Smiths Medical supply a wide range of Tracheal and Tracheostomy tubes and different designs fall into different MRI classifications. Definitions of MRI classification are generally taken from ASTM standard for "Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment", F2503.
Product safety in an MRI environment is generally dictated by the presence of metal components within the product. For a Smiths Medical Tracheal or Tracheostomy Tube, metal can be present either in the form of a small spring within the cuff inflation valve or as a reinforcement spring within the wall of the tube itself. The influence of the intense magnetic field on metal in a product can create any of 3 risks: a heating effect, a projectile danger from induced forces and image distortion in the vicinity of the metallic part which may in turn cause an inability to interpret the image.
There are three different MRI classifications:
MR-Safe: This classification can only be applied to products that do not contain any metallic elements and therefore only Tracheal and Tracheostomy tubes that have no cuff and which do not have a reinforced shaft fall into this classification. These products can be considered completely safe with no potential for interaction with the MR field. (e.g. un cuffed Blue Line Tracheostomy tube)
MR-Conditional: These are products that are safe to use within an MRI environment if the user is aware of the safe conditions of use and takes the necessary precautions. Testing has demonstrated that:
1. None of the Smiths Medical Tracheal and Tracheostomy tubes suffer from an MRI induced temperature rise that would cause any clinical danger.
2. Smiths Medical Tracheal and Tracheostomy tubes with metal reinforced shafts and/or cuffed tubes (which will by necessity have metallic inflation line valves) can be used safely if (for a cuffed tube) the inflation line is taped down securely away from the area of interest of the scan and (for a reinforced tube) if the area of interest of the scan is not in the close vicinity of the tube shaft.
Cuffed Blue Line Tracheostomy tubes fall into category 2 above and hence they are safe to use if the inflation line valve is taped down away from the area of interest of the scan.
MR-Unsafe: These are products which must not be used in an MRI environment. Any MR-Unsafe product will always have this clearly specified in the Instructions for Use that accompany the product.
Note: The above information is provided for guidance where there is none given in the Instructions for Use that accompany the product. If there is any conflict between the above information and that provided in the Instructions for Use, then the latter should always be adopted.