AST Guidelines for Best Practices for Safe Use of Pneumatic Tourniquets

16 of a tourniquet. 25,80 The nerve injury is greatest at the distal and proximal edges of the cuff where the shear stress is greatest. 11,25 Nerve injuries are more common in the upper limb versus lower limb. 11 The radial nerve is the most commonly injured nerve in the upper limb followed by the median and ulnar nerves, whereas, the common peroneal nerve is most the most commonly injured nerve in the lower extremity. 11,25 The pathophysiological cause of nerve injury by the use of a tourniquet is believed to be from compression and ischemia with compression playing more of a role in the injury. 11 The prognosis of nerve injuries is good with most injuries healing within six months. 80,81 To assist with avoiding nerve injuries, the CST must confirm that the pressure display on the tourniquet machine is accurate in providing the cuff pressure. There is a correlation between some nerve injuries and faulty pressure displays, resulting in an excessive cuff pressure. 78 Muscle injuries are uncommon, but can occur due to the ischemia and mechanical distortion of the tissues caused by tourniquets. 11 Muscle is more susceptible to ischemic damage than nerves. 10 Ischemia can result in metabolic and microvascular changes that increase as the time of cuff inflation increases. 81,82 Muscle injuries seem to occur more often in the elderly, most likely due to an increased susceptibility of older skeletal muscle to ischemia and reperfusion injury. 83 A. The surgeon and anesthesia provider consider many clinical factors when determining the pressure including size and weight of patient, patient preexisting conditions, extremity circumference and blood pressure. B. Studies have supported that limb occlusion pressure (LOP) is an effective and safe method for determining the minimum pressure. 7 However, the majority of studies regarding LOP have focused on adult patients with very few studies validating the technique for pediatric patients. Reilly et al. (2009) conducted a blind, prospective randomized controlled trial involving twenty-one patients undergoing a pediatric anterior cruciate ligament reconstructive surgical procedure. Their data confirmed the use of a wide contour cuff and LOP can significantly reduce the mean tourniquet cuff pressure in pediatric patients compared with the standard 250 or 300 mm Hg. 84 Therefore, the risk of tourniquet-related complications may be reduced by use of the LOP method. 84,85 Modern day tourniquet systems have been developed that automatically measure the LOP. 6.25 A definition of LOP is the minimum pressure required to stop the flow of arterial blood into the limb distal to the cuff. 11 The LOP is determined by gradually increasing the tourniquet pressure until distal blood flow is interrupted. 11 1) The guidelines for determining the LOP for the adult and pediatric patient are: a) The pressure should never exceed 500 mm Hg. 50 b) LOP <130 mm Hg – add 40 mm Hg. 11 c) LOP between 131 – 190 mm Hg – add 60 mm Hg. 11 d) LOP >190 mm Hg – add 80 mm Hg. 11