WO2011024182A1

WO2011024182A1 - A drop indicator

Info

Publication number: WO2011024182A1
Application number: PCT/IL2010/000719
Authority: WO
Inventors: Itay Rozenman
Original assignee: Itay Rozenman
Priority date: 2009-08-31
Filing date: 2010-08-31
Publication date: 2011-03-03
Also published as: IL200650A0

Abstract

A drop indicator for use with a drip chamber, the drop indicator including a circuit, a switching element coupled to the circuit, wherein passage of a drop through the switching element causes the switching element to switch the circuit, an indicator coupled to the circuit for providing an indication upon switching of the switching element, and a power source coupled to the circuit for energizing the indicator, wherein the circuit, the switching element, the indicator and the power source are mounted as part of the drip chamber.

Description

A DROP INDICATOR

FIELD OF THE INVENTION

The present invention relates to a drop indicator, in general and, in particular, to a drop indicator for a drip chamber in an infusion set.

BACKGROUND OF THE INVENTION

Intravenous infusion sets include an infusion fluid bag for holding the fluids to be administrated, a drip chamber having a drop former for forming drops, means for administering the fluids into the patient's body and means for connecting the drip chamber to the fluid inside the fluid bag. Drip chambers are well known in the art and are designed to convert the flow of administered fluids into drops. The drops permit a nurse or a medical attendant or the patient to observe the flow and the flow rate, thus visually verifying the proper function of the infusion set. A conventional drip chamber typically includes a cylindrical tube having a narrow inlet, which forms drops by interrupting the steady flow of fluid from the infusion bag.

One example of a drip chamber is disclosed in US Patent 4,013,072 to Jess describing a drip chamber for use in an intravenous liquid infusion set. The drip chamber is a generally vertically disposed hollow chamber provided with inlet means and outlet means, with the chamber being adapted to maintain a liquid level of the intravenous liquid to be administered. In the drip chamber disclosed by Jess, observing the drops dripping into the drip chamber is dependent solely on the eyes of the nurse. However, these drops falling into the drip chamber cannot be seen from a distance by the eye and certainly cannot be seen in the dark. In addition, recognizing colorless drops dripping inside the drip chamber is often difficult for untrained observers.

US Patent 3,890,968 to Pierce discloses a flow controller that repeatedly opens and closes a magnetic check valve for periods of time which determine the flow rate through the valve. The parenteral fluid controller has a drip chamber for collecting drops of fluid falling from a reservoir. A drop detector is provided for producing a signal each time a drop is formed. The latter signal controls the opening and closing i of the valve and thus controls the flow of the parenteral fluid. Pierce further discloses a lamp on an adjacent control box which lights each time a drop is detected, thus indicating the flow rate. However, the drop detector disclosed by Pierce is formed as part of a flow control apparatus which requires sophisticated components, and thus requires a pricy production line.

Additionally, known drop detectors require a specially designed infusion set, which cannot replace or be integrated with a standard infusion set. Furthermore, operating these drop detectors requires special skills, since they form an integral part of complex medical apparatus.

Accordingly, there is a long felt need for a simple device which can be simply and easily incorporated into conventional infusion sets for detecting the drops as they fall into the drip chamber and providing an indication, so as to permit observation and monitoring of the dripping from a distance, and it would be very desirable to have such a device which is easy and simple to couple to a drip chamber.

SUMMARY OF THE INVENTION

There is provided according to the present invention a drop indicator for use with a drip chamber. The drop indicator includes a circuit and a switching element coupled to the circuit, wherein passage of a drop through the switching element causes it to switch the circuit. The drop indicator further includes an indicator coupled to the circuit for providing an indication upon switching of the switching element, and a power source coupled to the circuit for energizing the indicator. The circuit, switching element, indicator and power source are mounted as part of the drip chamber.

According to a preferred embodiment of the invention, the drop indicator includes a housing mounted as part of the drip chamber, and the switching element, indicator and power source are mounted in the housing. According to another preferred embodiment of the invention, the housing is sized and configured to seat inside the drip chamber and float on fluid in the drip chamber.

According to another embodiment of the invention, the housing is further adapted and configured to selectively seal the bottom end of the drip chamber.

According to a preferred embodiment of the invention, the switching element, indicator, and power source are affixed to a cover of the drip chamber.

According to another embodiment of the invention, the indicator is a visible indicator or an audible indicator.

According to another embodiment of the invention, the said switching element includes a pair of electrodes mounted as part of the drip chamber to be contacted simultaneous by said drop.

According to another embodiment of the invention, the electrodes are selectably positioned at a distance from the top end of the drip chamber, for determining the duration of said indication.

According to yet another embodiment of the invention, the switching element includes a photodetector and a light source held in registration with the photodetector, wherein the photodetector is adapted and configured to switch the circuit upon passage of a drop through the drip chamber.

According to another embodiment of the invention, the switching element includes a pair of contacts arranged to contact one another when a drop hits one of the pair of contacts.

According to yet another embodiment of the invention, the switching element includes a barrier adapted and configured to pivot downwardly by the weight of a falling drop, causing the switching element to switch the circuit.

According to another embodiment of the invention, the drop indicator further includes a transmitter coupled to the circuit for sending a wireless signal upon switching of the circuit, and a remote indicator adapted and configured to provide an indication in response to the wireless signal. According to another embodiment of the invention, the switching element and power source are mounted as part of the drip chamber and the indicator is positioned where the indicator can be observed from a distance.

There is provided according to the present invention a method for forming a drop indicator for use with a drip chamber, the method including the steps of providing a circuit, coupling a switching element to the circuit, wherein passage of a drop through the switching element causes the switching element to switch the circuit, coupling an indicator to the circuit for providing an indication upon switching of the switching element, coupling a power source to the circuit for energizing the indicator, and mounting the circuit, the switching element, the indicator and the power source as part of the drip chamber.

According to another embodiment of the invention, the switching element, the indicator and the power source is mounted as part of the drip chamber, and the indicator is positioned where it can be observed from a distance.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further understood and appreciated from the following detailed description taken in conjunction with the drawings in which:

Figure Ia is a schematic illustration of a drip chamber having a drop detector constructed and operative in accordance with one embodiment of the present invention;

Figure Ib is a schematic illustration a portion of the electrode arrangement of the drop indicator of Figure Ia;

Figure 2a is a schematic illustration of a drop indicator having a spherically shaped housing, according to one embodiment of the invention;

Figure 2b is a schematic illustration of the drop indicator of Figure 2a having a spherically-cylindrically shaped housing, according to another embodiment of the invention; Figure 3 is a schematic illustration of an arrangement of electrodes according to one embodiment of the invention;

Figure 4 is a schematic illustration of a drip chamber having a drop indicator constructed and operative in accordance with another embodiment of the present invention;

Figure 5a is a schematic illustration of an arrangement of electrodes according to another embodiment of the invention;

Figure 5b is an exploded illustration of the arrangement of electrodes of Figure 5a;

Figure 6a is a schematic illustration of a drip chamber, constructed and operative in accordance with another embodiment of the present invention, having a drop indicator in an activated state;

Figure 6b is a schematic illustration of the drip chamber of Figure 6a with the drop indicator in a deactivated state;

Figure 7a is a schematic illustration of a drip chamber having a drop indicator constructed and operative in accordance with another embodiment of the present invention;

Figure 7b is an exploded view of the drop indicator of the drip chamber of Figure 7a;

Figure 8a is a side schematic illustration of a drip chamber having a drop indicator in an electrically coupled state, constructed and operative in accordance with another embodiment of the present invention;

Figure 8b is a side schematic illustration of the drip chamber of Figure 8a having the drop indicator in an electrically decoupled state;

Figure 9a is a side schematic illustration of a drip chamber having a drop indicator in an electrically decoupled state, constructed and operative in accordance with another embodiment of the present invention;

Figure 9b is a side schematic illustration of the drip chamber of Figure 9a with the drop indicator in an electrically coupled state; Figure 10a is a side schematic illustration of a drop indicator in an electrically decoupled state, constructed to be disposed inside a drip chamber in accordance with another embodiment of the present invention;

Figure 10b is a side schematic illustration of the drip chamber of Figure 10a with the drop indicator in an electrically coupled state;

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a drop indicator for use with a drip chamber of an infusion set. The drop indicator detects the drops in the drip chamber and provides a visible or audible indication of the dripping and its rate, which can be used to determine the functioning of the infusion set from a distance, as well as from near by. The drop indicator includes a switching element, an indicator and a power source coupled to an electric circuit. The switching element can include a pair of electrodes disposed such that a passage of a drop through the drip chamber contacts simultaneously both electrodes thus switching the circuit and providing an indication of the passage of the drop. The power source energizes the switching element and the indicator. Preferably, all of these elements are mounted, on or in or part on and part in, the drip chamber as a as a part thereof. According to another preferred embodiment of the invention, the switching element, the indicator and the power source are all integrally formed with a housing. The indicator provides an indication upon detection of passage of a drop by the switching element. According to one embodiment, the drop indicator includes a spherocylindrical housing, which is disposed inside the drip chamber for detecting and indicating each drop passing through the drip chamber. According to this embodiment, the drop indicator floats on the fluid present in the drip chamber during operation. Thus, it may serve also as a fluid level indicator. When the fluid is drained out of the drip chamber, the drop indicator can serve as a seal of the bottom end of the drip chamber for blocking air from entering through the infusion set into the patient's vascular system. According to another embodiment, the housing of the drop indicator is formed as a releasably detachable clip mounted on a drip chamber or an infusion set tube. According to one embodiment, a blinking indicator indicates the proper functioning of the drip chamber, while a non-blinking, continuous indication, either on or off, indicates faulty functioning.

Figure Ia is a schematic front view of a drip chamber 10 having a drop indicator constructed and operative in accordance with one embodiment of the present invention. Drip chamber 10 includes a cylindrical side wall 12 and a top cover 14 having an inlet aperture 16. An inlet tube 18 is disposed in inlet aperture 16, and includes an inlet stem 19 protruding into the chamber 13 formed by wall 12. Inlet stem 19 has a conical tapered shape, causing the formation of drops. Inlet tube 18 further includes an infusion spike 17, protruding outside chamber 13, for penetrating an infusion bag. Drip chamber 10 further includes a bottom cover 20 having an outlet aperture 22, and an outlet tube 24 disposed therein, as known.

Drip chamber 10 further includes a drop indicator 30, for providing an enhanced visual indication of drops dripping through chamber 13. Drop indicator 30 includes a visual indicator 32, here illustrated as an LED lamp, and two electrodes 36a and 36b disposed adjacent one another and insulated from one another (not shown), and arranged to sense the passage of a drop. It will be appreciated that the visual indicator may be positioned in the vicinity of the drip chamber or the fluid bag or in any place in the room or the room entrance or outside the patient's room in a prominent, noticeable place that is readily visible from a distance by the medical staff. Each of electrodes 36a and 36b further includes a plurality of contacts 33a and 33b, respectively, disposed adjacent one another and insulated from one another, as is more clearly illustrated in Figure Ib. Visual indicator 32 and electrodes 36a and 36b are electrically coupled to an electrical power source 34, such as a battery. Electrodes 36a and 36b are configured to allow each drop falling from inlet stem 19 to simultaneously contact at least one of contacts 33a and at least one of contacts 33b so as to close an electric circuit and cause a flow of current through visual indicator 32. According to this embodiment, visual indicator 32 and power source 34 are disposed inside a housing 35 having a sealed bottom and configured to float on fluid accumulating on the bottom of drip chamber 10. Visual indicator 32 and power source 34 are encased inside housing 35 and are isolated from the drops and fluids in drip chamber 10. Electrodes 36a and 36b, on the other hand, are mounted on the outside of housing 35, so as to be contacted by each drop dripping into chamber 13. It will be appreciated that housing 35 and electrodes 36a and 36b are formed of a neutral, biocompatible material that will not affect or be affected by the fluid dripping through the drip chamber. It will further be appreciated that housing 35 is configured to retain electrodes 36a and 36b in an upward position, in order to ensure that contact between the two electrodes is made only by the falling drops, and not by the fluid accumulating at the bottom of drip chamber 10. In order to maintain electrodes 36a and 36b above the liquid level in the drip chamber, they can be mounted, for example, on top of housing 35. Preferably, power source 34 is mounted on the bottom portion of housing 35, so as to lower the center of gravity of the housing and, thus, prevent it from turning upside down.

Housing 35 is, preferably, a spherical body having a diameter slightly smaller than the inner diameter of chamber 13. This arrangement permits the housing to float on the liquid collecting in the drip chamber and to slide up and down according to the change of level of the liquid in the drip chamber, while permitting the drops falling into the drip chamber to pass around the housing and reach the bottom of the drip chamber. It will be appreciated that housing 35 can be filled with a transparent or translucent insulating filling material, for example, silicone, to insulate the electric components and conductors from each other and to hermetically seal the housing. Alternately, housing 35 can free of air or be filled with any transparent gas.

Alternatively, housing 35 may be a cylindrical body, have a disc like shape, or be a spherocylindrical body.

Figure 2a is a side sectional view of a drop indicator 40 constructed and operative in accordance with one embodiment of the present invention. Drop indicator 40 includes a transparent or translucent housing 50, preferably having a spherical shape. A voltage/current source 44 having two terminals 45a and 45b and an LED indicator 46 having a cathode 48a and an anode 48b are mounted in housing 50. Mounted on the outer shell of housing 50 are two separate electrodes 42a and 42b. Electrode 42a includes at least one contact and preferably a plurality of contacts 43a, and electrode 42b includes at least one contact and preferably a plurality of contacts 43b. Contacts 43a and 43b are mounted in proximity to each other so that when a drop passes therebetween, it electrically couples or shortcircuits electrodes 42a and 42b. The arrangement of the electrodes and contacts is similar to the arrangement described above with reference to Figures Ia and Ib.

Terminal 45a of power source 44 is electrically coupled by a conductor 47 to electrode 42a, anode 48b of LED indicator 46 is electrically coupled to electrode 42b, and cathode 48a of LED indicator 46 is electrically coupled to terminal 45b of power source 44. When a drop of liquid falls on the arrangement of electrodes 42a and 42b, at least one of contacts 43a and at least one of contacts 43b are electrically coupled to close an electric circuit in which current flows through terminal 45a of power source 44, conductor 47, electrode 42a, contact 43a, contact 43b, electrode 42b, anode 48b and cathode 48a of LED indicator 46, and terminal 45b, thus activating LED indicator 46. As the liquid drop gravitates through the arrangement of electrodes 42a and 42b, the electrical coupling between contacts 43a and 43b is broken. As a result, current ceases to flow through the above described electric circuit, thus LED indicator 46 is deactivated. Accordingly, drop indicator 40 provides a visual signal as long as a drop maintains an electric contact between contacts 43a and 43b, thus indicating the falling of a drop into the drip chamber.

It will be appreciated by those skilled in the art, that the visible indication of LED indicator 46, of the drops falling into the drip chamber, can be configured to be brighter, dimmer, longer, shorter etc., as desired, through various electrical circuitry designs of electrical components, as known in the art. It will be further appreciated that LED indicator 46 can be replaced by or added to various audible indicators, such as an alarm or a speaker, which can provide a desired sound whenever a drop electrically engages contacts 43a and 43b simultaneously. According to the present invention, the visible indication of the liquid flow in an infusion set, which is provided by the drip chamber in the form of drops, is boosted by the drop indicator of the invention, thus permitting a medical attendant or a patient to observe from a distance the liquid flow and its rate.

Figure 2b is a side sectional view of a drop indicator 60 constructed and operative in accordance with a preferred embodiment of the present invention. Drop indicator 60 includes a housing 62 of a spherical-cylindrical shape having a cylindrical portion 64, a hemispherical top portion 66, and a hemispherical bottom portion 68. The diameter of cylindrical portion 64 is preferably slightly smaller than the inner diameter of the drip chamber, allowing drop indicator 60 to slide up and down in the drip chamber. As the liquid level in the drip chamber rises, drop indicator 60, which floats on the liquid, slides upwardly, and when the liquid level drops, drop indicator 60 slides downwardly. This way, a medical attendant, or other person observing the drip chamber, receives an indication of the liquid level in the drip chamber. The cylindrical shape of a portion of housing 62 precludes drop indicator 60 from rotating about its horizontal axis, and thus ensures proper functioning of drop indicator 60.

Hemispherical portion 66, according to this embodiment, includes an array arrangement of electrical contacts 74 and 76 disposed in alternating rows about the hemispherical top portion 66. Rows of contacts 74 and rows of contacts76 are disposed in proximity to each other yet are electrically insulated from each other, so that when a drop falls on hemispherical top portion 66, it electrically couples or short circuits at least one contact 74 and at least one contact 76. It will be appreciated that contacts 74 and 76 can be disposed on hemispherical top portion 66 in various arrangements, provided that they are insulated from each other, but in such proximity that permits a single drop to short circuit them. The hemispherical shape of portion 66 also facilitates the trickling of the drop around drop indicator 60 to the bottom of the drip chamber.

According to other embodiments, hemispherical portion 66 may be replaced with a flat top, or a cone shape top.

Hemispherical bottom portion 68 is adapted and configured to seal the bottom outlet aperture of the drip chamber and prevent air from entering the patient's vascular system when the liquid in the infusion container is drained. It will be appreciated that hemispherical top portion 66 and preferably the entire housing 62 can be formed of hydrophobic material, urging the liquid drop to gravitate to the bottom of the drip chamber.

Figure 3 is a top view illustration of an electrode arrangement 90 for mounting on a drop indicator, constructed and operative in accordance with another embodiment of the present invention. Electrode arrangement 90 includes a top contact wire 92 and a bottom contact wire 94. Both contact wires are shaped in a winding pattern and are disposed horizontally in parallel to each other, whereas their windings, which are arranged in perpendicular to each other, form a mesh pattern. Contact wires 92 and 94 are further arranged one over the other at a distance which is sufficient to insulate electrically contact wire 92 from contact wire 94, yet permit a drop falling through the mesh to simultaneously engage the top and bottom contact wires, thereby coupling them electrically. According to one embodiment of the invention, electrode arrangement 90 is adapted and configured to be mounted on top of the drop indicator.

According to other embodiments of the invention, each contact of one electrode may be substantially surrounded by but isolated from the contacts of the second electrode, so as to facilitate closure of an electric circuit by each drop.

Figure 4 is a side schematic illustration of a drip chamber having a drop indicator constructed and operative in accordance with another embodiment of the present invention. Drip chamber 100 is substantially the same as drip chamber 10 of Figure 1, and includes a cylindrical side wall 102, a sealed top end 104 having an inlet aperture 106, and a sealed bottom end 110 having an outlet aperture 112. The drop indicator according to this embodiment includes an electrode arrangement 114 disposed inside drip chamber 100. A visual indicator and a power source (not shown) can be mounted inside or outside drip chamber 100. Electrodes arrangement 114 includes a top contacts grid 116a and a bottom contacts grid 116b, each having a plurality of parallel bars 118a and 118b, respectively. Parallel bars 118a define spaces 119a and parallel bars 118b define spaces 119b between each pair of bars. Contacts grids 116a and 116b are disposed horizontally and in parallel to one another. Contacts grid 116b is disposed below contacts grid 116a thus defining a gap 108 therebetween. Gap 108 is sized to keep contacts grid 116a and 116b electrically isolated from one another, yet it is smaller than the length of a drop passing through this electrodes arrangement so as to ensure that such a drop simultaneously contacts top contacts grid 116a and bottom contacts grid 116b. Preferably, parallel bars 118a of contacts grid 116a are disposed horizontally and perpendicular to parallel bars 118b of contacts grid 116b. The visual indicator (not shown) and the power source (not shown) according to this embodiment may be disposed outside drip chamber 100, and the indicator and power source may be electrically coupled to electrodes arrangement 114 by means of conductors 115 extending through cylindrical side wall 102. Alternatively, a visual indicator and a power source may be disposed inside drip chamber 100. A drop falling into drip chamber 100 passes through top contacts grid 116a and gap 108 and simultaneously contacts at least one bar of parallel bars 118a and at least one bar of parallel bars 118b, thereby electrically coupling top and bottom contacts grid 116a and 116b. As a result, an electric current flows between the power source and the visual indicator activating it. As the drop falls down towards the bottom of drip chamber 100, no longer contacting grids 116a and 116b, top and bottom contacts grid 116a and 116b are electrically decoupled, thus deactivating the visual indicator. Spaces 119a are sized to be smaller than the diameter of a falling drop, so as to ensure that a drop falling on contacts grid 116a contacts at least one bar of parallel bars 118a. The same holds true for spaces 119b and parallel bars 118b defined by contacts grid 116b.

It will be appreciated that, through sizing of gap 108, the duration of the indication by the drop indicator can be selected. For example, when gap 108 is small, such that the distance between bars 118a and 118b is small, a drop falling through contacts grids 116a and 116b will create an electric contact for a relatively long period, whereas when gap 108 is large, the electric contact will be momentary. It will be appreciated that the distance of positioning of electrodes arrangement 114 from the top end of the drip chamber along the length of cylindrical side wall 102 will also determined the duration of the indication by the drop indicator. For example, when electrodes arrangement 114 is disposed near the top end 104 of drip chamber 100, the velocity of the drop falling on the electrodes is lower and, thus, the duration of the indication is longer. Whereas, when electrodes arrangement 114 is disposed near the bottom end 110 of drip chamber 100, the velocity of the drop is higher, and thus, the duration of the indication is shorter.

Figures 5a and 5b are a top view and an exploded top view, respectively, of an electrodes arrangement 120, according to another embodiment of the present invention. Electrodes arrangement 120 includes a first contact comb 122a, having a plurality of protruding parallel bars 124a, defining a plurality of gaps 126a therebetween, and a second contact comb 122b, having a plurality of protruding parallel bars 124b, defining a plurality of gaps 126b therebetween. Contact combs 122a and 122b are configured to interleave when they are assembled to form electrodes arrangement 120, whereby each one of bars 124a is disposed in a corresponding gap of gaps 126b and each one of bars 124b is disposed in a corresponding gap of gaps 126a. First contact comb 122a further includes a conductor 128a, which can be electrically coupled, for example, to a visual indicator, and second contact comb 122b includes a conductor 128b, which can be electrically coupled, for example, to a power source. According to one embodiment of the present invention, electrodes arrangement 120 is mounted substantially in a horizontal position on the drop indicator disposed in a drip chamber, allowing a drop which falls vertically into the drip chamber to create an electric contact between the first and second contact combs 122a and 122b simultaneously. It will be appreciated that gaps 126a and 126b are sized to enable a drop falling therethrough to make contact with at least one of protruding bars 124a and at least one of protruding bars 124b, simultaneously. When a drop touches and thereby electrically couples two contact combs 122a and 122b, electric current flows in the electric circuit of the power source and the drop indicator.

Figure 6a is a side schematic illustration of a drip chamber having a drop indicator constructed and operative in accordance with another embodiment of the present invention. Drip chamber 160 is substantially the same as drip chamber 10 of Figure 1, and includes a cylindrical side wall 162, a closed top end 164 having an inlet aperture 166, and a closed bottom end 170 having an outlet aperture 172. An inlet tube 168 including an inlet stem 169 is inserted into drip chamber 160 through inlet aperture 166. Inlet stem 169 has a conical tapered shape, causing the formation of a drop. Inlet tube 168 further includes an infusion spike 167, for penetrating an infusion bag.

According to this embodiment, drip chamber 160 further includes an internal electrode 174 mounted inside drip chamber 160 directly below inlet stem 169. The distance between inlet stem 169 and internal electrode 174 is arranged to be smaller then the length of a drop falling into drip chamber 160. Internal electrode 174 extends outside drip chamber 160 through a sealing ring 180 mounted in an aperture in closed top end 164. Drip chamber 160 further includes an external electrode 176 sealingly inserted into infusion spike 167. Drip chamber 160 further includes a visual indicator 178, here illustrated as an LED having an anode 178a and a cathode 178b. In addition, drip chamber 160 includes a power source 188, and having a first terminal 189a and a second terminal 189b. Visual indicator 178, and power source 188 according to one embodiment are affixed to top end 164. Alternatively, visual indicator 178 and a power source 188 may be hermetically disposed inside drip chamber 160.

According to one embodiment, internal electrode 174 is electrically coupled to terminal 189a of power source 188, and external electrode 176 is electrically coupled to anode 178a of visual indicator 178. In addition, cathode 178b of visual indicator 178 is electrically coupled to terminal 189b of power source 188.

Fluid from an infusion bag (not shown) flows through inlet tube 168 into inlet stem 169 where a drop is formed. A drop 175 emerging from inlet stem 169 falls on internal electrode 174 disposed directly below. Since the distance between inlet stem 169 and internal electrode 174 is smaller than the length of drop 175, an electric contact is created by the drop between the fluid inside inlet stem 169 and the internal electrode 174. The fluid inside inlet stem 169 and inlet tube 168 electrically couple internal electrode 174 and external electrode 176. Thus, an electric current can flow in the circuit formed by terminals 189a and 189b of power source 199, anode 178a of visual indicator 178, external electrode 176, the liquid in inlet tube 168, stem 169 and the drop, and internal electrode 174, resulting in the activation of visual indicator 178. As illustrated in Figure 6a, when drop 175 gravitates inside drip chamber 160, the electric contact between drop 95 and the liquid in inlet stem 169 is broken. As a result, internal electrode 174 is electrically decoupled from power source 188 and current flow ceases, thus visual indicator 178 is deactivated.

According to one embodiment of the present invention, internal electrode 174, which extends through top end 164, includes an adjusting handle 185. Adjusting handle 185, permits a user to move internal electrode 174 up and down inside drip chamber 160 to a desired distance from inlet stem 169. Positioning internal electrode 174 at a short distance from inlet stem 169 will permit drop 175 to contact internal and external electrodes 174 and 176 for a longer period of time, and thus, to create a longer indication. Positioning internal electrode 174 at a longer distance from inlet stem 169 results in drop 175 maintaining the contact for a shorter period of time, and thus, a shorter indication is generated.

According to yet another embodiment of the present invention, the electrodes can be replaced with a microphone which is adapted to detect the sound generated by a drop falling on top of a drop indicator disposed inside the drip chamber, or alternatively a drop falling to the bottom of the drip chamber. The microphone may be coupled to a speaker or any other known sound generating device which generates a sound indicating the fall of the drop inside the drip chamber. Both microphone and speaker are coupled to a power source as known, and all are mounted in the drop indicator. Alternatively, the microphone may generate an electric signal which, in turn, may activate a visual indictor.

Figure 7a is a side schematic illustration of a drip chamber having a drop indicator constructed and operative in accordance with another embodiment of the present invention. Drip chamber 210 is substantially the same as drip chamber 10 of Figure 1, and includes a cylindrical side wall 212 a top end closure 214 having an inlet aperture 216, and a bottom end closure 220 having an outlet aperture 222. A drop indicator 224 is mounted on the outside of cylindrical side wall 212. Drop indicator 224 includes a clamping arrangement 230, having first and second arms 232a and 232b adapted to clamp a drop indicator onto drip chamber 210. As illustrated in Figure 7b, arm 232a holds a light source 226, preferably, an LED emitting light in the IR spectrum, and arm 232b holds a photodetector 228, adapted to detect the light emitted from light source 226. According to one embodiment, photo detector 228 is a photodiode adapted to create an electric signal as result of light absorption, preferably, in the IR spectrum. When clamping arrangement 230 is mounted on drip chamber 210, light source 226 and photo detector 228 are held substantially in registration with one another on both sides of cylindrical side wall 212. Drop indicator 224 further includes a visual indicator 234 disposed on arm 232a. It will be appreciated that indicator 234 can be disposed on any portion of the drop indicator. Preferably, arms 232a and 232b further include semi cylindrical clips 233 for improving the engagement of the arms with cylindrical side wall 212. Preferably clips 233 are made of an elastic material and having a diameter substantially the same as the outer diameter of cylindrical side wall 212.

When light source 226 is activated, photo detector 228 detects the light passing through the transparent side wall 212 and generates current for as long as the light source emits light. However, when a drop falls into the drip chamber 210 and passes between clip arms 232a and 232b, most of the light rays emitted by light source 224 are deflected by the drop and do not reach photo detector 228, thus interrupting the generation of electric current by photo detector 228, or significantly reducing it. It will be appreciated that interruption of the electric current can be utilized either to activate or deactivate visual indicator 234. Preferably, visual indicator 234 is activated when a drop falls through drip chamber 210 which can be achieved by means of suitable electronic circuitry, as known in the art. Alternatively, visual indicator 234 may be deactivated by a drop falling into drip chamber 210, also by means of suitable electronic circuitry, as known in the art. Figure 8a is a side schematic illustration of a drip chamber 240 having a drop indicator constructed and operative in accordance with another embodiment of the present invention. Drip chamber 240 is substantially the same as drip chamber 10 of Figure Ia, and includes a cylindrical side wall 242 a top end closure 244 having an inlet aperture 246, and a bottom end closure 250 having an outlet aperture 252. Drip chamber 240 further includes a first contact 254 and a second contact 256. First contact 254 is fixedly mounted inside drip chamber 240, and extends through top end closure 244. A first end of contact 256 is pivotally mounted on a pivot (not shown) inside drip chamber 240 and is electrically coupled to a third contact 258, and a second end of contact 256 is coupled to a conductive plate 255, which extends substantially perpendicular to contact 256 so as to block the path of a drop 245, dropping inside drip chamber 240. Plate 255 is configured to selectively create a contact with first contact 254. Second contact 256 and plate 255 are configured to pivot away from first contact 254 by the weight of drop 245 hitting the plate as it falls. According to one embodiment, an indicator 260 and a power source 262 are mounted outside drip chamber 240, but it will be appreciated that they can alternatively be mounted elsewhere on the drip chamber or in proximity thereto. Indicator 260 is coupled to first contact 254, and power source 262 is coupled to second contact 256 by means of third contact 258.

In a stationary state, plate 255 is in contact with first contact 254, thereby electrically coupling first and second contact 254 and 256. However, when drop 245 hits plate 255, plate 255 and second contact 256 are urged to pivot away from first contact 254, causing first contact 254 and second contact 256 to decouple, as illustrated in Figure 8b. As second contact 256 pivots, plate 255 is slanted downwardly, thereby allowing drop 245 to gravitate off plate 255 and toward the bottom of drip chamber 240. Preferably, a return mechanism, such as a spring, for example, urges second contact 256 and plate 255 back to their stationary state, when plate 255 is in electric contact with first contact 254. Preferably, visual indicator 260 is deactivated when contacts 254 and 256 are coupled, and is activated when drop 245 causes contacts 254 and 256 to decouple as described above, by means of suitable electronic circuitry, as known in the art.

It will be appreciated that coupling and decoupling of contacts 254 and 256 by the weight of falling drop 245 may be configured in various alternative ways. One example is illustrated in Figures 9a and 9b, showing a drip chamber 270 having first contact 272 and a second contact 274, both fixedly mounted on top end closure 278. According to this embodiment, a first end of contact 272 extends out of drip chamber 270 while a second end of contact 272 is pivotally mounted on a retractable hinge 276 inside drip chamber 270. A first end of second contact 274 extends out of drip chamber 270 while a second end of contact 274 extends under contact 272 inside drip chamber 270. The second ends of both contacts 272 and 274 are configured inside drip chamber 270 directly in the path of the gravitating drops. As drop 275 hits first contact 272, the weight of the drop causes the second end of first contact 272 to pivot about hinge 276 downwardly, thereby contacting the second end of second contact 274, as can be seen in Figure 9b. It will be appreciated that the second end of first contact 272 may be shaped to readily receive a falling drop on its upper surface and contact the second end of second contact 274 on its lower surface. First and second contacts 272 and 274 are configured to allow the passage of drop 275 toward the bottom of drip chamber 270.

Figures 10a is a side sectional view of a drop indicator 280 which is configured to be disposed inside a drip chamber. Drop indicator 280 is substantially the same as drop indictor 40 of Figure 2a, and includes a housing 282, a power source 284, and an indicator 286. Housing 280 further includes a first electrode 288, mounted on the outer shell of housing 280. Drop indicator 280 further includes a second electrode 290, pivotally mounted outside housing 282 on a retractable hinge 285. Second electrode 290 is mounted adjacent first electrode 288, and is arranged to create a contact with first electrode 288, when pivoting downwardly about hinge 285. First electrode 288 is electrically coupled to power source 284, and second electrode 290 is electrically coupled to indicator 286. As can be seen in Figure 10b, when a drop 295 hits second electrode 290, the weight of the drop urges second electrode 290 downwardly, until it physically contacts first electrode 288 and closes the electric circuit of the indicator and the power source. As a result, electric current flows from power source 284 to indicator 286 through first and second electrodes 288 and 290.

According to another embodiment, the drop indicator can include a barrier (not shown) horizontally hinged on the top wall of the housing of the drop indicator, and adapted to pivot downwardly by the force of a falling drop. This drop indicator further includes an on/off switch mounted under the barrier, so that when the barrier pivots downwardly by the weight of the drop, it presses the switch which, in turn, activates the visual indicator. A returning mechanism, such as a spring, can be provided for urging the barrier to retract to it horizontal position.

According to one embodiment, the drop indicator may be provided with a screen that blocks the visible indication, which could be irritating for the patient, but at the same time allowing a medical attendant to see the indication from afar. The visible indication is preferably positioned to face the entrance of the room, allowing the medical attendant to observe the functioning of the drip chamber from the entrance.

According to yet another embodiment, the visual indicator may be replaced by, or the drop indicator may further include, a transmitter, sending a wireless signal to a remote indicator each time the switching element is switched by a drop falling in the drip chamber. The remote indicator may be a light positioned on the nurses' station or outside the patient's room readily visible by the medical staff, or an indicator on a remote computer or an indicator on a cell phone.

If desired, the drop indicator can be disposable, i.e., formed of material for one time use. Alternatively, the drop indicator can be sterilizable for multiple uses.

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. It will further be appreciated that the invention is not limited to what has been described hereinabove merely by way of example. Rather, the invention is limited solely by the claims which follow.

Claims

1. A drop indicator for use with a drip chamber, the drop indicator comprising:

a circuit;

a switching element coupled to said circuit, wherein passage of a drop through said switching element causes said switching element to switch said circuit;

an indicator coupled to said circuit for providing an indication upon switching of said switching element; and

a power source coupled to said circuit for energizing said indicator;

wherein said circuit, said switching element, said indicator and said power source are mounted as part of the drip chamber.

2. The drop indicator according to claim 1, further comprising a housing mounted as part of the drip chamber, wherein said switching element, said indicator and said power source are mounted in said housing.

3. The drop indicator according to claim 2, wherein said housing is sized and configured to seat inside the drip chamber and float on fluid in the drip chamber.

4. The drop indicator according to claim 3, wherein said housing is further adapted and configured to selectively seal the bottom end of the drip chamber.

5. The drop indicator according to claim 1, wherein said switching element, said indicator, and said power source are affixed to a cover of the drip chamber.

6. The drop indicator according to any of the preceding claims, wherein said indicator is a visible indicator.

7. The drop indicator according to any of claims 1 to 5, wherein said indicator is an audible indicator.

8. The drop indicator according to any of the preceding claims, wherein said switching element includes a first and second electrodes.

9. The drop indicator according to claim 8, wherein said first and second electrodes are mounted as part of the drip chamber to be contacted simultaneous by said drop.

10. The drop indicator according to claim 8, wherein each of said first and second electrodes includes a grid having a plurality of bars.

1 1. The drop indicator according to claim 10, wherein each grid of said first and second electrodes includes a plurality of contacts.

12. The drop indicator according to claim 11, wherein at least one of said contacts of said first electrode is disposed adjacent to at least one of said contacts of said second electrode and in a proximity which permits a single drop to simultaneously contact said at least one of said contacts of each of said electrodes.

13. The drop indicator according to claim 11, wherein said contacts of said first electrode and said contacts of said second electrode are disposed in alternating rows.

14. The drop indicator according to claim 10, wherein said bars of said second electrode are disposed substantially below said bars of said second electrode.

15. The drop indicator according to claim 14, wherein said bars of said first and second electrode are selectably positioned at a distance from the top end of the drip chamber, for determining the duration of said indication.

16. The drop indicator according to claim 14 or claim 15, wherein said bars of said first electrode are selectably positioned at a distance from said bars of said second electrode, for determining the duration of said indication.

17. The drop indicator according to claim 10, wherein said bars of said first electrode are adapted and configured to interleave with said bars of said second electrode.

18. The drop indicator according to claim 1 or 2, wherein said switching element includes a photodetector and a light source held in registration with said photodetector, and wherein said photodetector is adapted and configured to switch said circuit upon passage of a drop through the drip chamber.

19. The drop indicator according to claim 1 or 2, wherein said switching element includes a pair of contacts arrange to contact one another when a drop hits one of said pair of contacts.

20. The drop indicator according to claim 1 or 2, wherein said switching element includes a barrier adapted and configured to pivot downwardly by the weight of a falling drop, causing said switching element to switch said circuit.

21. The drop indicator according to claim 20, further including an on/off switch mounted underneath said barrier, wherein the pivoting downwardly of said barrier by the weight of the drop causes switching of said on/off switch.

22. The drop indicator according to claim 1 or 2, further comprising a transmitter coupled to said circuit for sending a wireless signal upon switching of said circuit, and a remote indicator adapted and configured to provide an indication in response to said wireless signal.

23. A drop indicator for use with a drip chamber, the drop indicator comprising:

a circuit;

a power source coupled to said circuit for energizing said indicator;

wherein said switching element and said power source are mounted as part of the drip chamber and said indicator is positioned where said indicator can be observed from a distance.

24. A method for forming a drop indicator for use with a drip chamber, the method comprising:

Providing a circuit;

coupling a switching element to said circuit, wherein passage of a drop through said switching element causes said switching element to switch said circuit;

coupling an indicator to said circuit for providing an indication upon switching of said switching element;

coupling a power source to said circuit for energizing said indicator; and mounting said circuit, said switching element, said indicator and said power source as part of the drip chamber.

25. The method of claim 24, wherein said step of mounting includes:

mounting said circuit, said switching element, said indicator and said power source in a housing.

26. The method of claim 24, wherein said step of mounting includes:

mounting said switching element and said indicator and said power source as part of the drip chamber; and

positioning said indicator where it can be observed from a distance.