ELECTRICAL SAFETY Ongoing Testing

Medical equipment is tested for electrical safety throughout its lifetime. Baseline tests are run during acceptance testing. Tests are also run during PM, following equipment repair, upgrade, or patient incident. The measurements are recorded and compared to previous readings. Changes indicate possible electrical degredation that must be investigated to eliminate electrical hazards before an incident can occur. Training of equipment users in electrical safety concepts is also im­portant.

Electrical Safety Analyzers. Electrical safety analyzers are used to determine that electrical devices, ac receptacles, and conductive surfaces meet required safety standards and are safe for use. These solid-state instruments incorporate true rms measurement capability. They allow testing of portable medical equipment and fixed (hard-wired) installations. In­ternal circuitry [AAMI test load (14)] simulates the human body’s impedance to current flow. The measurements made are representative of the leakage currents (if present), which could flow through the body. Normal and reverse polarity tests, as well as current source tests, are run (32).

Micro – and Macroshock

Electrical safety as related to medical instrumentation con­cerns itself with limiting the amount of electric current al­lowed to pass through the body to a few microamps. This lim­its the current density (current per unit area) to values below a threshold that could affect or damage tissue and vital or­gans such as the heart and brain (33).

In a health-care setting patients are compromised when their skin is punctured and catheters are inserted, or when their skin is prepped (rubbed and cleaned with alcohol) prior to the placement of electrodes, and where moist environments exist. The electrical resistance of patient’s bodies to current flow is reduced from its normal range of 10,000 П to 100,000 П, to a range of 1000 П to 10,000 П. Under normal conditions 110 V ac applied to the skin results in currents of 1 mA to 10 mA. Under these compromised conditions larger currents of 10 mA to 100 mA result.

Macroshock (current above 1 mA) can be hazardous when delivered at the body’s surface. For example, 100 mA applied at the skin could cause ventricular fibrillation. Microshock (current below 1 mA) can be hazardous when delivered di­rectly or close to heart tissue. For example, current in the order of 0.1 mA may cause ventricular fibrillation. Currents such as these that can injure the patient are usually too low to affect the uncompromised equipment operator.

Ac Leakage Current

Ac leakage currents are found in electrical instruments other than battery-operated direct-current (dc) devices. Leakage currents are produced as a result of the ac signal coupling to the chassis of the instrument due to capacitance effects. Such currents flow from chassis to ground when a low-resistance path is made available.

The ground wire within the equipment’s three-wire line cord provides a safe low-resistance path for the leakage cur­rent. It is for this very reason that two-wire line cords are prohibited for hospital use. The ground wire is connected to the chassis of the instrument on one end and to the ground pin of the ac plug on the other. While this connection is intact the leakage current is safely conducted away from the pa­tient, as it flows from the chassis through the ground wire to ground via the ac wall outlet. Should this path open or pres­ent a high resistance from chassis to ground due to a loose wire connection in the plug, or an improperly grounded ac outlet, the leakage current seeking other pathways could flow through the compromised patient. Leakage currents can also flow between patient leads and ground due to poor lead isola­tion. The large number of medical devices that surround and could route electrical current to the patient compounds the problem.

Manufacturers limit leakage current by (34):

Incorporating patient isolation circuitry utilizing isolation amplifiers, optical coupling, and infrared transmission techniques

Doubly insulating some devices with an outer nonconduc – tive plastic housing so that even if touched, they cannot conduct electricity

Using specially constructed low-leakage ac line cords

Incorporating isolation transformers into systems, which have components whose total leakage current exceeds safety standards

Hospital Grade Plugs and Outlets

Safety is also provided by use of heavy-duty hospital grade ac plugs (with a green dot). These plugs are mechanically keyed to prevent polarity reversal. Explosion-proof plugs previously used due to the explosive nature of some anesthetic gases are no longer prevalent. Prior to opening new clinical areas, in addition to having the clinical gases certified, all ac outlets should be tested with a tension tester to verify that the ac outlets will tightly grip equipment plugs when inserted and with an ac polarity checker to ensure that the wiring has been properly done.

PROCUREMENT OF MEDICAL DEVICES Reasons for Equipment Acquisition

Equipment is acquired by a health-care facility for a multi­tude of reasons, including the following:

Replacement of obsolete equipment that cannot be re­paired as parts are no longer available or that is not cost-effective to repair as a new unit would be compara­ble in price to the repair cost. Included is equipment that breaks down frequently, resulting in lost patient revenue to the institution. Such equipment replacement increases the hospital’s cost-effectiveness and reduces its risk exposure.

Replacement of technologically obsolete equipment that is not as precise as newer microprocessor equipment, to improve diagnostic and therapeutic efficiency.

Introduction of new types of technologies, such as magnetic resonance imaging (MRI) and Catscan to provide en­hanced services.

Requirement of additional units of a type already being used in the facility to reduce equipment downtime and patient waiting.

Attracting highly qualified physicians including new de­partment chairmen.

Provided free of charge to the institution as part of a dis­posable contract.

Brought into the facility by clinicians for specific practice purposes.

Loaned to, or rented by, the institution.

Clinical Capital Equipment Committee

Equipment acquisition usually starts with a perceived need expressed by a clinician, a hospital administrator, or clinical engineer and a request is forwarded to the institution’s Clini­cal Capital Equipment Committee. However, equipment is sometimes purchased on an emergency basis based upon med­ical contingencies or for political reasons without committee input.

The Clinical Capital Equipment Committee is made up of clinical department chairpersons, physicians, hospital admin­istrators, as well as representatives from nursing, clinical en­gineering, finance, and purchasing. The committee reviews the equipment requests. Clinical engineering staff provides equipment inventory lists, instrumentation repair trends, and other equipment management information requested to expe­dite the decision-making process. Priorities are determined, a purchase list is generated, and requesting departments are notified. They prepare appropriate purchase requisitions, and necessary hospital administration signatures are obtained. The purchase requisitions are then submitted to clinical engi­neering for technical review.

"Turn-Key" Installations

Large ‘‘turn-key’’ installations require a request for quotation (RFQ) to be prepared for a bid process. Turn-key installations require the vendor to provide all equipment, materials (ca­bles, mounting devices, etc.), and labor to install the system completely, and, when ready, to turn it over to the institu­tion for acceptance testing. The RFQ document includes equipment specifications, environmental specifications, and legal requirements that address issues of noncompliance and penalties. During installation, such systems may require ex­tensive vendor-clinical engineering interaction and problem­solving, as fully detailed documentation is not always possible. They also require extensive acceptance testing. Sub­sequent to the bid award, a detailed purchase requisition is generated.

Purchase Requisition Review

Assists the clinician in obtaining needed equipment, ensuring that everything required (peripheral items, supplies, etc.) is being ordered and that all items are compatible with each other and with existing equipment. It also ensures that the physical plant is ready (e. g., water, gas, special electrical re­quirements) so that equipment installation and use will not be delayed.

Requisitions are first reviewed to determine the following:

If equipment falls within clinical engineering jurisdiction (i. e., items used in the health-care facility for which clinical engineering is responsible).

If the FDA has approved the equipment for clinical use. If approved only for investigational purposes (i. e., a re­search phase requiring clinical trial to prove its effi­cacy), clinical engineering staff could assist the clinician in obtaining IRB clearance for clinical trials.

If the equipment utilizes a new technology requiring an engineering evaluation and clinical trial period prior to purchase. Evaluation may also be required if several vendors have viable products that should be compared. Visits to other health-care institutions are sometimes required to view the equipment in use. Larger systems such as replacement of all of an institution’s obsolete physiological monitoring equipment necessitates input from future users including physicians and nurses.

If the equipment requires special physical plant utilities or has physical attributes (size, weight) that the facilities engineering department must be made aware of. If so, the facilities engineering manager’s purchase approval is required.

If equipment or accessories require special treatment to not pose an infection threat to patient or user (i. e., spu­tum chamber certification). If so, the infection control department should be notified so that appropriate hos­pital policies will be generated.

If equipment is year 2000 (Y2K) compliant. If not, the im­pact of this equipment on patient care must be deter­mined.

If sole-source justification (exemption from advertisement) is required. Sole-source acquisition is justifiable if the unit must be compatible with an existing item, a vendor holds a service contract and must supply parts, the unit has unique features needed by the requester, or no com­petition by manufacturer or vendor exists.

Purchase requisitions are next checked to ensure the fol­lowing (35):

All needed accessories have been specified and are compat­ible.

Vendor or manufacturer will uncrate, assemble, or cali­brate the unit (if required).

Vendor will assist with acceptance testing (if required).

Vendor will install the equipment (if required, i. e., mount to walls, etc.).

Vendor will provide (or loan) test kits or fixtures (i. e., phantom for diagnostic imaging) or simulators specifi­cally geared to the unit.

Vendor will provide user in-service training.

Vendor will provide sufficient number of operator and ser­vice manuals.

Vendor will provide VCR training tapes.

Vendor will provide acceptance testing and PM protocols.

Vendor will provide clinical engineering service training.

Vendor will provide an equipment loaner in the event of delayed delivery.

Vendor will provide system isolation transformers (if re­quired).

Specification of the correct delivery location (clinical engi­neering). This is true even for large items so that the clinical engineering department will be aware of deliv­ery, at which time the receiving department could be notified to route the unit to the intended user site.

Contact person has been specified should the vendor have to make arrangements with the clinical engineering de­partment or for training purposes.

Sufficient start-up materials are specified both for accep­tance testing and for start of clinical use.

Warranty period is specified and service contract specified (if required).

Although clinical engineers must concentrate on the tech­nical issues, they might also verify quotations, specify dis­counts if appropriate, ensure that buying service pricing is adhered to, determine if special promotions are offered, see if trade-in of obsolete equipment is feasible, and check on avail­ability and delivery dates.

The requisition is next submitted to the purchasing de­partment. A copy of the entire paperwork package, including all technical information gathered, is stored in clinical engi­neering’s open purchase requisition file awaiting equipment delivery. After delivery and acceptance, it will be stored in the equipment’s history file.

Bid Review

This review assists the clinician and purchasing department in determining if a low bidder offering an “equivalent” unit to what has been specified meets clinical requirements.

Depending upon the institution, equipment cost, and if a sole source is not justifiable a bid process may be required. Following bid opening a purchasing department bid analysis is sent to the clinical engineering staff and to the clinical re­quester. Working together, they determine if the ‘‘equivalent’’ device proposed by the low bidder is a viable alternative that meets clinical needs and the important specifications of the desired unit. If not, the more expensive unit may be justifi­able. This process requires comparison of the low bidder’s equipment to the unit originally specified and bid comparison to ensure that items have not been excluded that could artifi­cially lower the price. The low bidder may have to supply a loaner unit for engineering test and clinical trial. Subse­quently, a letter of justification is written, the award is made, and the equipment delivered.

Equipment Acceptance Testing

Equipment acceptance testing, also know as initial checkout or incoming inspection, ensures that all items ordered have been received and are undamaged, the equipment functions as per the manufacturer’s performance specifications, and the equipment is safe for both the clinical user and the patient.

Acceptance testing uncovers equipment defects including those not readily apparent, prior to the equipment being used on or for patients so as to reduce liability to the institution. Such testing is usually more in-depth than PM testing and is

Figure 8. Acceptance testing, endoscopic system. Acceptance testing assures that medical equipment functions properly, meets manufac­turers’ specifications, and is safe for use. It also verifies that all items ordered have been received, and appropriate in-service education is provided to the clinical and engineering staff. Shown here, an endo­scopic video system is undergoing an acceptance test. Such devices allow intra-body images to be displayed on monitors for ease of view­ing and allow their documentation via video recording or printout.

much more than just electrical safety testing (leakage current and grounding resistance). All medical equipment (whether purchased, leased, rented, loaned, physician owned, used as a demonstration model, or donated) should undergo acceptance testing. Short-term items are given a ‘‘loaner tag,’’ while long­term items are assigned an inventory number.

Acceptance testing should be thorough (36). A visual in­spection externally, as well as internally (when justified), en­sures that the instrument was not damaged in transit and has no loose or extraneous components. The visual inspection also verifies that the device is new, of the latest model, and has not been previously used (occasionally factory refurbished demonstration units may be purchased). Devices are checked for electrical safety, mechanical safety, and functionality and to assure that they meet the manufacturer’s own performance specifications (an important concept). Built-in diagnostics are run to provide future confidence in them (Fig. 8).

A report is generated documenting test results, conversa­tions with the manufacturer, and information learned about the device, such as electromagnetic compatibility. These data serve as a baseline for future repair and PM testing and to help answer questions posed by the clinical staff. Acceptance testing also provides a practical training ground for the clini­cal engineering staff, keeping them current should emergency clinical situations develop or a patient incident occur involv­ing this equipment. All defects uncovered and the steps taken to resolve them should be documented in a defect log, which becomes part of the equipment history file. Until the defects are resolved, the equipment should not be released for clinical use. There is typically a 60-day period starting with equip­ment delivery in which acceptance testing is expected to be concluded. Should there be a defect (or should only a partial shipment of equipment be received) expenditures processing must be notified immediately so that they can inform the ven­dor that the payment clock has been stopped to avoid the in­stitution paying a penalty. Also, equipment warranty must not start until acceptance testing is successfully concluded. The documentation showing that the hospital did thorough testing is invaluable to the institution during a lawsuit.

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