What is the first nursing intervention for a patient with a casted leg complaining of throbbing pain?

First Nursing Intervention for Throbbing Pain in Casted Leg

The first nursing intervention should be to assess the pedal pulse (Option C), as this is the critical initial step to evaluate for compartment syndrome or vascular compromise—both limb-threatening emergencies that require immediate recognition before any other intervention.

Clinical Rationale

Why Assessment of Pedal Pulse Comes First

• Throbbing pain in a casted limb is a red flag for compartment syndrome, where pain out of proportion to the injury is often the earliest sign of developing acute compartment syndrome (ACS), which threatens limb viability 1

• Assessing pedal pulse is the essential first step in the diagnostic pathway for acute limb ischemia, which presents with the "five Ps": pain, pulselessness, pallor, paresthesias, and paralysis 1

• Pulselessness indicates severe vascular compromise and represents a late sign of acute limb ischemia that threatens limb viability if not promptly recognized 1

• The presence or absence of pedal pulses provides critical diagnostic and prognostic information: when pedal pulses are present, ankle indices are typically above 50% and toe systolic pressures above 40 mmHg, indicating relatively preserved perfusion 2

The Algorithmic Approach

Step 1: Assess pedal pulse immediately 1

• Palpate dorsalis pedis and posterior tibial pulses
• Compare to contralateral limb
• Document pulse quality (present, diminished, or absent)

Step 2: Assess for other signs of compartment syndrome 1

• Pain on passive stretch of affected muscle compartment (most sensitive early sign)
• Sensory changes (paresthesias)
• Motor weakness
• Compartment swelling and firmness
• Note: Loss of pulse, paralysis, and pallor are LATE signs indicating significant vascular compromise

Step 3: If pulse is absent or diminished, or if multiple clinical signs are present, notify provider IMMEDIATELY 1

• This represents a potential vascular emergency
• Time to intervention is critical for limb salvage

Step 4: Only after assessment, consider other interventions 1

• Do NOT remove cast without provider order (could worsen injury)
• Do NOT give pain medication first (masks critical diagnostic symptom)

Critical Pitfalls to Avoid

• Never administer pain medication before assessment: Pain out of proportion is the earliest and most important diagnostic sign of compartment syndrome, and masking it with analgesia can delay life-threatening diagnosis 1

• Never remove the cast independently: This is outside nursing scope and could destabilize the fracture; however, if compartment syndrome is confirmed, the provider will need to bivalve or remove the cast emergently 1

• Do not rely on pulse presence alone to exclude compartment syndrome: While absent pulse is a late sign, compartment syndrome can develop with pulses still present; the combination of severe pain and pain on passive stretch has 68% positive predictive value 1

• Recognize that clinical signs have limitations: Individual signs have low sensitivity (pain alone ~25% predictive), but as the number of clinical signs increases, diagnostic accuracy improves dramatically 1

Documentation Requirements

• Record all findings systematically using a scoring chart approach 1:

  • Pulse quality (present/diminished/absent)
  • Pain severity and character
  • Pain on passive stretch
  • Sensory changes
  • Motor function
  • Compartment firmness
  • Comparison to contralateral limb

• Serial assessments are essential in high-risk patients to detect progression 1