CPB FMEA #10 roller pump failure to turn – a lethal incident review.
This is the third in a new series of bi-weekly postings from the Safety Committee that looks at dangerous perfusion incidents from the standpoint of failure modes and effects analyses (FMEAs). Some conceptual incidents that could potentially occur may be discussed. But, for the most part, these incidents are genuine like the one described below. This incident will be examined in the light of an existing FMEA to determine why the incident occurred. Was the FMEA deficient in management of the incident or did ignorance of the FMEA management actions result in the incident? You will be the judge. Comments are welcome.
Gary Grist RN CCP Emeritus <[login to unmask email]>
“Be prepared” is the motto of the Boy Scouts. Perfusionists should adopt it with the following modification, “Be prepared ….or else!” Because when a perfusionist is unprepared bad things happen to good people, as the following true story illustrates.
Once upon a time, an elderly patient was receiving the modern-day miracle of elective cardiac surgery to repair a diseased heart valve. The lone perfusionist on the case was not without experience and did not anticipate any complications. Regrettably, instead of this story ending with healing and happiness, it became a nightmare.
Suddenly and without warning the arterial pump stopped at a critical time while the patient was on CPB. The perfusionist looked for the cause of the failure but could not find it. Finding no hand crank on the pump, the perfusionist left the immediate area to locate one. The perfusionist had never received any formal training for hand cranking this make of pump before, nor had the perfusionist practiced hand cranking this model of blood pump before this case. Upon return, the retrieved hand crank was not the correct one for the failed pump. So, hand cranking could not be performed in the heat of the moment. The perfusionist left the room again, since there was no perfusion-educated assistance to help, to bring in another pump which was used to finish the surgery. In the mean-time, the patient experienced no perfusion to the brain for fourteen minutes and died soon after the surgery. A law suit resulted in a multimillion-dollar settlement against the perfusionist and the hospital employer.
This story prompts the review of “CPB FMEA #10 roller pump failure to turn*”. (See below.) The cause of the patient’s death was human error due to unfamiliarity with equipment or inadequate training, not the failed pump. A well prepared perfusionist should be able to safely deal with a failed arterial pump. Tragically, there are at least four pre-emptive management and management interventions in this FMEA which, if any one of them were followed, would have prevented or safely mitigated this incident. There is another management intervention which hopefully was followed. Post-traumatic stress disorder therapy should be available if needed for the perfusionist and/or other surgery team members, particularly if the patient experiences an adverse outcome.
If you are thinking that you are not so irresponsible as to not to have a hand crank ready before starting a case, think about this. Hand cranking a roller pump is exhausting if performed for more than a few minutes. This is true even for centrifugal pump cranks. In addition, hand cranking draws attention away from the other important controls, instrumentation and adjustments. Have you thought about the next step beyond cranking? Do you have a battery powered centrifugal pump at the ready in the room that can take over and finish the case? You might be thinking that the backup C-pump would never be used. Wrong! It will be used at least annually by each staffer to practice an arterial pump switch over. If you are a lone perfusionist, you might want to practice even more often to perfect your technique. And if the backup pump is never used for an actual emergency, consider yourself and your patients lucky.
*This FMEA applies to arterial centrifugal pumps as well.
CPB FMEA #10 roller pump failure to turn
I. Failure Mode: Roller pump failure to turn.
II. Potential Effects of Failure:
- Failure to initiate CPB or unintentional termination of CPB if arterial roller pump fails.
- No blood being delivered to patient
- Need to hand crank pump
- Organ failure
- Failure to initiate cardioplegia, ultrafiltration, ventricular venting or field suckers if secondary pumps fail.
III. Potential Cause of Failure:
- Human error due unfamiliarity with equipment or inadequate training.
- Internal mechanical or electrical malfunction
- Power cable loose, disconnected or power supply failure
- Internal overload tripped due to over occlusion
- Pump motor, drive belt, main bearing or speed control failure.
- Total OR power failure.
- Interventions to Prevent or Mitigate the Failure:
- Routine table top scenario discussion or wet lab simulation of a roller pump failure should be regularly performed at least annually or whenever new personnel or unfamiliar equipment is added. The discussion/simulation should include any servo-regulated alarm scenario that could disable the roller pump.
- Use detailed rather than generalized checklists to reduce failures. Confirm checklist item with action accompanied by conscious out loud verbal repetition before check-off.
- A flash light or other battery powered portable lighting should always be available ON THE PUMP and checked for proper function should there be an overall loss of power in the OR. Emergency flood lights in the OR do not satisfy this need.
- All pump instrument stacks should have an uninterruptable DC battery power source in case the AC power source fails. Test for proper battery function and capacity during priming by temporarily disconnecting the AC power source.
- Confirm by checklist the secure placement of wall plug and proper operation of individual components during set-up and prime.
- During priming, listen for any unusual noises that might indicate an internal malfunction.
- Adjust occlusion of each pump head according to accepted practices during set-up and prime.
- Observe ‘Load’ light of each pump for excessive current use indicating over occlusion or internal power overload.
- All pumps should undergo a manufacturer or qualified clinical engineering routine maintenance regularly that specifically includes a battery check or replacement.
- Hand cranks should be available for each pump head.
- A back-up, portable, battery powered centrifugal pump should be available to emergently take over from a malfunctioning arterial roller pump. The process of replacing a modular arterial roller pump with a back-up roller pump may require too much time to safely perform.
- Back-up roller pumps should be available to replace ancillary roller pumps.
- Secondary personnel (perfusion assistants or clinical perfusionists) should always be nearby to obtain back-up equipment and assist in emergency procedures.
- Power loss can be to the entire heart-lung unit or be localized to individual components of the heart-lung unit.
- Immediately clamp venous line to prevent patient exsanguination in an arterial pump failure.
- Begin hand cranking in the correct direction at appropriate RPMs before removing the venous line clamp.
- Monitor flow with an independent flow meter.
- The perfusionist and secondary personnel should each perform designated scenario-practiced tasks.
- Check for displacement of electrical plug from wall power or at main connection to pump or circuit breaker if entire instrument stack becomes powerless.
- If over occlusion or internal overload is suspected temporarily stop pump and loosen occlusion.
- If occlusion mechanism is defective replace pump with back-up immediately.
- If main bearing is frozen hand cranking will not be possible. Replace with back-up unit immediately.
- If individual pump is powerless, turn pump switch off, reset circuit breaker and turn pump back on.
- If pump is still inoperative, replace with back-up unit.
- If the arterial pump fails, clamp arterial and venous lines and transfer raceway to a back-up centrifugal pump by cutting the raceway and attaching to the C-pump head.
- If speed controller failure occurs, pump may not respond to speed control knob and even “runaway” at maximum RPMs. Turn off power to pump immediately, begin hand cranking. Replace with back-up unit.
- Post-traumatic stress disorder therapy should be available if needed for the perfusionist and/or other surgery team members, particularly if the patient experiences an adverse outcome.
Note: Specialized cardioplegia pumps may have no manual operation option should they fail unless specialized hand cranks have been supplied by the manufacturer.
V. Risk Priority Number (RPN): (select the number from each category that you feel best categorizes the risk).
A. Severity (Harmfulness) Rating Scale: how detrimental can the failure be:
1) Slight, 2) Low, 3) Moderate, 4) High, 5) Critical
(The problems that this failure causes are 5, critical if the perfusionist is working alone without perfusion educated assistance. If educated assistance is readily available the risk would be Moderate, 3.)
B. Occurrence Rating Scale: how frequently does the failure occur:
1) Remote, 2) Low, 3) Moderate, 4) Frequent, 5) Very High
(This is a rare problem. So, occurrence should be 1; remote.)
C. Detection Rating Scale: how easily the potential failure can be detected before it occurs:
1) Very High, 2) High, 3) Moderate, 4) Low, 5) Uncertain
(This problem may not be detectable before it occurs. So, the detection RPN should be 5, uncertain.)
D. Patient Frequency Scale:
1) Only a small number of patients would be susceptible to this failure, 2) Many patients but not all would be susceptible to this failure, 3) All patients would be susceptible to this failure.
(This could happen to any patient. So the Patient Frequency RPN should be a 3.)
Multiply A*B*C*D = RPN. The higher the RPN the more dangerous the Failure Mode.
The lowest risk would be 1*1*1*1* = 1. The highest risk would be 5*5*5*3 = 375. RPNs allow the perfusionist to prioritize the risk. Resources should be used to reduce the RPNs of higher risk failures first, if possible.
(The total RPN for this failure is 5*1*5*3 = 75 if there is no educated assistance available. With assistance the RPN would be 3*1*5*3 = 45.)