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EQUIPMENT MAINTENANCE, BIOMEDICAL

ARIF SUBHAN

Masterplan Technology

Management

Chatsworth, California

INTRODUCTION

Preventive maintenance (PM) is one of the many functions of a clinical engineering department. The other functions include incoming inspection/testing, prepurchase evaluation, coordination of outside equipment service, hazard and recall notification, equipment installation, equipment repair and upgrade, purchase request review, equipment replacement planning, device incident review, and regulatory compliance maintainance. The primary objective of a PM program for biomedical equipment is to prevent failure, which is achieved through (1) detecting the degradation of any non-durable parts of the device and restoring them to like-new condition; (2) identifying any significant degradation of the performance of the device and restoring it to its proper functional level; and (3) detecting and repairing any partial degradation that might create a direct threat to the safety of the patient or operator.

The term preventive maintenance has its origins with mechanical equipment that has parts that are subject to wear and need to be restored or replaced sometime during the useful lifetime of the device. PM refers to the work performed on equipment on a periodic basis and should be distinguished from ‘‘repair’’ work that is performed in response to a complaint from the equipment user that the device has failed completely or is not working properly. The term ‘‘corrective maintenance’’ is often used instead of the term ‘‘repair.’’

Today, medical equipment uses electronic components that fail in an unpredictable manner, and their failure cannot be anticipated through measurements and checks performed during a PM (1). Also, equipment failures that are attributable to incorrect set up or improper use of the device or the use of wrong or defective disposable accessory cannot be prevented by doing PM (2). It has been argued that current medical devices are virtually error-free in terms of engineering performance. Device reliability is an intrinsic function of the design of the device and cannot be improved by PM. In modern equipment, the need for performance and safety testing is greatly reduced because of the design and self-testing capability of the equipment (3,4). For example, the Philips HeartStart FR2þ defibrillator performs many maintenance activities itself. These activities include daily and weekly self-tests to verify readiness for use and more elaborate monthly self-tests that verify the shock waveform delivery system, battery capacity, and internal circuitry. The manufacturer also states that the FR2þ requires no calibration or verification of energy delivery. If the unit detects a problem during one of the periodic self-tests, the unit beeps and displays a flashing red or a solid red warning signal on the status indicator (5).

The term ‘‘scheduled (planned) maintenance’’ was introduced in 1999 by a joint AAMI/Industry Task Force on

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Servicing and Remarketing while developing a document for submission to the FDA entitled ‘‘Joint Medical Device Industry Proposed Alternative to the Regulation of Servicers, Refurbishers, and Remarketers’’ (6). However, many still use the traditional term preventive maintenance rather than this new, more carefully defined term. According to the document developed by the AAMI/Industry Task Force, the term scheduled (planned) maintenance ‘‘consists of some or all of the following activities: cleaning; decontamination; preventive maintenance; calibration; performance verification; and safety testing.’’ Among these activities, the three key activities are (1) preventive maintenance (PM); (2) performance verification (PV) or calibration; and (3) safety testing (ST).

These three terms are defined by the AAMI/Industry Task Force as follows. ‘‘Preventive maintenance is the inspection, cleaning, lubricating, adjustment or replacement of a device’s nondurable parts. Nondurable parts are those components of the device that have been identified either by the device manufacturer or by general industry experience as needing periodic attention, or being subject to functional deterioration and having a useful lifetime less than that of the complete device. Examples include filters, batteries, cables, bearings, gaskets and flexible tubing.’’ PM performed on a medical device is similar to the oil, filter, and spark plug changes for automobiles.

‘‘Performance Verification is testing conducted to verify that the device functions properly and meets the performance specifications; such testing is normally conducted during the device’s initial acceptance testing.’’ This testing is important for detecting performance deterioration that could cause a patient injury. For example, if the output of the device (such as temperature, volume, or some form of energy) is not within specifications, it could result in an adverse patient outcome (7). If the performance deterioration can be detected by visual inspection or by a simple user test, then periodic performance verification becomes less critical. The data obtained during maintenance will also assist in determining the level and intensity of performance verification.

‘‘Safety testing is testing conducted to verify that the device meets the safety specifications, such testing is normally conducted during the device’s initial acceptance testing.’’

HISTORICAL BACKGROUND

The concept of a facility-wide medical equipment management program first emerged in the early 1970s. At that time, there was little management of a facility’s medical equipment on a centralized basis. Examples of the lack of proper management that affected the quality of care are described in detail in the literature (8) and include poor frequency response of ECG monitors, heavy accumulation of dirt inside equipment, delay in equipment repair, little attention to the replacement of parts that wear over time, and the consequential high cost of repairs.

The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) has played an important role in

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promoting equipment maintenance programs in hospitals in the United States. Almost all hospitals in the United States are accredited by the JCAHO and are required to comply with their standards.

Poor or nonexistent equipment maintenance programs

(8) coupled with the ‘‘great electrical safety scare’’ of the early 1970s (9) created the impetus that has popularized electrical safety programs in hospitals. Since then, equipment maintenance and electrical safety testing has been an important part of clinical and biomedical engineering programs in hospitals. The JCAHO standards in the mid1970s required that all electrically powered equipment be tested for leakage current four times a year (10).

In 1983, the Medicare reimbursement program for hospitals changed to a much tighter fixed-cost approach based on so-called Diagnostic Related Groups (DRGs). In 1979, JCAHO increased the maximum testing interval for patient care equipment to six months. This change was made in response to pressure from hospitals to reduce the cost of complying with their standards. It has been reported that there was no other rationale for changing the testing intervals (10).

In 2001, JCAHO removed the annual PM requirement for medical equipment (11). The reason cited for the change was that the safety and reliability of medical equipment had improved significantly during the prior decade. It was also stated that some equipment could benefit from maintenance strategies other than the traditional ‘‘intervalbased’’ PM. Other PM strategies suggested included predictive maintenance, metered maintenance (e.g., hours of usage for ventilators), and data-driven PM intervals.

INVENTORY

A critical component of an effective PM program is an accurate inventory, which has been a key requirement in the JCAHO equipment standards since they were introduced in the early 1970s. The 2005 JCAHO standard (EC.6.20) requires a current, accurate, and separate inventory of medical equipment regardless of ownership (12). The inventory should include all medical equipment used in the hospital (owned, leased, rented, physician-owned, patient-owned, etc.). A complete and accurate inventory is also helpful for other equipment management functions including tracking of manufacturer’s recalls, documenting the cost of maintenance, replacement planning, and tracking model-specific and device-specific issues. The equipment list should not be limited to those devices that are included in the PM program (13).

INCLUSION CRITERIA

In 1989, JCAHO recognized that not all medical devices are equally critical with respect to patient safety and introduced the concept of risk-based inclusion criteria for the equipment management program. Fennigkoh and Smith developed a method for implementing a risk-based equipment management program by attributing numerical values to three variables; ‘‘equipment function,’’ ‘‘physical risks associated with clinical application,’’ and ‘‘mainte-

nance requirements’’ (14). They compounded these values into a single variable; the equipment management (EM) number. The EM was calculated as follows: EM ¼ Function rating þ Risk rating þ Required Maintenance rating. The three variables were not weighted equally. Equipment function constituted 50% of the EM number whereas risk and maintenance each constituted 25%. The authors acknowledge the somewhat arbitrary nature of weighting the equipment function rating at 50% of the EM number; however, they viewed this variable as the device’s most significant attribute. The authors also arbitrarily set a level for the EM number at greater than or equal to 12 to determine whether the device will be included in the EM program. Devices included in the EM program are assigned a unique control number. Devices with an EM number less than 12 were excluded from the EM program and are not assigned a control number.

Although risk-based calculators using the original Fennigkoh and Smith model are still widely used, criticism of this method exists on the basis that this particular riskbased approach is arbitrary. The factors used in the calculation, their weighting, the calculated value above which one decides to include the device in the management program, and what PM interval to use are criticized as all being somewhat subjective or arbitrary (13).

SELECTING THE PM INTERVAL

Selecting an appropriate PM interval is a very important element of an effective maintenance program. Several organizations have offered guidelines, requirements, and standards for the selection of an appropriate PM interval for the various devices. This list includes accreditation organizations (e.g., JCAHO), state authorities (e.g., California Code of Regulations, Title 22), device manufacturers, and national safety organizations (e.g., NFPA). JCAHO is the primary authority that most people look to for minimum requirements for the PM intervals for medical devices. However, the JCAHO 2005 Standards [EC.6.10 (4) and EC.6.20 (5)] put responsibility back on the hospital to define PM intervals for devices based on manufacturer recommendations, risk levels, and hospital experience. JCAHO also requires that an appropriate maintenance strategy be selected for all of the devices in the inventory (12).

According to one source (7) two approaches exist to determining the proper PM interval. One is fixed and the other is evidence-based. Other sources present some contradictory views on how to select a PM interval for a device. Some (13,15) argue that PMs should not necessarily follow the manufacturer’s recommended intervals but should be adjusted according to the actual PM failure rate. Ridgway and Dinsmore (16,17) argue that if a device is involved in an incident where a patient or staff member is injured, a maintainer who has not followed the manufacturer’s recommendations will be deemed to have some legal liability for the injury, irrespective of how the device contributed to the injury. Dinsmore further argues that the manufacturer recommendations should be followed

Table 1. Conflicting Recommendations for the PM Intervals of Some Devices

 

ASHE PM

ECRI PM

Device Type

Interval (months)

Interval (months)

 

 

 

Defibrillator

3

6

Apnea monitor

6

12

Pulse oximeter

6

12

 

 

 

because the manufacturer developed the device and proved its safety to the FDA. He states that if no recommendations exist from the manufacturer, then it is up to the clinical engineering department to decide on the maintenance regimen. National organizations such as the American Society of Hospital Engineering (18) and ECRI (2) have published recommendations on PM intervals for a wide range of devices. The recommendations by ASHE were published in 1996 and ECRI in 1995. However, conflicting recommendations exist for certain devices in the list (see Table 1).

The ANSI/AAMI standard EQ56 (19) ‘‘Recommended Practice for a Medical Equipment Management Program’’ does not attempt to make specific recommendations for PM intervals for devices. And, in many cases, PM interval recommendations from the manufacturers are not readily available. Those that have been made available are often vague with little or no rationale provided. In some cases, their recommendations simply state that testing should be conducted periodically ‘‘per hospital procedures’’ or ‘‘per JCAHO requirements.’’

Intervals for the electrical safety testing of patient care equipment are discussed in the latest edition of NFPA 99-2005, Health Care Facilities, Section 8.5.2.1.2.2. Although this document is a voluntary consensus standard and not a regulation, many private and government agencies reference and enforce NFPA standards. The following electrical safety testing intervals are recommended. The actual interval is determined by the device’s normal location or area in which the device is used. For general care areas, the recommended interval is 12 months; for critical care areas and wet locations, the recommended interval is 6 months. The standard does allow facilities to use either longer or shorter intervals if they have a documented justification from previous safety testing records or evidence of unusually light or heavy use (20).

In a similar fashion, the evidence-based method allows adjustment of the interval up or down depending on the documented finding of prior testing (7). This method is based on the concepts of reliability-centered maintenance (21). Ridgway proposes an evidence-based method using a PM optimization program that is based on periodic analyses of the results of the PM inspections. His approach takes into consideration the severity of the problems found during the PMs. It classifies the problems found into one of the four PM problem severity levels, level 1 through 4. This method incorporates the concepts found in Failure Modes and Effects Analysis (FMEA)—a discipline that has been recently embraced by the JCAHO. It requires the classification of the problems discovered during the PM testing

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into four levels of criticality. Level 1 problems are potentially life-threatening, whereas the other levels are progressively less severe. Examples of level 1 problems include defibrillator output energy being significantly out of specification or an infusion pump significantly underor overinfusing. For a more detailed explanation of this method, see Ref. (22). Others (23,24) have used maintenance data in a similar way to rationalize longer maintenance intervals.

It should be noted that some regulations, codes, or guidelines and some manufacturer’s recommendations may advance more stringent requirements than other standards for the same type of device or an interval that the facility has used successfully in the past. In these instances, the facility needs to balance the risks of noncompliance, which may include injury to the patient, liability, and penalties for the organization, against the cost of compliance. Many factors exist that need to be evaluated before modifying the generally recommended intervals, including equipment maintenance history and experience, component wear, manufacturer recommendations, device condition, and the level of technology used in the device (2).

Note also that the manufacturer’s recommendations for their newer models of medical devices are generally less stringent than those for their older models. In many instances, the recommended PM intervals are greater than 12 months.

PM PROCEDURES

Selecting an appropriate PM procedure is another important element of an effective maintenance program. Both ECRI (2) and ASHE (18) have published PM procedures for a broad range of devices. It should be noted that the manufacturers usually provide more detailed PM procedures for their specific devices than those published by ECRI and ASHE. It is recommended that manufacturers’ recommendations that appear to be too complex be evaluated to see if they can be simplified (2). See Fig. 1 for a sample PM procedure for an infusion pump.

EVALUATION OF A PM PROGRAM

The facility’s PM completion or completed on-time rates are parameters that have been favored by both facility managers and external accreditation agencies (7). However, the value of PM completion rate as an indicator of program quality has been debated for many years (25). Until 2003, to pass the maintenance portion of the medical equipment program, the JCAHO required a consistent 95% PM completion rate. The shortcoming of this standard is that the 5% incomplete PMs could, and sometimes did, include critical devices such as life-support equipment. To address this undesirable loophole, the JCAHO, in 2004, discontinued the 95% requirement. The 2005 standard EC.6.20 now segregates medical equipment into two categories: life-support and nonlife-support devices. Life-support equipment is defined by JCAHO as those devices that are intended to sustain life and whose failure to perform their primary function is expected to result in death. Examples include ventilators, anesthesia

226

EQUIPMENT MAINTENANCE, BIOMEDICAL

 

 

For: INFUSION PUMP

PM Procedure No. IP001

 

Interval: xx months

Estimated annual m-hrs: x.0

Check the AC box if Action Completed and the AMR box if Adjustment or Minor Repair was required to bring the device into conformance with the performance or safety specifications. In this case provide a note* on the nature of the problem found, in sufficient detail to identify the level of potential severity of the problem.

AC/AMR Preventive Maintenance

SM1. Inspect/clean the chassis/housing especially any moving parts including any user-accessible areas under covers (if applicable). Examine all cable connections. Replace any damaged parts, as required.

SM2. Confirm that all markings and labeling are legible. Clean or replace, as required.

SM3. Replace or recondition the battery, as required.

AC/AMR

Performance Verification

PV1.

Verify that the flow rate or drip rate is within specification. Perform self-test, if applicable.

PV2.

Verify that all alarms (including occlusion and maximum pressure) and interlocks operate correctly.

PV3. Verify that the battery charging system is operating within specification.

PV4.

Verify the functional performance of all controls, switches, latches, clamps, soft touch keys, etc.

PV5.

Verify the functional performance of all indicators and displays, in all modes.

PV6.

Verify that the time/date indication is correct, if applicable.

AC/AMR Safety Testing

ST1. Check that the physical condition of the power cord and plug, including the strain relief, is OK.

ST2. Check the ground wire resistance. ( < 0.5 ohm ).

ST3. Check chassis leakage to ground. ( < 300 micro amps ).

* Notes:

Figure 1. Sample PM procedure for an infusion pump.

machines, and heart–lung bypass machines (12). ECRI suggests that the following additional devices be included in the life-support category: anesthesia ventilators, external pacemakers, intra-aortic balloon pumps, and ventricular assist devices (26). The completion of PMs for lifesupport equipment is scored more stringently than the completion rate performance for nonlife-support equipment. It is theoretically possible that if the PM of a single life-support device is missed, an adverse, noncompliance ‘‘finding’’ could be generated by the survey team. However, it has been reported that the surveyors will probably be more focused on investigating gaps in the process that led to the missed PM (27).

The 2005 JCAHO standards do not contain an explicit PM completion requirement. However, many organizations appear to have set the goal for on-time PM completion rate for life-support equipment at 100% and the goal for the nonlife-support equipment at better than 90%. An important aspect of PM completion is calculating the on-time PM completion rate. The JCAHO does not state how the PM completion rate should be calculated. Hospitals are free to specify in their management plan that they have allowed themselves either 1 or 2 months of extra time to complete the scheduled maintenance. It is important for those devices that have maintenance intervals of three months or less, or are identified as life-support equipment, that the PMs be completed within the month they are scheduled for PM. Sometimes, additional time may be needed for devices that are unavailable because they are continuously in use. In this case, the appropriate department and the safety/ environment of care committee should be informed about the delay.

The real issue to be addressed is the effectiveness of the program. However, ‘‘effectiveness’’ of a PM program is difficult to measure. If the purpose of the restoration of any nondurable parts is to reduce device failures, then the effectiveness of this element can be measured by the resulting reduction in the device failure rate. In principle, repair rates and incident analyses can provide a relationship between PM and equipment failures (7).

Two challenges associated with achieving an acceptable PM completion rate exist. The first is to find the missing equipment listed on the monthly PM schedule. Multiple documented attempts should be made to locate any devices that are not found, which should be followed with a written communication to the clinical users seeking their assistance in locating the device. It is important to get a written acknowledgment from the users that they have attempted to locate the devices in question. This acknowledgment will help when explaining to the surveyors that efforts were made to locate the device. However, if the devices cannot be located after this extended search it must be assumed that they are no longer in use in the facility. The question now is, are they still on site but deliberately or accidentally hidden away? Or have they really been removed from the facility? Until these questions can be answered, no satisfactory way to deal with accounting for the failure to complete the overdue PM exists. One strategy to reduce the potential administrative paperwork is to classify the missing equipment as ‘‘unable to locate.’’ This action (classifying the devices as unable to locate) should be commu-

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nicated to the appropriate departments including the user departments, the safety/environment of care committee, materials management, and security. Consistent loss or unable to locate device(s) should be viewed negatively by the facility and should serve as an indicator that the facility needs to re-evaluate its security plan. The users should be reminded not to use the missing device(s) if they reappear. These device(s) should be readily identifiable with the ‘‘out- of-date’’ PM sticker. The service provider should be notified so that they can give the re-emerging device(s) an incoming inspection and restart its PM sequence.

The second challenge is to gain access to equipment that is continually in use for patient care. It is difficult to complete the PM if the device is in constant use for monitoring or treatment of patients. Examples of devices that often fall into this category include ventilators, patient monitors, and certain types of laboratory or imaging equipment. Ideally, to alleviate this problem, a back-up unit should be available to substitute while maintenance is performed on the primary unit. This spare unit can also serve as a back-up for emergency failures as well. A good working relationship with the users is very helpful in these circumstances.

DOCUMENTATION

Documentation of maintenance work is another important element of an effective maintenance program. The 2005 JCAHO standards require the hospital to document performance, safety testing, and maintenance of medical equipment (12).

Complete scheduled maintenance and repair documentation is required when a device is involved in an incident, or when the reliability of the device is questioned, and also to determine the cost of maintenance. Most accrediting and regulatory organizations accept a system of exception reporting, which is recording only the results of steps failed during performance verification as part of scheduled maintenance or after repair (18). It has been generally accepted that it is reasonable to record only what went wrong during the PM procedure (13). Having extensive documentation is considered a safe practice. ECRI supports the use of exception reporting and recommends that before deciding on using exception reporting the hospital take into account that exception reporting, with its lack of affirmative detail, may be less than convincing evidence in the event of a liability suit (2).

Two ways to document scheduled (planned) maintenance exist. One is to record the maintenance by hand on a standard form or preprinted PM procedure and file the records manually. The other is to use a computerized maintenance management system (CMMS). Computerized records should help in reducing the time and space required for maintaining manual documentation. Even with CMMS, the department may need to have a way to store or transpose manual service reports from other service providers. Other technologies like laptops and personal data assistants (PDAs) can further assist in implementing the maintenance program. A comprehensive review of CMMSs, that are currently in use can be found in

228 EQUIPMENT MAINTENANCE, BIOMEDICAL

the literature (28). The CMMS helps the clinical engineering staff to manage the medical equipment program effectively. The core of the CMMS consists of equipment inventory, repair and maintenance record, work order subsystem, parts management subsystem, reporting capabilities, and utilities. A CMMS can be classified broadly as internally developed (typically using commercial off-the- shelf personal computer hardware and database software) and commercially available applications (desktop and webbased) (29).

STAFFING REQUIREMENTS

The number of full-time equivalents (FTEs) required to do scheduled maintenance varies based on the experience of the staff, the inventory mix, and the inventory inclusion criteria. See Ref. 30 for the method to determine the number of FTEs required for maintenance. Based on a clinical engineering practice survey, an average of one FTE is required to support 590 medical devices (31). The generally cited relationship between the support required for scheduled maintenance and repair for a typical inventory mix of biomedical devices is 750–1250 devices per FTE. Cost of the maintenance program includes salaries, benefits, overtime and on-call pay, cost of test equipment and tools, and training and education expenses. Salaries for the clinical engineering staff can be obtained from the annual survey published by the Journal of Clinical Engineering and the 24 7 magazine.

PM STICKERS

PM stickers or tags are placed on a device to indicate that maintenance has been completed and the device has been found safe to use. They also convey to the user a warning not to use the device when the sticker is out-of-date. Colorcoded stickers (see Fig. 2) or tags are not required by the JCAHO, but they can be very helpful in identifying devices that need maintenance (2,32).

ENVIRONMENTAL ROUNDS

Conducting environmental rounds is another important aspect of the medical equipment maintenance program. The intent of these rounds is to discover situations, which are, or could lead to, an equipment-related hazard or safety problem. The clinical engineering staff should conduct

Figure 2. Color coded sticker.

regular inspections of all clinical areas that are considered to be ‘‘medical equipment-intensive’’ areas (e.g., ICU, CCU, NICU, ER, and surgery). The interval between these equip- ment-related environmental safety rounds should be adjusted according to the frequency with which hazards are found. Other areas that are considered less equipmentintensive such as medical/surgical and other patient care floors, laboratory areas, and outpatient clinics should also be surveyed for electrical safety hazards but less frequently. The equipment items in these areas are usually line-powered items that do not have nondurable parts requiring periodic attention and they usually do not require periodic calibration or performance checking. These items need periodic visual inspections to ensure that they are still electrically safe (i.e., that no obvious defects exist such as a damaged power cord or evidence of physical damage that might electrify the case or controls). The search should be focused on the physical integrity of the equipment, particularly the power cord and the associated connectors and other equipment defects such as dim displays, torn membrane switches, taped lead wires, and so on. Items with power cords that are exposed to possible abuse from foot traffic or the wheels of other equipment should receive closer attention than those items with less exposed cords. Damaged wall outlets should be noted, as should the use of extension cords or similar ‘‘jury-rigged’’ arrangements. Other indicators that should be noted and investigated further are equipment enclosures (cases) that are obviously distorted or damaged from being dropped. In addition to these potential electrical safety hazards, other targets of this survey are devices with past-due PM stickers or with no sticker at all. When a safety hazard is identified, or a past due or unstickered item is found, appropriate corrective actions should be taken immediately and documented as required (33).

BIBLIOGRAPHY

Cited References

1.Wang B, Levenson A. Are you ready? 24 7 2004; Jan: 41.

2.ECRI. Health Devices Inspection and Preventive Maintenance System, 3rd ed. Plymouth Meeting (PA): ECRI; 1995.

3.Keil OR. Evolution of the clinical engineer. Biomed Technol Manag 1994; July–Aug: 34.

4.Keil OR. The buggy whip of PM. Biomed Technol Manag 1995; Mar–Apr: 38.

5.Philips. HeartStart FR2þ defibrillator. Instructions for use. M3860A, M3861A, Edition 8, 4-1, 4-9. Seattle (WA): Philips; 2002.

6.Hatem MB. From regulation to registration. Biomed Instrument Technol 1999;33:393–398.

7.Hyman WA. The theory and practice of preventive maintenance. J Clin Eng 2003;28:31–36.

8.JCAHO. Chapter 1. The Case for Clinical Engineering. The Development of Clinical Engineering. Plant, Technology & Safety Management Series Update Number 3. Chicago (IL): JCAHO; 1986. pp 9–11.

9.Nader R. Ralph Nader’s most shocking expose. Ladies Home J 1971;88: 98 176–178.

10.Keil OR. Is preventive maintenance still a core element of clinical engineering? Biomed Instrument Technol 1997;31: 408–409.