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

Clinical Specialty or Hospital Department
Clinical/Biomedical Engineering; Obstetrics and Gynecology; OR / Surgery

Device Factors
Design / labeling error; Improper maintenance, testing, repair, or lack or failure of incoming inspection

Document Type
Hazard Reports

External Factors
*Not stated

Mechanism of Injury or Death
Embolism (gaseous or particulate); Fire

Support System Failures
Use of inappropriate devices

Tampering and/or Sabotage
*Not stated

User Errors
Failure to perform pre-use inspection; Improper connection

UMDNS
Insufflators, Laparoscopic [16-849]; Medical Gas Cylinders [16-501]

Improper Connection of Laparoscopic Insufflators and Gas Cylinders



Hazard [Health Devices May 1992;21(5):181-2]

Problem

While replacing a CO2 gas cylinder during a laparoscopic procedure, a member hospital unintentionally connected a cylinder containing a N2/CO2 /He gas mixture, which is intended for use only with laser equipment, to the laparoscopic insufflator. This improper connection occurred as a result of using two sealing washers instead of one between the insufflator's yoke and the gas cylinder's valve assembly. The patient was not injured, even though the error was detected after completing the procedure. However, introducing a gas or gas mixture that has a low blood solubility and the ability to support combustion can lead to the formation of a gas embolism or fire, respectively.

Discussion

A CO2 pin-indexed gas cylinder yoke is supplied with most laparoscopic insufflators to ensure connection to only COgas cylinders. To produce a gastight seal, a single washer is needed when inserting the insufflator's yoke inlet into the gas cylinder's valve outlet. In the reporting hospital, all insufflators' yokes and all gas cylinders are equipped with a washer. In the reported incident, both washers were left in place. Consequently, when the yoke and valve assembly were connected, the combined width of the two washers created sufficient space between the pins and pinholes to defeat the yoke's pin-indexed safety feature, thus allowing virtually any gas cylinder to be connected (see figure).

Related problems

We previously reported a similar problem associated with the use of two washers between an oxygen regulator and a gas cylinder's yoke (see our Hazard Report, "Oxygen Regulator Fire Caused by Use of Two Yoke Washers," ). Many medical devices are routinely equipped with a pin-indexed yoke that has a sealing washer, and they are often used with gas cylinders that also have a sealing washer; therefore, this problem is not unique to laparoscopic insufflators. Precautions should be taken with any medical device that uses an external gas source; introducing an improper gas into the body can place the patient at considerable risk.

Manufacturer action taken

Some manufacturers of laparoscopic insufflators are aware of this problem. Recently, two of them added a cautionary advisory to their operator's manuals, instructing customers to use only one washer between the insufflator's yoke and gas cylinder's valve assembly.

Recommendations

  1. Ensure that all hospital personnel who deal with laparoscopic insufflators are aware of this report.
  2. Determine whether a sealing washer is present on the yoke inlets of the insufflators and the valve outlets of the gas cylinders in your hospital. Implement an appropriate policy (e.g., remove the washers from all of your hospital's gas cylinders) to ensure that only one washer is used between the yoke and valve assembly. If not already present, this information should be appended to the operator's manual of each laparoscopic insufflator. Affix an appropriate label or tag to the insufflator yoke; for example: This yoke inlet is equipped with a washer. Remove washer from gas cylinder's valve outlet, if present.
  3. Before operating the insufflator, verify that its yoke is connected to the proper gas cylinder with only one washer between them.
  4. Always have a second CO2 gas cylinder available during a laparoscopic procedure to avoid the possibility of connecting an improper gas tank to the insufflator when the primary cylinder starts to lose pressure.
  5. During routine, periodic equipment inspections, verify that a single washer is being used and that no differences in procedure (e.g., using a new tank supplier) have occurred that would necessitate a change in procedure.

UMDNS Terms

  • Insufflators, Laparoscopic [16-849]
  • Medical Gas Cylinders [16-501]

Cause of Device-Related Incident

Device factors: Design/labeling error; Improper maintenance, testing, repair, or lack or failure of incoming inspection

User errors: Failure to perform pre-use inspection; Improper connection

Support system failure: Use of inappropriate devices

Mechanism of Injury or Death

Embolism (gaseous); Fire


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