A Bier (intravenous regional) block is performed for forearm surgery using lidocaine 0.5%. After injection of the drug below an inflated double tourniquet, what is the minimum interval the cuff must remain inflated before it can be safely deflated?
- A 5 minutes
- B 20 to 25 minutes ✓
- C 45 minutes
- D 60 minutes
Correct answer: B. 20 to 25 minutes
Explanation
Local anaesthetic must remain trapped under the cuff for roughly 20 to 25 minutes so that tissue binding and redistribution reduce the free drug concentration before venous return resumes. Earlier deflation releases a large bolus of unbound lidocaine into the circulation and risks seizures and arrhythmias. Total cuff time is limited instead by tourniquet pain and ischaemia, usually around 90 minutes, which rules out the longer intervals.
Reference: Miller's Anesthesia, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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