Effects of dexmedetomidine vs. magnesium sulfate on hemodynamics in spine surgeries: a systematic review and meta-analysis.

BACKGROUND

Blood loss and hemodynamic instability are common challenges in spine surgery, often managed with controlled hypotension. Dexmedetomidine (DEX), a selective α2-adrenoceptor agonist, and magnesium sulfate (MgSO₄), an NMDA receptor antagonist and calcium channel blocker, are commonly used for this purpose, but their comparative efficacy and safety remain unclear. This comprehensive systematic review and meta-analysis aim to critically evaluate and compare the hemodynamic effects of both drugs in spinal surgeries.

METHODS

We conducted a systematic review and meta-analysis in accordance with PRISMA guidelines, searching PubMed, Scopus, Web of Science, and Google Scholar up to August 15, 2025. We identified randomized controlled trials comparing intravenous DEX vs. MgSO₄ in spine surgeries. Outcomes included blood loss; changes in mean arterial pressure (MAP), heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP); recovery time; first time to analgesic needs; total opioid consumption; extubation time; and incidence of bradycardia and tachycardia. Effect sizes were pooled using random-effects models.

RESULTS

Analysis of nine RCTs involving 463 patients showed that DEX significantly reduced intraoperative blood loss (MD = - 1.447 mL; p = 0.009), SBP (MD = - 0.448 mmHg; p = 0.012), tachycardia (RR = 0.330; p = 0.004), and prolonged the time to first analgesic request (MD = 1.409 min; p = 0.004). DEX was associated with an increased risk of bradycardia (RR = 4.819; p = 0.001) and delayed MAP recovery (p = 0.030). No significant differences were observed for MAP, HR, DBP, recovery time, postoperative opioid use, extubation time, or ephedrine requirement. Several outcomes showed high heterogeneity.

CONCLUSIONS

Our study showed that dexmedetomidine offers superior blood-sparing and analgesic effects compared to magnesium sulfate but carries a higher risk of bradycardia and delayed MAP recovery. Magnesium sulfate remains effective for analgesia and muscle relaxation. Larger, well-designed RCTs are required to validate these findings and guide drug selection in spine surgery. Nevertheless, these findings should be interpreted with caution, given the extremely high heterogeneity observed across several pooled outcomes, which considerably constrains the reliability and generalizability of the estimates.