where LBF is local blood flow, PV is local venous pressure, PA is local arterial pressure, and R is local resistance. Normal myocyte metabolism requires a 5–7 mm Hg oxygen tension that can readily be obtained with a CPP of 25 mm Hg and an interstitial tissue pressure of 4–6 mm Hg. The rising intracompartmental pressure causes the venous pressure to rise and the capillaries to collapse. This activates histamine-like substances that increase vascular permeability and also increase sludging in the capillaries. Reperfusion activates neutrophils and the production of free oxygen radicals, producing a simultaneous double hit injury that causes damage and dysfunction of cellular membranes and further acceleration of intracellular and extracellular edema. Nerve conduction decreases and the switch to anaerobic metabolism occurs. Myoglobin release occurs and then progresses to renal failure, contributing to loss of limb and life [4, 5].
When intracompartmental pressure rises above 30 mm Hg, fasciotomy is advocated. Delta p is a measure of perfusion pressure (diastolic pressure-intracompartmental pressure). There is an urgent need for fasciotomy when the level is 30 mm Hg.
11.4 Diagnosis
Six main symptoms of compartment syndrome exist (the 6 Ps): pain, paresthesia, paresis, pain with stretch, pulse examination, and pink skin color. These signs can be elicited only in the fully conscious patient. Early diagnosis is difficult in patients with central nervous system compromise, in the very young and the very old patients, and in patients with substance abuse. To distinguish between ischemic pain and pain caused by fracture, contusion, or muscle injury can sometimes be difficult. The presence of distal pulses never excludes compartment syndrome.
The deep peroneal nerve lies in the anterior compartment in the leg with its four compartments (anterior, lateral, deep posterior, and superficial posterior). Its sensory territory is confined to the web space between the first and the second toes and it subserves active dorsiflexion of the toes. The superficial peroneal nerve runs through the lateral compartment and supplies sensation to the dorsum of the foot, except to the first web space. The posterior tibial nerve lies in the deep posterior compartment, providing sensation to the plantar surface of the foot, its motor function being flexion of the toes. The superficial posterior compartment can be examined by testing the sural nerve sensation along the lateral border of the foot [3–6].
11.4.1 Chronic Exertional Compartment Syndrome (CECS)
CECS is another subset of compartment syndrome that has been described as a reversible muscle ischemia in an osteofascial compartment secondary to muscular volume increase during exercise. CECS has been defined as preexercise intracompartmental pressures of 15 mm Hg, followed by a 1-min posterxercise pressure reading of greater than 30 mm Hg, and a 5-min postexercise pressure reading greater than 20 mm Hg. These findings along with clinical symptoms lead to the diagnosis.
11.4.2 Laboratory Parameters
Seriously elevated levels of creatinine phosphokinase can indicate severe muscle damage or ischemia. In the absence of clinical signs, it may indicate an unsuspected compartment syndrome. For early diagnosis, it is clearly not helpful.
11.4.3 Compartment Pressure
Measuring the compartment pressure should only be undertaken when the clinical signs are unclear and only in patients whose consciousness level is impaired. A needle technique and a catheter technique are possible. The catheter systems provide a continuous pressure recording for up to 24 h.
11.5 Treatment
If compartment syndrome is suspected, all circumferential dressings should be removed and normal blood pressure should be achieved by dealing with any cause of hypotension. The extremity should not be elevated because that reduces the already impaired blood flow. Supplementary oxygen to improve tissue oxygenation is helpful [2, 7, 8].
11.5.1 Upper Arm
Decompression of the anterior and posterior compartment on the upper arm is performed either by a lateral or, in case of vascular injury, a medial approach.
11.5.2 Forearm
The volar compartment is decompressed by a volar-ulnar incision. The lacertus fibrosus must be incised. The superficial and deep flexor compartments must be decompressed. The transverse carpal ligament must be divided. The extensor compartment is decompressed by an incision from the dorsal side.
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