Extremity Tourniquets : Wheeless' Textbook of Orthopaedics

- Factors Related to Extremity Injury:
- duration of use;
- it is thought that muscles are more sensitive than nerves to duration of tourniquet use;
- use of tourniquet for > 2 hours & pressures of > 350 mm of mercury in lower extremity and 250 mm of mercury in upper extremity increases risk of compression neurapraxia;
- intermittent reperfusion:
- classic teaching mandates that, if more than 2 hours is required, the tourniquet is deflated for 5 min during every 30 min of inflation time;
- in the report by Mohler LR, et al (1999), intermittent reperfusion failed to diminsh the clinical and functional  consequences of the neurologic injury;
- these authors point out that prolonged tourniquet times cause both muscle and nerve damage, and that most reports on tourniquet use have focused on muscle injury rather than nerve injury;
- they point out that a high percentage of patients demonstrate EMG abnormalities after routine tourniquet use which can last several months;
- in their study, any protective effect from intermittent reperfusion (for muscle recovery) was overshadowed by nerve injury which did not recover;
                            - Intermittent reperfusion fails to prevent posttourniquet neurapraxia.
    tourniquet location:
- tourniquet applied to forearm may allow longer patient tolerance of tourniquet (in cases of local anesthesia);
- ref: A prospective, randomized, controlled trial of forearm versus upper arm tourniquet tolerance
- inflation pressure;
- it is thought that nerves are more sensitive than muscles to tourniquet inflation pressure;
- insufficient pressure, resulting in passive congestion of part, w/ hemorrhagic infiltration of the nerve;
- esmarch tourniquet:
- associated w/ high incidence of radial nerve palsy, which is most likey due to either insufficient or excessive tourniquet pressure;
- size of the cuff;
- tissure pressure (under the cuff) decreases w/ depth and toward the edges of the cuff;
- hence, obese patients will require a wide cuff w/ high inflation pressure;
- tourniquet comfort:
- consider subcutaneous injection of marcaine just above the site of tourniquet application, in order to numb the cutaneous nerves that cause tourniquet discomfort;

- Techniques to Avoid Tourniquet Complications:
- consider cooling the extremity (local hypothermia);
- consider two tourniquets, juxta-posed and alternating their inflation on hourly intervals (thought to lessen direct pressure over ischemic muscles and nerves);
- padding is used beneath the tourniquet to distribute the pressure more evenly in the arm and to avoid pinching the skin;
- prepping solution may burn the skin and is avoided by placing a towel around the distal edge of the tourniquet to prevent the solution from soaking through;
- in the upper extremity, a temporary radial nerve palsy can be a common manifestation of post-tourniquet syndrom;
- relative contra-indications:
- prosthetic vascular grafts;
- patients at risk for pre-existing DVT (such as a multi-trauma patient who has remained immobilized for several weeks)