For the best patient outcome, it is important that all equipment is assembled, calibrated, and tested prior to its use. The following sections highlights some key considerations during equipment assembling, calibration and testing.
Assembling equipment and supplies
Efficiency in the operating room demands that all of the necessary equipment and supplies be assembled before the patient arrives in the room. For procedures that will require the use of a pneumatic tourniquet, the following equipment and supplies are necessary:
- Mounting: Some types of tourniquet instruments are mounted on IV poles; others are mounted on portable stands or are placed on a table top.
- Tourniquet instrument: Modern electronic tourniquet instruments have a power cord that must be plugged into a properly grounded power source. The more sophisticated instruments have a backup battery which charges automatically when the unit is plugged in, and therefore the unit should be plugged in whenever possible. Note that some instruments do not have a backup battery and therefore must be plugged in at all times during use.
Some old tourniquet instruments require a connection to hospital pressurized gas supply; for such older systems, ensure that the source is of the appropriate type and pressure as specified by the tourniquet manufacturer. Modern electronic tourniquet instruments utilize an internal electrical pump to compress the ambient air; these systems do not require an external pressure sources such as portable tanks, or built-in hospital gas systems.
- Manufacturer’s guides: Keep an operating manual readily available and attach a troubleshooting guide to every tourniquet instrument.
- Connecting tubing: Virtually all systems have a hose and connector assembly (positive-locking or Luer) for attaching the cuff to the tourniquet instrument. Ensure that the connectors on the cuff and instrument hose(s) are compatible. If a dual-port system is being used, ensure that the cuffs are also dual-port; similarly for single-port systems ensure that the cuffs have a single port. Do not use adapters other than those that may be provided by the instrument manufacturer for connecting the cuff to the instrument.
For systems requiring a hospital pressurized gas supply, another hose attaches the tourniquet to the external pressure source. Ensure that this hose has appropriate connectors and sufficient length.
- Tourniquet cuff: Be sure to select the appropriate cuff style, width, and length as outlined in Tourniquet Cuff Selection.
- Limb Protection: High pressures, high pressure gradients and shear forces applied to skin and soft tissues underlying a tourniquet cuff can cause injuries to the skin and soft tissues. To reduce the nature and extent of these injuries, studies have been published that evaluate the relative effectiveness of no protective material, underlying padding, underlying stockinette, and underlying limb protection sleeves that are matched to specific limb sizes and cuff sizes [1-3]. Study results provide evidence that limb protection sleeves improve safety by protecting the skin underlying tourniquet cuffs during tourniquet use, and further provide evidence that greatest safety is achieved through the use of limb protection sleeves specifically matched to the limb size and cuff size. Click here to learn more about matching limb protection sleeves.
Do not use cotton cast padding, sheet padding, Webril, or any material that may shed loose fibers; lint from these materials can become embedded in the hook and loop cuff fasteners and reduce their effectiveness, possibly leading to an unexpected release of the cuff during the procedure .
- Drape: The size of the drape depends on the limb. It is used to protect the skin from chemical burns and to keep the tourniquet cuff clean. In particular the drape chosen must prevent fluids from collecting between the patient’s skin and the cuff, which can cause skin injury.
- Measuring tape: Use a nonstretch measuring tape to obtain limb circumference. Preferably, the tape should measure both inches and centimeters so the measurement can be compared to available tourniquet cuff sizes.
- Pressure display testing equipment: A calibration kit is available from many manufacturers; a mercury manometer adapted for the testing of the tourniquet display may also be used.
- Elastic bandage: A tensor bandage or other elastic bandage should be available for exsanguination; in some cases, gravity exsanguination alone will be sufficient and a bandage will not be used.
Calibrating the tourniquet instrument
Some pneumatic tourniquet instruments, particularly older non-electronic types, can be subject to large and dangerous discrepancies between the pressure indicated on the display and that exerted by the cuff bladder. Such discrepancies can result in over-pressurization or under-pressurization of the cuff and underlying soft tissue. The perioperative staff can minimize potentially hazardous pressure variations by learning how to perform the manufacturer’s recommended calibration tests. Some manufacturers of older, non-electronic tourniquets recommend that calibration be checked before each patient use.
As an accessory, most manufacturers make available a calibration kit with a gauge specifically designed for calibrating the pressure display. If a calibration kit is not provided, a mercury manometer can be used. For a preoperative calibration check, a T-shaped connector can be fitted between the pneumatic tourniquet instrument and the cuff. A manometer is then attached to the T connector. When the cuff is inflated, the pressure display should equal that of the mercury manometer. The display should also be checked for pressure changes (drift) by ensuring that the pressures remain equal over several minutes. If a substantial difference or drift is observed, the tourniquet instrument should not be used and should be sent for repair.
Most modern electronic tourniquet instruments have a self-test mode that is activated when the power switch is turned on. The self-test rapidly verifies all alarm systems and the pressure accuracy of the display. A manual calibration check is normally unnecessary for these units, and if required is performed by appropriately trained biomedical engineering or technologist personnel.
If either a manual calibration test or the computerized self-test indicates that the tourniquet display is in error, do not use the instrument. Immediately remove the instrument from service and send it to biomedical engineering for repair.
Testing the tourniquet system
It is important to test the pneumatic tourniquet system before every patient use. Patient safety demands that all tourniquet parts be functioning properly before the procedure.
Before each use, inspect the tourniquet instrument and mounting, connecting tubing, gas source (if used), and cuff. Make sure that all connections are in good condition and are securely fastened according to the manufacturer’s written instructions. To guard against accidental deflation, connect the cuff to a tourniquet instrument, wrap the cuff onto itself, secure all fasteners, and inflate the cuff. Check to make sure that there are no leaks in the cuff, tubing, or connectors. Some modern tourniquet instruments can automatically detect any leakage in the pneumatic system . If gas tanks are used, check the gas level before the procedure begins.
Reusable tourniquet cuff
A reusable tourniquet cuff is subject to wear and deteriorates with use. When inspecting the cuff before each use, give special attention to the following questions:
- Is there any physical damage (rips, tears, holes, etc.) to the cuff? If the cuff is not completely intact, it may leak or burst, causing an unexpected loss of pressure.
- Is (are) the connector(s) bent, broken or worn?
- If there is a ribbon tie, is it torn or the ribbon stitching broken?
- Is the contact closure torn or is any of the strap stitching broken?
- After cleaning, is more than 25% of the contact closure embedded with fibers that cannot be removed?
- Is there any other physical change or damage to the cuff that would compromise the cuff’s ability to maintain occlusion during the surgical procedure?
- Have permanent kinks or ridges formed in the stiff structure inside the cuff (palpable through the cuff outer material), particularly along the inner surface facing the patient’s limb?
Disposable tourniquet cuff
A single-use disposable tourniquet cuff is supplied in a sterile package. Before opening and selecting a single-use disposable tourniquet cuff, give special attention to the following questions:
- Is there any physical damage (rips, tears, holes, etc) to the package that may affect its sterility?
- Is the single-use disposable tourniquet cuff past its expiry date specified on the sterile package?
If any of the above conditions are present, do not use that particular cuff. Use of a damaged cuff could result in one or more of the following unwanted events:
- Loss of cuff pressure
- Release of the cuff from around the patient’s limb
- Movement of the cuff on the patient’s limb
- Excessive leakage of cuff pressure
- Pinching of tissue under the cuff leading to injury
- Some of these failures could cause serious injury to the patient by releasing blood into the surgical site or by releasing a bolus of anesthetic into systemic circulation.
 Tredwell SJ, Wilmink M, Inkpen K, McEwen JA. Pediatric tourniquets: analysis of cuff and limb interface, current practice, and guidelines for use. Journal of Pediatric Orthopaedics. 2001 Sep 1;21(5):671-6.
 Olivecrona C, Tidermark J, Hamberg P, Ponzer S, Cederfjäll C. Skin protection underneath the pneumatic tourniquet during total knee arthroplasty: a randomized controlled trial of 92 patients. Acta orthopaedica. 2006 Jan 1;77(3):519-23.
 McEwen JA, Jameson M, Gebert MA, Cheung WK, inventors; Western Clinical Engineering Ltd., assignee. Apparatus and method for estimating leakage in a surgical tourniquet system. United States patent US 8,083,763. 2011 Dec 27.