Cause of Device-Related Incident
Device factors; External factors; User errors

Clinical Specialty or Hospital Department
CCU / ICU / NICU; Clinical/Biomedical Engineering; Emergency Medicine; Facilities Engineering; Nursing; Obstetrics and Gynecology; OR / Surgery

Device Factors
Design / labeling error

Document Type
Hazard Reports

External Factors
*Not stated; Medical gas and vacuum supplies

Mechanism of Injury or Death

Support System Failures
*Not stated

Tampering and/or Sabotage
*Not stated

User Errors
Accidental misconnections

Medical Gas and Vacuum Systems [18-46]; Medical Gas Outlets [17-682]

Medical Gas System Fittings

Hazard [Health Devices Oct 1978;7(12):309]


A member hospital reported that a patient was injured when a suction regulator with a quick-connect fitting was inadvertently pushed into a quick-connect oxygen wall fitting. The patient, who was on intermittent suction for wound drainage, had been transferred in his bed to a new room. The suction system and regulator remained fully assembled and connected to the patient during the transfer. The attendant mistakenly pushed the regulator, with its suction fitting, into the central outlet in the new room. Although the suction fitting would not lock in place, attempts to make it lock were sufficient to open the oxygen valve, which momentarily delivered 50 psi oxygen to the regulator and the patient's suction system. The pressurized oxygen reportedly damaged the suction regulator and injured the patient.


The hospital sent a regulator and another oxygen outlet to ECRI. Our tests confirmed that the valve could be opened and that oxygen could flow through the regulator as long as the regulator was held forcibly in the outlet. The coded pins on the regulator fitting prevented full insertion and locking. While the reported incident involved a one brand of quick-connect fitting, it could occur with fittings of other manufacturers.

To determine whether such operation is unique to the quick-connect fittings in question, we attempted to insert a number of other common brands of vacuum hose fittings into an oxygen DISS wall outlet. While none of the hose fittings would lock into the DISS oxygen outlet, oxygen could be delivered through DISS outlets to many brands of quick-connect vacuum fittings as long as they were held in place. Some brands of quick-connect vacuum fittings opened the valve in the DISS oxygen outlet, but most of the oxygen blew out into the room, rather than through the vacuum fitting. We suspect that further tests would show that many other fittings designed to be incompatible will actually activate valves, at least momentarily, and thus present a variety of risks, depending on the gases and equipment involved.

Safety under all possible conditions of misuse cannot be guaranteed by either standard DISS fittings or proprietary quick-connects. The current systems of connectors offer many safeguards but are not perfect. A perfect system, if designed, could not be implemented for some years. Meanwhile, safety can be ensured only through careful use of connectors that are built to prevent most hazards. This incident emphasizes the need for greater care in the use of gas fittings.


  1. Never connect a patient, or keep a patient connected, to equipment before plugging it into vacuum, compressed gas, or electrical power outlets. First check the equipment for proper connections and operation, and then connect it to the patient. During moves, or even shutdowns, controls may be inadvertently moved or connections changes.
  2. Pay special attention to labeling, easy mating of keyed parts, color coding, and other features of equipment that help prevent improper connections.
  3. In-service training programs should stress the safe use of oxygen, vacuum, and other medical gas services.
  4. Check your central gas systems, which may have been installed during various phases of hospital construction and may include fittings supplied by various manufacturers. Test the different fittings in use for compatibility/incompatibility problems similar to the one reported here. If any potentially dangerous misconnection is possible, alert appropriate departments (e.g., respiratory therapy, anesthesia, and nursing) to the problem and see that precautionary measures are demonstrated in in-service programs.
  5. For any new construction in the hospital, if more than one system of fittings is in use, choose the one with the fewest compatibility problems.


  • Medical Gas and Vacuum Systems [18-46]
  • Medical Gas Outlets [17-682]

Cause of Device-Related Incident

Device factor: Design/labeling error

User error: Accidental misconnection

External factor: Medical gas and vacuum supplies

Mechanism of Injury or Death


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