An increased dose of spinal anaesthetic is indicated in a patient who has/is
**Core Concept**
The correct answer is related to the pharmacokinetics and pharmacodynamics of spinal anaesthetics, specifically the concept of dose adjustment in patients with varying body weights and heights.
**Why the Correct Answer is Right**
In spinal anaesthesia, the dose of local anaesthetic is typically calculated based on the patient's weight. However, this approach may not always be accurate, especially in patients with significant height or weight variations. A more reliable method of dose adjustment is based on the patient's body surface area (BSA), which is calculated using the formula of Dubois and Dubois. Increasing the dose of spinal anaesthetic in a patient with a larger BSA is indicated to ensure adequate anaesthesia coverage. This is because the BSA is a better predictor of anaesthetic requirements than body weight alone.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because increasing the dose of spinal anaesthetic in patients with a smaller BSA may lead to toxicity and adverse effects.
**Option B:** This option is incorrect because the patient's age is not a reliable predictor of anaesthetic requirements, and age-based dose adjustments are not recommended.
**Option C:** This option is incorrect because the patient's height alone is not a reliable predictor of anaesthetic requirements, and height-based dose adjustments are not recommended.
**Clinical Pearl / High-Yield Fact**
When calculating the dose of spinal anaesthetic, it is essential to consider the patient's body surface area (BSA) rather than relying solely on body weight. This ensures more accurate and safe dose adjustments.
**Correct Answer: D. Patient with a larger body surface area.**