What are the 6 Ps of compartment syndrome?

The 6 Ps of Compartment Syndrome

The six clinical signs or symptoms attributed to compartment syndrome are: pain, paresthesia, pressure, pallor, pulselessness, and paralysis. 1, 2

Understanding the 6 Ps and Their Clinical Significance

Early Signs (More Sensitive)

1. Pain

   • Pain out of proportion to the injury or clinical situation
   • Pain on passive stretch of the affected muscle compartment (considered one of the most sensitive early signs)
   • Often the earliest clinical indicator of developing compartment syndrome

2. Paresthesia

   • Decreased peripheral sensation
   • Numbness or tingling in the affected area
   • Results from nerve ischemia and irritation

3. Pressure/Tension

   • Physical swelling and increasing firmness of the compartment
   • Tense, hard feeling upon palpation of the affected area
   • The affected compartment becomes physically swollen and increasingly firm

Late Signs (Less Sensitive, Indicate Severe Damage)

1. Pallor

   • Pale appearance of the affected limb
   • Indicates significant disruption to vascularity
   • Sign of advanced compartment syndrome

2. Pulselessness

   • Absence of pulse in the affected limb
   • Indicates arterial occlusion
   • Late finding suggesting severe compromise

3. Paralysis

   • Loss of motor function
   • Weakness or inability to move the affected area
   • Very late sign indicating significant muscle ischemia has already occurred

Clinical Importance and Diagnostic Value

The sensitivity and positive predictive value of individual clinical signs are low, while specificity and negative predictive value are high 1. This means the absence of signs is more reliable in excluding compartment syndrome than their presence is in confirming it.

• In isolation, severe pain gives only about a 25% chance of correct diagnosis
• The combination of pain and pain on passive stretch increases positive predictive value to 68%
• When pain, pain on passive stretch, and paralysis are all present, the positive predictive value reaches 93% 1

Important Clinical Considerations

• Early Diagnosis is Critical: Diagnosis should be made before the onset of muscle ischemia, making the late signs (pallor, pulselessness, paralysis) less useful for early intervention 1

• Progression of Signs: As compartment syndrome worsens, signs typically progress from early (pain, paresthesia, pressure) to late (pallor, pulselessness, paralysis)

• Objective Measurement: When clinical diagnosis is uncertain, direct measurement of intracompartmental pressure is indicated (normal is <10 mmHg; concerning is >30 mmHg) 1, 3

• High-Risk Populations: Young men under 35 years with tibial fractures have an increased risk of developing compartment syndrome 1

• Monitoring Frequency: For high-risk patients, clinical assessments should be performed every 30 minutes to 1 hour during the first 24 hours 4

Remember that early recognition and treatment of compartment syndrome is essential to prevent irreversible tissue damage, functional impairment, and potentially life-threatening complications.