Ketamine should be avoided in –
**Core Concept**
Ketamine is an anesthetic agent with analgesic and sedative properties. It acts as an N-methyl-D-aspartate (NMDA) receptor antagonist, which can lead to its beneficial effects in anesthesia. However, its use is also associated with several potential complications.
**Why the Correct Answer is Right**
Ketamine should be used with caution in patients with a history of schizophrenia or other psychotic disorders. This is because ketamine can exacerbate psychotic symptoms and trigger a psychotic episode. The mechanism behind this is thought to be related to the blockade of NMDA receptors, which can lead to an increase in glutamate levels in the brain. Elevated glutamate levels can contribute to the development of schizophrenia-like symptoms. Additionally, ketamine's effects on the brain's default mode network can also contribute to the exacerbation of psychotic symptoms.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a contraindication for ketamine use. In fact, ketamine is often used as a rescue medication for acute pain management in patients with cancer.
**Option B:** While ketamine can cause hypertension, it is not a contraindication for its use. In fact, ketamine's sympathomimetic effects can be beneficial in certain clinical situations, such as cardiac arrest.
**Option C:** This option is not a contraindication for ketamine use. In fact, ketamine is often used in patients with chronic pain, including those with chronic back pain.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that ketamine can cause a dissociative state, which can be misinterpreted as a sign of improved analgesia. However, this dissociative state can also be a sign of ketamine toxicity, so it's crucial to monitor patients closely for signs of adverse effects.
**Correct Answer:** D. Patients with a history of schizophrenia or other psychotic disorders.