Background and aims The optimum choice of anaesthesia for patients with achondroplasia remains controversial; both general (GA) and central neuraxial anaesthesia (CNA) carry specific challenges for these high-risk patients.

We present a case where a triad of infrequently used anaesthetic interventions — ultrasound scanning before CNA, addition of ketamine to propofol (Ketofol) for sedation and high-flow-nasal-oxygenation (HVNO) — enabled safe regional anaesthesia and excellent patient feedback.

Methods A 23-year-old man with achondroplasia required bilateral corrective Ilizarov frames with osteotomies, prolonged surgery causing severe postoperative pain. He had typical appearance with anticipated difficult intubation, BMI 39, severe sleep apnoea, Type 1 Chiari malformation and significant anxiety. The patient understood the risks of GA, consented to CNA but insisted on deep sedation.

Results Ultrasound scanning revealed that the intercristal line was unreliable as a landmark and assisted an uncomplicated placement of a lower lumbar combined spinal-epidural.

Initial sedation mix (Propofol TCI and increments of Midazolam) caused respiratory acidosis: pH 7.25, pCO² 8.7kPa. Adding Ketamine (5:1) allowed a reduced TCI rate with effective anxiolysis, preserved airway patency, better respiratory drive and reversed acidosis: pH7.46 and pCO2 5.7kPa.

HFNO at 30–50 l/min maintained adequate oxygenation throughout the >5 hr procedure.

Postoperative period was uncomplicated The patient ranked his anxiety preoperatively at 10/10, intraoperatively at 0/10 and postoperatively at 1/10. His anaesthetic experience was ‘better’, ‘more relaxed’ and ‘much more positive’ than his previous GA.

Conclusions For achondroplastic patients requiring lower limb surgery, we recommend ultrasound-assisted CNA, Ketofol sedation and HFNO to enable reliable neuraxial anaesthesia, deep sedation without complications and excellent patient satisfaction.