CPB FMEA # 49 The Six Second Scan

Gary Grist, RN CCP Emeritus

CPB FMEA # 49 The Six Second Scan

This is the second 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 post part, these incidents are genuine like the one described below which was unique enough to prompt the writing of a new CPB FMEA. Other incidents will be examined in the light of existing FMEAs to determine why the incident or near miss 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

 CPB FMEA # 49 The Six Second Scan

 From my earliest days in perfusion, I was taught to perform a constant, sequential scan of all things relevant to the pump’s operation every few seconds unless I was performing a specific task like going on, coming off or giving cardioplegia. In later years I taught this to my students. Admonishing students to “be careful” is not enough. They must be taught a technique they can use to be vigilant. For the purposes of writing a CPB FMEA I am calling this technique a Six Second Scan (SSS). The SSS requires constant mental concentration and visual focus during the entire period of CPB. 

 The PIRSII incident* that prompted this FMEA describes an episode of lost concentration and lack of focus by a perfusionist.  After completion of a multiple valve repair, supposedly warm blood was running through the cardioplegia (CP) circuit to the beating heart with the cross clamp still on, resting the heart while waiting for stabilization of the heart rhythm. After thirty minutes of resting, the heart fibrillated. This was initially blamed on the removal of the pacing wires. But the real cause was that the temperature of the water going to the CP circuit had been mistakenly set at 2 degrees centigrade. After this discovery the water temperature to the CP heat exchanger was then correctly set at 37 degrees centigrade. The temperature normalized, the heart was defibrillated and the patient was weaned from CPB bypass successfully.


 Although the patient was not harmed after being exposed to selective myocardial perfusion at an incorrect temperature, he did spend unnecessary additional time on CPB. The reporter admits; “I could have been more diligent reconfirming the water temperature settings after altering the patient water temp change. Also, I could have spoken up about all the distractions going on around me at the time.” In other words, he lost concentration and focus during a lax time.  Even the surgeon had left the room while the heart was resting and being perfused unknowingly with cold blood. Nothing is mentioned about the anesthesiologist who must have observed that the heart rate was abnormal for a blood temperature thought to be 37 degrees. Maybe the pacer spike masked the heart’s underlying hypothermic rate. It was not until the heart fibrillated that anything wrong was noticed.  And the perfusionist only discovered the incorrect blood temperature after being questioned by the surgeon on his return to the theater.

 There is a fine line between inattention and negligence. Negligence is a failure to perform with the same level of care that someone of ordinary judiciousness would employ. Negligence may consist of slips or lapses when there is a duty to act correctly. Slips are errors of commission, incorrect actions. Lapses are errors of omission, failure to act when needed. Confusion about how to control the temperature on the heater/cooler or being distracted by banter in the room does not excuse the negligent actions of a professional. All perfusionists in their career will make a bone headed but harmless mistake of this ilk and experience that deprecating self-revelation that we are not infallible. At least this perfusionist had the courage to share his mistake with others so they can learn from it. Individual perfusionists learning from the mistakes of others is important. But the goal should be for the perfusion profession to formally acknowledge that a risk exists and to inform the entire perfusion community and future perfusionists on the best way to prevent or mitigate an incident. That is what we are trying to do with this FMEA.   

 This mistake was made because of a lack of diligence and ongoing distractions. How could the reporting perfusionist have mitigated this mistake once it was made? If he had been using a continuous SSS during the 30 minutes described, his eye would have seen the incorrect temperature setting 300 separate times. This would have made early detection of the lapse much more likely when it could have been easily corrected without drawing the attention of the surgeon.

 I cannot possibly write a CPB FMEA dealing with all the individual minor slips and lapses that can occur on CPB. But I can write one based on the method I used to actively avoid these mistakes. If you don’t think a six second scan is long enough, choose your own scan time. The important thing is to keep the eyes moving continually. That takes a lot of self-discipline especially during a long case.  I found that six seconds was long enough to detect significant changes in the items being scanned. If you have a method of your own, write an FMEA as evidence to risk managers, outside assessors and others that you are actively managing the non-specific risks of CPB. Then send me a copy!

 CPB FMEA #49 Failure to utilize a continuous six second scan (SSS) during CPB to prevent slips and lapses.


  1. Indeterminate, ranging from insignificant to lethal depending on the error.


  1. Human error due to failure to adapt the self-monitoring method of the six second scan to prevent non-specific errors


  1. When not performing a specific task such as ‘going on’, ‘coming off’ or ‘giving cardioplegia’, etc., maintain repetitive scans of the vital systems below using a six second time frame:
    1. Table activity; what the surgeon is doing or about to do.
    2. Patient monitoring: ECG, blood pressure, blood O2 saturation, temperatures, NIRS, etc.
    3. Pump monitoring: blood flow, system pressures, system temperatures, alarm settings, etc.
    4. Circuit monitoring: pump movement, reservoir level, leak free status, bubble free status, tubing tension, twists or kinks, etc.


  1. If a slip (error of commission, an incorrect action) or lapse (error of omission, failure to act when needed) occurs, subsequent six second scans will detect it in time to prevent injury to the patient.


  1. Severity (Harmfulness) Rating Scale: how detrimental can the failure be:

1) Slight, 2) Low, 3) Moderate, 4) High, 5) Critical

(If six second scanning is used, I would give this failure a Slight 1 RPN since the error would be quickly detected and corrected. If six second scanning is not used, the RPN should be 5 since an undetected error could develop into a critical situation.)

 Occurrence Rating Scale: how frequently does the failure occur:

1) Remote, 2) Low, 3) Moderate, 4) Frequent, 5) Very High

(If a perfusionist formally adopts the six second scan or some other formal self-monitoring system I would classify the Occurrence as Remote, so the RPN would be a 1. If such a system is not used the RPN would be 5.)

 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

(The Detectability RPN equals 1 if a six second scan is used. If not the RPN would be a 5.)

 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. (The RPN would be a 3. All patients would be at risk if the six second scan or other formal self-monitoring system is not used.)

 Multiply A*B*C*D = RPN.  The higher the RPN the more dangerous the Failure Mode.

The lowest risk for any failure would be 1*1*1*1* = 1 and 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 very low if the six second scan is used: 1*1*1*3 = 3. On the other hand, if the six second scan is not used the RPN would be 5*5*5*3 = 375. Without some form of effective self-monitoring system like the six second scan, the risk of a slip or lapse occurring and going undetected is 125 times greater.)


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