Feb 11, 2016 10:10 am (gmt-5:00) added by (b)(6): customer noted the --- in venous pressure and a message saying venous probe disconnected.
Also noted that it's reading part and pint without problem.
Customer changed the cable with the same result.
--- would indicate out of range values but the line was soft and not pressurized.
It was impossible to stop the alarm.
A +85mmhg as the negative pressure reading.
This value appeared all of a sudden when the --- disappeared.
This +85mmhg hasn't changed even if they modify rpm or give volume to the patient.
However, if the patient becomes hypovolemic, the flow will drop until fluid is given to the patient.
The +85mmhg never changes.
(b)(4).
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The item was returned to maquet for investigation, which took place on (b)(6) 2016.
The hls module was connected to the cardiohelp device.
A tightness test was performed and a leakage at the luer lock on the blood outlet connector was discovered and therefore the system could not be pressurized.
The crack was sealed with glue, so that further tests could be carried out.
The hls module was connected to the cardiohelp device once again, and all parameter values were displayed.
No further issues were found.
However, the manufacturer is aware of similar complaints showing a similar malfunction where customers described a drift of the venous pressure sensor readings, resulting in alarms and /or implausible pressure values.
An internal non-conformance (nc (b)(4)) was initiated to determine the most probable root cause and to implement appropriate corrective action.
The investigation found that the flex pcb of the venous pressure sensors of the oxygenators in question can corrode.
A white crystalline substance has been found on the pins of the pressure sensor.
The priming solution leads to electrolysis when the cardiohelp device starts to work.
The electrolysis starts immediately and causes a short circuit between the pins.
The short circuit leads to implausible sensor pressure readings.
It could be shown by a dried electrolyte plug that this state has no obvious impact on pressure sensor readings.
The investigation concluded that the varnish used on the flex pcb and pressure sensor pins is not completely resistant to the electrolysis effects related to the saline priming solution (the electrolyte etches the pins of the flex pcb).
A new, more resistant coating for the flex pcb is currently being developed within nc (b)(4).
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