This was an 11-year-old patient (weight 35 kg) scheduled for bilateral knee tenotomy to correct a knee "flexion" that prevented him from resting in the supine position. He had been diagnosed with DMD at 3 years of age by genetic study, and due to the progression of the disease he needed a wheelchair from the age of eight. Preoperatively, he had elevated transaminases (AST 131 mU.ml-1, ALT 187 mU.ml-1) and CPK 4226 UI/l. The rest of the biochemical control, haemogram and coagulation were within normal limits. Chest X-ray showed increased bronchovascular tract in the bases. A functional respiratory study could not be performed due to the patient's lack of cooperation, but the last one available (at 8 years of age) showed a severe restrictive disorder. The electrocardiogram (ECG) showed deep Q waves in the left precordial leads, with no repolarisation alterations.
The patient was premedicated with 7 mg midazolam orally. Anaesthetic induction was performed after cannulation of a peripheral line with propofol (2 mg/kg-1) and 0.5 µg/kg-1 slow bolus remifentanil. Endotracheal intubation was performed with a 6.5 Fr calibre flexometallic tube with pneumotap after neuromuscular blockade with mivacurium (0.2 mg/kg-1). Anaesthetic maintenance was performed with propofol (10-4 mg.kg-1) to achieve a bispectral index (BIS) of 40-60, remifentanil (0.25 µg.kg-1.min-1) and mivacurium (0.6 mg.kg-1.h-1) with the patient mechanically ventilated with O2-air. With the patient in lateral decubitus, before being placed in prone position for surgery, epidural anaesthesia was performed at L4-L5 level with an 18G-gauge Tuohy needle, through which a catheter (20G) was placed for post-surgical analgesia. Two ml of bupivacaine 0.25% with vasoconstrictor was administered as a test dose and 12 ml of ropivacaine 0.2%. The operation was uneventful and the patient could be extubated at the end of surgery, with good ventilatory mechanics. Recovery from the mivacurium muscle block, monitored with a neurostimulator, was not prolonged and reversal of the muscle block was not necessary. The patient was admitted to the ward under the care of traumatology and monitored by the Pain Unit of our hospital. As post-surgical analgesia, 7 ml.h-1 of ropivacaine 0.18% with 1 µg.ml-1 of fentanyl through the lumbar epidural catheter, achieving adequate analgesia (0 out of 10 on the visual analogue scale). However, eight hours after surgery, the ward was notified because the patient presented complete motor block (Bromage grade 3) with a sensitive level at T10, which reversed three hours after reducing the local anaesthetic (LA) concentration by half. No other adverse events were recorded. Epidural analgesia was effective (VAS < 2) with the new LA concentration. The epidural catheter was removed on postoperative day 5.
