Abstract:
An application for a disposable support/resuscitation system includes a pressurized gas inlet connected to a pressure relief device. The pressure relief device has a first pressure relief valve that opens at a setable gas pressure and, optionally, has a second pressure relief valve that opens at a pre-determined maximum gas pressure. Changing the first pressure release valve from a low pressure range to a high pressure range requires activation of a pressure range actuation button. A manometer is connected to the pressure relief valve. A manually operated valve is connected to the manometer, and a patient interface port is connected with the manually operated valve. The manually operated valve selectively controls administration of the pressurized gas to the patient. The manometer, pressure relief device, and manually operated valve are made from non-ferromagnetic materials for proper operation in the vicinity of a Magnetic Resonance Imaging System.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 14/025,3337, filed Sep. 12, 2013, which is a continuation-in-part of U.S. patent application Ser. No. 12/838,555, filed Jul. 19, 2010, the disclosure of which are hereby incorporated by reference. 
     
    
     FIELD 
       [0002]    This invention relates to the field of resuscitation and more particularly to a disposable system, method and apparatus for resuscitating a person, perhaps an infant, in the vicinity of a magnetic resonance imaging (MRI) system. 
       BACKGROUND 
       [0003]    In situations when a patient has a cardiac arrest or ceases to breath, emergency life support and/or resuscitation requires a way to supplement and hopefully revive the patient&#39;s breathing function. When equipment is unavailable, often the life support and/or resuscitation is performed by administration of Cardio-Pulmonary Resuscitation techniques, or CPR. 
         [0004]    In situations when equipment is available, such as in a hospital, life support and/or resuscitation are often accomplished by the use of a manually operated resuscitation device. These manually operated devices are fed with oxygen (or other breathable gases such as air) under pressure that is administered to the patient through a mask or tracheal tube, Administration is under the control of an administrator such as a doctor or a nurse. The administrator controls the flow and abatement of the oxygen to the patient, filling the patients lungs, then stopping the flow of oxygen, at which time the patient exhales. 
         [0005]    Manometers for measuring gas pressure in a patient ventilation system are well known. U.S. Pat. No. 5,557,049 to Jeffrey B. Ratner describes a Manometer for insertion into a patient ventilation system and is herein included by reference. 
         [0006]    There are several problems that prior life support/resuscitation systems and devices need overcome. The first problem is to limit the gas pressure so as not to over inflate the patient&#39;s lungs and possibly causing a rupture. The second problem is to provide feedback to the administrator to inform the administrator of the pressure within the breathing system and when the patient starts breathing on their own. Another issue relates to sterility of the life support/resuscitation systems and devices when used on the next patient. 
         [0007]    Another problem that needs to be overcome is using the device in the vicinity of magnetic resonance imaging (MRI) systems. Due to the strong magnetic fields created within and around these magnetic resonance imaging (MRI) systems, existing resuscitation systems are inadequate because several components such as non-ferromagnetic resilient members and shafts are typically made out of materials that are attracted by the magnetic forces generated by magnetic resonance imaging (MRI) systems, thereby causing erroneous readings on, for example, manometers and, in extreme cases, movement of the resuscitation devices under the pull of the magnetic resonance imaging (MRI) system. 
         [0008]    What are needed are support/resuscitation systems and devices that will provide control and status to the administrator at the patient locale and permit disposability. 
       SUMMARY 
       [0009]    In one embodiment, a disposable support/resuscitation system is disclosed including a pressurized gas inlet and a pressure relief device interfaced to the pressurized gas inlet. The pressure relief device has a first pressure relief valve that opens at a setable gas pressure and has a second pressure relief valve that opens at a pre-determined maximum gas pressure. The setable gas pressure is set by rotation of an adjustment knob within two pressure ranges such that rotation of the adjustment knob from a low pressure range of the two pressure ranges to a high pressure range of the two pressure ranges requires activation of a pressure range actuation button. A manometer is interfaced to the pressure relief valve, a manually operated valve is interfaced to the manometer, and a patient interface port is interfaced with the manually operated valve. The manually operated valve selectively controls administration of the pressurized gas to the patient and both the manometer and the manually operated valve are in close proximity to the patient. Close proximity is a term used to mean that both the manometer and the manually operated valve are close enough to the patient that a caregiver need not look away or turn away from the patient to operate the manually operated valve or to read the current gas pressure from the manometer. All sub-components of the disposable support/resuscitation system are fabricated from non-ferromagnetic materials. 
         [0010]    In another embodiment, a disposable support/resuscitation system is disclosed including a pressurized gas inlet and a pressure relief device that is interfaced to the pressurized gas inlet. The pressure relief device has a valve for adjustably regulating gas pressure and a valve for regulating the gas pressure below a pre-determined maximum gas pressure. The valve for adjustably regulating gas pressure has the ability to adjustably regulating gas pressure in two ranges of pressure settings. The two ranges including a low pressure range and a high pressure range. Transition from the low pressure range to the high pressure range requires activation of a pressure range actuation knob. There is a device for displaying the gas pressure and a device for modulating the gas pressure, both interfaced to the pressure relief valve. A patient interface port is connected to the device for displaying the gas pressure and to the device for modulating the gas pressure and provides modulated gas pressure to a patient. The device for modulating the gas pressure selectively controls administration of the gas pressure to the patient and both the device for displaying and the device for modulating the gas pressure are in close proximity to the patient. Close proximity is a term used to mean that both the device for modulating the gas pressure and the device for displaying the gas pressure are close enough to the patient that a caregiver need not look away or turn away from the patient to modulating the gas pressure or to read the current gas pressure from the device for displaying the gas pressure. All sub-components of the disposable support/resuscitation system are fabricated from non-ferromagnetic materials. 
         [0011]    In another embodiment, a disposable support/resuscitation system is disclosed including a pressure relief device that has an (e.g. industry standard) gas inlet and a gas output connector. The pressure relief device has a first pressure relief valve that opens at a setable gas pressure and a second pressure relief valve that opens at a pre-determined maximum gas pressure. The setable gas pressure is set by rotation of an adjustment knob within two pressure ranges such that rotation of the adjustment knob from a low pressure range of the two pressure ranges to a high pressure range of the two pressure ranges requires activation of a pressure range actuation button. The disposable support/resuscitation system includes a manometer and a gas delivery tube that fluidly connects the gas output connector to the manometer. A manually operated valve is also fluidly connected to the manometer and a patient interface port is connected to the manually operated valve. The manually operated valve selectively controls administration of pressurized gas from the gas inlet to the patient. The manometer and the manually operated valve are in close proximity to the patient to provide more accurate pressure readings, reduce administrator fatigue and reduce the need to look away from the patient. Close proximity is a term used to mean that both the manometer and the manually operated valve are close enough to the patient that a caregiver need not look away or turn away from the patient to operate the manually operated valve or to read the current gas pressure from the manometer. All sub-components of the disposable support/resuscitation system are fabricated from non-ferromagnetic materials. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention can be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which: 
           [0013]      FIG. 1  illustrates a schematic view of a resuscitation system of the prior art. 
           [0014]      FIG. 2  illustrates a perspective view of a disposable resuscitation system. 
           [0015]      FIG. 3  illustrates a view of the disposable resuscitation system in use in conjunction with an infant face mask. 
           [0016]      FIG. 4  illustrates a view of the disposable resuscitation system in use in conjunction with an infant tracheal tube. 
           [0017]      FIG. 5  illustrates a sectional view of a pressure relief device of the disposable resuscitation system. 
           [0018]      FIG. 6  illustrates an exploded view of a pressure relief device of the disposable resuscitation system. 
           [0019]      FIG. 7  illustrates a sectional view of a two-step pressure relief device of the disposable resuscitation system. 
           [0020]      FIG. 8  illustrates a second sectional view of a two-step pressure relief device of the disposable resuscitation system. 
           [0021]      FIG. 9  illustrates a view of an actuator button of the two-step pressure relief device. 
           [0022]      FIGS. 10, 11, and 12  illustrate views of a face of the two-step pressure relief device showing pressure reading pointer in various positions. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Throughout the following detailed description, the same reference numerals refer to the same elements in all figures. Throughout this document, the term “close proximity to the patient” means that the devices listed are close enough to the patient as to be monitored and operated without having to move away from the patient and/or without having to look away from the patient. This is important, for instance, when a patient is being resuscitated and it is important to constantly monitor the patient&#39;s color, breathing and the pressure in their lungs. 
         [0024]    Referring to  FIG. 1 , a schematic view of a resuscitation system of the prior art is shown. Resuscitation systems have a source of pressurized gas (e.g. pressurized air, oxygen, etc) such as an oxygen tank system  40 . Such sources of pressurized gas are well known and deliver sufficient gas pressure as to inflate a lung of a patient. The pressurized gas is fluidly coupled to an inlet  30  of a gas pressure control device  20 . Within the oxygen flow control device  20 , fluid pressure is monitored by a manometer  22  and a pressure is controlled by a maximum pressure valve  24  and a pressure adjustment valve  26 . The resulting controlled pressure gas exits from a gas outlet  28  through a gas delivery tube  16  that is often significant in length to reach the patient  100 . The gas delivery tube  16  is connected to a T-piece device  4  at an inlet port  14  and delivered to the patient  100  through a patient delivery port  10  that is connected to, for example, a face mask  8  covering the patient&#39;s mouth and nose. An adjustable finger valve  12  is operated by a finger  112  of the administration person  110  (e.g. doctor or nurse). The administrator  110  presses their finger  112  against the opening of the finger valve  12  to inflate the patient&#39;s  100  lungs and removes their finger  112  from the finger valve  12  to let the patient  100  exhale. In order to see the pressure reading on the manometer  22 , the administrator  110  looks away from the patient  100 . This distracts from carefully monitoring the patient  100  to observe lung activity, patient skin tone, obstructions to the air flow, etc. 
         [0025]    Additionally, only the gas delivery tube  16  (e.g. single-use patient supply lines), the T-piece device  4  and the face mask  8  (or tracheal tube—not shown) are disposable. Biological or chemical agents that make their way back into the gas pressure control device  20  are subject to be delivered, inadvertently, to the next patient since the gas pressure control device  20  is not disposable and is not easily sterilized. User manuals for some gas pressure control devices  20  include cleaning and service steps that only address cleaning and drying external surfaces. Should gas pressure from the source of pressurized gas drop suddenly (e.g. from a hospital supply system), back pressure from the patient&#39;s  100  lungs may push chemical or biological agents back into the gas pressure control device  20  and such may get inadvertently delivered to the next patient. The gas pressure control device  20  is not disposable and there is no apparent way to sterilize gas pressure control devices  20  between patients. 
         [0026]    Referring to  FIG. 2 , a perspective view of a disposable resuscitation system  50  for use in the vicinity of an MRI system is shown. Resuscitation systems have a source of pressurized gas  40  (e.g. pressurized air, oxygen, etc) such as an oxygen tank system  40 . Such sources of pressurized gas are well known and deliver sufficient gas pressure as to inflate a lung of a patient. 
         [0027]    The pressurized gas is fluidly coupled to an inlet of a pressure relief device  82  through a gas input coupling  86  as known in the industry. For use in the vicinity of an magnetic resonance imaging (MRI) system, it is anticipated that the source of pressurized gas  40  is located away from the magnetic resonance imaging (MRI) system, perhaps in a different room, and is coupled to the pressure relief device  82  through tubing, preferably non-ferromagnetic tubing. 
         [0028]    The pressure relief device  82  has one adjustable pressure relief valve that is controlled by an adjustment knob  84  and a second, fixed pressure relief valve that releases pressure at a pre-determined maximum pressure, thereby not permitting an output gas pressure to exceed the pre-determined pressure. 
         [0029]    The pressure relief device  82  is in fluid communication with a manometer  52  (pressure meter) and T-piece valve assembly  60 / 62 / 64 . In some embodiments, a colorimetric carbon dioxide detector  65  is in fluid communication with the patient interface port to detect proper intubation. A section of gas delivery tube  80  connects an output connector  88  on the pressure relief device  82  to an inlet port  70  of the T-piece valve assembly. The pressurized gas is then in fluid communication with the manometer  52 , the finger valve  60 / 62  and the patient port  64 . The patient port  64  is then interfaced to the patient  100  through, for example, a face mask  8  (see  FIG. 3 ) or a tracheal tube  6  (see  FIG. 4 ). The manometer  52  has an indicator  54  that moves around a hub  58  responsive to pressure values of the pressurized gas, pointing to gradients  56  indicative of the pressure at the patient  100 . The finger valve  60 / 62  is operated by, for example, a finger  112  of the administrator  110 . When finger  112  is pressed against the valve opening  62 , pressure increases and the patient&#39;s  100  lungs inflate and the pressure level is shown on the manometer  52 . When the finger  112  is released from the valve opening  62 , the pressure abates and the patient  100  exhales through the valve opening  62 . In some embodiments, the valve  60 / 62  is adjustable by turning the knob  60  to increase or decrease back pressure as the patient exhales. Such valves are known in the industry and any such valve that is operated by the administrator  110  is anticipated. 
         [0030]    Although a finger operated valve  60 / 62  is shown and preferred, any known valve is anticipated for modulating the gas pressure to the patient  100  including mechanical valves, electrically controlled valves, etc. 
         [0031]    U.S. Pat. No. 5,557,049 to Jeffrey B. Ratner describes a manometer for insertion into a patient ventilation system and is herein included by reference, though the disclosed manometer in U.S. Pat. No. 5,557,049 has metal, ferromagnetic resilient members that are not compatible with MRI systems. In this, the strong magnetic field of the MRI system will act upon the ferromagnetic resilient members within the manometer, generating false readings or, even worse, dislocate the manometer, potentially causing bodily harm. To overcome this problem, the manometer  50  is made without the inclusion of any ferromagnetic materials, in such the non-ferromagnetic resilient member (not visible), shaft (not visible), dial  54 , and all other components are made of a suitable, non-ferromagnetic material such as plastic. 
         [0032]    In some manometer/T-piece valve systems, a colorimetric carbon dioxide indicator  65  is disposed in the exhalation path. The colorimetric carbon dioxide indicator changes color under the presence of carbon dioxide and, since living beings exhale carbon dioxide, the color change is useful in determining that the patient is exhaling, indicating that a tracheal tube is properly inserted into the airway as opposed to being inserted in the esophagus. Alternately, it is anticipated that in some embodiments, additional ports are in fluid communication with the manometer/T-piece valve  50  for connection to an external carbon dioxide detector. 
         [0033]    Although not shown, it is anticipated that in some embodiments, a bacterial and/or viral filter is inserted in the gas supply path, thereby reducing flow of such agents back into the gas supply path or into the ambient air. When a filter is included, the filter is made from a non-ferromagnetic material. 
         [0034]    Although not shown, it is anticipated that in some embodiments, a nebulizer is fluidly inserted in the flow of gas for introducing a liquid mist into the gas. Such nebulizers are known in the industry and often include a nozzle and/or venturi to convert a liquid medication into a mist that is included in the gas supplied to the patient  100 . When a nebulizer is included, the nebulizer is made from a non-ferromagnetic material. 
         [0035]    Although not shown, it is further anticipated that in some embodiments, an injection port is included in fluid communication with the gas supply to allow injection of a fluid or gas directly to the patient  100  through the patient port  64 . When an injection port is included, the injection port is made from a non-ferromagnetic material. 
         [0036]    Referring to  FIG. 3 , a plan view of the disposable resuscitation system  50  in use in conjunction with an infant face mask  8  is shown. In this example, an infant or neonatal face mask  8  is interfaced to the patient port  64 . The administrator  110  (e.g. doctor) using the present invention need not look away from the patient  100  to determine gas pressure since the manometer  52  and finger valve  60 / 62  are at the location of the patient. When no longer needed, the resuscitation system  50  including the finger valve  60 / 62 , the manometer  52 , the gas tubing  80  and the pressure relief device  82 , as well as the face mask  8 , are disposed of according to hospital procedure. 
         [0037]    Referring to  FIG. 4 , a plan view of the disposable resuscitation system  50  in use in conjunction with an infant tracheal tube  6  is shown. In this example, an infant or neonatal tracheal tube  6  is interfaced to the patient port  64 . The administrator  110  (e.g. doctor) using the present invention need not look away from the patient  100  to determine gas pressure since the manometer  52  and finger valve  60 / 62  are at the location of the patient. When no longer needed, the resuscitation system  50  including the finger valve  60 / 62 , the manometer  52 , the gas tubing  80  and the pressure relief device  82 , as well as the tracheal tube  6 , are disposed of according to hospital procedure. 
         [0038]    Referring to  FIG. 5 , a sectional view of a pressure relief device  82  of the disposable resuscitation system  50  is shown. To enable disposability, the pressure relief device  82  is of minimal size, cost, complexity, weight, etc, thereby allowing efficient disposal at minimal cost. The pressure relief device  82  accepts pressurized gas (e.g. air, oxygen) at a, preferably, industry standard gas supply fitting  86 . Pressurized gases flow through the pressure relief device  82  and exit to a gas tube fitting  88  that is fluidly coupled to the manometer  52 , finger valve  60 / 62  and patient port  64 . It is important to limit the amount of gas pressure injected into a patient&#39;s  100  lungs. As pressure backs up from the patient  100  (e.g. the patient&#39;s  100  lungs fill), the first pressure relief valve  84 / 90 / 92 / 94  provides an adjustable pressure release. The administrator  110  turns the knob  84  which is threaded in a vented cover  103  of the housing  97  of the pressure relief device  82 . As the knob  84  is turned in one direction, by way of a screw action, it screws inwardly into the pressure relief device  82 , further compressing the non-ferromagnetic resilient member  90 . The more force on the non-ferromagnetic resilient member  90 , the more gas pressure needed to overcome the force of the non-ferromagnetic resilient member  90  to vent the gas pressure out between the valve cover  92  and the valve seat  94 . As the knob  84  is turned in the opposite direction, the force on the non-ferromagnetic resilient member  90  is abated and less gas pressure is needed to overcome the force of the non-ferromagnetic resilient member  90 . 
         [0039]    A second valve  96 / 98 / 101  is provided as a maximum pressure release should the first valve  84 / 90 / 92 / 94  fail or be adjusted to a dangerous pressure level. The second valve  96 / 98 / 101  is housed within a surface  99  that includes vent holes. A second non-ferromagnetic resilient member  96  holds the second valve cover  98  against a second valve seat  101 . If the gas pressure exceeds a pre-determined maximum pressure, the gas pressure pushing against the second valve cover  98  overcomes the force of the second non-ferromagnetic resilient member  96 , allowing gas to escape out of vent holes in the surface  99  until the gas pressure decreases, at which time the second non-ferromagnetic resilient member  96  has sufficient force as to close the second valve cover  98  against the second valve seat  101 . In the example shown, the pressurized air flows between the outer case  97  and an inner case  95  and is routed to the first valve  84 / 90 / 92 / 94  and the second valve  96 / 98 / 101 . 
         [0040]    For proper operation in the vicinity of an MRI system, all components of the pressure relief device  82  are made of a suitable, non-ferromagnetic material such as plastic. This includes the non-ferromagnetic resilient members  90 / 96 , knob  84  and all other components. 
         [0041]    Referring to  FIG. 6 , an exploded view of a pressure relief device  82  of the disposable resuscitation system  50  is shown. The standard gas supply fitting  86  connects to the outer case  97 . The gas tube fitting  88  is connected to or formed on an outer surface of the outer case  97 . The first pressure relief valve  84 / 90 / 92 / 94  includes the knob  84  which is threaded in the vented cover  103  of the housing  97 . The knob  84  is mechanically interfaced with the non-ferromagnetic resilient member  90 , providing adjustable force on the non-ferromagnetic resilient member  90 . The knob  84  is interfaced with a pointing member  91  that indicates a position of the knob  84 , and therefore, a pressure setting. 
         [0042]    The non-ferromagnetic resilient member  90  exerts force on the valve cover  92 , holding the valve cover  92  against the valve seat  94  until gas pressure forces the valve cover  92  away from the valve seat  94 . The second valve  96 / 98 / 101  is housed within a surface or cover  99  that also includes vent holes. The second non-ferromagnetic resilient member  96  holds the second valve cover  98  against a second valve seat  101  (not visible). 
         [0043]    Again, for proper operation in the vicinity of an MRI system, all components of the pressure relief device  82  are made of a suitable, non-ferromagnetic material such as plastic. This includes the non-ferromagnetic resilient members  90 / 96 , knob  84  and all other components. 
         [0044]    Referring to  FIGS. 7, 8, and 9 , sectional views of a two-step pressure relief device  82 A of the disposable resuscitation system are shown. In  FIG. 7 , the actuator button  200  has not been pressed and is in the blocking position while in  FIG. 8 , the actuator button  200  has been pressed and is in the enabling position.  FIG. 9  shows details of the actuator button  200 . 
         [0045]    The pressure relief device  82 A accepts pressurized gas (e.g. air, oxygen) from a supply fitting  86  (preferably, industry standard). 
         [0046]    Pressurized gases flow through the pressure relief device  82 A and exit to a gas tube fitting  88  that is fluidly coupled to the manometer  52 , finger valve  60 / 62  and patient port  64 . It is important to limit the amount of gas pressure injected into a patient&#39;s  100  lungs. As pressure backs up from the patient  100  (e.g. the patient&#39;s  100  lungs fill), the first pressure relief valve  84 / 90 / 92 / 94  provides an adjustable pressure release. The administrator  110  turns the adjustment knob  84  which is threaded in a vented cover  103  of the housing  97  of the pressure relief device  82 A. As the adjustment knob  84  is turned in one direction, by way of a screw action, it screws inwardly into the pressure relief device  82 A, further compressing the non-ferromagnetic resilient member  90 . The more force on the non-ferromagnetic resilient member  90 , the more gas pressure needed to overcome the force of the non-ferromagnetic resilient member  90  to vent the gas pressure out between the valve cover  92  and the valve seat  94 . As the knob  84  is turned in the opposite direction, the force on the non-ferromagnetic resilient member  90  is abated and less gas pressure is needed to overcome the force of the non-ferromagnetic resilient member  90 . 
         [0047]    A second valve  96 / 98 / 101  is provided as a maximum pressure release should the first valve  84 / 90 / 92 / 94  fail or be adjusted to a dangerous pressure level. The second valve  96 / 98 / 101  is housed within a surface  99  that includes vent holes. A second non-ferromagnetic resilient member  96  holds the second valve cover  98  against a second valve seat  101 . If the gas pressure exceeds a pre-determined maximum pressure, the gas pressure pushing against the second valve cover  98  overcomes the force of the second non-ferromagnetic resilient member  96 , allowing gas to escape out of vent holes in the surface  99  until the gas pressure decreases, at which time the second non-ferromagnetic resilient member  96  has sufficient force as to close the second valve cover  98  against the second valve seat  101 . In the example shown, the pressurized air flows between the outer case  97  and an inner case  95  and is routed to the first valve  84 / 90 / 92 / 94  and the second valve  96 / 98 / 101 . 
         [0048]    In many applications there is a preferred pressure range such as from zero to 40 centimeters of water (cm H 2 O) that is normal, with a need to increase the pressure into another, higher pressure range during rare occurrences, perhaps increasing the pressure within a range of 40 to 60 centimeters of water (cm H 2 O). For some patients, inadvertently adjusting the pressure over the preferred pressure range is apt to place the patient in danger, as this may be too much pressure, especially for tiny lungs of a pre-mature baby. To accomplish such, a pressure range actuator button  200  is provided. The pressure is settable in the first range (e.g. 0-40 cm H 2 O) by turning the adjustment knob  84 . As the adjustment knob  84  is turned, the pressure reading pointer  91  indicates the relative pressure setting (e.g., on a color-coded ring, green being safe, yellow being marginal). As the pointer  91  reaches the end of the marginal zone (e.g. around 40 cm H 2 O), the pointer is blocked by a selective blocking portion  202  of the pressure range actuator button  200 . As shown in  FIG. 7 , the pressure range actuator button  200  has not been pressed, and therefore, the selective blocking portion  202  does not permit the pressure reading pointer  91  to pass, thereby preventing adjustment of the pressure into the second pressure range (e.g. color coded on the ring as red). In instances where increased pressure is needed, the pressure range actuator button  200  is depressed (as shown in  FIG. 8 ) and the selective blocking portion  202  moves out of the way of the pressure reading pointer  91  and enter the second pressure range. Another non-ferromagnetic resilient member  204  biases the pressure range actuator button  200  towards the blocking position. 
         [0049]    In some embodiments, the selective blocking portion  202  of the pressure range actuator button  200  is sloped as shown (e.g. a 45 degree slope). As such, the selective blocking portion  202  blocks rotation of the pressure reading pointer  91  as it is rotated clockwise towards the second pressure zone, but after the pressure range actuator button  200  is pressed to allow the pressure reading pointer  91  to enter the second pressure zone (higher pressure) and the pressure range actuator button  200  is released, as the adjustment knob  84  is rotated toward the first pressure range (e.g. counter clockwise direction), when the pressure reading pointer  91  contacts the slope of the selective blocking portion  202 , the pressure reading pointer  91  causes the selective blocking portion  202  to temporarily displace, allowing the pressure reading pointer  91  to move to the first pressure range (lower pressure) without depression of the pressure range actuator button  200 . 
         [0050]    In alternate embodiments, the pressure range actuator button  200  remains in the pressed position (as shown in  FIG. 8 ) until the adjustment knob  84  is turned until the pressure reading pointer  91  enters the first pressure range, at which time, the pressure range actuator button  200  returns to the blocking position and, if needed, must be pressed again to re-enter the second pressure range. 
         [0051]    Although the examples shown utilize the pressure reading pointer  91  to interface/interfere with the selective blocking portion  202 , it is fully anticipated that in alternate embodiments, another feature interface to the adjustment knob  84  interfaces/interferes with the selective blocking portion  202 . 
         [0052]    For proper operation in the vicinity of an MRI system and improved recyclability, all components of the pressure relief device  82 A are made of a suitable, non-ferromagnetic material such as plastic. This includes the non-ferromagnetic resilient members  90 / 96 , knob  84  and all other components. 
         [0053]    Equivalent elements can be substituted for the ones set forth above such that they perform in substantially the same manner in substantially the same way for achieving substantially the same result. 
         [0054]    It is believed that the system and method as described and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely exemplary and explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.