A client with a lower-leg fracture in a cast reports rapidly worsening pain despite analgesia. Passive extension of the toes sharply increases the pain, and the foot feels numb. Which action should the nurse take first?

Escalating pain despite analgesia, pain with passive stretch, and numbness suggest acute compartment syndrome. Notify the clinician immediately and keep the limb near heart level while preparing for urgent pressure-relieving treatment.

Quick answer
Report suspected acute compartment syndrome immediately and keep the leg near heart level. The cluster of uncontrolled pain, passive-stretch pain, and sensory change signals threatened tissue perfusion.

Why this is correct
Pressure inside a closed muscle compartment can obstruct capillary flow and injure nerves and muscle. Delay can cause irreversible loss, so the nurse escalates for urgent cast release, pressure assessment, and possible fasciotomy rather than treating the pain alone.

Easy analogy or mental picture
A swollen muscle inside rigid fascia is like an expanding object trapped in a sealed box. Pressure rises because the walls do not give; the image explains urgency but cannot measure compartment pressure or replace surgical evaluation.

Memory hook
Pain out of proportion plus passive-stretch pain means pressure is threatening the limb.

NCLEX decision rule
After fracture or casting, treat rapidly increasing pain unrelieved by medication, pain with passive stretch, paresthesia, or motor change as a limb emergency. Escalate immediately and avoid interventions that further reduce arterial inflow.

Why the other choices are wrong
High elevation can reduce arterial perfusion, and ice does not relieve a closed-compartment emergency. More analgesia delays definitive assessment, while exercise increases muscle demand and does not lower the dangerous pressure.