Management of a case of ankylosing spondylitis for total hip replacement surgery with the use of ultrasound-assisted central neuraxial blockade
A 26-year-old male, known case of severe AS, symptomatic for the last 6 years, was listed for THR (right). He had a classical bamboo spine with no mobility of cervical or thoraco-lumbar spine []. Both the hip joints were totally fixed and he was unable to even sit for the last 3 years. The cardiac and respiratory systems were normal on examination and his haematological and biochemical parameters were also within normal limits.\nAirway was anticipated to be difficult because of the lack of any extension of cervical spine and mouth opening of about 2.5 cm. A difficult airway cart was kept ready along with a flexible fibreoptic bronchoscope.\nWritten informed consent was obtained for both general and regional anaesthesia and the patient was fasted adequately. The plan was to first attempt a spinal and/or epidural block, and in case of difficulty or failure, the alternative was a fibreoptic bronchoscope assisted awake intubation.\nLumbar punctures were attempted at different spinal levels by median or paramedian approach by two experienced anaesthesiologists, but they failed. The positioning of the patient for the puncture was extremely difficult as there was no flexion at the hip joints. The patient could not sit and could only lie straight in lateral position without bending at the hip at all. Awake fibreoptic assisted intubation was done by standard technique and general anaesthesia was administered for the surgery. Analgesia was maintained with opioids and nonsteroidal anti-inflammatory drugs (fentanyl and diclofenac intravenous) during the perioperative period. Three months later, the same patient was listed again for THR on the other side. This time, we planned a pre-procedural USG in the preoperative room to assess the possibility of a central neuraxial blockade. Mindray M5 Hand-carried Diagnostic Ultrasound System (Shenzhen Mindray Bio-Medical Electronics Co., Ltd. Shenzhen, China) with linear array transducer probe 7L4s (5-10 MHz) was used to visualise the spine with patient in lateral position. The spine was scanned from L2 spinous level downwards both in the transverse midline (TM) plane and parasagittal (PS) planes on both sides.\nThe interlaminar spaces were very narrow and poorly visualised because of hyperechoic shadows at all levels in the PS planes except at L2-3 where they could be distinguished more clearly []. With the transducer placed at the point of best visualisation, a line was drawn perpendicular to the midline of the transducer with the help of a marker pen []. The transducer was now placed in the TM plane and a complete scan was done. The ligamentum flavum/duramater complex and the posterior longitudinal ligament overlying the posterior aspect of the posterior vertebral body could be distinguished only at L2-3 level. A similar line was drawn perpendicular to the midline of the transducer. The point of insertion of the spinal needle was taken as the intersection of these two lines. The patient was taken to the operation suite and the standard monitors were placed. The patient was turned to left lateral position and after thorough asepsis, a 17-G Tuohy needle (a combined spinal-epidural set BD, Becton, Dickinson and Company, NJ, USA) was inserted from the marked point. The epidural space was identified with a loss of resistance to saline and then a 25-G Whitacre needle was introduced through it. The subarachnoid space was reached at about 5 cm from skin in a single attempt. After a free flow of cerebrospinal fluid, 2.5 ml of 0.5% hyperbaric bupivacaine was injected. A 19-G epidural catheter was advanced through the epidural needle and fixed to the skin at 9 cm.\nThe sensory and motor blocks were adequate and the patient remained haemodynamically stable intraoperatively. The surgery lasted for 2 h following which an epidural infusion was started with 0.125% bupivacaine and 2 mcg/ml fentanyl at 6 ml/h and continued for 72 h postoperatively. Diclofenac 1 mg/kg intravenous was given twice a day and the patient was comfortable in the postoperative period.