Patent Publication Number: US-2013247909-A1

Title: Nebulizer for use in mechanical respiratory ventilation therapy

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of respiratory ventilation therapy, and more particularly to a nebulizer for delivery of medications in the form of aerosols to a patient attached to a mechanical ventilator and receiving respiratory ventilation therapy. 
     BACKGROUND OF THE INVENTION 
     Respiratory ventilation therapy refers to forms of treatment used to assist breathing function in patients with a variety of diseases, conditions, or injuries. Typically, respiratory ventilation is provided for patients suffering from acute or chronic respiratory failure. In general, the treatment involves attaching the patient to a ventilator which is a mechanical and/or electrical device that is adapted to enable the respiratory processes to continue by providing a flow of respiratory gasses at a rate, volume and pressure needed by the patient. The patient typically is connected to the ventilator via an endotracheal tube inserted either through his nose or mouth, or through a surgical opening made in his trachea. 
     Patients for whom mechanical respiratory ventilation is necessary typically also need to be treated with one or more medicaments that for optimal effectiveness should also be delivered directly to their lungs, rather than administered parenterally or otherwise. Typically, such medicaments are provided by the drug manufacturer in liquid form, and these liquids must first be converted into an aerosol of tiny droplets before they can be administered to the lungs of the patient. The conversion of the liquid medicament into an aerosol typically is effected by means of a device called a nebulizer that is incorporated into the respiratory ventilation apparatus. The nebulizer is a container into which a measured amount of the liquid medicament is inserted. Oxygen (or a mixture of respiratory gasses) under pressure is directed into the container, the liquid in the container is aerosolized, and the aerosol is then mixed with the respiratory gasses flowing from the ventilator to the patient thereby reaching the lungs of the patient. 
     Once a patient is attached to a mechanical ventilator, all of his respiratory functions are provided by the ventilator—including the flow to his lungs of a volume of a mixture of gasses at a rate necessary for respiration, the application of sufficient pressure to inflate the lungs so as to enable inhalation, and cyclically allowing for the relaxation/deflation of the lungs so as to enable exhalation of carbon dioxide and other bi-products of respiration. All of these functions must occur in a regular, timed sequence, and must be maintained without interruption; otherwise the patient&#39;s lungs may collapse and he may cease to breathe. 
     Surprisingly, however, the nebulizers typically in use in hospitals today for delivery of medicaments to patients attached to mechanical ventilators are constructed in a manner such that their use often endangers the patients by undermining the integrity of the system. These nebulizers typically are constructed of a first portion that serves as a reservoir for receiving a measured amount of the medicament and in which the medicament is aerosolized (when oxygen or an oxygen/gas mixture flows thereto), and a second portion comprising a number of ports adapted for connecting various tubes thereto, including an entry port for conveying oxygen under pressure to the nebulizer, and an exit port for directing the aerosolized medicament to the tube conveying the respiratory gasses to the patient. Typically, the first and second portions of these nebulizers are manufactured as distinct sections that are adapted to fit one into the other, such as via a simple screw-type mechanism, after the insertion of the medicament. Because of this configuration, each and every time that it becomes necessary to fill or refill the reservoir with the liquid medication—and this typically occurs between 2 and 12 times a day for patients on a ventilator—the two portions of the nebulizer must be separated one from another. But when this occurs, the result is potentially catastrophic for the patient. There is an immediate loss of the volume of gasses needed by the patient for respiration, since all (or most) of the gasses that continue to flow from the ventilator now escape to the ambient environment. In addition, there is an immediate loss of pressure in the system, such that the pressure necessary for the patient to inhale (continue breathing) falls suddenly. The result is great distress for the patient—he feels as if he is choking—and since there is insufficient pressure to force the patient&#39;s lungs to expand, the lungs may collapse causing the alveoli of the lungs to adhere to each other (often an irreversible process). In addition, since the system of tubing is no longer closed, but is open to the ambient environment, the patient is exposed to an enhanced risk of infection from bacteria and other pathogens in the ambient environment. At the same time, the medical staff attending to the patient, and anyone else in the vicinity (other patients, family or visitors) are exposed to pathogens from the patient that are now being circulated from the open system to the ambient environment. 
     Thus, the nebulizers in use today are woefully inadequate. Clearly there is a need for an improved nebulizer for use in ventilation therapy that overcomes these drawbacks and provides a safe and sterile means for introducing medication into the nebulizer without undermining the integrity of the system and endangering the lives of the patients. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved nebulizer for delivering medication in the form of an aerosol to a patient attached to a mechanical ventilator and receiving respiratory ventilation therapy, the improvement comprising means for inserting the medication into the nebulizer without causing any disruption to the respiratory ventilation process. 
     In accordance with a preferred embodiment, the nebulizer of the present invention consists of a container having a volume sufficient to hold a therapeutically effective amount of a liquid medicament and to enable aerosolizing therein of the medicament upon the inflow thereto of a respiratory gas, the container comprising a first port adapted for attachment to a source of a respiratory gas, a second port adapted for attachment to the apparatus providing respiratory ventilation to the patient, and a third port adapted for inserting the medicament into the container without causing interruption to the respiratory ventilation therapy being provided to the patient. 
     In accordance with a preferred embodiment, the third port comprises a one-way valve adapted to allow insertion of medication into the nebulizer without causing a loss of pressure or gas volume, or a reduction in the flow rate of the oxygen/gas mixture, and without allowing the venting to the ambient environment of respiratory gasses being provided to the patient. 
     In accordance with a preferred embodiment, the third port comprises an insertion point for insertion of the medicament via a needle of a syringe, or any other apparatus capable of delivery of the medicament through the insertion point. 
     In a preferred embodiment, the insertion point is sealed with an elastomeric material. 
     In accordance with a preferred embodiment of the invention, the container has a unitary structure. The container may be constructed of any material suitable for use in a hospital environment, such as a hard plastic material. 
     Alternatively, the container may be constructed of two or more pieces that are conjoined prior to attachment to the respiratory ventilation apparatus. For maximum utility and benefit, the pieces are conjoined in a manner preventing their separation after the container is attached to the respiratory ventilation apparatus. 
     In accordance with yet another embodiment, the container further comprises a configuration adapted to facilitate aerosolizing of the medicament. In one aspect, the configuration comprises a bottom portion that tapers downward; in another aspect, the configuration comprises a narrow tube connected to the first port positioned so as to direct the oxygen (or mixture of respiratory gasses) flowing into the container towards the bottom of the container. 
     In accordance with yet another embodiment, the container further comprises a fourth port and apparatus adapted for draining residual liquid from the container without causing interruption to the respiratory ventilation therapy being provided to the patient. The apparatus comprises a collector and a valve mechanism having at least two positions, one position enabling drainage of the residual liquid from the nebulizer into the collector, and a second position enabling drainage of liquid from the collector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the present invention will be better understood with reference to the attached drawings wherein: 
         FIG. 1  presents a schematic view of a typical mechanical respiratory ventilation system that incorporates a nebulizer for dispensing medication to a patient; and 
         FIG. 2  presents a schematic view of the structure of one preferred embodiment of a nebulizer in accordance with the present invention. 
         FIG. 3  presents a schematic view of the structure of another preferred embodiment of a nebulizer in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides an improved nebulizer adapted to be used in connection with mechanical respiratory ventilation systems, such as those used in hospitals, that allows for the introduction of medicaments in the form of aerosols into the system without violating the integrity of the closed system, thereby preventing the deleterious effects experienced by patients today who are attached to ventilators when the nebulizers are opened to insert a medication. 
     The basic apparatus  10  of a typical respiratory ventilation system, in connection with which the present invention may be used, is represented graphically in  FIG. 1 . Apparatus  10  comprises a mechanical ventilator  110 , for providing air and/or oxygen and/or other respiratory gasses (e.g., NO) to a patient  120 . Ventilator  110  has one or more entry ports (not shown) adapted for attachment to sources of the gasses needed in connection with the mechanical ventilation of patients. Prior to the patient&#39;s attachment to the apparatus, an endotracheal tube  112  is inserted into the patient either through his nose or mouth, or through a surgical opening made in his trachea. Tube  112  is then attached to the ventilator apparatus typically via a Y-type connector  114  which in turn is connected to conduits  116  and  118 . Conduit  116  is adapted to receive one or more of the gasses under controlled pressure from ventilator  110  and direct them to the patient; conduit  118  is adapted to receive carbon dioxide and other bi-products of exhalation from the patient and direct them back to the ventilator. Conduits  116  and  118  may consist of a series of conduits, connectors, filters and the like (all not shown). 
     Ventilator  110  is powered by a power source (not shown), such as electricity or compressed gas. Associated with ventilator  110 , or built-in with it, are control and monitoring systems (not shown) that enable a health professional to determine various parameters of the system, such as the volume of the gas, the flow pressure, temperature, the timing of inhalation and exhalation, and the like. 
     Typically, the oxygen and other gasses delivered to the patient must be both warmed and humidified in order to prevent drying out of lung tissue. To that end, a humidifier (not shown) is hooked into the circuit of tubes at a convenient place, typically in proximity to ventilator  110 . 
     In order to deliver medication to the lungs of the patient simultaneously with the delivery of the respiratory gasses, a nebulizer  130  is provided in a manner that enables it to be removeably attachable to the system. Typically, nebulizer  130  is attached via a conduit  132  to a source of oxygen (or a mixture of oxygen and other respiratory gasses) under pressure; in the diagram, the source of oxygen is ventilator  110 , but a source independent of the ventilator will work equally as well. An exit port  134  of the nebulizer is connected to conduit  116 . When the nebulizer is filled with a liquid medicament, a flow of oxygen (or a mixture of oxygen and other respiratory gasses) is directed into the nebulizer which acts to convert the liquid to an aerosol; the aerosol is then directed to the patient via conduit  116 . 
     Once the patient is attached to ventilator  110 , his normal respiratory functions are provided by the ventilator—including the flow to his lungs of a volume of air and other gasses necessary for inhalation, the application of sufficient pressure to inflate the lungs so as to enable inhalation, and cyclically allowing for the relaxation/deflation of the lungs so as to enable exhalation of carbon dioxide and other bi-products of respiration. All of these functions must occur in a regular, timed sequence, and must be maintained without interruption; otherwise the patient may cease to breathe. 
     Surprisingly, however, the nebulizers typically in use in hospitals today for delivery of medicaments to patients attached to ventilators are constructed in a manner such that their use often undermines the integrity of the system and may even endanger the lives of the patients. These nebulizers typically are constructed of a first portion that serves as a reservoir for receiving a measured amount of the medicament and in which the medicament is aerosolized (when oxygen flows thereto), and a second portion comprising a number of ports adapted for connecting various tubes thereto, including an entry port for conveying oxygen under pressure to the nebulizer, and an exit port for directing the aerosolized medicament to the tube conveying the respiratory gasses to the patient. Typically, the first and second portions of these nebulizers are manufactured as distinct sections that are adapted to fit one into the other, such as via a simple screw mechanism, after the insertion of the medicament. Because of this configuration, each and every time that it becomes necessary to fill or refill the reservoir with the liquid medication—and this typically occurs between 2 and 12 times a day for patients on a ventilator—the two portions of the nebulizer must be separated one from another. But when this occurs, the result is potentially catastrophic for the patient. There is an immediate loss of the volume of gasses needed by the patient for respiration, since all (or most) of the gasses that continue to flow from the ventilator now escape to the ambient environment. In addition, there is an immediate loss of pressure in the system, such that the pressure necessary for the patient to inhale (continue breathing) falls suddenly. The result is great distress for the patient —he feels as if he is choking—and since there is insufficient pressure to force the patient&#39;s lungs to expand, the lungs may collapse because the alveoli of the lungs adhere to each other (often an irreversible process). In addition, since the system of tubing is no longer closed, but is open to the ambient environment, the patient is exposed to an enhanced risk of infection from bacteria and other pathogens in the ambient environment. At the same time, the medical staff attending to the patient and anyone else in the vicinity (other patients, family or visitors) are also at risk of exposure to pathogens originating from the patient that are now being circulated from the open system to the ambient environment. 
     The nebulizer of the present invention provides a simple and effective way for overcoming these drawbacks. It allows a patient attached to a ventilator to receive repeated dosages of aerosolized medication without exposing him to the dangers described above inherent in the nebulizers commonly in use today. 
     In accordance with a preferred embodiment ( FIG. 2 ), in its simplest form, the nebulizer of the present invention consists of a container  200 , having an inner volume  210  that will accommodate a therapeutically effective amount of a liquid medication and yet have sufficient additional space to allow for the aerosolizing of the liquid upon the introduction of a flow of oxygen (or a mixture of respiratory gasses) thereto. In one embodiment, the container may accommodate up to about 20 cc of a liquid medication; however, containers both larger and smaller than this are also within the scope of the present invention. 
     Container  200  may be formed of any suitable material. Typically, it is formed of a rigid plastic as is known in the art and as is commonly used for many short-term-use or disposable medical devices. 
     In a preferred embodiment, container  200  has a unitary structure and comprises three ports as more fully described below. In other embodiments, container  200  may be constructed of two or more pieces that are conjoined prior to attachment to the respiratory ventilation apparatus. However, for maximum utility and benefit, the pieces are conjoined in a manner preventing their separation after the container is attached to the respiratory ventilation apparatus. 
     Container  200  has an entry port  220  adapted for connection to a conduit (such as conduit  132  in  FIG. 1 ) delivering respiratory gasses under pressure. Container  200  preferably has a shape and internal structure that facilitates the process of aerosolizing the liquid medication. In one embodiment shown in  FIG. 2 , the bottom of container  200  is tapered to a point  230 , and the respiratory gasses flowing into the container via entry port  220  are directed towards the bottom of the container by a narrow conduit  240  which extends almost to the bottom of the container. However, these features are merely representative of the type of features that may be incorporated into the structure of the nebulizer of the present invention to accomplish this purpose, and that could be readily be designed by a person of the art. 
     Container  200  has an exit port  250  adapted for connection to the conduit delivering the respiratory gasses to the patient (such as conduit  116  in  FIG. 1 ); typically, the connection is effected via a “T”-shaped connector  260  as shown, but other forms of connectors are also possible within the scope of the present invention. Once container  200  is attached both to the source of oxygen via entry port  220  and to the conduit delivering the respiratory gasses to the patient via exit port  250 , container  200  is effectively sealed to the ambient environment, and forms an integral component of the closed circuit that is providing the required sequenced volume of respiratory gasses under pressure to the patient. 
     Container  200  has one additional port  270  adapted for enabling the introduction of liquid medication into the container. However, port  270  is a sealed port—sealed by any means adapted both to allow the introduction of a liquid medicament into the container and yet to prevent the escape of aerosol or respiratory gasses from the container. In one embodiment, the port is sealed by a one-way valve, that allows for the insertion of a medicament into the container but does not allow for the exit of any liquid or gas from the container. In a preferred embodiment, port  270  is sealed by an “insertion point,” i.e., by an elastomeric material, as is known in the art, such as that found on devices designed for the introduction of fluids into intravenous feeds. The elastomeric material of the insertion point may be penetrated by the needle of a syringe without destroying the utility of the material as a seal. In the practice of the present invention, a standard syringe is filled with a measured amount of the medication needed to treat the patient attached to the ventilator, and the liquid is inserted into the nebulizer (container  200 ) by piercing the covering of port  270  with the needle of the syringe. Once all the liquid in the syringe is emptied into container  200 , the needle is withdrawn, without damaging the seal, and without causing any loss in the volume of the gasses being delivered to the patient or without any loss of pressure needed to maintain the regular cycle of respiration for the patient. It will also be appreciated that as soon as the liquid medication is introduced into the container via the insertion point, (oxygen-respiratory gasses) under pressure may be directed to the nebulizer to start the process of aerosolizing the liquid, and the aerosol can then begin to flow towards the patient via exit port  250 . 
     Another preferred embodiment of the nebulizer of the present invention may be appreciated with reference to  FIG. 3 . As can be seen in  FIG. 3 , the nebulizer  300  of this embodiment is identical in most aspects to nebulizer  200  described above with reference to  FIG. 2 . However, nebulizer  300  has an additional feature—an apparatus and mechanism  310  either integral to the nebulizer or removeably attachable to the nebulizer at its bottom portion that is adapted to enable effective removal of residual and/or unwanted medicament from the nebulizer without interruption to the ongoing operation of the respiratory ventilation system. In its simplest form, apparatus and mechanism  310  comprises a container  320  and a valve  330 . Valve  330  may take the form of a stopcock or any similar device that may be operated in at least two positions In one position, the valve is operable to open an exit port (not shown) on the bottom of the nebulizer to allow for the residual medicament to drip into the collector. When the valve is in this position, the integrity of the nebulizer is maintained, since it remains sealed to the ambient environment. In a second position, the valve is operable to seal the exit port on the bottom of the nebulizer while opening up a drainage port (not shown) on the bottom of the collector. When the valve is in this position, any liquid that had dripped into the collector may be drained out and yet the integrity of the nebulizer and the respiratory system is still maintained 
     It will be appreciated that the embodiments of the present invention described above are only provided for illustrative purposes only. A person of the art will appreciate that many other structural variations are possible within the scope of the present invention which is limited only by the following claims: