Efficacy of low-dose hypobaric anesthetics in spinal anesthesia for cesarean delivery: systematic review and meta-analysis

Many studies have compared the anesthetic effects of different doses of hypobaric local anesthetics (without glucose) in spinal anesthesia for cesarean sections. Therefore, a meta-analysis of these trials is warranted. Systematic review and meta-analysis of eligible randomized controlled trials comparing the efficacy of low-dose spinal hypobaric anesthetics (Bupivacaine &lt; 10 mg, levobupivacaine &lt; 10 mg, ropivacaine &lt; 15 mg) with conventional dose (Bupivacaine/Levobupivacaine ≥ 10 mg, ropivacaine ≥ 15 mg) in elective and subemergency Cesarean sections in data sources <b>(</b>PubMed, Embase, Web of Science, and Cochrane Central) from inception to February 2025. We obtained data from 1,280 patients from 17 published trials. Low-dose hypobaric local anesthetics reduce hypotension occurrence (risk ratio [RR], 0.56; 95% confidence interval [CI], 0.43 to 0.73; low evidence grade) but comprise anesthesia effect (analgesic-supplementation risk: RR 3.13, 95%CI 2.14 to 5.59, moderate evidence grade). In the subgroup analysis (based on whether opioid adjuvants mixed with local anesthetics were equal), there were no differences in anesthetic effects between low-dose local anesthetics mixed with opioid adjuvants and conventional-dose local anesthetics without opioid adjuvants between the two groups (analgesic-supplementation risk: RR 1.32, 95%CI 0.58 to 3.00, moderate evidence grade). Other secondary outcomes, including hypotensive side effects (nausea/vomiting and bradycardia), ephedrine consumption, and highest block plane, were observed less or lower in the low-dose group. No significant differences were found in trembling, pruritus, time to maximum block, or neonatal outcomes between the two groups. Low-dose hypobaric local anesthetics in spinal anesthesia may reduce maternal side effects (hypotension, nausea/vomiting, and bradycardia) but comprise anesthetic efficacy (analgesic-supplementation risk). Furthermore, intrathecal opioid adjuvants improve anesthetic efficacy. The protocol for this systematic review was registered on PROSPERO (CRD42024533150).