The Storm After The Near-Failed Epidural Anaesthesia

To the Editor:

Sub-arachnoid or sub-dural injection or migration of the catheter is a known complication of the epidural block. The test dose helps in ruling out a sub-arachnoid or vascular injection. We report a case of accidental sub-dural injection of drug as a complication of epidural anaesthesia.

A 38 year old woman, with 5'5” height and 55 kg weight was scheduled for vaginal hysterectomy under epidural anaesthesia. Her pre-operative pulse rate was 85 bpm and blood pressure 130/86 mm of Hg. After local anaesthesia infiltrations, a 16 gauge epidural needle was used through para-median approach at L₃-L₄ level by loss of resistance to air technique. After confirmation of negative aspiration of blood and CSF, an epidural test dose of 3cc of 2% lignocaine with adrenaline was administered. Absence of motor blockade and tachycardia confirmed the epidural placement of needle. 20cc of 0.25% bupivacaine + 1% lignocaine with 25 g fentanyl was injected. Haemodynamics were monitored and sensory level checked. At the end of twenty minutes the blockade was patchy & around T₁₀-T₁₁ segments. Assuming a failed epidural, preparations were made to administer general anaesthesia. However a sudden bradycardia was seen with pulse rate drop to 40 bpm and BP uptown 50 mm of Hg. It was corrected by injection atropine 1.2 mg iv. On checking, the level was T₂. Rest of surgery was uneventful. The unexpected, extensive delayed block with high sympathetic blockade made us suspect on sub-dural injection. Hypotension and dense motor block also favored our diagnosis.

Unfortunately sub-dural injection of drug has no preventive measures for a time- tested technique like epidural block.