Paramedian versus midline approach of spinal anesthesia: a systematic review and meta-analysis with trial sequential analysis

Purpose Midline approach of spinal anesthesia has been widely used for patients undergoing surgical procedures. However, it might not be effective for obstetric patients and elderly with degenerative spine changes. Primary objective was to examine the success rate at the first attempt between the paramedian and midline spinal anesthesia in adults undergoing surgery.Methods Databases of MEDLINE, EMBASE, and CENTRAL were searched from their starting date until February 2023. Randomized clinical trials (RCTs) comparing the paramedian versus midline approach of spinal anesthesia were included. The primary outcome was the success rate at the first attempt of spinal anesthesia.Results Our review included 36 RCTs (n = 5379). Compared to the midline approach, paramedian approach may increase success rate at the first attempt but the evidence is very uncertain (OR: 0.47, 95% CI 0.27-0.82, rho = 0.007, level of evidence:very low). Our pooled data indicates that the paramedian approach likely reduced incidence of post-spinal headache (OR: 2.07, 95% CI 1.51-2.84, rho < 0.00001, level of evidence:moderate). The evidence suggests that the paramedian approach may result in a reduction in the occurrence of paresthesia (OR: 1.61, 95% CI 1.06-2.45, rho = 0.03, level of evidence:low).Conclusions Our meta-analysis of 36 RCTs showed that paramedian approach may result in little to no difference in success rate at the first attempt owing to its very low level of evidence. However, given the low level of evidence and studies with small sample sizes, these findings need to be interpreted with caveat.