Inadvertent C-arm Movements: Potential Cause of Patient and Staff Injury

Article Outline

• Clinical Case
• What Happened, and Why Did it Happen?
• Discussion
• References
• Copyright

Abbreviation: IEC, International Electrotechnical Commission

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Clinical Case 

A critically ill trauma patient with multiple orthopedic external fixation devices was being transferred from the fluoroscopy table in the interventional radiology suite to a large air bed in preparation for his return to the intensive care unit. Numerous radiologic technologists and intensive care unit personnel were present in the room. In preparation for the transfer, the tableside control boxes for the c-arm and imaging functions were moved from their usual position on the side rail of the patient table to allow the bed to be positioned next to the patient table. The control boxes were placed on the patient table, at the end of the table.

The patient was placed on a backboard. The c-arm gantry was positioned at the foot of the fluoroscopy table. The bed was brought into the procedure room and locked in place adjacent to the patient table. Radiology and intensive care unit staff were present on either side of the patient and at the head of the bed. An experienced radiologic technologist was at the foot of the bed, between the bed and the c-arm. As the patient was being moved, the backboard came to rest on the joystick that controls the c-arm motion. The joystick was depressed and moved laterally by the backboard, causing the c-arm to rotate. The inferior portion of the c-arm moved toward the bed, trapping the technologist’s leg against the foot of the bed. A second technologist realized that the c-arm was moving, and shouted to have the bed unlocked to free the technician’s leg. The injured technologist sustained a large hematoma on the anterior aspect of her lower leg, needed to use crutches for a period of time, and missed 4 days of work. Had the second technologist not observed the c-arm motion and called for the bed to be unlocked, a much more severe crush injury would probably have occurred.

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What Happened, and Why Did it Happen? 

Transferring critically ill or injured patients to the fluoroscopy table is often a chaotic event. With large specialty beds and numerous tubes, wires, and hardware, many people are required to safely transfer patients. Some of these individuals will not be aware of potential movements of the fluoroscopy unit or operation of the controls for these components. This makes accidents possible.

The bed or wheelchair into which a patient is being transferred must be locked in place to prevent patient injury. However, this can also create a potential hazard. In this case, unintentional activation of the c-arm trapped the technologist between the c-arm and the locked bed.

Numerous safety requirements for interventional fluoroscopy equipment have been developed. They are codified in international standards developed by the International Electrotechnical Commission (IEC), the leading global organization that prepares and publishes international standards for all electrical, electronic, and related technologies. The IEC charter includes x-ray equipment. A current IEC standard requires that two switches be activated to move the table or c-arm. These switches can be built into a single controller (1). The fluoroscopic unit in question has this safety feature—the c-arm control must be depressed and toggled. Unfortunately, this measure was not sufficient to prevent this accident.

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Discussion 

Unintended motion of interventional fluoroscopy equipment is uncommon, but does occur. The United States Food and Drug Administration’s Manufacturer and User Facility Device Experience Database is a database of reports of medical devices that may have malfunctioned or caused a death or serious injury. This database is searchable by the public (2). Three cases of unintended motion have been reported, not including the case described herein. Many “close calls” and incidents involving staff, as opposed to patients, likely go unreported.

The IEC is currently revising the safety standard for interventional fluoroscopy equipment. The committee responsible for the revision, after reviewing the Food and Drug Administration’s Manufacturer and User Facility Device Experience Database, has decided to include a requirement for a separate switch to permit disabling all equipment motions that have dual switch activation (Donald Miller, MD, personal communication, 2006). This motion disabling switch would prevent the kind of accident described herein, and would also prevent injury to cleaning staff and other individuals who might otherwise inadvertently initiate equipment motions.

The change to the IEC standard described herein is a long-term fix. Manufacturers need not comply until introduction of the first new models after adoption of the revised standard. In the interim, we have adopted new procedures in the interventional radiology department. Tableside controls are placed out of the way during patient transfers. A qualified radiology technician is responsible for monitoring the controls and ensuring that patient or staff movements do not accidentally activate the equipment. Until built-in safety measures are present, heightened vigilance by interventional radiology staff is required.

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References 

1. International Electrotechnical Commission. Medical electrical equipment–part 2-32: particular requirements for the safety of associated equipment of X-ray equipment. Report 60601 Geneva: IEC; 1994;60601-2-32
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2. US Food and Drug Administration. MAUDE Database. Rockville, MD: Center for Devices and Radiological Health; 2006;http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfMAUDE/search.cfmAccessed December 12, 2006
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