SENHANCE
Report
- Report Number
- 3007593944-2022-00001
- Event Type
- Malfunction
- Date Received
- February 22, 2022
- Date of Event
- February 1, 2022
- Report Date
- February 22, 2022
- Manufacturer
- ASENSUS SURGICAL, INC.
- Product Code
- NAY
- UDI-DI
- 00815440022082
- PMA / PMN Number
- K212054
- Product Problem
- Yes
- Report Source
- Manufacturer report
- Reporter Location
- GM
- Reporter Occupation
- PHYSICIAN
- Health Professional
- Yes
Narratives
THE SENHANCE SURGICAL SYSTEM IS A CONSOLE-BASED, MULTI-ARM SURGICAL SYSTEM THAT ENABLES A SURGEON TO REMOTELY CONTROL SURGICAL INSTRUMENTATION DURING LAPAROSCOPIC SURGERY. THE SENHANCE COCKPIT AND MANIPULATOR ARMS ARE PART OF THE CAPITAL EQUIPMENT OF THE SENHANCE SURGICAL SYSTEM. THE COCKPIT IS THE STATION WHERE THE SURGEON INPUTS INFORMATION THROUGH HAND AND EYE MOVEMENTS TO DIRECT THE MOTION OF THE MANIPULATOR ARMS IN THE SURGICAL FIELD. THE INTELLIGENT SURGICAL UNIT (ISU) WAS IN USE AS A RELAY UNIT CONNECTING THE COCKPIT INPUTS TO THE MANIPULATOR ARM. SENHANCE ADAPTERS AND SURGICAL INSTRUMENTS ARE ASSOCIATED DEVICES USED IN CONJUNCTION WITH THE SENHANCE SYSTEM. THE SENHANCE SYSTEM IS DESIGNED TO BE QUICKLY CONVERTED TO TRADITIONAL LAPAROSCOPY, WHEN NECESSARY. DETAILS OF THE DEVICES INVOLVED IN THE EVENT: COCKPIT (ISU CONFIGURATION): PN: X9007707, UDI: (B)(4), SN: (B)(4). MANIPULATOR ARM (ISU CONFIGURATION): PN: X9007708, UDI: (B)(4), SN: (B)(4). DETAILS OF THE ASSOCIATED DEVICES (ATTACHED TO THE MANIPULATOR ARM): ADAPTER BIPOLAR LARGE GRASPING FORCEPS Ø 5 MM X 310 MM: PN: X9000056, UDI: (B)(4). BIPOLAR LARGE GRASPING FORCEPS Ø 5 MM X 310 MM: PN: X0005146, UDI: (B)(4), LOT 968476. THE INVESTIGATION WAS INITIATED IMMEDIATELY FOLLOWING THE EVENT. ACCORDING TO THE FIELD SERVICE WORK ORDER, THE FIELD SERVICE ENGINEER (FSE) FOUND DURING HIS TROUBLESHOOTING ACTIVITIES THAT A METAL CABLE WAS OUT OF PLACE IN THE LTM ASSEMBLY. IN PARTICULAR, THE CABLE AROUND THE ROLL ENCODER APPEARED TO BE LOOSE. FOR REFERENCE, THE HANDLES (LAPAROSCOPIC TELEOPERATION MASTERS) IN THE COCKPIT ARE USED BY THE SURGEON TO CONTROL THE SURGICAL INSTRUMENTS MOUNTED ON THE MANIPULATOR ARMS AND RECEIVE FORCE FEEDBACK. THE LTM ASSEMBLY IS COMPRISED OF THE HANDLES, THEIR SUPPORT, THE INTERFACE AND THE MOTOR ENCODERS. THE LEFT LTM ASSEMBLY WAS REPLACED BY THE FSE. AND AS A PRECAUTIONARY MEASURE, BOTH LEFT AND RIGHT HANDLES WERE ALSO REPLACED. FOLLOWING REPLACEMENT OF THE COMPONENTS, A SYSTEM VERIFICATION AND ELECTRICAL SAFETY TEST WAS PERFORMED AND PASSED AS PER SPECIFICATION. A SERVICE HISTORY REVIEW WAS ALSO PERFORMED WITH NO ANOMALOUS FINDINGS. MULTIPLE HANDLES AND LTM ASSEMBLY SERVICE ACTIVITIES HAD BEEN PERFORMED AT THE SITE, NONE OF WHICH WERE ASSOCIATED WITH THE ISSUE REPORTED IN THIS PRODUCT COMPLAINT. A DETAILED ANALYSIS WAS PERFORMED BY THE R&D SOFTWARE TEAM, WHICH CONCLUDED THE FOLLOWING: NORMALLY, THE CABLE ALLOWS THE CONTROL OF THE SCREW THROUGH THE HANDLES. THE MOTION IS READ BY THE ENCODER AND A PROPORTIONAL INCREMENT IS SENT TO THE MANIPULATOR ARM, GENERATING A MOTION. THE SCREW IS ALSO CONTROLLED BY A DEDICATED MOTOR, WHICH IS RESPONSIBLE FOR THE FORCE FEEDBACK ON LTM HANDLES. CYCLICALLY, LTM READS THE FORCE VALUE MEASURED FROM THE 6-AXIS SENSOR OF THE MANIPULATOR ARM AND STORED IN THE SHARED MEMORY. EACH FORCE VALUE IS MULTIPLIED BY A SPECIFIC CONVERSION FACTOR AND BOUND TO AVOID STRESSING OR EVEN DAMAGING LTM MOTORS. THE OUTPUT VALUE FOR THE DAC IS SET THROUGH LSWDRV_DAC (FOR YAW, PITCH, ROLL AND INSERTION) AND LSWDRV_PWM (FOR GRIPPER) MODULES, USING RTPHWLIB_LSW LIBRARY. THE FORCE VALUES THEN MODULATE THE MOTOR VELOCITY TO GIVE FORCE FEEDBACK. THE ROLL AND GRIPPER FORCE FEEDBACK VALUES ARE NOT CURRENTLY USED. FOR THIS REASON THE ROLL FEEDBACK VALUE FOR THE DAC IS KEPT CONSTANT TO 2048, WHICH IS THE DAC VALUE CORRESPONDING TO ZERO TORQUE APPLIED TO PITCH, YAW, INSERTION AND ROLL MOTORS. NORMALLY, WHEN THE CABLE IS ROLLED UP AROUND THE SCREW, THE MOTION IMPOSED BY THE MOTOR CONSEQUENTLY TO THE FORCE FEEDBACK IS OPPOSED BY THE CABLE, CONTROLLED BY THE HANDLES, AND RETURNS THE HAPTIC FEEDBACK. WHEN THE CABLE IS LOOSE, THE MOTOR IS FREE TO MOVE. FOR THE ROLL MOTOR, EVEN IF THE MOTOR VOLTAGE IS KEPT CONSTANT AT THE ZERO VALUE BY THE SOFTWARE, A RESIDUAL VOLTAGE ACROSS THE MOTOR IS PRESENT. IF THE CABLE IS TIGHTENED, THE FRICTION KEEPS THE ROLL SCREW IN PLACE, OTHERWISE THE RESIDUAL VOLTAGE IS ENOUGH TO KEEP THE SCREW IN MOTION. CONSEQUENTLY, IF THE MOTOR IS MOVING, THE MOTION IS ALSO DETECTED BY THE ENCODER AND AS A RESULT AN INCREMENT IS SENT TO THE MANIPULATOR ARM WHICH MOVES ACCORDINGLY. IF THE FORCE FEEDBACK IS TURNED OFF OR THE SYSTEM IS NOT IN TELEOPERATION, ALL THE FORCE FEEDBACK MOTORS ARE DISABLED AND THE ISSUE DOES NOT OCCUR. THE SIGNAL USED TO ENABLE/DISABLE THE MOTORS IS COMMON TO ALL THE DEVICES. ALL MOTORS ARE EITHER ENABLED OR DISABLED AT THE SAME TIME. THE SAME ISSUE CAN BE REPRODUCED ALSO ON INSERTION AND PITCH ENCODERS. FROM THE HARDWARE POINT OF VIEW, FIVE DRIVERS ARE EMPLOYED IN ORDER TO DRIVE THE DC-MOTORS. TWO SIGNALS ARE USED BY SW TO CONTROL THE MOTORS: SD: THIS SIGNAL CAN BE ENABLED/DISABLED THE DRIVE THAT CONTROLS THE MOTOR. IT IS NOT POSSIBLE TO ENABLE/DISABLE A SINGLE MOTOR BECAUSE THIS SIGNAL IS COMMON TO ALL MOTORS. DACX: THIS SIGNAL IS USED FOR CONTROLLING DIRECTION (FORWARD OR REVERSE) AND SPEED OF ROTATION OF EACH DC-MOTOR. THE VOLTAGE APPLIED TO THE MOTOR IS PROPORTIONAL TO THE DACX SIGNAL. THE TORQUE (AND THE SPEED) OF THE MOTOR DEPEND ON THE STRENGTH OF THE MAGNETIC FIELD GENERATED BY THE ENERGIZED WINDINGS OF THE MOTOR, WHICH DEPEND ON THE CURRENT THROUGH THEM. THEREFORE, ADJUSTING THE ROTOR VOLTAGE (AND CURRENT) WILL CHANGE THE TORQUE (AND THE SPEED). WHEN THE CABLE IS LOOSE, THE MOTOR IS IN "NO-LOAD" CONDITION. THE RESIDUAL VOLTAGE APPLIED ACROSS THE MOTOR IS ENOUGH TO GENERATE A RESIDUAL TORQUE. BECAUSE THE STATIC FRICTION IS LOWER THAN RESIDUAL TORQUE, THE RESIDUAL TORQUE IS ABLE TO GENERATE A MOVEMENT OF THE MOTOR. THE ROOT CAUSE OF THE ISSUE WAS IDENTIFIED TO BE A HARDWARE MALFUNCTION OF THE FAULTY CABLE WHICH LOST ITS TIGHTNESS AND UNWRAPPED FROM THE ROLL ENCODER PLACED IN THE COCKPIT LTM ASSEMBLY. THEREFORE, THE RESIDUAL TENSION PRESENT INSIDE THE ENCODER MOTOR WAS NOT COUNTERED BY THE FRICTION IMPOSED BY THE CABLE, NOT RETURNING THE CORRECT HAPTIC FEEDBACK OF THE HANDLES LEADING TO THE UNINTENDED ROTATION OF THE MANIPULATOR ARM. THE SURGEON CORRECTLY RELEASED THE FOOT PEDAL TO INTERRUPT THE TELEOPERATION PREVENTING ANY FURTHER UNINTENDED MOTION OF THE MANIPULATOR ARM. AFTER THE REPLACEMENT OF THE LEFT LTM ASSEMBLY AND BOTH HANDLES, THE SYSTEM VERIFICATION AND ELECTRICAL SAFETY TEST PASSED ACCORDING TO SPECIFICATION. ADDITIONALLY, THERE ARE CONTROL MEASURES IN PLACE TO MITIGATE THE RISKS ASSOCIATED TO THIS EVENT. THE RISK OF AN UNINTENDED MOTION OF THE MANIPULATOR ARM CAUSED BY AN ERROR IN THE ACQUISITION OF THE HANDLES POSITION DUE TO A MECHANICAL FAILURE. THE REPORTED HARM IS "INTERNAL LACERATION" AND THE FOLLOWING MITIGATION HAS BEEN IDENTIFIED AND APPLIED TO STOP THE ARM MOVEMENT: TELEOPERATION IS ENABLED ONLY BY REDUNDANCY OF THE FOOT PEDAL ACTIVATION AND HUMAN PRESENCE SENSOR ACTIVATION. DUE TO THE FACT THAT TELEOPERATION IS ENABLED ONLY BY PRESSING THE FOOT PEDAL OF THE COCKPIT, RELEASING THE FOOT PEDAL IS SUFFICIENT TO EXIT TELEOPERATION AND STOP THE SYSTEM'S MANIPULATOR ARMS MOVEMENT AVOIDING ANY UNINTENDED MOTION. IN THIS CASE, NO IMPACT TO THE PATIENT AND TO THE SURGERY WAS REPORTED AS THE SURGEON RELEASED THE PEDAL INTERRUPTING ANY MANIPULATOR ARM MOTION AS SPECIFIED IN THE ABOVE MITIGATION. THE RISK OF A PATIENT INJURY AFTER THE MITIGATION'S INTRODUCED IS CONSIDERED ACCEPTABLE ACCORDING TO THE RISK MATRIX, RMP-001-00000 RISK MANAGEMENT PLAN, SENHANCE SYSTEM. OTHER MITIGATIONS INTRODUCED FOR AN UNINTENDED MOTION OF THE MANIPULATOR ARM ARE AS FOLLOWS: ACTIVATION OF THE HUMAN PRESENCE SENSORS IS REQUIRED WHEN USING THE HANDLES TO TELEOPERATE AND USE GO-TO OR FOLLOW ME. CONTINUOUS PRESSURE OF THE ACTIVATOR BUTTONS ON THE HANDLES IS REQUIRED FOR ENDOSCOPE MOTION IN PAN AND ZOOM. MANUAL MOVEMENT OF THE MANIPULATOR ARM IS ENABLED ONLY WHEN BOTH ACTIVATION BUTTONS ON THE INSTRUMENT INTERFACE ARE CONTINUOUSLY ENGAGED. THE LTM MONITORS THE HEALTH STATUS OF THE COMMUNICATION LINK WITH THE MANIPULATOR ARM AND WILL EXIT TELEOPERATION IF COMMUNICATION IS DISTURBED. THE FOOT PEDAL HAS A REDUNDANT DOUBLE ACTION FOOT PEDAL CONSISTING OF TWO SWITCHES CLOSED AT DIFFERENT HEIGHTS FOR THE ACTIVATION OF TELEOPERATION. THE SYSTEM STOPS THE MANIPULATOR ARM MOTION IF EXCESSIVE FORCE IS APPLIED TO THE INSTRUMENT, ENDOSCOPE OR INSTRUMENT INTERFACE (LIA). THE SYSTEM MONITORS THE DIFFERENCE IN POSITIONS REPORTED BY THE HANDLES AND THE MANIPULATOR ARM.
THE EVENT OCCURRED ON (B)(6) 2022 AT (B)(6) HOSPITAL LOCATED IN (B)(6). THE EVENT WAS REPORTED TO THE COMPANY BY THE ASENSUS SURGICAL FIELD SERVICE ENGINEER. THE EVENT INVOLVED X9007707 SENHANCE COCKPIT (ISU CONFIGURATION) AND X9007708 SENHANCE MANIPULATOR ARM (ISU CONFIGURATION). IT WAS REPORTED THAT DURING THE SURGICAL CASE, RIGHT INGUINAL HERNIA REPAIR, THE SENHANCE MANIPULATOR ARM ASSIGNED TO THE LEFT TELEOPERATION HANDLE OF THE SENHANCE COCKPIT STARTED TO ROTATE UNEXPECTEDLY. AFTER THE SURGEON RELEASED THE FOOT PEDAL, THE MANIPULATOR ARM [LIA] STOPPED ROTATING AND WHEN THE FOOT PEDAL WAS PRESSED AGAIN, THE MANIPULATOR ARM [LIA] STARTED TO ROTATE AGAIN. THERE WAS NO INJURY TO THE PATIENT. THE SURGICAL PROCEDURE WAS COMPLETED BY TRADITIONAL LAPAROSCOPY. THE INSTRUMENT INTERFACE/LIA (LAPASCOPIC INSTRUMENT ACTUATOR) IS THE PART OF THE MANIPULATOR ARM WHERE THE INSTRUMENT ATTACHES TO THE ARM. WHILE PERFORMING TROUBLESHOOTING ACTIVITIES, THE FIELD SERVICE ENGINEER (FSE) DISCOVERED THAT A METAL CABLE WAS OUT OF PLACE IN THE LAPAROSCOPIC TELEOPERATION MASTERS (LTM) ASSEMBLY. IN PARTICULAR, THE CABLE AROUND THE ROLL ENCODER APPEARED TO BE LOOSE. THE INVESTIGATION CONCLUDED THAT THE ROOT CAUSE OF THE ISSUE WAS A HARDWARE MALFUNCTION CAUSED BY THE FAULTY CABLE LOCATED INSIDE THE LTM ASSEMBLY. IT WAS DETERMINED THAT THE SURGEON CORRECTLY RELEASED THE FOOT PEDAL TO INTERRUPT TELEOPERATION PREVENTING FURTHER UNINTENDED MOTION OF THE MANIPULATOR ARM [LIA]. THE LEFT LTM ASSEMBLY AND BOTH HANDLES (LEFT AND RIGHT) HAVE BEEN REPLACED. SYSTEM VERIFICATION AND ELECTRICAL SAFETY TESTING WAS PERFORMED AND PASSED ACCORDING TO SPECIFICATION.
Devices
| Seq | Brand | Generic | Product Code | Manufacturer | Model | Lot | UDI-DI |
|---|---|---|---|---|---|---|---|
| 557623 | SENHANCE | SENHANCE SURGICAL SYSTEM | NAY | ASENSUS SURGICAL, INC. | X9007707 | 00815440022082 |
Patients
| Seq | Age | Sex | Outcome | Treatment |
|---|---|---|---|---|
| 1 | 32 YR | Male |