Question

A nurse is assessing for compartment syndrome in a client who has a short leg cast. which of the following findings should the nurse identify as manifestation of this condition?

Answer 1

Compartment syndrome is a condition in which increased pressure within one of the body's anatomical compartment results in insufficient blood supply to tissue within that space.

There are two main types: pavitr and chronic. Compartments of the leg or arm are most commonly involved.

Short Leg Casts

Short leg casts are most commonly used for fractures to the metatarsals (bones in the feet), ankles, and lower tibia and fibula. The tibia is the bone on the big toe side of the lower leg, and the fibula is the bone on the pinky toe side of the lower leg. In addition to bone fractures, short leg casts are also often used to provide stabilization following surgery to the foot or ankle or to treat severe ankle sprains.

Short leg casts usually extend from a couple inches below the knee joint to the base of the toes. When these casts are applied, the ankle is usually positioned at a 90 degree angle. Extra padding is frequently put in the cast at the location of each of the malleoli, which are the round bones that stick out from each side of the ankle.

Sign and symptoms

Symptoms may include severe pain, sensation of pins and needles and weakness of the affected area.

swelling, internal bleeding, muscle weakness, nerve injury, pallor, or sensation of pins and needles.

The six P's

All characteristics of the six P's may not be present in every individual. Furthermore, presentation of these symptoms will vary depending on time that has lapsed since the initial pressure began to rise, the rate of ICP increase, blood pressure, and damage within the compartment.

Pain

As ACS progresses, the extremity becomes edematous and tense. There is increased pressure placed on nerve fibers and injured components within the compartment. Pain is characteristically described as being out of proportion to the injury with passive stretching.

Pulselessness and Pallor

A late finding is pulselessness which is a poor indicator of ACS, whereas pallor is a less common finding. Arterial insufficiency is atypical in the early stages of ACS thus both dorsalis pedis and posterior tibial pulses are palpable; capillary refill is brisk and the extremity is typically pink. However, as ICP rises, loss of limb pulses and pallor indicates compression of arterial perfusion.

Paresthesia and Paralysis

As ICP increases, neuronal tissues become ischemic and this contributes to nerve dysfunction and paresthesia, paresis, and ultimately paralysis. Paresthesia may occur within 30 minutes following injury to nerves. Motor function may deteriorate within four hours of muscle tissue ischemia. At eight to 24 hours of ischemia, functional losses may be irreversible. The loss of light touch sensation commonly emanating from increased pressure on the deep peroneal nerve often precedes limb weakness. Light touch assessment can be assessed using two-point discrimination or pin prick testing.

Poikilothermia

Poikilothermia is described as a change in temperature or the presence of coolness in the affected extremity.

Intra-Compartmental Pressure Monitoring

Pressure

Normal resting limb ICP is 0-4 mmHg. With exertion, typical limb ICP may increase up to10 mmHg. With ACS, an ICP of 30 mmHg or above is considered critical and treatment with emergent surgical decompression should be considered. Time is of essence to salvage motor and sensory function of the limb. Within eight hours of an ICP at 30 mmHg, nerve conduction is disrupted. However, the higher the ICP, the quicker damage to compartment structures occurs (at an ICP of 80 mmHg, damage to limb compartments could occur within two hours).

The most common and validated method to measure limb ICP is by using the handheld Stryker Intra-Compartmental Pressure (STIC) Monitor System . This device assists medical professionals with the diagnosis of compartmental syndrome. Use of the STIC monitor involves injection of saline into the compartment of interest. The system is designed to measure tissue fluid pressure. An alternative method to determine limb ICP is the use of a delta pressure (ΔP). The ΔP is defined as the difference between the diastolic blood pressure and measured compartment pressure. A ΔP of ≤ 30mmHg is diagnostic of ACS.

Ancillary testing

Laboratory tests

The use of blood or urine testing to assess degree of muscle damage (the presence of rhabdomyolysis) can be helpful in the clinical assessment of ACS.

The most common of these tests include measurements of serum creatinine phosphokinase (CPK) and the presence of urine myoglobin.3The normal level of blood CPK is <130 international units (IU). In ACS, levels of CPK may exceed 1000 international units (IU). Severe rhabdomyolysis may lead to acute kidney dysfunction and failure.

Vascular and Noninvasive Testing

Angiography may help identify focal arterial or venous injury and perfusion defects contributing to increased ICP. Additionally, the use of magnetic resonance imaging (MRI), ultrasonography, and near-infrared spectroscopy or laser doppler flowmetry have also been evaluated in diagnosing ACS as an adjunct to clinical findings and ICP measurement but not in the primary diagnosis of ACS.

MRI is favorable for chronic conditions of exertional compartment syndrome; while, ultrasonography allows for noninvasive, serial monitoring of compartment pressures. Near-infrared spectroscopy or laser doppler flowmetry is commonly used to determine oxygenation in muscles and decreases as ICP increases; however, its use is problematic in hypoperfused conditions.

Treatment

The standard treatment for ACS is emergent surgical fasciotomy. Fasciotomites can vary in surgical technique. Currently, both single and double incision techniques are used by surgeons. The single incision technique involves a single long incision made from the head of the fibula to the lateral malleolus.

However, the most common fasciotomy method performed is the double-incision, four compartment technique incorporating two longitudinal anterolateral and posteromedial incisions. Important principles of fasciotomy include:

(1) an adequate length, depth and accurate landmark of incision,

(2) full release of the constricted compartment,

(3) avoidance in injuring major underlying structures such as the superficial peroneal nerve,

(4) debridement of ischemic and necrotic tissue,

(5) return to the operating room every 24 to 72 hours for dressing changes, debridement as necessary and assessment of tissue viability, and last

(6) closure of skin (skin grafting may be necessary) and incision within 7 to 10 days.

Nonoperative treatment

Whenever safe and possible, simple treatment measure in ACS include loosening ace wraps, compression dressings, splints and uni- or bivalving casts.6 Elevation of extremity no higher than the level of the heart facilitates venous drainage, reduces edema and maximize tissue perfusion.6 Further, avoidance of knee flexion and foot dorsiflexion will facilitate uncompromised circulation throughout a limb and limit increases in ICP in the deep posterior compartment respectively.

Postoperative care

Postoperative care following ACS fasciotomy focuses on the following:

(1) completion of frequent neurovascular examinations to ensure both adequate release of the affected compartment and that no new damages were incurred during the operative procedure,

(2) tissues, if left open, are pink and viable,

(3) use of negative pressure devices such as the wound vacuum assisted device to facilitate sealing of wound and removal of wound exudate, and last

(4) control of swelling.