PERFECT FIT The wider the tourniquet cuff, the less pressure needed to stop arterial blood flow.

Performing hand surgery without a tourniquet? Famed surgeon Sterling Bunnell, MD, once said it'd be like "trying to fix a watch in a bottle of ink." When deciding on which tourniquet is right for the patients and extremity procedures you host, and to best avoid tourniquet-related complications, consider the following 6 factors.

IDEA THAT WORKS If you don't have access to a curved tourniquet, pull the skin or soft tissue around the application site to create a more cylindrical surface.

1. Size and shape
The wider the tourniquet cuff, the less pressure needed to stop arterial blood flow. Tourniquets should apply pressure evenly, so match the shape of the tourniquet's cuff to the extremity being operated on. Limbs of muscular or obese patients, for example, are more conical than cylindrical, meaning curved cuffs — which require less pressure to stop blood flow — would be best suited to apply even pressure. If you don't have access to curved tourniquets, pull the skin or soft tissue around the application site to create a more cylindrical surface.

2. Skin protection
Place elastic sleeves underneath tourniquets to avoid skin breakdowns caused by pressure from skin wrinkles or the surface of the tourniquet's underside. A 2006 study appearing in the Nordic journal Acta Orthopaedica (tinyurl.com/74emjdz) assessed the efficacy of elastic sleeves, soft cast padding or nothing placed under tourniquet cuffs on total knee arthroscopy patients. The researchers reported that no patients with elastic sleeves developed skin blisters, while twice as many patients with nothing under the tourniquet developed blisters than patients who wore soft cast padding.

Elevate the limb about to be operated on and use an elastic wrap to squeeze blood from the extremity's vessels before inflating the tourniquet in order to help achieve a bloodless field, but avoid this technique on patients with fragile skin or visible skin infections.

3. Application times
The risks of soft-tissue damage and other complications start as soon as tourniquets are inflated. How long is too long to keep them applied? Clinical research is inconclusive, but does note that complication risks increase with extended tourniquet use. However, 2 hours is widely accepted as the cutoff time before serious and irreversible complications such as muscle fatigue or damage, nerve damage, coagulation issues and edema can occur. While some surgeons deflate tourniquets intermittently during surgery in an effort to prevent these complications from developing, the practice has not proven effective and in fact can make performing the planned procedure more difficult.

PRE-OP PLANNING

Who's at Increased Risk For Intraoperative Bleeding?

BLEEDER? Know who's at increased risk for excessive bleeding during surgery.

Be sure patients' pre-op assessments include information about their bleeding histories, and confirm that information during pre-procedure phone calls. Here are a few questions that help identify who's at increased risk for excessive bleeding during surgery:

• Does the patient bruise or swell easily?
• Does the patient have an acquired or family history of bleeding disorders?
• Is the patient currently on blood-thinning medications such as coumadin or aspirin that could result in bleeding-related complications?
• Did patients experience any bleeding issues during previous surgeries, including minor dental procedures?

Part of the surgeon's surgical plan should include 2 simple ways to limit intraoperative bleeding: targeting approaches to the surgical field through bloodless planes and meticulous soft-tissue dissection.

— Ravi Karia, MD

4. Post-op care
Once the tourniquet is released, a fresh supply of oxygenated blood and nutrients — and possibly such surgery-related substances as cement or fat emboli — flow back to the extremity, which can cause pulmonary reactions and renal tubular damage. To sidestep these complications, adequately hydrate patients during and after surgery. Also forego the use of bone cement and avoid working in a bone's intramedullary canal when tourniquets are applied. Should you release tourniquets before or after wound closure? The topic is controversial, but the consensus indicates you should release tourniquets before wound closure if dissection takes place near vital vessels. On the other hand, close the wound and apply a compressive dressing before releasing the tourniquet if it was used for an extended time near small-caliber vessels.

5. Minimal pressure
Current tourniquet models are computerized, allowing for direct control of pressure settings and alarms that can be set for specified time-points. Set the tourniquet at the lowest pressure possible to achieve arterial occlusion. Some tourniquets on the market today come with suggestions to set the pressure 50mmHg to 150mmHg over systolic blood pressure, with lower recommended settings in upper extremities and higher recommended settings in lower extremities. These recommendations achieve a bloodless surgical field, but can result in overshooting pressure settings.

6. Injury risks
Burning of the skin under the tourniquet is a devastating, but easily prevented, complication. Burns occur when excess skin prepping solution soaks the padding of the tourniquet's cuff and is held under high pressure on the patient's skin for extended periods. (Prepping solutions with high alcohol content are common culprits.) Wall off the tourniquet's cuff and padding with impervious drape material before prepping — regardless of the prepping solution used — and replace the padding if it gets wet during surgery.

Nerves can experience temporary failure of conduction due to tourniquet compression. Nerve injury is perhaps the most common and underreported complication related to tourniquet use, likely because changes in nerve sensation are expected in extremities following surgery. Larger myelinated nerves are more susceptible to pressure-related damage, with primary microscopic damage often noticed around the approximately 1 ?m-wide gaps formed between myelin sheath cells, which become displaced under the pressure of the tourniquet.

Sensitive muscle tissue is most susceptible to damage caused by the restriction of blood supply. Tourniquet-related muscle damage is also underreported, likely because extremities are expected to function abnormally following surgery, the surgery weakens muscles, post-op pain limits motion and strength in the extremity, and extremities are often immobilized following surgery and unable to be assessed for muscle damage.

Muscle weakness and decreased motion can persist for weeks to months after tourniquet use. It's generally thought that muscle damage can be avoided by limiting tourniquet use to less than 3 hours, although it's difficult to determine if muscle damage was caused by the surgery itself or the initial injury that prompted the surgery.