Background
This study was designed to evaluate the efficacy of dexmedetomidine as a hypotensive agent in comparison to sodium nitroprusside in scoliosis surgery.
Method
Forty patients ASA I or II aged (12–16) year scheduled for scoliosis surgery were randomly assigned to receive either dexmedetomidine 1 μg/kg over 10 min before induction of anesthesia followed by 0.2–0.5 μg/kg/h infusion during maintenance (DEX group) or sodium nitroprusside 1–10 μg/kg/min infusion after induction of anesthesia (SNP group) to maintain mean arterial blood pressure between (60–65 mmHg). Mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), systemic vascular resistance index (SVRI) and stroke index (SI) were recorded. The two groups were compared with reference to reversibility of hypotensive state, intraoperative blood loss and transfusion requirement.
Results
Dexmedetomidine administration resulted in significant reduction in MAP, HR and CI. During the steady state hypotension SNP group showed significant increase in HR and CI compared to baseline and to DEX group ( < 0.05). SVRI was significantly lower during controlled hypotension in SNP group compared to DEX group ( < 0.001). Time to restoration of baseline MAP was longer with DEX group (10.21 ± 1.52 min) than SNP group (4.87 ± 0.86 min) ( < 0.001). Blood loss and transfusion requirement were significantly lower in DEX group than SNP group [1095.62 ± 128.9 6 ml versus 1287.50 ± 182.54 ml,  = 0.0013] and [855.42 ± 140.23 versus 1006.00 ± 154.66 ml,  = 0.0026], respectively.
Conclusion
Dexmedetomidine is a safe and effective drug for controlled hypotension in scoliosis surgery. It may offer the significant advantage of reducing blood loss and transfusion requirement.