Ketamine is contraindicated in
Ketamine is a dissociative anesthetic. Common contraindications include conditions where increased intracranial pressure is a risk, like head injuries. Also, patients with hypertension or cardiovascular issues might be at risk because ketamine can increase blood pressure. It's also contraindicated in certain psychiatric conditions, maybe psychosis or a history of seizures. So possible options could be things like hypertension, closed-angle glaucoma, history of seizures, or head injury.
The correct answer is likely head injury or increased intracranial pressure. Let me check standard sources. Yes, ketamine is contraindicated in patients with increased intracranial pressure because it can increase cerebral blood flow and metabolic demand, worsening the condition. So if the options included head injury, that would be correct. The other options might be things like asthma, but ketamine is actually used in asthma because it doesn't suppress respiration. Or maybe renal failure, but ketamine is metabolized by the liver, not the kidneys. So if the options had renal failure, that's not a contraindication.
So the core concept is that ketamine increases cerebral metabolism and blood flow, which is bad in increased ICP. The correct answer would be head injury. The wrong options are conditions where ketamine is not contraindicated. The clinical pearl is to remember that ketamine is not used in raised ICP. Now, structure the explanation accordingly.
**Core Concept**
Ketamine, a dissociative anesthetic, increases cerebral blood flow and metabolic demand, making it contraindicated in conditions with elevated intracranial pressure (ICP). Its use in such scenarios can worsen cerebral edema and neurological outcomes.
**Why the Correct Answer is Right**
Ketamine is contraindicated in **head injury with increased ICP**. It stimulates sympathetic activity, raising blood pressure and cerebral perfusion pressure, which can exacerbate brain swelling. This mechanism is particularly harmful in traumatic brain injury, where maintaining cerebral autoregulation is critical.
**Why Each Wrong Option is Incorrect**
**Option A:** *Hypertension* is not an absolute contraindication; while ketamine may transiently elevate blood pressure, it is often used cautiously in controlled settings.
**Option B:** *Asthma* is not a contraindication; ketamine is preferred in asthmatic patients due to its bronchodilatory effects.
**Option C:** *Renal failure* is not a contraindication, as ketamine is primarily metabolized hepatically.
**Clinical Pearl / High-Yield Fact**
Never use ketamine in patients with **traumatic brain injury or raised ICP**. Remember the mnemonic: **"Ketamine = Kicks up ICP"**. For asthma, it’s a **friend** (bronchodilator), but for head injury, it’s an **enemy** (raises ICP).
**Correct Answer: C. Head injury with increased intracranial pressure**