Cause of Device-Related Incident
Device factors; Support system failures

Clinical Specialty or Hospital Department
CCU / ICU / NICU; Clinical/Biomedical Engineering; Nursing; OR / Surgery; Pulmonary / Respiratory Therapy; Radiology / Ultrasound / Nuclear Med.

Device Factors
Improper maintenance, testing, repair, or lack or failure of incoming inspection

Document Type
Hazard Reports

External Factors
*Not stated

Mechanism of Injury or Death
Mechanical (puncture, perforate, lacerate, break, cut, tear, nick, crush)

Support System Failures
Error in hospital policy

Tampering and/or Sabotage
*Not stated

User Errors
*Not stated

Beds, Birthing [15-732]; Beds, Electric [10-347]; Collimators, Radiographic [16-389]; Enclosures, Aerosol Treatment [18-048]

Inspection and Preventive Maintenance--Don't Forget the Nuts and Bolts

Hazard [Health Devices Mar 1998;27(3):116-7]


ECRI has received several reports of a wide variety of medical equipment failures related to loose or missing fasteners (e.g., screws, bolts). In almost all these instances, proper inspection and preventive maintenance (IPM) of the equipment could have prevented the failures. Examples of these reports are as follows:

  • Assembly hardware came loose on a number of bed frames:
On several beds, the shoulder bolts supporting the four corners were found to be very loose. On two occasions, the   bolts fell out, making the beds uneven and unstable and presenting a hazard to both patients and staff.

A shoulder screw on the intermediate frame of a birthing bed from a different manufacturer came out of place while a patient was being prepared for childbirth. This failure caused the foot of the bed to drop and the head of the bed to rise suddenly.

  • An x-ray unit's collimator fell off the tube because a screw from the collar that holds the collimator in place was missing. No one was reported to have been hurt, but the failure could easily have led to patient or staff injury.
  • Set screws came loose in two aerosol treatment enclosure units—devices that are used to isolate patients and protect bystanders from contamination by infectious aerosols or toxic drugs during pulmonary treatments (e.g., for patients infected with tuberculosis or HIV). Reportedly, in each unit, a set screw designed to keep one of the blower assembly pulleys in place came loose, allowing the center of the pulley to grind against the blower shaft. As a result, metal shavings were created; these shavings exited the rear of the unit and then were sucked back into the front of the unit where the patient was receiving treatment.


As these examples illustrate, loose or missing fasteners on medical equipment can present hazards to both patients and staff. Therefore, we remind readers that it is important to check all fasteners on all medical devices during both incoming inspections and routine preventive maintenance.

Each procedure in ECRI's Health Devices IPM System specifies that the device's chassis/housing be checked; this is listed as the first qualitative test that should be performed. As part of the procedure, we typically recommend that the person performing the test ensure that all assembly hardware (e.g., screws, fasteners) is present and tight. This can be done by jiggling the device and then moving any movable parts through their normal range of motion. If any unexpected movements or noises occur, all fasteners in the affected area should be checked and tightened or replaced as appropriate.

For some devices, threadlocking products (e.g., Loctite, Permalok) or lock washers can be used to keep screws and bolts tight. However, it is important to verify with the manufacturer (e.g., by checking the service manual) that a specific threadlocking compound is appropriate for a given situation. Some threadlocking compounds are permanent, while others can be broken if necessary. Also, some compounds cannot be used with plastic components because they degrade the plastic.

To avoid the types of problems described in this report, we recommend that all staff be instructed to report the presence of loose fasteners on medical equipment to the clinical engineering department (or to other personnel responsible for maintaining the equipment). We also encourage readers to continue reporting such problems to ECRI.


  • Beds, Birthing [15-732]
  • Beds, Electric [10-347]
  • Collimators, Radiographic [16-389]
  • Enclosures, Aerosol Treatment [18-048]

Cause of Device-Related Incident

Device factor: Improper maintenance, testing, repair, or lack or failure of incoming inspection

Support system failure: Error in hospital policy

Mechanism of Injury or Death


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