Patent Abstract:
An inventive apparatus and method as disclosed for the automatic identification of a given one of a predetermined plurality of cuff assemblies interconnectable to a sphygmomanometer for use in a blood pressure measurement procedure. The invention provides for the obtainment of a pressure measurement(s) during deflation of an inflatable cuff, and utilization of such measurement(s) to identify the cuff assembly. More particularly, each different cuff assembly may be provided with a corresponding gas-flow restrictor which allows the pressure measurement(s) made during deflation of a given cuff assembly to be correlated in fashion that allows for identification. Preferably, first and second pressure transducers are provided for automatic pressure measurements both upstream and downstream of a cuff assembly during the deflation portion of a cuff identification operation. The upstream and downstream pressure measurements may be utilized to calculate a sequence of ratio values which in turn may be employed in the cuff identification procedure.

Full Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of non-invasive blood pressure measurement, and more particularly to a method and apparatus for automatically identifying a given one of a predetermined plurality of non-invasive blood pressure cuffs employable in a sphygmomanometric system. 
     BACKGROUND OF THE INVENTION 
     The use of automated sphygmomanometers for the measurement of blood pressure typically entails the placement of an inflatable cuff about an arterial vessel of a body appendage, e.g. the upper arm of a patient. The cuff contains an inflatable bladder which is positioned around the appendage and inflated via an air pump. The inflated bladder provides a constricting pressure against the blood inside the artery. The inflation pressure is generally established to be above a patient&#39;s systolic pressure and should serve to partially occlude the artery. After inflation, gas may be slowly bled from the inflated cuff to gradually reduce the pressure acting upon the artery. During deflation, pressure perturbations, or oscillometric pulses, generated by the partially-occluded artery may be transmitted through the cuff gas supply line for sensing. The sensed pulses may then be analyzed to allow for calculation of the systolic, diastolic and/or mean arterial pressure(s) of a patient, as well as the heart rate of a patient. 
     It should be noted that, if the pressure of the inflated cuff significantly exceeds a patient&#39;s systolic pressure, blood flow may be unacceptably impeded for purposes of obtaining meaningful measurements. Additionally, high inflation pressures may cause patient discomfort. On the other hand, if the cuff pressure is insufficient, arterial occlusion may be insufficient to yield oscillometric pulses in a pressure range that allows accurate measurements to be taken. 
     As will be appreciated, the initial inflation pressure desirable for a given patient (e.g. to achieve the desired arterial occlusion) will depend upon the physical attributes of the patient. Specifically, the desired inflation pressure will normally increase with the size of the patient. 
     The establishment of the desired cuff pressure is closely correlated to the size of a given cuff (e.g. the circumference thereof). It is important to use a cuff which is large enough to distribute the bladder over a relatively large surface area so that the resulting inflation pressure will be largely uniform. Thus, a properly fitted cuff on an adult will be larger than a properly fitted cuff on a child, and a properly fitted cuff on a child will be larger than a properly fitted cuff on a neonate. 
     In this regard, it is recognized that medical personnel will generally select the cuff size deemed most appropriate for a given patient. It is also recognized that for the given cuff size selected by medical personnel there will be a corresponding inflation pressure, or range of pressures, desirable for achieving the above-noted partial arterial occlusion appropriate for blood pressure measurement. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, a primary objective of the present invention is to provide a method and apparatus that provides for the automatic identification of a given one of a predetermined plurality of non-invasive blood pressure cuffs employed in a given blood pressure measurement procedure. Such identification facilitates selection of a desirable initial inflation pressure to be utilized in the blood pressure measurement procedure. 
     An additional objective of the present invention is to provide for automatic cuff identification in a manner that does not compromise the flexibility or application of the blood pressure measurement system. 
     Yet a further objective of the present invention is to provide for automated cuff identification in a manner that is both convenient and reliable. 
     One or more of the above objectives and additional advantages are realized in the inventive method and apparatus of the present invention that provide for a cuff identification operation prior to a blood pressure measurement procedure. The inventive method includes the steps of inflating, at least partially, an inflatable cuff in a pneumatic circuit by flowing gas thereinto; and deflating, at least partially, the inflatable cuff by passing at least a portion of the gas out of the inflatable cuff. The method further provides for the obtainment, during the deflating step, of at least one gas pressure measurement in the pneumatic circuit. Such gas pressure measurement may then be utilized to identify the inflatable cuff being utilized. Preferably, the gas pressure measurement is obtained downstream of the inflatable cuff. 
     In conjunction with the inventive method, a first pressure measurement means may be employed in the pneumatic circuit to obtain the downstream pressure measurement(s), and the deflation step may further provide for the passage of the gas through a gas-flow restriction means (e.g. a member having a shaped orifice therethrough) interconnected with the pneumatic circuit upstream from the first pressure measurement means. More particularly, the gas-flow restricting means may be located downstream from the inflatable cuff, and fixedly interconnected therewith. In the later regard, it should be noted that each of a predetermined plurality of inflatable cuffs employable with the present invention may be provided with a corresponding different one of a predetermined plurality of corresponding gas-flow restrictors, wherein each of the restrictors serves to restrict, or resist, gas flow therethrough to a differing, discernable degree, thereby facilitating automatic cuff identification. 
     In a related aspect of the inventive method, the deflation step may provide for both the passage of the gas through a first gas-flow restriction means that is located in the pneumatic circuit upstream from the first pressure measurement means and downstream from the inflatable cuff (e.g. fixedly interconnected therewith), and the passage of the gas through a second gas-flow restriction means interconnected with the pneumatic circuit downstream of the first pressure measurement means. The deflation step may also provide for the selective opening of a bleed valve located in the pneumatic circuit downstream of the second gas-flow restricting means, e.g., wherein the bleed valve may be controlled to provide for a gradual, linear release of gas from the pneumatic circuit. In the later regard, it should be noted that second gas-flow restricting means may actually comprise a bleed valve that is operable to provide a desired degree of gas-flow resistance when opened, thereby obviating the need for a separate gas-flow restrictor and release valve. 
     The inventive method may further provide for conducting at least one gas pressure measurement in the pneumatic circuit upstream of the inflatable cuff (e.g. via the use of a second gas pressure measurement means). Such upstream pressure measurement(s) may then be utilized with the downstream pressure measurement(s) to determine a measurement, e.g. a value corresponding with a ratio therebetween. In turn, such ratio value may be utilized in the cuff identification step. 
     In another aspect of the inventive method, the inflating step may provide for the inflation of a cuff to a degree corresponding with a first predetermined pressure (e.g. as measured by the first pressure measurement means), and the deflating step may provide for cuff deflation to a degree corresponding with at least a second predetermined pressure. The obtainment of downstream pressure measurement(s) may be terminated upon at least one of two conditions. First, the obtaining step may be terminated when the inflatable cuff has deflated to a degree corresponding with the second predetermined pressure. Alternatively, the obtaining step may be terminated when a predetermined amount of time has lapsed after initiation of the deflating step. Preferably, the obtaining step will be terminated upon the earliest of the two above-noted conditions. 
     In one arrangement, the inventive method provides for the obtainment of a plurality of pressure measurements both upstream and downstream of the inflatable cuff during the deflating step, such upstream and downstream pressure measurements being obtained in a synchronous , paired fashion. The pairs of upstream and downstream pressure measurements are then utilized to determine a corresponding plurality of ratio values. The plurality of ratio values may be utilized in a predetermined algorithm to determine an average ratio value, a maximum ratio value and a minimum ratio value. The average ratio value may be employed to identify the inflatable cuff being utilized, which in turn allows for the automatic selection of an appropriate initial inflation pressure to be utilized in the actual blood pressure measurement procedure that follows. In this regard, the average ratio value may be compared with predetermined reference ratio value ranges (e.g. corresponding with each potential cuff to be identified) in the cuff identification operation. For example, cuff #1 (e.g. for neonates) may have a first predetermined reference value range; cuff #2 (e.g. for children) may have a second predetermined reference value range that is greater than the first range and separated therefrom by a predetermined “guard band”; cuff #3 (e.g. for adults) may have a third predetermined ratio value range that is greater than the first and second ranges and separated from the second range by a predetermined “guard band”; and cuff #4 (e.g. for obese patients) may have a fourth predetermined ratio value range that is greater than the first, second and third ranges and separated from the third range by a predetermined “guard band”. In the event that a given average ratio value falls within a “guard band”, the method may provide for reinitiation of the cuff identification operation and/or termination of the operation with an indication provided to the user (e.g. a message display after a predetermined sequence of “guard band” readings). 
     The maximum and minimum measured ratio values may be employed to ensure the integrity of the cuff identification. That is, for example, if the difference between the maximum ratio value and the minimum ratio value exceeds a predetermined reference value, the cuff identification operation may be reinitiated and/or a corresponding indicator may be otherwise provided to a user (e.g. a display message after a predetermined number of iterations). 
     In accordance with the described arrangement, the inventive method may further provide for a predetermined delay period between the inflation step and the deflation step of the cuff identification operation. During such predetermined time period, gas pressure measurements may be obtained both upstream of the inflatable cuff and downstream of the inflatable cuff (e.g. via the first and second measurement means). Such measurements may then be compared to ensure the integrity of the pneumatic circuit. In the event that such comparison indicates a difference that exceeds a predetermined reference value, the method may provide for an automatic response. By way of example, such response may include the provision of an indication to a user (e.g. to check for pneumatic line kinks, etc.), reinitiation of the cuff identification operation and/or termination of the cuff identification operation. 
     In conjunction with the present invention, an inventive apparatus is also provided for identifying at least one inflatable cuff interconnectable to a sphygmomanometer. The apparatus comprises inflation and deflation means, interconnectable in a pneumatic circuit with an interconnectable inflatable cuff, for selectively inflating and deflating the cuff. The apparatus further includes a processor preprogrammed to automatically receive at least one pressure measurement from a first pressure measurement means in the pneumatic circuit during operation of the deflation means in a cuff identification operation. The processor is further preprogrammed to automatically employ the pressure measurement to identify the given inflatable cuff interconnected to the apparatus. Preferably, the first pressure measurement means is located in the pneumatic circuit downstream of the interconnectable cuff. 
     As will be appreciated, the processor means may be operatively interconnected with the inflation means and deflation means and preprogrammed to control the operation of each in the cuff identification operation. More particularly, the processor means may be preprogrammed to successively operate an air pump comprising the inflation means, and open a bleed valve comprising a deflation means. 
     The inventive apparatus may further include a second pressure measurement means for obtaining at least one pressure measurement in the pneumatic circuit upstream of the interconnectable inflatable cuff. The second pressure measurement means may also be interconnected with the processor means, wherein the processor is preprogrammed to automatically receive at least one upstream pressure measurement (i.e. relative to the inflatable cuff) and at least one downstream pressure measurement (i.e. relative to the inflatable cuff), and to automatically calculate a ratio therebetween. Most preferably, a plurality of upstream and downstream pressure measurements will be synchronously obtained by the processor in corresponding pairs, wherein each pair is utilized to determine a corresponding ratio value for use in cuff identification. 
     Of note, the interconnectable inflatable cuff may be fixedly and pneumatically attached to a first gas-flow restricting means (e.g. a gas orifice), wherein the first gas-flow restricting means restricts the flow of gas therethrough at a predetermined resistive level. In this regard, the inventive apparatus may be provided to identify any given one of a predetermined plurality of inflatable cuffs when interconnected in the pneumatic circuit, wherein each of the predetermined plurality of inflatable cuffs is fixedly and pneumatically interconnected to a corresponding one of a plurality of gas-flow restricting means, each of said gas-flow restricting means being different. 
     To normalize the various pressure measurements obtainable in conjunction with cuff identification, the inventive apparatus may further include a second gas-flow restricting means. More particularly, the second gas-flow restricting means may be located in the pneumatic circuit downstream of the interconnectable cuff, first gas-flow restricting means, and/or second pressure measurement means. As noted, the second gas-flow restricting means may comprise a bleed valve. When a separate restrictor and bleed valve are employed, the restrictor means may be provided upstream of the bleed valve. 
     In view of the foregoing, it should be appreciated that an overall inventive system may also be provided for use in obtaining blood pressure measurements. Such system may include a predetermined plurality of inflatable cuffs, each of the predetermined cuffs being fixedly and pneumatically interconnected to a corresponding one of a plurality of gas-flow restricting means, wherein each of the gas-flow restricting means restricts the flow of gas therethrough to a differing degree. The system may further include a monitor that is pneumatically interconnectable to any one of the predetermined plurality of inflatable cuffs. The monitor may house inflation means and deflation means for selectively inflating and deflating, respectively, a given, interconnected one of the predetermined plurality of inflatable cuffs. The monitor is operable to automatically identify the given connectable one of the predetermined plurality of inflatable cuffs based upon at least one pressure measurement obtained during operation of the deflation means in a cuff identification operation. The monitor may include first and second pressure measurement means, as previously noted, to obtain a corresponding plurality of upstream and downstream pressure measurements (i.e. relative to the given interconnected inflatable cuff). Outputs from the first and second pressure measurement means may then be employed (e.g. in a ratio value) to provide a relative measure of the pressure drop between the first and second pressure measurement means across the gas-flow restricting means of the given interconnected, inflatable cuff. Again, a processor may be provided for automatically controlling operation of the inflation means and deflation means, for automatically receiving measurements from the first and second pressure measurement means, and for automatically utilizing the measure values to identify the interconnected cuff. 
     Numerous advantages are provided by the present invention. In particular, the inventive method and apparatus accommodate the use of varying lengths of pneumatic lines to interconnect a cuff and a monitor while monitoring accuracy in cuff identification. Similarly, the present invention yields high accuracy regardless of variations in the tightness or quality of the wrap of a given cuff about a patient appendage. Similarly, accuracy of the present invention is maintained despite wear of the inflation means employed (e.g. an air pump). Finally, the present invention is relatively easy and inexpensive to implement and lends itself to a variety automated approaches for enhancing overall reliability. Numerous additional advantages and aspects of the present invention will become apparent upon consideration of the further description that follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 schematically illustrates a pneumatic circuit of interconnected components in one embodiment of the present invention. 
     FIG. 2 presents a signal flow schematic corresponding with the embodiment of FIG.  1 . 
     FIGS. 3A-3C present a process diagram corresponding with the operation of embodiment of FIG.  1 . 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 schematically illustrates one embodiment of the present invention comprising an inflatable cuff assembly pneumatically interconnected to a monitor  100  via a dual-lumen hose  200 . 
     Cuff assembly  10  is an exemplary one of a predetermined plurality of different cuff assemblies employable with monitor  100  in a fashion that allows monitor  100  to automatically identify the particular given cuff assembly interconnected thereto. By way of primary example, the predetermined plurality of cuff assemblies may vary in size (e.g. corresponding with obese/very large patients, normal adults, normal children, neonates) and/or corresponding intended application (e.g. arm, leg, finger, etc) and/or manufacturer. The exemplary cuff assembly  10  includes an inflatable cuff  20  sized for selective positioning about a predetermined patient appendage (e.g. an arm portion, leg portion, finger, etc.). The cuff  20  may comprise an inflatable bladder and an exterior cover adapted for bodily contact. The cuff  20  may also include a securing means (e.g. a hook and loop patch with interfacing strips) for selectively securing the cuff  20  to the intended patient appendage (e.g. via wrapping the cuff  20  about the appendage). Cuff assembly  10  further includes a cuff plug  30  pneumatically and fixedly interconnected to cuff  20  via a single-lumen line  50  (e.g. comprising soft, flexible rubber or plastic tubing) for inflating/deflating cuff  20 . In other arrangements, a dual-lumen tubing could be utilized in place of the single-lumen line  50 , wherein the separate lines are used for inflation and deflation. 
     As schematically shown in FIG. 1, cuff plug comprises a housing  32  and gas-flow circuit lines  34  and  36  which are pneumatically interconnected at a distal end for gas-flow through port  38  to/from the single-lumen line  50 . Gas-flow line  34  and gas-flow line  36  each separately terminate at then proximal ends at an interconnection port  40  that is adapted for selective, pneumatic circuit interconnection/disconnection with a first connection port  202  of dual-lumen hose  200 , wherein lumen  206  of hose  200  is pneumatically interconnectable to gas-flow line  34  and lumen  208  of hose  200  is pneumatically interconnectable to gas-flow line  36 . In turn, a second connection port  204  of dual-lumen hose  200  may be provided for selective, pneumatic circuit interconnection/disconnection with a connection port  102  provided at monitor  100 . Alternatively, port  40  of the cuff plug may be provided for direct interconnection/disconnection with port  102  of the monitor  100 . As will be appreciated, ports  40 ,  202 ,  204  and  102  may be provided with registration means to facilitate the desired pneumatic interconnections upon adjoinment. 
     Cuff plug  30  further comprises a gas-flow restrictor  42  (e.g. a plug member having a shaped orifice) positioned in gas-flow line  36  so as to restrict the flow of gas therethrough. Gas-flow restrictor  42  functions to identify the particular interconnected cuff assembly  10 . In this regard, a predetermined plurality of cuff assemblies may be utilized, wherein each of the corresponding cuff plugs is provided with a differently sized gas-flow restrictor. For example, wherein the smaller the size of the corresponding cuff  20  the greater the flow resistence provided by the corresponding gas-flow restrictor  42 . 
     Turning now to the monitor  100  shown in FIG. 1, a gas-flow pump  104  is provided for supplying gas through a first flow line  106  to port  102  to inflate an interconnected cuff  20 . More particularly, pump  104  may be selectively operated so as to draw gas (e.g. air) through an intake port  108  and particulate filter  110 , and to pump such gas through a second particulate filter  112  in first flow line  106 . In turn, gas pumped through first flow line  106  may flow on through the gas flow line  34  of an interconnected cuff assembly  30 . Such flow may pass directly via ports  102  and  40 , or via ports  102 ,  204 ,  40  and first lumen line  206  when dual lumen hose  200  is employed. The first flow line  106  may be also pneumatically interconnected via dump line  114  to a dump valve  116  within monitor  100  for selectively exhausting gas through first flow line  106  to exhaust port  118 . Additionally, a gas pressure sensor  120  (e.g. a pressure transducer) may be pneumatically interconnected to first flow line  106  to selectively measure the gas pressure therewithin. 
     Monitor  100  further includes a second flow line  126  having one end that terminates in connection port  102 . Such end of the second flow line  126  is disposed for selective pneumatic interconnection with the second lumen  208  of the dual lumen hose  200 , when employed, or directly with gas-flow line  36  of cuff plug  30 . As shown in FIG. 1, second flow line  126  passes through a gas-flow restrictor  128  (e.g. an orifice member) to bleed valve  130 . Bleed valve  1 is operable to selectively exhaust gas passing through second flow line  126  to exhaust port  132 . Of note, a gas pressure sensor  134  (e.g. a pressure transducer) is pneumatically interconnected to second flow line  126 , upstream from the gas-flow restrictor  128 . In other embodiments, the bleed valve  130  may be provided to integrally function as gas-flow restrictor (e.g., via a controlled gas release), thereby obviating the need for restrictor  128  so as to reduce part count. In such embodiments, gas pressure sensor  134  may be located just upstream from the bleed valve  130 . 
     As will be appreciated, the above-described cuff assembly and monitor  100 , as well as dual lumen hose  200  when employed, define a pneumatic circuit in which gas is pumped through first flow line  106 , first lumen  206  (if hose  200  is employed), gas-flow line  34  and line  50  to inflate cuff  20 . The pneumatic circuit further provides for the flow of gas through line  50 , gas-flow line  36 , second lumen  208  (if hose  200  is employed), and second flow line  126  during deflation of inflatable cuff  20 . 
     Referring now to FIG. 2, a signal flow schematic of monitor  100  is illustrated. In particular, a processor  140  is interconnected with memory  142  and clock  144  to provide for automatic control, monitoring and response to the various flow control and measurement components of monitor  100 , including in particular, pump  104 , the first and second pressure sensors  120  and  134 , dump valve  116  and bleed valve  130 . Additionally, monitor  100  may include a display output  150  and user input controls  152  to provide preprogrammed functionalities and user selected functionalities as will be described further hereinbelow. 
     Operation of the illustrated embodiment will now be described with reference to FIGS. 3A-3C in combination with FIGS. 1 and 2. As will be appreciated, an automatic cuff identification operation will be normally initiated at the outset of a blood pressure measurement procedure, but prior to actual blood pressure measurement. 
     To initiate the procedure, monitor  100  is turned on, a given cuff assembly is secured to a patient (e.g. wrapping cuff  20  about the patient&#39;s arm), and cuff assembly  10  is pneumatically interconnected to monitor  100 . For example, connector  40  may be directly interconnected with connector  102  of monitor  100 , or connector  40  may be interconnected with connector  202  of a dual lumen hose  200 , and connector  204  of the dual lumen hose  200  may be interconnected with connector  102  of monitor  100 . Hose assembly  200  may be provided in a wide range of varying lengths. 
     In conjunction with the initial interconnections, the pneumatic inflation/deflation circuit is allowed to reach a quiescent state, wherein valves  116  and  130  are open and pump  104  is off. In this regard, it should be noted that monitor  100  may be provided so that a given cuff identification operation may be automatically undertaken upon start-up, or alternatively, so that such operation may be manually initiated via a user input at control  152  of monitor  100 . Similarly, monitor  100  may be provided so that an initiated operation may be selectively overridden by a user via user input controls  152 . 
     To ensure that the cuff  20  is adequately deflated for the identification procedure, one or more pressure readings may be taken at the first pressure sensor  120 . More particularly, a plurality of pressure readings may be taken by sensor  120  (e.g. over a one second time period) and received by preprogrammed processor  146  for computation of a mean measured value. Such value may then be compared to a predetermined acceptable value (e.g. 20 torr). In the event that the measured value exceeds the predetermined acceptable value, the test may be repeated for a predetermined number of times and/or over a predetermined period. If the test is not passed, the automated cuff identification procedure may be automatically terminated and an error message may be displayed at the display output  150  of monitor  100 . 
     Assuming the cuff deflation test is passed, processor  140  may then affect the closure of valves  116  and  130 . Thereafter, processor  140  may transmit appropriate control signals to pump  104  so as to initiate the operation thereof in accordance with a predetermined, ramped drive protocol. By way of example, pump ramping may begin at a predetermined first duty cycle (e.g. 25%), and then increased by a predetermined percentage (e.g. 2%) for each predetermined time increment (e.g. each ten milliseconds) up to a maximum predetermined duty cycle (e.g. 100%). Such ramping function may reduce over-inflation instances associated with certain types of cuffs. 
     In conjunction with the ramped-up operation of pump  104 , the second pressure sensor  134  may take pressure readings on an ongoing basis to monitor the pressure within the pneumatic circuit, and in particular the pressure downstream of cuff  20 . As will be appreciated, such readings may be received by processor  140  for preprogrammed processing. When the pressure monitored by second pressure sensor  134  reaches a predetermined level (e.g. 50 torr), processor  140  may transmit control signals to terminate operation of pump  104 . After the pump has been turned off, pneumatic circuit pressure may be allowed to equalized during a predetermined wait period (e.g. 0.5 seconds). During this period, valves  116  and  130  should remain closed. 
     After the delay, a test may be conducted to determine whether any of the pneumatic lines are blocked or may have a leak. Such test may be performed at processor  140  via a comparison of pressure readings taken by sensors  120  and  134  and received by processor  140 . If the difference between the first and second sensor  120 ,  134  readings exceeds a predetermined level, such difference may indicate a blockage or a leak within the pneumatic circuit and an error message may be provided at display output  150 . A user may then check for blockage or leakage, and depending upon the results of such investigation, may re-initiate the cuff identification operation or take other steps as may be appropriate in the given situation. 
     Assuming circuit line integrity is confirmed, processor  140  may then effect the opening of bleed valve  130  to a predetermined degree (e.g. a fully open position), while dump valve  116  is maintained in a closed state. Upon the opening of bleed valve  130 , gas restrictor  128  provides a desired degree of gas flow resistance, thereby enhancing the measurement process (e.g., by normalizing the pressure reading to be taken). As previously noted, bleed valve  130  may be provided to function as restrictor  128 , e.g., via controlled opening of the valve to a predetermined degree appropriate to establish the desired gas flow resistance. As gas is released from valve  130 , pressure readings from both pressure sensor  120  and pressure sensor  134  may be obtained in synchronous pairs at processor  140  . Such pressure readings may be processed until the first of the following occurs: 
     i) the pressure monitored by first pressure sensor  120  drops below a predetermined level (e.g. 30 torr); or 
     ii) a predetermined time period elapses from opening the bleed valve  130  (e.g. 0.5 seconds). 
     The above-noted pairs of pressure readings from the first sensor  120  and second sensor  134  may be processed by processor  140  to identify the given interconnected cuff  20 . Such processing may provide for a comparison of the paired values. In one approach, such comparison may entail the computation of a ratio therebetween. In turn, the computed ratios for each of the plurality of synchronous pressure reading pairs may be employed to compute maximum, minimum and mean ratio values. As will be appreciated, such values will depend upon the degree of gas flow restriction through restrictor  32  of the given cuff assembly interconnected to monitor  100 . As such, such values may be utilized by processor  140  (e.g. via reference to a predetermined look-up table stored at memory  142 ) to automatically identify which of the predetermined plurality of cuff assemblies is being employed. 
     In order to enhance the accuracy of cuff identification, processor  140  may be preprogrammed so that if a given mean ratio value falls between reference values corresponding with two different interconnectable cuff assemblies  10 , processor may automatically provide for the display of an error message at display output  150  and/or a reinitiation of the cuff identification operation. More particularly, where a look-up table approach is employed for cuff identification at processor  140 , “guard bands” may be utilized in the look-up table of predetermined reference values corresponding with the various predetermined plurality of cuff assemblies. For example, the look-up table may provide a plurality of non-overlapping ranges of reference values, wherein each of the ranges corresponds with one of a predetermined plurality of different sizes of cuff assemblies  10  (e.g. and corresponding different restrictors  32 ), and wherein the various ranges are separated by predetermined “guard bands”. In the event that a given measured mean ratio value falls within a “guard band” of the look-up table, the processor  140  may be preprogrammed so as to provide an appropriate message at display output  150  and to reinitiate the cuff identification operation. 
     As noted, processor  140  may also compute maximum and minimum ratio values from the paired readings received from first sensor  120  and second sensor  134 . Such maximum and minimum ratio values may be employed to reduce misidentification instances. In particular, processor  140  may be preprogrammed to compare the maximum and minimum ratio values and to determine whether a difference therebetween exceeds a predetermined threshold value. In this regard, it is recognized that wide variations between the maximum value and minimum value may indicate excessive patient motion during the cuff identification operation, which in turn may lead to an incorrect cuff identification. As such, the threshold value may be selected so that if the difference between the maximum and minimum ratio values exceeds such threshold value, an error message is displayed at display output  150  and/or the cuff identification operation is reinitiated. 
     Upon identification of a given cuff assembly  10 , the processor  140  may effect closure of bleed valve  130  and then further select a predetermined protocol stored at memory  142  for use in a subsequent blood pressure measurement procedure. For example, such protocol may provide for the inflation of the interconnected cuff assembly  10  to a predetermined pressure level determined to be most appropriate for the given type of interconnected cuff assembly  10 . 
     As previously noted, the described embodiment is particularly apt for use in identifying which of a plurality of cuff assemblies is interconnected to monitor  100 , wherein such predetermined plurality of cuff assemblies comprises a group consisting of two or more of the following: 
     i) an arm cuff intended for a very large adult/obese patient; 
     ii) an arm cuff intended for an average adult; 
     iii) an arm cuff intended for a child; and 
     iv) an arm cuff intended for use on a neonate. 
     In such an application, it will be appreciated that each of the different intended cuff applications will correspond with a different size cuff  20  in the corresponding cuff assembly  10 . For each of such different sized cuffs  20 , a different set of pressure settings may be appropriate for conducting the blood pressure monitoring procedure. In particular, initial pressure settings for the blood pressure monitoring procedure may be set as follows: 
     i) for a very large adult/obese patient the initial inflation pressure should equal at least approximately 200 mmHg, with a safety maximum of about 300 mmHg; 
     ii) for average adult the initial inflation pressure should equal approximately 160 mmHg, with a safety maximum of about 300 mmHg; 
     iii) for child the initial inflation pressure should equal approximately 160 mmHg, with a safety maximum of about 215 mmHg; and 
     iv) for neonate the initial inflation pressure should equal no more than approximately 120 mmHg, with a safety maximum of about 150 mmHg. 
     The embodiment description provided above is for purposes of facilitating an understanding of the present invention and is not intended to limit the scope in any way. Numerous modifications, adaptations and extensions will be apparent to those skilled in the art and are intended to be within the scope of the present invention as defined by the claims that follow.

Technology Classification (CPC): 0