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Medical device incident investigations, November 2002
A femoral head impactor was accidentally dropped during a procedure at a NSW hospital. After the event, blood was noticed to have "spurted out" from the gap between the plastic (polyoxymethylene, also known as acetal and Delrin) cap on the femoral head impactor and the metal part to which it was attached. The two parts were held together by means of a rivet and were not designed to be taken apart. The rivet was removed and the instrument was dismantled. Both fresh and dried blood was found underneath the plastic component.
Further examination by the TGA revealed contamination underneath many of the plastic components in this range of instruments, including the handles. Invariably, the plastic components could not be separated from the metal parts for cleaning. The deposits appeared to be dried blood, but this could not be conclusively determined.
In another instance, blood was found underneath the plastic heel of a tibial impactor. When the TGA examined other examples of the same instrument, bone cement was found lodged underneath the plastic component. Again this plastic component was riveted into place and was not designed to be dismantled for cleaning.
Both the femoral head impactor and handles, and the tibial impactor are the subject of recalls for product correction [Note: the users of these devices have been contacted directly>. However, the TGA understands that this is an issue that potentially affects all types of reusable surgical instruments. For this reason, the TGA's Medical Device Incident Report Investigation Scheme (IRIS), has undertaken a survey of reusable surgical instruments to assess whether there are design problems with other instruments that affect their ability to be adequately cleaned before sterilisation.
If reusable surgical instruments are not properly cleaned before autoclaving, then they cannot be assumed to be sterile. Thus inadequate cleaning, either through poor procedures or some aspect of instrument design, represents an infection hazard. Reusable medical devices should be made in such a way that, wherever possible:
- They are made from a single piece of material without any joins or joints;
- They can be fully dismantled and the user is instructed to do so for cleaning;
- Any joins or joints are watertight so that it is impossible for contamination to get inside the crevices.
From experience gained by the TGA during the investigation of this issue, press-fit plastic handles, for example, are not watertight. Rust and other deposits have been found underneath handles and other components made from this material. On the other hand, the TGA has dismantled several fabric-filled phenolic resin handles from instruments that had reached end of service life, and found no evidence (eg rust, dried blood etc) of residues that fluid had gathered underneath these handles. Presumably, the superior dimensional stability of the fabric-filled composite had prevented the problem in this case.
Users of reusable surgical instruments must ensure that instruments are being cleaned and disinfected in accordance with appropriate procedures. More information in this regard can be found in AS4187: 1998 - "Cleaning, Disinfecting and Sterilizing Reusable Medical and Surgical Instruments and Equipment, and Maintenance of Associated Environments in Health Care Facilities" and "Infection Control Guidelines for the Prevention of Transmission of Infectious Diseases in the Health Care Setting" (Draft endorsed in 2002: NHMRC / Communicable Diseases Network of Australia).
Features of instrument design that render an instrument difficult to clean adequately should be raised with the instrument supplier and/or reported to the TGA's Medical Device Incident Report Investigation Scheme.
Potential embolisation and/or unravelling of guide-wires following insertion of central venous catheters
The following is a transcript of a Safety Alert that was sent by the TGA to all public and private hospitals in Australia. The Alert is addressed to the attention of all hospital staff, but especially:
- Medical Practitioners
- Nursing staff
- Intensive Care Units
- Operating Theatres
- Hospital Wards
- Hospital Executive.
Description of the Problem
The TGA has received reports from both Australia and New Zealand of serious adverse events associated with guide-wires used with Peripherally Inserted Central (venous) Catheters (PICCs).
The reports relate to the inadvertent cutting of the guide-wire while trimming the length of the catheter at the time of insertion, resulting in a piece of guide-wire remaining within the patient's circulatory system and requiring further intervention to retrieve it. In one instance, it was noticed that the guide-wire was difficult to withdraw. Once withdrawn, x-rays revealed that a section of the guide-wire had separated and had been left in the pulmonary artery. In most other cases, inadvertent cutting of the guide-wire during shortening of the catheter caused it to unravel inside the patient when an attempt was made to remove the guide-wire. A few guide-wires and catheters have been trimmed before attachment of the injecting hub because the user thought that the guide-wire was part of the catheter.
Guide-wires have also caused embolisation, vessel damage or have travelled via the patient's circulatory system into the heart, lungs or lower limbs causing further problems such as infection.
Guide-wires are of slightly different design depending on the catheter, but most often consist of an outer coil of guide-wire wrapped around and welded to a central core of wire at the proximal and distal ends.
It is important that the manufacturer's instructions for use are followed when inserting these catheters. Shortening of the catheter should be avoided whenever possible. This reduces the likelihood of guide-wires being inadvertently cut. The instructions for use of most PICCs caution against the inadvertent cutting of the guide-wire prior to insertion of the catheter. If it is necessary to shorten the catheter, the catheter manufacturer's instructions for doing so should be carefully followed, taking precautions to ensure that the guide-wire has not been inadvertently cut.
Some catheters are cut prior to the catheter being placed in the patient. For these types of catheters, the instructions for use direct the user to measure the length required and then trim the catheter at the insertion end. The guide-wire must be pulled back at least 4cm more than the length of the catheter to be cut. This guide-wire must not be pushed back down the catheter as it may damage the inner lumen and the guide-wire. There should be very little resistance when the catheter is cut. If there is resistance or difficulty in cutting the catheter the guide-wire may have been inadvertently cut. After cutting the catheter check that there is no wire in the cut portion.
Other catheters should only be shortened after the catheter has been inserted and the guide-wire has been removed. When inserting a catheter that is thread over a guide-wire, ensure that this guide-wire is visible at the distal or external end of the catheter following insertion of the catheter. This guide-wire should be removed before the catheter is trimmed and the injection hub connected to the catheter.
Extra copies of the alert may be obtained by contacting the TGA's Medical Device Incident Report Investigation Scheme (IRIS) on facsimile: (02) 6232 8555 or by email: firstname.lastname@example.org.
Radiographic Tables: Possibility of injury to patient's feet or fingers when the table pedestal cover is damaged
Radiographic table pedestal covers can be damaged when the table is lowered and the cover hits an obstacle, such as a footstool. Footstools are found often in this environment.
The covers are designed to move up and down with the height of the table and any damage may not initially appear to be dangerous, particularly as this damage may be hidden because the covers overlap at lower table heights. As the table is raised, a gap may appear when the top cover passes the limit of the bottom cover, the gap being an effect of the damage. The possibility of injury is higher for children, or when patients are sitting next to the table when having an arm or hand radiographed, as the patient's other hand or foot may move unnoticed at the side of the table.
Check radiography table pedestal covers carefully and regularly - such checks should be included in the regular maintenance schedule for the equipment, as well as a daily systems check. The table should also be carefully checked for damage after events such as collisions with footstools, trolleys or other equipment.
Any damage should be repaired quickly but, if the repair is difficult or will take some time, a rubber flap can be attached to temporarily cover the defect.
French health officials have banned the sale or exportation of zirconia femoral head prostheses made by St Gobain Advancees Desmarques using their tunnel furnace sintering process. The decision follows a year-long investigation into high fracture rates associated with this product and an FDA warning relating to Good Manufacturing Practice (GMP) violations.1
The TGA received initial notification about problems with this product from France's Agence Française de Sécurité Sanitaire des Produits de Santé (AFSSPS) in July 2001 through a vigilance report exchange program. The St Gobain zirconia femoral heads were used in several implant manufacturers' hip replacement systems. In August 2001, after extensive consultations with the companies involved and the TGA's Therapeutic Device Evaluation Committee Advisory Panel on Orthopaedic Devices, the TGA issued a Hazard Alert about the devices and cancelled affected products from the Australian Register of Therapeutic Goods. St Gobain zirconia femoral head prostheses have not been available in Australia since then.
The problem is related to a change from using batch furnaces in the sintering stage of manufacture of the ceramic to using a continuous ("tunnel") furnace. Products made using both types of processes met all design specifications and passed all accepted tests, however implants sintered using the new furnace were subject to higher, unacceptable rates of early fracture compared to those made using the batch furnaces. It is now thought that the ceramic made with the continuous furnace undergoes a change in crystalline structure, which causes it to fracture.
In September 2001, the manufacturer conducted a worldwide recall of nine batches of the product that had experienced higher than "normal" fracture rates. The TGA was not presented with enough evidence to justify restricting the Hazard Alert and Recall only to some batches, so in Australia, the Hazard Alerts and Recalls covered all batches of femoral heads made using the continuous furnace.
The TGA's own Hazard Alert on this issue may be found: Zirconia femoral head hip prostheses. Further information on the technical aspects of this issue may be found on the Prozyr website.
Readers should note that expert opinion does not recommend preventative replacement of any of these implants at this stage. Replacement should only be considered if the femoral head has failed or if the implant requires revision for other reasons.
1. The GMP Newsletter, FDA News, Issue 271, August 2002, p3.
Device incident reports 01/04/2002 to 30/06/2002
Number received: 115
|Not Device Related||12|
|Hospital Supply Service||20|
|No Further Action||47|
|Problem Not Confirmed||1|
|Refer to GMP||7|
- The problem causes are not mutually exclusive. For example, a material deficiency may have led to a mechanical malfunction or a biocompatibility problem.
- Every report received by IRIS receives a risk analysis by the Scheme Coordinator and is discussed by a panel of technical and clinical professionals. In the case of reports that are "Not Investigated" the panel has made a decision that further investigation of the particular event is not necessary at that time. However, these reports are logged into the database for future reference and the trend of reports is monitored. In making their decision, the panel considers whether any similar reports have been received previously.