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C.VEN/BA-M1/06

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Contents

Detailed Proof Table for this specific manufacturer-model (Brand A - Model 1) maintained at the manufacturer-recommended maintenance interval (6m)

Each individual segment of the Summary Proof Tables (Table 5) is provided with a "drill down" link that reveals the Detailed Proof Table shown below. This table shows a breakdown of the various batches of data (in this case four batches) that support the aggregated data shown in the Summary Proof Table. This example is using hypothetical data and is for illustrative purposes only. Please refer to the notes below the table for an explanation of the analysis used to derive the various parameters shown in the table.


This table was last updated on 7-14-17

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Data aggregator/ provider ID code Facility code Data
batch #
Sample size
(# of
devices)
(N)
Time period
(years)
(E/N=)
(T)
Experience base
(# of
device-yrs) (E)
Is the size of
the experience base
acceptable?
(Table 11)
# of
MR 1 failures

(M)
# of
PM Code 9 failures

(W)
Total # of
DR-related failures

(M+W=)
(R)
MTBF
for
DR-related reliability
(E/R)
Level of
Severity of
DR-related
failure modes
Is the level of
DR-related reliability
acceptable?
(Table 12)
PM Priority level

(See
Table 12)
# of (PM
Code F)
SV-related
failures
(S)
MTBF
for
SV-related reliability
(E/S)
Level of
Severity of
SV-related
failure modes
Is the level of
SV-related reliability
acceptable?
(Table 12)
PM Priority level

(See
Table 12)
System S1 F45 C.VEN/BA-M1/06/DB1 40
devs
2.0
yrs
80.0
dev-yrs
Yes
- Good
0 1 1 80
years
LOS 3
(Life-
threatening)
Yes - Good
reliability and safety
2 40
years
LOS 3
(Life-
threatening)
No - Poor
reliability and safety
Facility F2 F2 C.VEN/BA-M1/06/DB2 12
devs
1.0
yrs
12.0
dev-yrs
No
- Inadequate
0 1 1 12
years
LOS 3
(Life-
threatening)
No - Poor
reliability and safety
0 Undeter
-mined
(>12
years)
LOS 3
(Life-
threatening)
Unknown
ISO Contractor
C1
F21 C.VEN/BA-M1/06/DB23 100
devs
4.0
yrs
400.0
dev-yrs
Yes
- Very good
2 2 4 100
years
LOS 3
(Life-
threatening)
Yes - Good
reliability and safety
1 400
years
LOS 3
(Life-
threatening)
Yes -Very good
reliability and safety
CMMS
Vendor
V1
F17 C.VEN/BA-M1/06/DB12 500
devs
2.0
yrs
1000.0
dev-yrs
Yes
- Substantial
2 6 8 125
years
LOS 3
(Life-
threatening)
Yes
- Good
reliability and safety
3 333
years
LOS 3
(Life-
threatening)
Yes - Very good
reliability and safety
Aggregated data for this man-model at this interval All
sources
C.VEN/BA-M1/06 652
devs
2.3
yrs
1492
dev-yrs
Yes
- Substantial
4 10 14 107
years
LOS 3
(Life-
threatening)
Yes - Good
reliability and safety
PM
Piority
2*
6 249
years
LOS 3
(Life-
threatening)
Yes -Very good
reliability and safety
PM
Priority
3

Analysis


With respect to the experience base being considered acceptable. The reported total of 1492 device-years (line 6 column 6) is considered to be "Substantial" since it is >500 device-years. (Table 11).

With respect to this device being classified as device restoration-critical at LOS 3 (potential for life-threatening injury). Based on the reported total of 14 DR-related failures (line 6 column 10), the MTBF (mean time between failures) for this type of device, when maintained at a 6-month interval is 107 years (1492 device -years/ 14 failures), which makes its DR-related reliability/ safety Acceptable at the "good reliability" level (75-150 years). See Table 12

With respect to this device being classified as safety verification-critical at LOS 3 (potential for life-threatening injury). Based on the reported total of 6 SV-related failures (line 6 column 15), the MTBF (mean time between failures) for this type of device, when maintained at a 6-month interval is 249 years (1492 device -years/ 6 failures), which makes its SV-related reliability/ safety Acceptable at the "very good reliability" level (>150 years). See Table 12

Based on these findings - although potentially-critical this particular manufacturer-model should not be considered a PM Priority 1 device. In spite of the high level of the severity of the outcome if it fails (potentially life-threatening), its demonstrated good - very good level of reliability means that it should be considered a 'PM Priority 2 device. See Table 12

Table 5A Thresholds for acceptability of the size of the experience base (Copied from Table 11 - Still tentative)


Experience base thresholds
(tentative)
Amount of data
(device-yrs)
Inadequate <50
Good 50-200
Very good 200-500
Substantial >500

Table 5B Definitions of the five different levels of device risk (copied from Table 12 - Still tentative)

The level of risk associated with a device failure caused by not completing the device's PM in a timely manner (which increases the risk that the device will fail) is determined by both the level of severity of the potential adverse outcome if the device fails (LOS 1, LOS 2, or LOS 3) and the device's demonstrated PM-related reliability (expressed as an MTBF* or mean time between failures).

So, devices that have at least one high severity failure mode (LOS 3) combined with a demonstrated poor PM-related reliability (MTBF less than 75 yrs) should be considered to represent the highest risk and labeled PM Priority 1 devices.

Devices with better levels of reliability (represented by longer MTBFs) and/or lower severity outcomes should be considered PM Priority 2, 3, 4 or 5 devices. The full hierarchy of different combinations of the worst-case severity of the result of the device failing and the device's demonstrated reliability is shown in the table below.


(This table was last updated on 4-9-16)






Level
of
potential risk
Outcome Severity Level
A, B, C, or D

Devices with
at least one
failure mode
with severity level
LOS 3
(Life-threatening
injury)
Outcome Severity Level
E, F, or G

Devices with
at least one
failure mode
with severity level
LOS 2
(Possible patient
injury)
Outcome Severity Level
H

Devices with
at least one
failure mode
with severity level
LOS 1
(Disruption of
patient care)
"PM Priority 1 device"
(potentially)
high risk
Poor
reliability

(MTBF <75 yrs)
"PM Priority 2 device"
(potentially)
mod - high risk
Good
reliability

(MTBF 75-150 yrs)
Poor
reliability

(MTBF <50 yrs)
"PM Priority 3 device"
(potentially)
moderate risk
Very good
reliability

(MTBF >150 yrs)
Good
reliability

(MTBF 50-100 yrs)
Poor
reliability

(MTBF <25 yrs)
"PM Priority 4 device"
(potentially)
low risk
Very good
reliability

(MTBF >100 yrs)
Good
reliability

(MTBF 25-50 yrs)
"PM Priority 5 device"
(potentially)
very low risk
Very good
reliability

(MTBF >50 yrs)
  • For definitions of Outcome Severity Levels A thru H - see column 5 of Table 4


Abbreviations
DR Device restoration, as in the device restoration-related tasks listed in a device's recommended PM procedure.
SV Safety verification, as in the safety verification-related tasks listed in a device's recommended PM procedure.
Level of Severity (LOS) 1 A device whose failure could be life-threatening i.e. that could cause the patient (or the user) to lose his or her life.
Level of Severity (LOS) 2 A device whose failure could cause a patient injury.
Level of Severity (LOS) 3 A device whose failure could cause a disruption of care, such as, delaying treatment or diagnosis, or requiring one or more patients to be rescheduled.
MTBF Mean Time Between Failures - is the inverse of the device's failure rate. For example, a device that failed twice in nine years has an MTPF of 4.5 years.

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