A patient undergoing caesarean section following prolonged labour under subarachnoid block developed carpopedal spasm. Lignocaine was’ used as anaesthetic agent. The most likely’ diagnosis is:
**Core Concept**
The scenario describes a patient undergoing a caesarean section under subarachnoid block with lignocaine, who developed carpopedal spasm. This situation highlights the potential for local anesthetics to cause systemic toxicity, particularly with high doses or rapid absorption. The underlying principle is the mechanism of local anesthetic systemic toxicity (LAST), which involves the blockage of sodium channels in the nervous system.
**Why the Correct Answer is Right**
Carpopedal spasm is a classic manifestation of LAST, resulting from the blockage of sodium channels in the nervous system. Lignocaine, being a local anesthetic, can cause systemic toxicity when its concentration exceeds the therapeutic range in the bloodstream. This can occur due to high doses, rapid absorption, or impaired metabolism. The symptoms of LAST can range from mild to severe and include numbness, tingling, muscle weakness, and in severe cases, carpopedal spasm, seizures, and cardiac arrest.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the scenario, as it does not describe a known complication of local anesthetic use.
* **Option B:** While hypocalcemia can cause muscle cramps and spasms, it is not directly related to the use of lignocaine in subarachnoid block.
* **Option C:** This option is a distractor, as it does not accurately describe the clinical presentation of LAST.
**Clinical Pearl / High-Yield Fact**
In cases of suspected LAST, it is essential to stop the administration of the local anesthetic agent immediately and provide supportive care, including oxygenation, ventilation, and cardiac monitoring. The treatment of LAST involves the administration of lipid emulsions, such as intravenous fat emulsion, which can help to bind and neutralize the local anesthetic.
**Correct Answer: C. Local anesthetic systemic toxicity (LAST)**