What is the vascular injury associated with lying on an arm for hours, causing compression, a significantly decreased pulse, and potential neurovascular compromise?

Acute Compartment Syndrome Due to Prolonged Arm Compression

Prolonged compression of an arm resulting in decreased pulse and neurovascular compromise represents acute compartment syndrome, which requires immediate surgical fasciotomy to prevent permanent tissue damage, nerve injury, and potential limb loss.

Pathophysiology and Clinical Presentation

• Acute compartment syndrome occurs when pressure within a closed fascial compartment increases to a level that compromises the circulation and function of tissues within that space 1, 2
• The condition results from decreased perfusion within the compartment, often due to external compression, as in the case of lying on an arm for hours 2, 3
• The classic signs of acute compartment syndrome include:
  • Pain out of proportion to the injury (typically the earliest finding) 4
  • Paresthesias (sensory deficits) 4
  • Pallor (pale appearance of the limb) 5
  • Pulselessness or significantly decreased pulse (as mentioned in the question) 5, 4
  • Poikilothermia (cool temperature of the affected limb) 5
  • Paralysis (motor deficits, a late finding) 5, 4

Diagnostic Approach

• Direct measurement of intracompartmental pressure is the most reliable diagnostic test for compartment syndrome 2, 4
  • A compartment pressure >30 mmHg for eight hours or more can cause cell death by interfering with microcirculation 2
• Clinical diagnosis is primarily based on pain and paresthesias 2
• Peripheral pulses or capillary flow are not specific indicators of compartment well-being, but a significantly decreased pulse as mentioned in the question is concerning 2
• Imaging studies such as CT angiography may be helpful to evaluate the extent of vascular compromise 1

Management

• Immediate surgical decompression via fasciotomy is the treatment of choice for acute compartment syndrome 2, 4
• The procedure should be performed within the first 12-24 hours after diagnosis for optimal outcomes 3
• Delay in surgical intervention can lead to:
  • Muscle necrosis 1, 2
  • Nerve damage 1
  • Rhabdomyolysis 1
  • Permanent functional impairment 4
  • Potential limb loss in severe cases 4

Important Considerations

• Removal of any circumferential dressings or constrictive items is essential 2
• Limb elevation is NOT recommended as it does not reduce compartment pressure and may actually decrease perfusion pressure 2
• Maintenance of mean arterial pressure is important to ensure adequate perfusion 2
• Patients should be monitored for systemic complications such as rhabdomyolysis and acute kidney injury 4

Common Pitfalls to Avoid

• Relying solely on the presence of peripheral pulses to rule out compartment syndrome (pulses may be present even with significant compartment pressure) 2
• Delaying surgical intervention while waiting for additional diagnostic tests when clinical signs are present 4
• Failing to recognize that pain is typically the earliest finding in compartment syndrome 4
• Misattributing symptoms to other conditions, particularly when the mechanism (prolonged compression) is a known cause of compartment syndrome 3, 6

Special Considerations for Arm Compression

• The forearm contains multiple compartments that can be affected by compression 7
• Vascular injury or compromise, as indicated by decreased pulse, can exacerbate compartment syndrome 7, 6
• Patients with prolonged compression may develop monomelic ischemic neuropathy, an acute neuropathy with global muscle pain and weakness 1