Ultrasound guidance versus anatomical landmarks for neuraxial anaesthesia in adults.

Rationale: Neuraxial anaesthesia can be difficult to administer successfully, because the targeting space imagined by palpation of anatomical position can deviate from the actual position. Successful neuraxial anaesthesia, with as few punctures as possible, is important to reduce complications and increase patient satisfaction. Neuraxial anaesthesia by ultrasound guidance may be a useful way to increase success rates.

Objectives: To assess the clinical efficacy and safety of ultrasound guidance compared with anatomical landmarks for neuraxial anaesthesia in adults.

Search methods: We searched CENTRAL, MEDLINE, Embase, Web of Science, and two trials registries, together with reference checking and citation searching, to identify studies that are included in the review. After the original search on 11 October 2022, we updated the electronic searches on 28 November 2023.

Eligibility criteria: We included randomised controlled trials (RCTs) that compared ultrasound guidance with the use of conventional anatomical landmarks for neuraxial anaesthesia in adults (≥ 18 years). We excluded studies on non-anaesthetic neuraxial procedures, such as lumbar puncture for diagnosis.

Outcomes: Our critical outcomes were: (1) number of attempts until success or procedure termination; (2) procedure time; and (3) participant satisfaction during the procedure. Our important outcomes were: (1) first-attempt success; (2) technical failure; (3) pain during the procedure; and (4) any adverse events.

Risk of bias: We used the Cochrane RoB 2 tool to assess risk of bias in the included studies for the seven critical and important outcomes.

Synthesis methods: We synthesised results for each outcome, where possible, by using a random-effects analytical model. We calculated risk ratios (RR) for dichotomous outcomes, and mean differences (MD) or standardised mean difference (SMD) for continuous outcomes, each with 95% confidence intervals (CI). Where meta-analysis was not possible due to the nature of the data, we summarised the results narratively. We used GRADE to assess the certainty of evidence for each outcome.

Included studies: We included a total of 65 studies with 6823 participants. The studies were conducted in Africa, Asia, Europe, the Middle East, North America, and Oceania, and were published between 2001 and 2023. Thirty-two studies evaluated obstetric populations undergoing labour epidural or caesarean section (3149 participants); the remaining studies evaluated participants who received surgery under neuraxial anaesthesia. Thirty-three studies evaluated spinal anaesthesia, 15 studies evaluated lumbar epidural anaesthesia, 12 studies evaluated combined spinal and epidural anaesthesia, and the remaining four studies evaluated thoracic epidural anaesthesia. Four studies evaluated real-time ultrasound as an intervention arm. Two studies were three-arm trials, which evaluated pre-procedural ultrasound and real-time ultrasound. For participant satisfaction, a variety of measurement scales were used, so we synthesised participant satisfaction using SMD.

Synthesis of results: Our meta-analyses demonstrated that compared with anatomical landmarks, ultrasound guidance reduces the number of attempts until success or procedure termination (MD -0.41 attempts, 95% CI -0.51 to -0.31; 57 studies, 6192 participants; high-certainty evidence), and procedure (needling) time (MD -33.8 seconds, 95% CI -47.22 to -20.39; 43 studies, 4178 participants; high-certainty evidence). Ultrasound guidance likely increases the rate of first-attempt success (RR 1.40, 95% CI 1.29 to 1.52; 50 studies, 5205 participants; moderate-certainty evidence). Ultrasound guidance may result in little to no difference in participant satisfaction (SMD 0.16, 95% CI -0.03 to 0.35; 25 studies; low-certainty evidence), or in technical failure (RR 0.89, 95% CI 0.62 to 1.29; 40 studies, 4581 participants; low-certainty evidence). The evidence is very uncertain about the effects of ultrasound guidance on pain during the procedure (MD -0.20 points, 95% CI -0.52 to 0.13; 13 studies, 1532 participants; very low-certainty evidence), and adverse effects (RR 0.71, 95% CI 0.48 to 1.03; 15 studies, 1692 participants; very low-certainty evidence).

Authors' conclusions: Compared to anatomical landmarks, ultrasound guidance for neuraxial anaesthesia in adults reduces the number of attempts required for success and reduces procedure (needling) time. It likely increases the rate of first-attempt success. Low-certainty evidence suggests that ultrasound guidance may result in little to no difference in participant satisfaction or technical failure. The evidence is very uncertain about the effect of ultrasound guidance on pain and adverse events. Although ultrasound guidance can be beneficial for neuraxial anaesthesia without increased risk, these results should be interpreted with caution due to some uncertainties in the evidence.

Funding: None.

Registration: Protocol available via doi.org/10.1002/14651858.CD014964.