Ultrasound-guided anterior iliopsoas muscle space block versus posterior lumbar plexus block in hip surgery in the elderly

BACKGROUND: Ultrasound-guided posterior lumbar plexus block is widely used for hip fracture surgery but it requires a change of position, which may be painful. OBJECTIVES: Our primary objective was to describe a new technique, the anterior iliopsoas muscle space block, which can be performed in the supine position, and to test the hypothesis that its analgesia for hip surgery was similar to that of the traditional posterior lumbar plexus block. DESIGN: Randomised, double-blind study. SETTING: Shanghai 6th People's Hospital, China, from February to August 2019. PATIENTS: Forty-eight patients scheduled for unilateral hip fracture surgery were included in the study. The exclusion criteria were infection at the puncture site, history of hip surgery, pre-existing neurological deficits of the lower extremity, contraindications for regional anaesthesia, allergy to local anaesthetics, coagulopathy, abuse of medicine or alcohol, or daily consumption of analgesics. INTERVENTIONS: Patients were randomised to receive a lateral sacral plexus block with either an anterior iliopsoas muscle space block or a posterior lumbar plexus block, using 0.33% ropivacaine (30 ml each). MAIN OUTCOME MEASURES: The main outcome was verbal numerical scale (VNS) pain intensity 1 h after surgery in the postanesthesia care unit, and the secondary outcome was the dose of intra-operative fentanyl. The differences in VNS scores and fentanyl use between the groups were analysed. RESULTS: Based on previous work, we considered a difference (confidence interval [CI]) of 1.6 on the VNS to be significant. The median [IQR] pain scores in postanesthesia care unit were similar in the anterior 0 [0 to 3] and posterior groups 1.5 [0 to 3]. The median scores for intra-operative fentanyl use were similar in the anterior 20 [10 to 42.5] μg and posterior groups 15 [0 to 50] μg (P = 0.34). The difference in the median pain score at-rest was NS: anterior group 0.5 [0 to 5], posterior group 0 [0 to 2], median difference -0.5 (95% CI -2 to 0). The median post to preblock difference in VNS was higher in the anterior -0.5 [-2 to 0] than in the posterior group 0 [-1.25 to 0], median difference 0.5 (95% CI 0 to 1). The median block onset time was longer in the anterior 11 [6 to 14.25] min than in the posterior group 6 [4.75 to 8] min (P = 0.002), median difference -5 (95% CI -7 to -1). CONCLUSION: The anterior iliopsoas muscle space block had the same effect as the posterior lumbar plexus block on peri-operative analgesia for hip surgery, but with a longer onset time. Therefore, anterior iliopsoas muscle space block can be recommended as a routine technique for hip and lower limb procedures. TRIAL REGISTRATION: http://www.chictr.org.cn identifier: ChiCTR1900021214.