Abstract:
A sensor adapter cable provides medical personnel with the convenience of utilizing otherwise incompatible optical sensors with multiple blood parameter plug-ins to a physiological monitor, where the plug-ins each have keyed connectors that mechanically lock-out incompatible sensors in addition readers that poll sensor identification components in each sensor so as to electrically lock-out incompatible sensors.

Description:
PRIORITY CLAIM TO RELATED PROVISIONAL APPLICATIONS 
     The present application claims priority benefit under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61/330,586 filed May 3, 2010, titled Sensor Adapter Cable; the above-cited provisional patent application is hereby incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     Pulse oximetry systems for measuring constituents of circulating blood have gained rapid acceptance in a wide variety of medical applications, including surgical wards, intensive care and neonatal units, general wards, home care, physical training, and virtually all types of monitoring scenarios. A pulse oximetry system generally includes an optical sensor applied to a patient, a monitor for processing sensor signals and displaying results and a patient cable electrically interconnecting the sensor and the monitor. The monitor may be specific to pulse oximetry or may be a multi-parameter monitor that has a pulse oximetry plug-in. A pulse oximetry sensor has light emitting diodes (LEDs), typically one emitting a red wavelength and one emitting an infrared (IR) wavelength, and a photodiode detector. The emitters and detector are typically attached to a finger, and the patient cable transmits drive signals to these emitters from the monitor. The emitters respond to the drive signals to transmit light into the fleshy fingertip tissue. The detector generates a signal responsive to the emitted light after attenuation by pulsatile blood flow within the fingertip. The patient cable transmits the detector signal to the monitor, which processes the signal to provide a numerical readout of pulse oximetry parameters such as oxygen saturation (SpO 2 ) and pulse rate. 
     SUMMARY OF THE INVENTION 
     A sensor adapter cable provides medical personnel with the convenience of utilizing otherwise incompatible sensors with multiple SpO 2  monitors or monitor plug-ins. For example, each monitor plug-in may have a keyed connector that mechanically locks-out incompatible sensors. Further, each sensor may have sensor identification (ID) components that can be read by a pulse oximetry monitor or monitor plug-in so as to electrically lock-out incompatible sensors. The sensor adapter cable advantageously allows the interconnection of these otherwise incompatible devices. In an embodiment, a sensor adapter cable allows the use of any of a Masimo sensor with a ProCal ID, a Masimo sensor with an EEPROM ID and a Nellcor/Philips sensor with an R-cal ID with either of a Masimo SET plug-in or a Philips FAST-SpO2 plug-in to a Philips IntelliVue™ monitor, all available from Philips Medical Systems, Andover, Mass. 
     A sensor adapter cable has both a mechanical and an electrical interface to a monitor plug-in so as to provide multiple sensor compatibility. In an embodiment, a dual key 8-pin D-shape connector (D8) at one end of an adapter cable provides mechanical compatibility with two-types of plug-in input connectors, as described in U.S. patent application Ser. No. 11/238,634 (Pub No. US2006/0073719 A1) titled Multiple Key Position Plug filed Sep. 29, 2005 and incorporated by reference herein. Further, a family of sensor adapter cables has sensor connector configurations that include MC8, M15 and DB9 connectors, as shown and described below. 
     The limited pins available on a D8 connector require sharing of pins to accommodate various sensor ID components. For example, an EEPROM sensor ID and a R-cal resistor sensor ID may need to share the same D8 pin. Such an approach, however, creates the potential for the EEPROM to effect the R-cal measurement in Philips FAST equipped devices and for the R-cal voltage drop to effect the ability of Masimo SET equipped devices to read the EEPROM. 
     An 8-pin dual-key cable which is capable of working correctly with any combination of Philips or Masimo SET equipped SpO2 plug-ins requires the connection of the proper ID component(s) to the SpO2 plug-ins while at the same time electrically disconnecting components that are not used or that could potentially interfere with the connected SpO2 technology. Further, this solution cannot impact the ability of each of the SpO2 technologies to operate correctly across its entire range of sensors and accessories. 
     One aspect of a sensor adapter cable provides medical personnel with the convenience of utilizing otherwise incompatible optical sensors with multiple blood parameter plug-ins to a physiological monitor. The plug-ins each have keyed connectors that mechanically lock-out incompatible sensors in addition to readers that poll sensor identification components in each sensor so as to electrically lock-out incompatible sensors. The sensor adapter cable has a sensor connector, a plug-in connector, an interconnection cable and a pod. The sensor connector mechanically connects to a predetermined sensor and electrically communicates with sensor electrical elements within the predetermined sensor. The plug-in connector mechanically connects to a predetermined plug-in and electrically communicates with lug-in electrical elements within the predetermined plug-in. An interconnection cable mechanically attaches between and provides electrical communications between the sensor connector and the plug-in connector. A pod is incorporated within the interconnecting cable that electrically interfaces the sensor connector to the plug-in connector. 
     In various embodiments, the pod has a cut in the interconnection cable that exposes cable wire ends. A circuit board is spliced to the cable wires end. A pre-mold encapsulates the cut, the circuit board, and the cable wire end, and an over-mold envelopes the pre-mode so as to define the pod. The circuit board comprises a first switch that, when closed, connects a resistor ID on the circuit board to the plug-in connector so as to enable a first plug-in attached to the plug-in connector to communicate with a sensor attached to the sensor connector. The circuit board also comprises a second switch that, when closed, connects an EEPROM ID on the circuit board to the plug-in connector so as to enable a second plug-in attached to the plug-in connector to communicate with a sensor attached to the sensor connector. The sensor adapter cable disconnects the resistor ID and the EEPROM ID when the first switch and the second switch are both open. The first switch may incorporate an n-channel MOSFET that turns on in response to a positive control signal from the first plug-in so as to switch in the resistor ID. The second switch may incorporate a p-channel MOSFET that turns on in response to a negative control signal from the second plug-in so as to switch in the EEPROM ID. 
     Another aspect of a sensor adapter cable is a method of interfacing any of multiple physiological monitor plug-ins to any of multiple optical sensors. An interface cable has a sensor connector on a first end and a plug-in connector on a second end. Resistive and memory IDs are incorporated within the cable. A sensor ID read signal is asserted at the plug-in connector. A particular one of the IDs is presented to the plug-in connector in response to the read signal. In various embodiments, unselected IDs are isolated from the plug-in connector and the selected ID. Switches are integrated with the IDs and are responsive to the read signal so as to connect the selected ID and disconnect the remaining IDs. A first switch is closed and a second switch is opened so as to select either a resistive ID or a memory ID. Both the first switch and the second switch are opened so that the sensor adapter cable functions as a patient cable. A circuit board with the switches and IDs is spliced between a portion of the interface cable conductors. The circuit board is encapsulated into a calibration pod portion of the interface cable. 
     A further aspect of a sensor adapter cable is a plug-in connector means for connecting to a plug-in module for a physiological monitor. A sensor connector means connects to an optical sensor. An interface cable mechanically and electrically interconnects the plug-in connector means and the sensor connector means. A pod means is integrated with the interface cable for allowing sensors to connected to and be recognized by the plug-in module. In various embodiments, the pod means comprises a circuit board means for splicing sensor IDs into the interface cable. A switching means selectively activates and isolates the sensor IDs so that only a single sensor ID is presented to the plug-in connector. A control means is in communications with the plug-in connector means for making the switching means responsive to a ID read signal from the plug-in module. The pod means further comprises an encapsulation means for enclosing the circuit board means within the pod means, where an encapsulations means embodiment comprises a premold of at least one of an epoxy, HDPE and PVC and an overmold of medical grade PVC. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a general block diagram of a physiological parameter monitoring system that incorporates a sensor adapter cable; 
         FIGS. 2A-B  are top, side and end views of a sensor adapter cable embodiment employing a M15 sensor connector and a D8 plug-in connector; 
         FIGS. 3A-C  are a M15 connector end view; a cable schematic and a D8 connector end view, respectively; 
         FIG. 4  is a detailed schematic of a sensor adapter circuit; 
         FIGS. 5A-B  are top, side and end views of a sensor adapter cable embodiment employing a MC8 sensor connector and a D8 plug-in connector; 
         FIGS. 6A-C  are a MC8 connector end view; a cable schematic and a D8 connector end view, respectively; 
         FIGS. 7A-B  are top, side and end views of a sensor adapter cable embodiment employing a DB9 sensor connector and a D8 plug-in connector; 
         FIGS. 8A-C  are a DB9 connector end view; a cable schematic and a D8 connector end view, respectively; 
         FIGS. 9A-B  are a perspective view and an exploded perspective view, respectively, of a sensor adapter cable pod; 
         FIGS. 10A-B  are a perspective views of a sensor adapter circuit board and cable assembly; 
         FIG. 10C  is a cable-side view of a sensor adapter circuit board; 
         FIG. 10D  are cable prep top and side views; and 
         FIGS. 11A-C  are transparent top, end and front views, respectively, of the pod. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  illustrates a physiological parameter monitoring system  100  that incorporates a sensor adapter cable  120  or a family of sensor adapter cables so as to interconnect various sensors  110  with parameter processing plug-ins  130  to a physiological monitor  140 . The sensors  110  include various types and configurations of optical devices as described above. Sensors typically have ID components that identify the sensor to a plug-in  130  so as to insure compatibility. Examples of ID components include an active component ID  114 , such as a memory, or a passive component ID  112 , such as one or more resistors having a specified range of values. In a particular embodiment, an active component ID  114  includes an EEPROM and a passive component ID  112  includes a ProCal resistor (Masimo) or an R-cal resistor (Philips/Nellcor). 
     Also shown in  FIG. 1 , a sensor adapter cable  120  has a sensor connector  122 , a plug-in connector  124 , a pod  900  and an interconnecting cable  128 . The sensor connector  122  mechanically and electrically interfaces to one or more sensors  112 ,  114 . The plug-in connector  124  interfaces to one or more plug-ins  130 . The plug-ins  130 , in turn, mechanically and electrically connect with a physiological monitor  140 . The sensors  110  provide sensor signals to the plug-ins, which are used to calculate oxygen saturation (SpO2) and pulse rate among other parameters. The monitor  140  controls the plug-in operating modes and displays the parameter calculations accordingly. In an embodiment, the plug-ins are any of Masimo® SET® modules (Masimo Corporation, Irvine, Calif.) or Philips FAST-SpO2 modules, all available from Philips Medical Systems, Andover, Mass. In an embodiment, the physiological monitor is any of various IntelliVue™ monitors also available from Philips. The sensor connector and/or the plug-in connector can be any of various D8, M15, MC8 and DB9 connectors to name a few. 
       FIGS. 2A-B  illustrate a sensor adapter cable embodiment  200  employing a M15 sensor connector  210  and a D8 plug-in connector  10 . A cable  20  interconnects the sensor connector  210  and the plug-in connector  10 . A pod  900  integrated with the cable  20  contains a sensor adapter circuit  400  ( FIG. 4 ) that insures electrical compatibility between a passive and an active ID  110  ( FIG. 1 ) and a particular plug-in  130  ( FIG. 1 ). 
       FIGS. 3A-C  further illustrate a sensor adapter cable embodiment  200 , showing the respective pinouts of the M15 connector  210  and the D8 connector  10 . Also shown are the corresponding cable  20  color-coded wires, inner shield and outer shield. Further shown is a sensor adapter circuit  400  and its connections relative to the connectors  10 ,  210  and cable  20  wires. 
       FIG. 4  illustrates the sensor adapter circuit  400  having plug-in connections  410  and sensor connections  420 . The plug-in connections  410  (J1, J2, J3) connect to the plug-in connector  10  ( FIGS. 2-3 ,  5 - 6 ,  7 - 8 ). The sensor connections  420  (J4, J5) connect to the sensor connector  210  ( FIGS. 2-3 );  510  ( FIG. 5-6 ) or  710  ( FIGS. 7-8 ). Table 1 below defines the signal names and associated connections to the plug-in connector pins. 
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Adapter Circuit and Plug-in Connector Pinouts 
               
             
          
           
               
                   
                   
                 Reference 
                   
               
               
                   
                 Signal Name 
                 Designation 
                 Plug-in Connector Pin # 
               
               
                   
                   
               
               
                   
                 R-TYPE/EEPROM 
                 J2 
                 3 
               
               
                   
                 RCAL/CONTROL 
                 J1 
                 4 
               
               
                   
                 OUTER SHIELD 
                 J3 
                 7 
               
               
                   
                   
               
             
          
         
       
     
     The switch components  430 ,  440  used in this design (Si2312 and Si2351 or equivalents) are high impedance MOSFET devices that have no impact on R-cal and R-TYPE resistor measurements due to the fact that the MOSFET gates do not require current to activate. When the cable is connected to a Philips FAST equipped device, the RCAL/CONTROL signal will be a positive voltage. The RCAL/CONTROL voltage is 2.9V without a sensor connected and can be as low as 1.1V with the minimum value RCAL resistor of 6.04 KΩ. This is understood to represent the entire range for the RCAL/CONTROL voltage. When the cable is connected to a Masimo XCaI capable SpO2 module, a negative voltage will be applied to RCAL/CONTROL signal. This will turn on Q 2  and turn off Q 1  which will allow the Masimo system to read the EEPROM contents. Table 2, below, describes how the switches (Q 1 , Q 2 ) operate. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Adapter Circuit Switch Truth Table 
               
             
          
           
               
                   
                 RCAL/ 
                   
                   
                   
               
               
                 SpO2 
                 Control 
                   
                   
                   
               
               
                 Module 
                 Signal 
                 Switch Q1 
                 Switch Q2 
                 Comments 
               
               
                   
               
               
                 Philips 
                 Positive  
                 Closed 
                 Open 
                 Philips FAST 
               
               
                 FAST 
                 voltage 
                   
                   
                 module can 
               
               
                   
                   
                   
                   
                 measure RCAL and 
               
               
                   
                   
                   
                   
                 R-TYPE resistors 
               
               
                 Masimo 
                 Open (No 
                 Open 
                 Open 
                 Same as patient 
               
               
                 ProCal 
                 driving  
                 (Don&#39;t 
                 (Don&#39;t 
                 cable 
               
               
                 Technology 
                 voltage) 
                 care) 
                 care) 
                   
               
               
                 Masimo 
                 Negative  
                 Open 
                 Closed 
                 Masimo board will 
               
               
                 XCal 
                 voltage 
                   
                   
                 read EEPROM; 
               
               
                 Technology 
                   
                   
                   
                 negative voltage will 
               
               
                   
                   
                   
                   
                 be supplied by the 
               
               
                   
                   
                   
                   
                 Masimo board 
               
               
                   
               
             
          
         
       
     
     The n-channel transistor (Q 1 )  430  was chosen with a very low turn-on threshold (0.85V max) so that it is guaranteed to turn on and switch in the R-TYPE resistor even at the lowest RCAL/CONTROL voltage of 1.1V. The on-resistance of the FET is so low (less than 100 mΩ) that it will not affect the measured R-TYPE resistor value. At the same time, the p-channel FET (Q 2 )  440  will be turned off since the gate-to-source voltage (Vgs) will be positive. Even in the worst possible case, the Vgs will be −0.3V which is not low enough to turn-on the p-channel device. The minimum turn-on threshold for the p-channel is −0.6V. The purpose of resistors R 1  and R 2  and ESD protection diodes D 1  and D 2  are to protect the MOSFET devices. This sensor adapter embodiment ensures proper operation and ample margin in all possible combinations of sensor and device types and therefore meets the design requirements necessary to allow Masimo SET or Philips FAST systems to work correctly with a dual key D8 connector capable of plugging into either type of system. 
     Resistor R 3  of  FIG. 4  is a passive ID element on the sensor adapter circuit  400 . U1  450  is an EEPROM and is an active ID element on the sensor adapter circuit  400 . 
       FIGS. 5A-B  illustrate a sensor adapter cable embodiment  500  employing a MC8 sensor connector  510  and a D8 plug-in connector  10 . A cable  20  interconnects the sensor connector  510  and the plug-in connector  10 . A pod  900  integrated with the cable  20  contains a sensor adapter circuit  400  ( FIG. 4 ) that insures electrical compatibility between a passive and an active ID  110  ( FIG. 1 ) and a particular plug-in  130  ( FIG. 1 ). 
       FIGS. 6A-C  further illustrate a sensor adapter cable embodiment  500 , showing the respective pinouts of the MC8 connector  510  and the D8 connector  10 . Also shown are the corresponding cable  20  color-coded wires, inner shield and outer shield. Further shown are the sensor adapter circuit  400  connections relative to the connectors  10 ,  510  and cable  20  wires. 
       FIGS. 7A-B  illustrate a sensor adapter cable embodiment  700  employing a DB9 sensor connector  710  and a D8 plug-in connector  10 . A cable  20  interconnects the sensor connector  710  and the plug-in connector  10 . A pod  900  integrated with the cable  20  contains a sensor adapter circuit  400  ( FIG. 4 ) that insures electrical compatibility between a passive and an active ID  110  ( FIG. 1 ) and a particular plug-in  130  ( FIG. 1 ). 
       FIGS. 8A-C  further illustrate a sensor adapter cable embodiment  700 , showing the respective pinouts of the DB9 connector  710  and the D8 connector  10 . Also shown are the corresponding cable  20  color-coded wires, inner shield and outer shield. Further shown are the sensor adapter circuit  400  connections relative to the connectors  10 ,  710  and cable  20  wires. 
       FIGS. 9A-B  illustrate a pod  900  that splices the sensor adapter circuit  400  ( FIG. 4 ) into the sensor adapter cable  20 . The pod  900  has a overmold  910 , a premold  920 , a copper foil shield  930 , a circuit board  940  and heat-shrink tubing  950 . The circuit board  940  provides the sensor adapter circuit  400  ( FIG. 4 ) described above. The board  940  is mounted to the cable  20  and electrically interconnected to the cable wires and outer shield, as described with respect to  FIG. 4 , above. The premold  920  is manufactured to envelop the circuit board  940  and spliced cable portion. The copper foil shield  930 , if used, envelops the premold  920 , and the overmold  910  envelops all of the pod  900  components. 
       FIGS. 10A-D  illustrate attachment of the circuit board  940  to the adapter cable  20 . Shown is cable preparation ( FIG. 10D ) for splicing with the circuit board  940  ( FIG. 10C ). Also shown are preparation of the cable wires ( FIG. 10B ) and mounting of the circuit board  940  to the cable wires.  FIGS. 11A-C  further illustrates the assembled pod  900 . 
     A sensor adapter cable has been disclosed in detail in connection with various embodiments. These embodiments are disclosed by way of examples only and are not to be construed as limiting the scope of this disclosure. One of ordinary skill in the art will appreciate many variations and modifications.