Conventional landmark palpation versus preprocedural ultrasound for neuraxial procedures in nonobstetric patients: A systematic review with meta-analysis and trial sequential analysis of randomised controlled trials.

BACKGROUND Central neuraxial modalities can occasionally be challenging to perform, particularly if the underlying anatomy is altered or obscured. OBJECTIVES To compare the efficacy, efficiency and the safety of preprocedural ultrasound to landmark palpation in the nonobstetric adult population. DESIGN Systematic review of randomised controlled trials with meta-analysis and trial sequential analysis. DATA SOURCES Systematic search of Central, CINAHL, Embase, Global Health, MEDLINE, Scopus and Web of Science to 13th February 2020. ELIGIBILITY CRITERIA Randomised controlled trials of nonobstetric adult patients having diagnostic and/or therapeutic neuraxial procedures using standard preprocedural ultrasound interpreted by the operator as the intervention and conventional landmark palpation as the comparator. KEY DEFINITIONS A skin puncture was defined as the insertion or reinsertion of the needle through the skin; needle redirection was the backward followed by the forward movement of the needle without its removal from the skin; first skin puncture referred to a single skin puncture with or without needle redirections; and first pass was a single skin puncture with no needle redirection. RESULTS In all, 18 randomised controlled trials with 1800 patients were included. The first pass success rate was not different between landmark and ultrasound methods [risk ratio 1.46; 95% confidence interval (CI), 0.99 to 2.16; P = 0.06, I2 = 76%; moderate quality of evidence] and the trial sequential analysis demonstrated the futility of further randomisation of patients in modifying this finding. Preprocedural ultrasound increased the total time taken (mean difference 110.8 s; 95% CI, 31.01 to 190.65; P = 0.006; I2 = 96%; moderate quality of evidence). Subgroup analyses revealed no influence of the predicted difficulty of the neuraxial procedure on outcomes. Compared with the landmark method, ultrasound increased the first skin puncture success rate (risk ratio 1.36; 95% CI, 1.18 to 1.57; P < 0.001; I2 = 70%), and decreased the need for three or more skin punctures (risk ratio 0.46; 95% CI, 0.33 to 0.64; P < 0.001; I2 = 29%) and the number of needle redirections (mean difference -1.24; 95% CI, -2.32 to -0.17; P = 0.020; I2 = 83). The incidence of bloody tap was reduced with the use of ultrasound (risk ratio 0.61; 95% CI, 0.40 to 0.93; P = 0.020; I2 = 42%). CONCLUSIONS The use of preprocedural ultrasound for neuraxial procedures in the nonobstetric adult population did not enhance the first pass success rate and increased the total time taken to a clinically insignificant extent. Improvement in secondary outcomes, including other markers of efficacy, should be interpreted with caution.