Cast Care in Nursing
On this page
Direct answer
Wet plaster is fragile and the limb inside it is invisible, so cast nursing is mostly an exercise in vigilance for what you cannot see. Plaster of Paris takes 24-72 hours to dry — handle it with the palms, never the fingertips, elevate the limb above heart level for the first 48 hours, and keep it uncovered so moisture escapes. Neurovascular checks run every one to two hours during that window: the five Ps of pain, pallor, pulselessness, paraesthesia and paralysis. The earliest warning of compartment syndrome is pain out of proportion, worse on passive toe or finger stretch, and not relieved by analgesics — that limb needs the cast split immediately, not another dose of painkiller.
What you must remember
- Drying and handling: plaster of Paris dries in 24-72 hours (synthetic casts set within about an hour); support the cast on pillows using palms, because fingertips dent wet plaster and the dent presses a sore into skin.
- Five Ps of neurovascular assessment: pain, pallor, pulselessness, paraesthesia, paralysis — check distal to the cast alongside skin temperature and capillary refill; a weak or absent pulse is a late sign, never the first.
- Compartment syndrome earliness ladder: pain out of proportion and pain on passive stretch come first; paraesthesia follows; pallor, pulselessness and paralysis are late — by pulselessness the damage is largely done.
- Immobilisation complications: pressure ulcers over bony points beneath the cast, nerve compression (a tight proximal tibial or fibular region pressing the common peroneal nerve causes foot drop), disuse atrophy, DVT, and joint stiffness.
- Cast syndrome: nausea and vomiting from duodenal compression by the superior mesenteric artery in body and hip spica casts — vomiting in a body cast is a notification, not an antiemetic.
- Patient teaching: never insert anything to scratch, keep the cast dry, exercise the unencasted joints and perform isometric and toe exercises, and report burning, numbness, colour change, smell or fever at once.
- Edge care: petal rough edges with tape; a window cut for wound inspection must be resealed, or tissue swells through the gap.
- Home red flags for immediate return: increasing pain despite elevation and analgesia, numbness or tingling, blue or white digits, foul smell or drainage, fever.
The first night in a below-knee plaster
A young man returns from the plaster room with a below-knee cast for an ankle fracture. The nurse elevates the leg on two pillows, checks — not asks about — the toes: warm and pink, capillary refill brisk, sensation intact, dorsalis pedis pulse present, and documents the baseline. She teaches him to wiggle the toes hourly and she means the teaching: the mother at the bedside is asked to repeat the danger signs back. At 2 am he calls — pain is worsening, and the analgesic has not touched it. On passive flexion of his toes he winces badly. The nurse elevates no further and does not wait for the next round: the physician is called, the cast is split (bivalved) down both sides and the padding opened, relieving the pressure before paraesthesia ever appears. Had the call been answered with "the pain is normal, take another tablet", the ward would have discharged a foot with a fixed deformity.
The Indian orthopaedic ward
Plaster of Paris remains the default in Indian government hospitals — cheap, mouldable, and dependent on exactly the drying and handling discipline above. Two ward realities sharpen the nursing role: attendants who scratch inside casts with knitting needles and hairpins (the foreign object ends as an abscess), and long distances that make an unread danger sign a foot lost by travel back — so discharge teaching in the local language, with a written or picture-based list of return-now symptoms, is the true standard of care. INC viva questions orbit the same points examiners have asked for decades: drying time, the five Ps in order of appearance, why fingertips are forbidden on wet plaster, the earliest sign of compartment syndrome, and which nerve is compressed to produce foot drop under a knee cast.
Frequently asked questions
How long does a plaster of Paris cast take to dry?
Twenty-four to seventy-two hours; during this window it is handled only with palms, elevated, and left uncovered to let moisture evaporate.
What is the earliest sign of compartment syndrome under a cast?
Pain out of proportion to the injury, worsened by passive stretching of the digits and unrelieved by analgesia — pallor and pulselessness arrive late, after damage is advanced.
Why must wet plaster be handled with palms rather than fingertips?
Fingertip pressure dents the setting plaster, and each dent becomes a hard internal pressure point that ulcerates the skin beneath it.
What is cast syndrome?
Nausea, vomiting and abdominal distress from duodenal compression by the superior mesenteric artery in body or spica casts, requiring immediate physician notification.
Why should nothing be inserted into a cast to scratch?
Objects break skin, introduce infection and are often forgotten inside; the resulting abscess may require removing the cast entirely.