opposite sides
thereof to define a syringe-type grip with one end of said
housings.
10. Sensing apparatus as in claim 3, wherein said clamping means
includes coil spring means within said housing for urging said
sleeve across said sensing gap.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to drop flow sensing
devices and, more particularly, to a new and improved device for
sensing the presence of a drop of fluid in the drip chamber of an
intravenous set or the like used in medical applications.
The usual medical procedure for the gradual intravenous
introduction of fluids into the human body, such as liquid
nutrients, blood or plasma makes use of apparatus which is commonly
referred to in the medical arts as an intravenous set. The
intravenous set comprises a bottle of fluid, normally supported in
an inverted position, and a valve mechanism which allows the fluid
to drip out of the bottle at a controlled rate into a drip chamber
below the bottle. The drip chamber serves the dual function of
allowing a nurse or other attendant to observe the rate at which
the fluid drips out of the bottle and also creates a reservoir for
the fluid at the lower end of the chamber to insure that no air
enters the main feeding tube leading to the patient.
While observation of the rate of drop flow via the drip chamber is
a simple and effective way of controlling the amount of fluid fed
to a patient over a period of time, its ultimate effectiveness
requires that a relatively constant vigil be maintained on the drop
flow, lest it cease due to exhaustion of the fluid supply or become
a continuous stream and perhaps increase the rate of fluid
introduction to the patient to a dangerous level.
In recent years, electronic monitoring systems have been developed
to automatically sense and indicate drop rate, either at the
feeding site or at a remote location. Such electronic devices can
also activate an aural or visual alarm when a potentially dangerous
condition exists, thus freeing medical personnel for other duties.
While such electronic drop rate monitoring systems have generally
served their purpose, they have not proven entirely satisfactory
from the standpoint of compactness, ease of installation and
removal, and consistency of sensing calibration for different sizes
of drip chambers. The present invention obviates these
difficulties.
SUMMARY OF THE INVENTION
Briefly, and in general terms, the present invention is directed to
improvements in sensing devices for detecting the presence of a
falling drop at a specified location in a drop flow system, such as
an intravenous set or the like.
In a presently preferred embodiment of the sensing device of the
present invention, a relatively narrow reference beam of light
enters one side of a drip chamber or the like and strikes a
photocell located on the opposite side of the chamber A drop of
fluid falling through the drip chamber interrupts the reference
beam, and the resultant change in the electrical response of the
photocell indicates the presence of the drop.
The light source and photocell may be mounted in two respective,
axially aligned sections of a substantially tubular housing. A
sensing gap between the two sections is externally bridges by a
fixed member. The light source and photocell are thus maintained at
a constant distance from each other. Clamping means are provided
for mounting the sensing device without altering the distance
between the light source and photocell, thus resulting in a uniform
response characteristic for different sizes of the drip
chamber.
In the preferred embodiment of the invention the clamping means may
comprise a concentric sleeve surrounding one of the housing
sections and spring-biased to move across the sensing gap so that
the sensing device can be mounted on a drip chamber with the
chamber clamped between one of the housing sections and the
sleeve.
The spatial relationship between the light source, drip chamber and
photocell is such that the light source is closest to the drip
chamber, so that a falling drop interrupts a relatively large part
of the reference light beam.
The clamping sleeve may be provided with rodlike extensions on
opposite sides of the sleeve so that the overall structure
resembles the conventional syringe familiar to most hospital
personnel. Such personnel can thus grip the sensing device
naturally for attachment to or detachment from a drip chamber.
The present invention therefore provides a sensing device which is
structurally compact, provides uniform response for any size drip
chamber, can be quickly and easily installed or removed, and is
naturally handled with confidence and ease by hospital
personnel.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a presently preferred embodiment of
a sensing device, in accordance with the present invention, the
sensing device being shown installed on a conventional intravenous
set and electrically connected to an appropriate electronic
indicator;
FIG. 2 is an enlarged, end elevational view taken in the direction
of the arrow 2 in FIG. 1;
FIG. 3 is an enlarged sectional view, taken along the line 3-3 in
FIG. 1;
FIG. 4 is a sectional view, taken along the line 4-4 in FIG. 3;
and
FIG. 5 is a combined block diagram and electrical schematic of a
complete drop flow monitoring system utilizing the sensing device
of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawing, and particularly to FIG. 1 thereof, a
presently preferred embodiment of a sensor 10, constructed
according to the present invention, is shown clamped onto a drip
chamber 12 of an intravenous set 14. In operation, a bottle 15 of
the intravenous set 14 is suspended from a hook 16 extended from a
vertical pole 18. An electronic indicator 20 is shown in FIG. 1
mounted upon the pole 18, and an electric cable 22 connects the
indicator to the sensor 10.
While the sensor 10 is illustrated and described in connection with
its application in a monitoring system for intravenous feeding, it
is to be understood that this is only by way of example, and the
sensor 10 may be utilized in any drop flow sensing application
without departing from the spirit and scope of the present
invention.
As best observed in FIGS. 3 and 4, the sensor 10 generally
comprises a tubular housing 24 constructed with a centrally located
sensing gap 26 between a combined lamphouse and clamping section 28
and a coaxial transducer section 30. The two sections 28, 30 are
supported in fixed spatial relationship by an external bridge
member 32. The sensor 10 is adapted to be detachably secured to the
drip chamber 12 by frictional engagement between the clamping
section 28 and a spring-biased concentric sleeve 34 slidably
mounted on the transducer section 30. The internal end of the
clamping section 28 is provided with a substantially V-shaped notch
31 defining a clamping jaw for firmly engaging the chamber 12.
A reference beam of light from a light source 36 in the section 28
projects through the drip chamber 12 onto a photocell 38 in the
transducer section 30 of the housing 24. The reference light beam
is interrupted whenever a fluid drop 40 falls through the drip
chamber 12, and this interruption is electrically communicated to
the indicator 20 via the cable 22.
A pair of finger grip rods 42 extend radially outward from opposite
sides of the sleeve 34 and, in conjunction with the outer sealed
end 44 of the transducer section 30 of the housing 24, forms a
syringe-type grip for selectively retracting the sleeve to enable
mounting or removal of the sensor 10 with respect to the drip
chamber 12.
The housing 24 of the sensor 10 is preferably formed of molded
plastic or the like An integrally formed end wall 46 seals the
external end of the clamping section 28. As best observed in FIG.
3, the bridge member 32 of the housing 24 is hollow to accommodate
a pair of electrical conductors 50 for connection to the photocell
38.
The the cavity source 36 is in a central cavity 56 provided in a
mounting block 58 positioned just behind the notch 31 in the
clamping section 28. A relatively small columnating aperture 60
extends from the cavity 56 through the block 58 and defines a
relatively narrow reference light beam. The spatial relationship
between the aperture 60, the mounting block 58 and the notch 31 is
such that the reference light beam passes approximately through the
center of the drip chamber 12 when it is positioned in the
notch.
The photocell 38, preferably of the germanium-type, is mounted in a
close-fitting cavity 62 provided in a mounting block 64 which is
positioned at the internal end of the transducer section 30 of the
housing 24. A columnating aperture 66 extends from the cavity 62 to
the outermost face of the mounting block 64. The light source 36,
columnating apertures 60, 66, and the photocell 38 are coaxially
aligned to define an optical axis for the sensing system, and to
minimize off axis photocell response to stray light.
When the sensor 10 is mounted on the drip chamber 12, the sleeve 34
is urged toward the drip chamber 12 by means of a compressed coil
spring 68 in the transducer section 30 of the housing 24. The
sleeve 34 is concentric with and slidable along the transducer
section 30 of the housing 24, with clearance for the bridge member
32 being provided by means of a slot 67 in the sleeve.
One end of the spring 68 abuts a pin 70 which passes through the
section 30 and sleeve 34 and is affixed to the sleeve. The pin 70
travels in a pair of aligned slots 72 in opposite sides of the
transducer section 30 (see FIGS. 3 and 4). The finger grip rods 42
are mounted on the outer ends of the pin 70 projecting beyond the
external surface of the sleeve 34. The end of the spring 68
opposite that in abutment with the pin 70 abuts an end cap 74 which
snaps over the open end 48 of the transducer section 30.
The capped end 44 of the transducer section 30 of housing 24 and
the finger grip rods 42 form a syringe-type grip familiar to most
hospital personnel. The sensor 10 is mounted upon the drip chamber
12 by retracting the spring-biased sleeve 34, positioning the drip
chamber in the sensing gap 26, and then releasing the sleeve 34 to
engage the chamber.
The light source 36 and photocell 38 are electrically connected to
the indicator 20 by means of cable 22 which enters the clamping
section 28 of the housing 24. One conductor 76 is connected to one
terminal of the light source 36 and a second conductor 78 is
connected to the other terminal of the light source. The second
conductor 78 is common to both the light source circuit and the
photocell circuit and is also connected by means of one of the
conductors 50 to one terminal of the photocell 38. The third
conductor 80 in the cable is connected to the other conductor of
the conductor pair 50 and is thereby electrically connected to the
second terminal of the photocell 38.
The manner in which the light source 36 and photocell 38 are
connected to a power source 82 and monitor 84, respectively, in the
indicator 20 is illustrated schematically in FIG. 5.
The sensing device of the present invention satisfies a long
existing need in the art for a compact, reliable, versatile, and
easily utilized drop flow sensor.
It will be understood that, while a particular form of the
invention has been illustrated and described, various modifications
of design and construction can be made without departing from the
spirit and scope of the invention Hence, the invention is not to be
limited except as defined by the appended claims.
* * * * *