**Core Concept**
The management of a patient with raised intracranial pressure (ICP) requires careful selection of anesthetic agents to avoid exacerbating the condition. The goal is to reduce ICP and ensure cerebral perfusion pressure (CPP) is maintained. Certain anesthetic agents can increase cerebral blood volume, leading to increased ICP.

**Why the Correct Answer is Right**
The anesthetic agent that is contraindicated in a patient with raised ICP is **suxamethonium** (succinylcholine). This is because suxamethonium causes a transient increase in ICP due to the release of potassium ions from the muscle cells, leading to a hyperkalemic response. This can cause cerebral vasodilation, increasing cerebral blood volume and ICP. Additionally, suxamethonium can cause a significant increase in systemic blood pressure, which can further increase ICP.

**Why Each Wrong Option is Incorrect**
* **Option A:** Isoflurane is actually used to decrease ICP due to its ability to cause cerebral vasoconstriction, reducing cerebral blood volume.
* **Option B:** Vecuronium is a non-depolarizing neuromuscular blocker that does not cause significant changes in ICP.
* **Option C:** Propofol is a sedative-hypnotic agent that can decrease ICP due to its ability to cause cerebral vasoconstriction and reduce cerebral metabolic rate.

**Clinical Pearl / High-Yield Fact**
Always consider the potential effects of anesthetic agents on ICP when managing patients with head injuries or raised ICP. Suxamethonium should be avoided in these patients, and alternative agents such as vecuronium or rocuronium should be used instead.

**Correct Answer: D. Suxamethonium**