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Table 5.3HE Critical care ventilators (illustrative hypothetical example)

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Summary Proof Table - for one particular potentially PM-Priority 1 device type

  • Each individual row of the Summary Proof Table (below) provides a summary of the data collected on a particular manufacturer-model version of this particular device type. Each row of summary data is provided with a "drill down" link (on the third row of each cell in C1) to a Detailed Proof Table that shows a breakdown of the various batches of data that are aggregated into the summary data shown in each row of the table. The link is the abbreviation in the first column (C1) of each row (e.g. C.VEN/BA-M1/06).
  • Columns C2 and C3 show the total amount of data in device-years (the experience base) collected for this particular manufacturer- model and an indication as to whether or not this exceeds the amount of data that the Task Force has (tentatively) set as the minimum acceptable level (see Table 11).
  • Columns C4 through C7 provide data on the likelihood that this manufacturer-model version of this particular device type will experience a failure that is attributable to the deterioration of a component that is scheduled to be restored by one or more device restoration tasks in the manufacturer's recommended PM procedure. During the test period such failures were coded as either an MR1 type of failure when the device was repaired - PM-preventable - (see Section 1.4 of HTM ComDoc 1) or as a PM Code 9 finding (serious physical deterioration) during a routine PM (see Section 1.7 of HTM ComDoc 1). Column C4 expresses this likelihood of the device failing from this particular type of PM-preventable failure as a reliability level (or risk level), based on the number of such failures reported over a substantial test period. The Task Force (tentatively) considers a mean time between failures (MTBF) greater than 75 years to represent an acceptable level of PM-related reliability (see Table 12). Devices showing reliability levels less than this are classified in column C7 as PM Priority 1 devices.
  • Columns C8 through C11 provide data on the likelihood that this manufacturer-model version of this particular device type will experience a hidden failure (see Section 1.6 of HTM ComDoc 1). Hidden failures, which are also described as safety verification (SV) related failures, are discovered during routine PMs and are coded as PM Code F findings (see Section 1.7 of HTM ComDoc 1). Column C8 expresses this likelihood of encountering a hidden failure as a reliability level (or risk level) based on the number of such encounters reported over the same substantial test period.
  • When there is a conflict between the two device risk levels (PM Priority levels) reported in columns C7 and C11, the lowest PM Priority level (which is also asterisked) should be considered to be the device's effective PM Priority level.
  • Column C12. Likelihood of failing (from a PM-preventable cause). Entries in this column provide an indication of whether or not this particular manufacturer-model version of this particular device type has a sufficiently substantial documented test period (i.e. an experience base of more than 50 device-years in column C2) showing an acceptable level of PM-related reliability. For devices with a possible outcome severity at the most serious level (LOS 3), the threshold for acceptable reliability is less than one failure every 75 years (i.e. an MTBF of greater than 75 years). Manufacturer-model versions of the device that do meet this level of reliability, when maintained at the interval indicated, should be considered eligible to be included in an AEM program. They are labeled in column C12 as "Unlikely - (eligible for AEM)"
  • Clicking on the device manufacturer - model link in the C1 cell of each row (e.g. Brand A Model 1) will take you to a direct quotation from the manufacturer's literature regarding the recommended PM interval - if the procedure is available and if there is a specific recommendation.
  • This link to the FDA's Global Universal Device Identification (GUDID) website (https://accessgudid.nlm.nih.gov) is provided here for possible use in the future.


This table was last updated on 5-9-16

C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11
Critical care ventilators Experience base
(# of
device-yrs)
Is the size of the
experience base
acceptable?
(See Table 11)
MTBF
for
DR-related reliability
Level of
Severity of
DR-related
failure modes
Is the level of
DR-related reliability
acceptable?
(See Table 12)
PM
Priority level

(SeeTable 12)
MTBF
for
SV-related reliability
Level of
Severity of
SV-related
failure modes
Is the level of
SV-related reliability
acceptable?
(See Table 12)
PM
Priority level

(SeeTable 12)
R1 Brand A
Model 1
(at MR 6m interval)
C.VEN/BA-M1/06
1492
device-yrs
Yes
- Substantial
107
years
LOS 3
(Life-
threatening)
Yes - Good
reliability and safety
PM
Priority
2*
249
years
LOS 3
(Life-
threatening)
Yes - Very good
reliability and safety
PM
Priority
3
R2 Brand A
Model 1
(at 12m interval)
C.VEN/BA-M1/12
80
device-yrs
Yes
- Good
13
years
LOS 3
(Life-
threatening)
No - Poor
reliability and safety
PM
Priority
1*
80
years
LOS 3
(Life-
threatening)
Yes - Good
reliability and safety
PM
Priority
2
R3 Brand B
Model 2
(at MR 6m interval)
C.VEN/BB-M2/06
600
device-yrs
Yes
- Substantial
100
years
LOS 3
(Life-
threatening)
Yes - Good
reliability and safety
PM
Priority
2*
200
years
LOS 3
(Life-
threatening)
Yes - Very good
reliability and safety
PM
Priority
3
R4 Brand B
Model 2
(at 12m interval)
C.VEN/BB-M2/12
160
device-yrs
Yes
- Good
80
years
LOS 3
(Life-
threatening)
Yes - Good
reliability and safety
PM
Priority
2*
80
years
LOS 3
(Life-
threatening)
Yes - Good
reliability and safety
PM
Priority
2*
R5 Brand C
Model 3
(at MR 6m interval)
C.VEN/BC-M3/06
810
device-yrs
Yes
- Substantial
90
years
LOS 3
(Life-
threatening)
Yes - Good
reliability and safety
PM
Priority
2*
270
years
LOS 3
(Life-
threatening)
Yes - Very good
reliability and safety
PM
Priority
3
R6 Brand C
Model 3
(at 12m interval)
C.VEN/BC-M3/12
300
device-yrs
Yes
- Very good
23
years
LOS 3
(Life-
threatening)
No - Poor
reliability and safety
PM
Priority
1*
43
years
LOS 3
(Life-
threatening)
No - Poor
reliability and safety
PM
Priority
1*
R7 Brand D
Model 4
(at MR 6m interval)
C.VEN/BD-M4/06
400
device-yrs
Yes
- Very good
40
years
LOS 3
(Life-
threatening)
No - Poor
reliability and safety
PM
Priority
1*
200
years
LOS 3
(Life-
threatening)
Yes - Very good
reliability and safety
PM
Priority
3
R8 Brand D
Model 4
(at 12m interval)
C.VEN/BD-M4/12
160
device-yrs
Yes
- Good
53
years
LOS 3
(Life-
threatening)
No - Poor
reliability and safety
PM
Priority
1*
160
years
LOS 3
(Life-
threatening)
Yes - Very good
reliability and safety
PM
Priority
3

Commentary

This table illustrates (with hypothetical data) how tables such as this provide evidence (or not) for the acceptability of the reliability and safety of several (hypothetical) manufacturer-model versions of this type of device.

  • With respect to the experience base. There is an adequate amount of data aggregated for each of the devices listed in the table, ranging from a low of 80 device-years to a very substantial 1492 device-years. The Task Force has tentatively set the minimum acceptable amount of data at 50 device-years (Table 11).
  • With respect to Brand A - Model 1. According to the illustrative PM Findings shown in rows R1 and R2, it appears that the Brand A - Model 1 critical care ventilator, when maintained at a 12-month interval, behaves like a PM Priority 1 device. As can be seen from the data in row R2, the frequency of device restoration-related (DR) failures is higher than the acceptable limit - with an MTBF of only 13 years, relative to the minimum acceptable level of 75 years (Table 12) - at this interval. Whereas the data in row R1 shows that the frequency of DR-related failures (with an MTBF of 107 years) is acceptable when the same devices are maintained at the manufacturer-recommended 6-month interval. This provides solid evidence that the recommended PM interval of 6 months provides an adequate level of safety, whereas the 12-month PM interval is too long.
  • With respect to Brand B - Model 2. In contrast to this, the PM Findings data for the Brand B - Model 2 ventilator shown in rows R3 and R4, shows that this specific device demonstrates an acceptable level of reliability even when it is maintained at a longer (12-month) interval than the manufacturer-recommended 6-month interval.
  • With respect to Brand C - Model 3. Yet another pattern is seen with the PM Findings data for the Brand C -Model 3 ventilator shown in rows R5 and R6. While it shows acceptable reliability and safety when it is maintained at the manufacturer-recomended 6-month interval, it shows an unacceptable frequency of performance and/or safety problems (with an MTBF of 43 years) when it is maintained at the longer 12-month interval, in addition to an unacceptable frequency of device restoration-related failures (with an MTBF of 23 years). Based on this empirical evidence, this particular model should be classified as a PM Priority 1 device when it is maintained at the 12-month interval.
  • With respect to Brand D - Model 4. A different and more concerning pattern is seen with the PM Findings data for the Brand D - Model 4 ventilator shown in rows R7 and R8. The data demonstrates unacceptable levels of reliability and safety at both maintenance intervals - apparently related to the poor reliability of the device‚Äôs non-durable parts. Based on this evidence this particular model should be classified as a PM Priority 1 device when maintained at either interval and consideration should be given to using a shorter (maybe 3-month) PM interval.
  • It would certainly be prudent to continue to monitor the levels of patient safety (see Section 3.10 of HTM ComDoc 3) being achieved by the current procedures or by any of the more efficient procedures (if they were chosen) for - at least - all devices categorized as PM Priority 2.
  • Before making any changes to the facility's PM program we also recommend reading the cautionary note that can be found in Section 4.11 of HTM ComDoc 4.


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