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Table 12

From HTMcommunityDB.org

Definitions of the different levels of a device's priority for PM

The level of risk associated with the PM-preventable failure of a device (one caused by not completing the device's required PM competently and in a timely manner) is determined by both the level of severity of the potential adverse outcome of the device's failure (either LOS 1, LOS 2, or LOS 3) and the device's demonstrated PM-related reliability (expressed as an MTBF or mean time between failures). Demonstrated levels of PM-related reliability at both the manufacturer-recommended intervals and at various other intervals are documented in Table 13.

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 *) represent the highest risk and are categorized as PM Priority 1 devices.

Devices with higher PM-related reliability (showing longer MTBFs) and/or lower severity outcomes are considered to be 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.

  • 75 yrs*. This is a tentative/placeholder number based on the retrospective analysis of some data that was not as well standardized as the Maintenance Practices Task Force is now requiring (see New Welcome Package). Determination of what level of PM-related reliability should be considered to provide a sufficient level of patient safety is still under investigation by the Task Force. Table 13 is currently being populated with data conforming to the new data standardization criteria. This table shows how performing the manufacturer-recommended preventive maintenance on a variety of different devices results in a quite wide range of different levels of PM-related reliability. Currently the range of MTBFs extends from about 10 years to 342 years.


(This table was last updated on 8-28-18)



Device's
PM Priority level

(Level
of PM-related 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
(Possible disruption of
patient care)
"PM Priority 1 device"
(high PM-related risk)
Poor PM-
related reliability;
failure ="Quite likely"

(MTBF <75 yrs)
"PM Priority 2 device"
(moderate PM-related risk)
Good PM-
related reliability;
failure = "Unlikely"
(MTBF 75-150 yrs)
Poor PM-
related reliability;
failure = "Quite likely"
(MTBF <50 yrs)
"PM Priority 3 device"
(low PM-related risk)
Very good PM-
related reliability;
failure = "Very unlikely"
(MTBF >150 yrs)
Good PM-
related reliability;
failure = "Unlikely"
(MTBF 50-100 yrs)
Poor PM-
related reliability;
failure ="Quite likely"
(MTBF <25 yrs)
"PM Priority 4 device"
(very low PM-related risk)
Very good PM-
related reliability;
failure = "Very unlkely"
(MTBF >100 yrs)
Good PM-
related reliability;
failure = "Unlikely"
(MTBF 25-50 yrs)
"PM Priority 5 device"
(extremely low PM-related risk)
Very good PM-
related reliability;
failure ="Very unlikely"
(MTBF >50 yrs)
  • For definitions of Outcome Severity Levels A thru H - see column 5 of Table 4
  • MTBF (mean time between failures) is a measure of the device's demonstrated level of reliability. It is the inverse of the device's average failure rate. A higher MTBF indicates that the device is more reliable.


Definitions of the different levels of a device's priority for PM

As can be seen from the table -

  • PM Priority 1 devices have PM-related failures that could result in a serious, life-threatening injury (LOS 3) and are considered to be "quite likely" to fail from a PM-preventable cause (i.e. they have a poor PM-related reliability)
  • Devices that are considered to be PM Priority 2 devices represent just two combinations of severity and risk
  • Devices that are considered to be PM Priority 3 devices represent three combinations of Level of Severity and PM-related reliability
  • Devices that are considered to be PM Priority 4 devices represent just two combinations of severity and risk
  • Devices that are considered to have the lowest priority (PM Priority 5 devices) are devices with the lowest level of outcome severity (LOS 1) and the lowestlikelihood of failing ("Very unlikely").


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