Compartment syndrome

Introduction

Compartment syndrome is a serious medical condition in which increased pressure within a confined anatomical space compromises circulation and tissue function. Early recognition and intervention are crucial to prevent permanent damage to muscles, nerves, and other soft tissues. This article provides a comprehensive overview of the anatomy, physiology, and pathophysiology of compartment syndrome.

Anatomy and Physiology of Compartments

Muscle Compartments

Muscle compartments are enclosed spaces within the body that contain muscles, nerves, and blood vessels. These compartments are bounded by fascia, a strong connective tissue that provides structural support but limits the ability of the compartment to expand. The compartments vary depending on anatomical location and have clinical relevance in the development of compartment syndrome.

• Upper limb compartments: Include the anterior and posterior compartments of the arm and forearm. The anterior compartments generally contain flexor muscles, while the posterior compartments contain extensor muscles.
• Lower limb compartments: Include the anterior, lateral, and posterior compartments of the leg and thigh. These compartments house muscles responsible for dorsiflexion, plantarflexion, and other lower limb movements.
• Other anatomical sites: Compartment syndrome can also occur in less common areas such as the hand, foot, gluteal region, and abdominal wall.

Fascial Boundaries and Compartment Pressure

The fascia surrounding each compartment provides rigidity and defines its boundaries. Because fascia is relatively inelastic, any increase in fluid volume, blood, or edema within the compartment leads to elevated pressure. Normal compartment pressures range from 0 to 10 mmHg, and pressures exceeding 30 mmHg or within 30 mmHg of diastolic blood pressure are considered dangerous and can compromise perfusion.

• Role of fascia: Acts as a containment barrier for muscles, vessels, and nerves, limiting their ability to expand during injury or swelling.
• Pressure dynamics: Increased intracompartmental pressure reduces capillary blood flow, leading to tissue ischemia and potential necrosis if untreated.

Pathophysiology

Mechanisms of Increased Pressure

Compartment syndrome develops when the volume within a confined space increases, surpassing the capacity of the surrounding fascia. This leads to elevated intracompartmental pressure and compromised tissue perfusion. Multiple mechanisms contribute to this increase in pressure.

• Trauma-induced swelling: Injury to muscles or soft tissue can result in edema, causing a rapid rise in compartment pressure.
• Bleeding within the compartment: Fractures or vascular injuries may lead to accumulation of blood, further increasing pressure.
• External compression: Tight casts, bandages, or prolonged immobilization can restrict compartment expansion and precipitate syndrome.

Effects on Tissue Perfusion

Elevated compartment pressure reduces capillary blood flow and tissue perfusion. Muscles and nerves are particularly vulnerable to ischemia. If uncorrected, these changes can result in irreversible damage.

• Ischemia of muscles and nerves: Reduced oxygen delivery leads to muscle necrosis and nerve dysfunction.
• Cellular hypoxia and necrosis: Prolonged ischemia triggers cell death, releasing toxic metabolites that can further damage surrounding tissues and contribute to systemic complications such as rhabdomyolysis.

Etiology

Traumatic Causes

Trauma is the most common precipitating factor for acute compartment syndrome. Several types of injuries are frequently implicated.

• Fractures: Long bone fractures, especially of the tibia and forearm, are a major cause due to associated bleeding and soft tissue injury.
• Crush injuries: Significant compression of tissues increases compartmental pressure and may cause extensive muscle damage.
• Burns: Circumferential burns produce tight eschars that limit tissue expansion, increasing the risk of compartment syndrome.

Non-Traumatic Causes

Compartment syndrome can also occur without direct trauma. These cases often involve repetitive activity or vascular compromise.

• Reperfusion injury: Restoration of blood flow after ischemia can lead to tissue edema and elevated compartment pressure.
• Intense exercise: Exertional compartment syndrome occurs in athletes performing repetitive high-intensity activities, commonly in the lower limbs.
• Vascular obstruction or surgery-related causes: Arterial or venous obstruction, post-surgical swelling, or prolonged limb compression can precipitate compartment syndrome.

Classification

Compartment syndrome is classified based on onset, duration, and underlying cause. Understanding the type is important for guiding diagnosis and treatment.

• Acute Compartment Syndrome: Develops rapidly, usually following trauma or injury. It is a surgical emergency and requires prompt intervention to prevent permanent tissue damage.
• Chronic or Exertional Compartment Syndrome: Develops gradually, often during repetitive physical activity such as running or cycling. Symptoms typically resolve with rest, and management may include activity modification or surgical intervention in refractory cases.

Clinical Features

Symptoms

The clinical presentation of compartment syndrome is primarily characterized by pain and sensory disturbances. Early recognition of these symptoms is critical to prevent irreversible damage.

• Pain out of proportion to injury: Severe, persistent pain that is not relieved by analgesics and is disproportionate to the apparent trauma.
• Paresthesia: Tingling, numbness, or burning sensations due to nerve compression within the compartment.
• Swelling and tightness: The affected limb may feel tense or firm, with visible swelling in the overlying skin.

Signs

Physical examination reveals characteristic signs, some of which indicate advanced or late-stage compartment syndrome.

• Pain on passive stretch: Stretching muscles within the compartment exacerbates pain, a key early sign.
• Palpable tenseness of compartment: The compartment feels firm or woody on palpation.
• Pulselessness and pallor: Reduced or absent distal pulses and pale skin are late findings, indicating severe ischemia.

Diagnosis

Clinical Diagnosis

Diagnosis of compartment syndrome is primarily clinical and relies on careful assessment of history and physical examination. Early recognition is essential to prevent permanent damage.

• History and physical examination: Identify recent trauma, repetitive activity, or vascular compromise. Assess for pain, paresthesia, and swelling.
• Recognition of early warning signs: Severe pain disproportionate to injury and pain on passive stretch are critical early indicators.

Investigations

While clinical evaluation is paramount, several investigations can support the diagnosis or assess severity.

• Compartment pressure measurement: Direct measurement using a needle or catheter provides quantitative confirmation. Pressures above 30 mmHg or within 30 mmHg of diastolic blood pressure are concerning.
• Imaging modalities: Ultrasound or MRI may detect edema or muscle changes but are primarily supportive and should not delay treatment.
• Laboratory findings: Elevated creatine kinase, myoglobinuria, and electrolyte disturbances may indicate muscle breakdown and systemic involvement.

Management

Immediate Interventions

Early management focuses on reducing compartment pressure and preventing further tissue injury before definitive treatment.

• Removal of constrictive dressings or casts: Any tight bandage, splint, or cast should be promptly removed or loosened.
• Positioning and limb elevation: The limb should be kept at heart level to optimize perfusion without increasing pressure.

Definitive Treatment

Surgical intervention is often required to relieve pressure and restore perfusion.

• Fasciotomy techniques: Incision of the fascia allows decompression of the compartment. The procedure may involve single or multiple incisions depending on the affected area.
• Postoperative care: Includes wound monitoring, infection prevention, and gradual rehabilitation to restore function.

Medical Management

Supportive care is crucial to address pain and systemic effects of muscle injury.

• Pain control: Analgesics and, if necessary, opioid therapy are used to manage severe pain.
• Fluid resuscitation and supportive therapy: Adequate hydration and correction of electrolyte imbalances are important, especially in cases complicated by rhabdomyolysis.

Complications

If compartment syndrome is not recognized and treated promptly, it can lead to serious and sometimes permanent complications. Early intervention is critical to prevent these outcomes.

• Permanent nerve damage: Prolonged compression of nerves can result in sensory and motor deficits, including weakness or paralysis of affected muscles.
• Muscle necrosis and contractures: Ischemic muscle tissue may undergo necrosis, leading to fibrotic changes and permanent contractures, commonly referred to as Volkmann ischemic contracture in the forearm.
• Rhabdomyolysis and renal failure: Muscle breakdown releases myoglobin into the bloodstream, which can precipitate acute kidney injury if not managed appropriately.
• Infection: Open fasciotomy wounds or necrotic tissue increase the risk of local or systemic infection, potentially complicating recovery.

Prognosis

The outcome of compartment syndrome depends largely on the timing of diagnosis and intervention. Prompt recognition and surgical decompression significantly improve the likelihood of full recovery.

• Factors affecting recovery: Severity of initial injury, duration of elevated compartment pressure, patient age, and comorbidities can influence outcomes.
• Outcomes based on timing of intervention: Early fasciotomy often results in complete functional recovery, whereas delayed treatment increases the risk of permanent muscle and nerve damage, contractures, and chronic pain.

Prevention

Preventing compartment syndrome involves early recognition of at-risk patients and minimizing factors that can increase compartmental pressure. Proper preventive strategies can significantly reduce morbidity.

• Early recognition and monitoring: Patients with fractures, crush injuries, burns, or those undergoing prolonged surgery should be closely monitored for signs of swelling and pain.
• Proper immobilization techniques: Splints and casts should be applied carefully to avoid excessive pressure. Frequent reassessment of limb circulation is essential.
• Education for athletes and medical personnel: Awareness programs can help athletes and healthcare providers recognize exertional compartment syndrome early and implement timely interventions.

References

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