Abstract:
A nitric oxide delivery device is provided that can be formed as a module that is insertable in a mating equipment bay in a gas delivery system found in one location, removed and used in conjunction with a transport gas delivery system when the patient is transported, and thereafter inserted in the equipment bay of a gas delivery system located at a second location. In a preferred embodiment, the device includes a housing having an NO supply port, an NO delivery port, a flow sensor port, and a conduit pneumatically connected to the NO supply port and the NO delivery port. A selector valve is positioned in the conduit and selectively moves between a first position wherein the NO supply port is pneumatically connected to the NO delivery port and a second position wherein the NO delivery port is pneumatically connected to a temporary supply of NO. The housing further has a power supply port, a temporary power source and a switch being selectively movable between a first position wherein power is provided to the NO delivery device via the power supply port and a second position wherein power is provided to the device from the temporary power source.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a device for delivering nitric oxide into the breathing gases of a patient that is modular in nature. The device may be used to advantage to maintain nitric oxide therapy when a patient is being transported from one location to another location. 
   Nitric oxide (NO) is a gas that, when inhaled, acts to dilate blood vessels in the lungs, improving oxygenation of the blood and reducing pulmonary hypertension. For this purpose, the nitric oxide is provided in the inspiratory breathing gases for the patient. The dosages of nitric oxide are small, typically 100 parts per million (ppm) or less. 
   In many cases, the inspiratory breathing gases for the patient will be provided by a gas delivery system such as a mechanical ventilator. U.S. Pat. No. 5,558,083 shows apparatus for administering NO into the inspiratory breathing gases provided by a mechanical ventilator. The apparatus includes a connection to a NO supply conduit inserted in the inspiratory limb of a patient breathing circuit connected to the ventilator. The NO supply conduit is connected through a controllable metering valve to a supply of NO containing gas. Flow sensors are provided in the NO supply conduit and in the inspiratory limb upstream of the NO supply conduit connection. The flow sensors are connected to a control that operates the metering valve based on the dosage of NO desired for the patient and the gas flows sensed by the concentration sensor. An analytical gas flow sensor is provided downstream of the NO supply conduit connection in the patient breathing circuit to analyze properties of the inspiratory breathing gases being supplied to the patient. The apparatus of the &#39;083 patent provides a generally continuous flow of NO containing gas during the supply of breathing gases to the patient. It is also possible to provide a discrete pulse of NO containing gas at a predetermined time in the inspiratory phase of the patient&#39;s breathing cycle. 
   In a commercial embodiment, NO delivery apparatus of the type described above is typically available as a stand alone unit that is used in conjunction with a breathing gas delivery system when NO therapy is desired for a patient. For this purpose, the breathing gas flow sensor, the nitric oxide supply conduit connection, and the gas analyzer sampling port may be provided in a common housing that can be inserted in the inspiratory limb of the breathing circuit. For best performance, the gas analyzer sample part is placed at a distance from the NO injection point to allow for proper gas mixing. Also, the gas sample point is normally positioned close to the inspiratory side of the wye connector to most accurately sense the level of NO 2  being produced. The commercial embodiment provides the advantage of allowing the apparatus to be used with a variety of different breathing gas delivery systems without being restricted to a particular model or to the products of a particular manufacturer. 
   However, the stand alone unit tends to be somewhat bulky. It is preferable to keep the NO supply conduit short and to administer the NO into the inspiratory breathing gases close to the patient to avoid/limit a reaction between the NO and oxygen in the breathing gases that leads to the production of toxic nitrogen dioxide in the breathing gases. This often means that the NO delivery apparatus is proximate to the patient and is in the way of other apparatus or attending patient caregivers. Also, with such apparatus, it may be difficult to maintain NO therapy when transporting a patient from one location to another as, for example, from an intensive care unit to a regular hospital room. 
   SUMMARY OF THE PRESENT INVENTION 
   The present invention addresses the foregoing problems by providing a NO delivery device that is compact in nature, thereby to facilitate continuance of NO therapy when a patient is being moved from one location to another. 
   The NO delivery device may be formed as a module that can be inserted in a mating equipment bay in a gas delivery system found in one location, removed and used in conjunction with a transport gas delivery system when the patient is being transported, and thereafter inserted in the equipment bay of a gas delivery system located at a second location. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a breathing gas delivery system with which the modular NO delivery device of the present invention may be utilized. 
       FIG. 2  is a perspective view of the modular NO delivery device of the present invention. 
       FIG. 3  is a generally schematic showing of the construction of one embodiment of the modular NO delivery device of the present invention. 
       FIG. 4  is a generally schematic showing of the construction of another embodiment of the modular NO delivery device. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a patient breathing gas delivery system  10  with which the modular nitric oxide delivery device of the present invention may be utilized. Breathing gas delivery system  10  may comprise a mechanical ventilator for providing breathing gases to patient  12 . Breathing gas delivery system  10  includes a user interface  14  that allows a clinician to establish the operating parameters for the gas delivery system, such as breath rate, tidal volume, minute volume, inspiratory/expiratory (I:E) ratio, breathing gas pressures, and the like. User interface  14  can also be used to set NO concentrations and display NO and NO 2  concentrations. These procedures may be carried out using data entry controls  16 . User interface  14  also includes screen  18  for providing a visual display of the operation of breathing gas delivery system  10  and the physiological functioning of patient  12 . 
   The pneumatic and mechanical portions of breathing gas delivery system  10  could be contained in housing  20  which may be mounted on wheeled carriage  22  to facilitate moving the gas delivery system into proximity with patient  12 . 
   Breathing gas delivery system  10  includes an inspiratory port  24  connected to inspiratory limb  26  of breathing circuit  28 . Inspiratory limb  26  is connected through wye-connector  30  to patient limb  32  that provides the inspiratory breathing gases to patient  12  through a face mask, endotracheal tube, and the like. Patient limb  32 , also receives the expiratory breathing gases of patient  12  and supplies them through wye-connector  30  to expiratory limb  34  of breathing circuit  28 . Expiratory limb  34  is connected to expiratory port  36  of breathing gas delivery system  10 . Breathing gas delivery system  10  includes appropriate check valves to carry out the flow of breathing gases in the manner described above. Among the sensors contained in breathing gas delivery system  10  is flow sensor  38  for measuring the flow of breathing gases in inspiratory limb  26 . 
   Breathing gas delivery system  10  includes modular equipment bay rack  40 . In a typical application for breathing gas delivery system  10 , the modules in modular equipment bay rack  40  comprise patient monitoring modules that can be selectively inserted in the rack, depending on the parameters of the patient to be monitored. To this end, the modules include patient leads  44  connected to patient  12 . Typical modules  42  may include one for carrying out hemodynamic measurements, such as non-invasive blood pressure measurement, blood oxygen measurement, and the like; an electrocardiograph module for obtaining electrocardiographic data; an electroencephalographic module for obtaining EEG data; and a gas monitoring module for measuring breathing gas components such as carbon dioxide, oxygen, nitric oxide, and anesthetic agents. 
     FIG. 2  shows modular NO delivery device  50  of the present invention. Modular delivery device  50  includes a housing  52  of a size suitable for placing in modular equipment bay rack  40  of breathing gas delivery system  10 . Modular equipment bay rack  40  may be suitable for receiving modules that are of a single standard width or a double standard width. It is presently contemplated that module  50  would be of a double width with respect to the bays in rack  40 . In  FIG. 1 , modular NO delivery device  50  is inserted in the lower bay of rack  40 . 
   Modular NO delivery device  50  includes a connector  54  for connection to NO supply line  56  connected through pressure regulator  58  to a source of NO containing gas, such as tank  60 . Tank  60  typically contains NO in an inert diluent gas, such as nitrogen. 
   In the embodiment of the invention shown in  FIG. 2 , NO delivery device includes NO injection element  75  that may be inserted at an appropriate location in inspiratory limb  26 , as shown in  FIG. 2 . Injection point  62  is connected to NO delivery device  50  by NO delivery line  64  connected to NO supply port  66  of delivery device  50 . A flow signal can be collected from injection element  75  via flow signal line  73 , which is connected to the NO delivery device  50  at connection  71 . In addition, an optional gas sampling port  68  can be located downstream of the point of NO injection to sense characteristics of the inspiratory breathing gases in inspiratory limb  26  and to allow for adequate blending prior to sampling. Sampling port  68  is connected to modular delivery device  50  at connection  70  by sampling line  72 . 
     FIG. 3  shows the components of modular NO delivery device  50 . Housing  52  for delivery device  50  has connectors  54 ,  66 ,  70 , and  71  for NO supply line  56 , NO delivery line  64 , sampling line  72 , and flow signal line  73 , respectively, on the surface  100  that is exposed when the module is inserted in modular equipment bay rack  40 . Surface  102  of housing  52  contains a plurality of connectors that mate with corresponding connectors in rack  40  when delivery device  50  is inserted in the rack. 
   NO supply line  56  is connected to conduit  104  in the module. Module  50  may contain a small supply of NO gas  106  for use during the period of time in which patient  12  is being transported. More likely however, the small supply of NO gas  106  comprises a separate container or cylinder that is externally connected to the module  50 . Selector valve  108  is connected to a selected one of conduit  104  or NO supply  106  to provide nitric oxide gas to NO dosing means  110 . Dosing means  110  contains flow control valve  112 . Valve  112  can be opened for a short period of time under the control of central processing unit  114  to supply a pulse dose of nitric oxide gas in conduit  116  to NO supply line  64 . It is also possible, and many times preferred to provide a continuous, proportional NO/N 2  gas flow to achieve a desired NO concentration. A flow restrictor  118  is provided at the output of valve  112  and pressure sensor  120  is connected downstream of flow restrictor  118  so that the pressure characteristics existing in conduit  116  may be used to confirm proper operation of valve  112 . Dosing means  110  for providing a pulse dose of NO into the breathing gases of the patient is shown in simplified form in  FIG. 3  and may incorporate further features of such a device such as those shown in U.S. Pat. Nos. 6,089,229; 6,109,260; 6,125,846; 6,164,276; and 6,581,592. 
   To control the operation of valve  112 , central processing unit  114  receives settings from gas delivery system  10  in conductor  122  as well as operating signals in conductor  124  indicating that gas delivery system  10  is providing inspiratory breathing gases in inspiratory limb  26 . For example, the signal in conductor  124  may comprise a signal from inspiratory flow sensor  38  in gas delivery system  10 . Alternatively, central processing unit  114  could receive inspiratory gas flow information from injector element  75 . This would allow controlled NO delivery while the module is not connected to an equipment rack. Central processing unit  114  provides operating data to gas delivery system  10  in conductor  126 . 
   A gas analyzer  128  is connected to sampling line  72  via conduit  130 . Gas analyzer  128  receives setting information from breathing gas delivery system  10  in conductor  132  for selecting the gases to be analyzed, typically NO, nitrogen dioxide, and oxygen, as well as alarm limits for the monitored gases. Gas analyzer  128  provides monitoring data in conductor  134  to breathing gas delivery system  10 . Gas analyzer  128  is also connected to alarm  136  for providing visual or audible alarms in the event the gas analysis data goes beyond an established alarm limit. The alarm data may also be provided to gas delivery system  10  in conductor  138 . 
   Modular NO delivery device  50  may be powered by a connection to power mains via gas delivery system  10  and a connector on the rear of the NO delivery module to provide line power to power feed  140 . Or, the NO delivery module may be powered by an internal battery  142 . Switches  144  and  146  allow connection of the appropriate power source as well as allowing battery  142  to be charged from the power in power feed  140 . 
   In use, modular NO delivery device  50  is inserted in modular equipment bay rack  40  of a gas delivery system  10  at one location, such as an intensive care unit. Injection element  62 , sampling port  68  and the flow sensor port are connected in inspiratory limb  26  by appropriate connectors. NO supply conduit  56  is connected to a source of NO  60  and to port  54 . 
   The desired operating parameters for gas delivery system  10  are entered in user interface  14 . The NO dosage amounts are similarly entered in interface  14  and provided to central processing unit  114  in NO delivery module  50  in conductor  122 . 
   Operation of gas delivery system  10  and NO delivery module  50  then commences. In the NO delivery module, central processing unit  114  operates valve  112  to provide continuous or pulsatile doses of NO to injector element  62  in NO supply line  64  in synchronism with the supply of breathing gases in inspiratory limb  62  via signals provided in conductor  124 . Gas analyzer  128  samples the breathing gases provided to the patient via sampling line  72  to provide monitoring data in conductor  134  and to operate alarm  136  if necessary. 
   When it is desired to transport patient  12  from a first location, such as an intensive care unit, to another location, such as a hospital room, the supply of breathing gases to patient  12  will be switched from a gas delivery device  10  to another gas delivery device, such as a transport ventilator. This is typically carried out by disconnecting inspiratory limb  26  and expiratory limb  34  from gas delivery system  10  and connecting them to appropriate ports on the transport ventilator. NO delivery module  50  is removed from rack  40  of the gas delivery device  10  at the first location. It can be inserted in a corresponding modular equipment bay in the transport ventilator. Or, a connection cable may be provided between the transport ventilator and NO delivery module  50 . The connection provides the data in conductor  124  necessary to synchronize the supply of NO with the supply of breathing gases by the ventilator. Module  50  may be switched to operation from battery  142 . If desired, nitric oxide supply  60  may be disconnected and valve  108  operated to supply nitric oxide gas from the transport supply  106  in module  50 . The connection to the transport ventilator may also permit monitoring information in conductors  126  and  134  to be provided to the transport monitor. 
   Central processing unit  114  maintains the operating parameters and NO dosage settings entered via user interface of the breathing gas delivery system at the first location as the patient is being transported. 
   Following completion of the patient transport, at the new location, the procedures carried out at the first location are essentially reversed. That is, patient  12  is disconnected from the transport gas delivery system  10  and placed on the gas delivery system  10  at the new location. 
   NO delivery module  50  is inserted in the modular equipment bay rack  40  of the gas delivery system  10  at the new location. The supply of power to module  50  reverts to line power provided in power feed  140 . If NO supply  60  has not been transported with the patient, NO supply line  56  is connected to a source  60  at the new location and valve  108  is operated to terminate NO supply from source  106  and commence NO supply from NO supply line  56  and conduit  104 . Central processing unit  114  and gas analyzer  128  are connected to the gas delivery system  10  at the new location to maintain the supply of continuous or pulsatile doses of NO in NO delivery line  64  and injection module  75 . Information from the analysis of the breathing gases by gas analyzer  128  is also provided to gas delivery system  10  at the new location. 
   It will be appreciated that the embodiment of the invention shown in  FIG. 3  may be used with a variety of ventilators manufactured by different manufacturers inasmuch as all the elements necessary for delivery of NO are contained in the module. This provides flexibility in the use of the NO delivery module. 
     FIG. 4  shows another embodiment of a NO delivery module as module  500 . Module  500  is simpler in construction than module  50  but is correspondingly more integrated with a particular breathing gas delivery system with which it is designed to be used. Hence, with the NO delivery module of  FIG. 4  the gain is simplicity over that of  FIG. 3  but the trade-off is somewhat less flexibility for use with a variety of different types of breathing gas delivery systems. In  FIG. 4 , elements corresponding to those of  FIG. 3  bear the same reference numerals. 
   In the application contemplated for NO delivery module  500 , the various gas monitoring and alarming functions are provided by the breathing gas delivery system rather than the NO delivery module. Hence, gas analyzer  128 , alarm  136 , and the related circuitry is omitted. 
   The portions of the module providing a continuous or pulsatile dose of NO remain generally the same. However, the nitric oxide dosage provided in conduit  116  at port  66  is provided to a supply conduit  502  that is connected to the breathing gas delivery system so that the NO dose is supplied to the breathing gases in the gas delivery system, such as a mechanical ventilator, rather than in the inspiratory limb of the breathing circuit. 
   Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.