Jim McEwen PhD
Pneumatic tourniquets are used many thousands of times per day in orthopaedic and non-orthopaedic surgical procedures in the United States and elsewhere, facilitating operations by reliably establishing a bloodless surgical field with a high level of safety.
As with any type of medical device there is considerable variation between tourniquet systems currently available in the market in terms of cost, capabilities and safety features. When considering a tourniquet system for purchase, buyers should take the following factors into consideration:
Within the last thirty years, there have been important improvements in the technology of tourniquet instruments and tourniquet cuffs. Buyers should be aware of the types of safety features and alarms that may be included in the instruments and cuffs they are considering for purchase and carefully review the specifications of each.
Modern electronic tourniquet instruments include a pressure regulator that maintains cuff pressure at the level set by the user and an automatic timer to provide an accurate record of tourniquet inflation time and alarm if the inflation time exceeds a limit set by the user. Tourniquet instruments also typically include audiovisual alarms to prompt the operator if hazardously high or low cuff pressures are present in the cuff. Other safety related features and alarms that may be present in a tourniquet instrument include:
- Self-test capabilities to provide automatic checks of system operation and calibration at each start-up of the instrument.
- Self-monitoring capabilities to continuously monitor the operation of the instrument.
- A backup battery to allow instruments to continue to operate normally during an unanticipated power interruption or during patient transport.
- Alarms to detect potentially hazardous air leakage from pressurized tourniquet cuffs.
- Alarms to detect occlusions of the tubing connecting the instrument to the cuff.
- Alarms to detect failure of a cuff to depressurize when deflation is intended.
- A cuff hazard interlock to prevent the instrument from being inadvertently powered off while a cuff is still inflated.
- Interlocks to help prevent inadvertent cuff deflation during intravenous regional anesthesia (Bier Block) procedures.
Additional features that may be found in some of the most modern tourniquet systems include:
- Automated estimation of Limb Occlusion Pressure, permitting individualized setting of safer tourniquet pressures.
- Integrated cuff testing, the capability to test cuffs, tubing and connectors for leaks.
- Interfaces to OR information systems to capture cuff pressures and inflation times.
In addition to the safety features listed above, the user interface of the tourniquet instrument may also include special safety features to help prevent inadvertent and unintended changes in cuff pressure by the user during a procedure.
The tourniquet cuffs that are applied to each patient should also be taken into consideration when selecting a tourniquet system. Proper cuff selection and application is essential for safe tourniquet use. Cuffs must provide adequate surgical exposure and properly fit the surgical limb. Buyers should consider if cuffs are available for the instrument to correctly fit the patient population for which the system is intended. Manufacturers offer cuffs in various sizes and shapes to fit a wide range of patient limbs, from the smallest pediatric patients to large bariatric patients. Some manufacturers also provide matching limb protection sleeves to be used between the cuff and the limb to help prevent damage to the skin beneath the cuff.
Two tubes or one?
Tourniquet instruments and cuffs are commonly available in dual port (two tubes per cuff) or single port (one tube per cuff) configurations. Dual port instruments and their corresponding cuffs have two separate tubing connections between the instrument and each attached cuff. One connection regulates the air pressure in the cuff and the other monitors the pressure in the cuff. Generally speaking, dual port instruments and cuffs provide the most accurate and reliable indication of pressure within the cuff. This is especially important when the tourniquet cuff is used to measure Limb Occlusion Pressure as described above.
Single port instruments and their corresponding cuffs have a single tube connecting the instrument to the cuff. The connection is used for both pressure regulation and monitoring. Single port instruments and cuffs usually cost less than dual port instruments.
Adaptors should not be used to connect single port cuffs to dual port instruments or to connect dual port cuffs to single port instruments.
One cuff or two?
Tourniquet instruments are available in single and dual channel configurations. Dual channel instruments can control the pressure in two cuffs simultaneously, facilitating bilateral and IVRA (Bier Block) procedures. Each cuff channel should have independent indicators for cuff pressure and inflation time and independent, well identified controls for cuff inflation and deflation. The controls, indicators and cuff connecting tubing should be color coded to help identify the cuff connected to each channel. For additional safety, interlocks are included in some systems to help prevent inadvertent cuff deflation during IVRA procedures.
Single channel instruments control the pressure in only one cuff. They are generally smaller and less costly than dual channel instruments. Two single channel instruments may be used together for bilateral and IVRA procedures. Under no circumstances should adaptors be used to connect two or more cuffs to a tourniquet instrument intended for single channel operation.
When selecting a tourniquet instrument and cuff system buyers should always consider their clinical needs and carefully review the safety features and performance specifications of the systems under consideration.Read Full Post | Make a Comment ( None so far )