Background: Dexmedetomidine and ketamine are recently used effectively for preventing shivering that follow spinal anesthesia (SA). Shivering inhibition occurs via reducing vasoconstriction (VC), lowering shivering threshold. This study compares intravenous (IV) dexmedetomidine (0.3 ug/kg) versus low-dose ketamine (0.25 mg/kg) in preventing shivering during elective cesarean section (CS) under SA.

Methods: This prospective randomized double-blind controlled trial involved 75 parturients with uncomplicated pregnancy ASA physical status class II, divided into three equal groups (25 each): Group C: parturients received 20 ml normal saline (NS). Group D: parturients received (0.3 ug/kg) dexmedetomidine diluted in 20 ml NS. Group K: parturients received (0.25 mg/kg) ketamine diluted in 20 ml NS. Over ten minutes, all study medications were administered via IV infusion after clamping umbilical cord. Shivering occurrences, hemodynamics & core temperature changes, sedation level, total consumed rescue pethidine and intraoperative complications were evaluated.

Results: Earlier significant onset of shivering was found in group C (13.23 ± 10.63) minutes, followed by group K (23.83 ± 3.53) minutes and lastly, group D (31.67 ± 1.24) minutes with (P < 0.05). Shivering episodes were shorter for those in Group D, Group K, and Group C, in that order (P<0.05). incidence and severity of shivering were significantly higher among group C when compared to group D as well as group K (P1 & P3 < 0.05).

Conclusion: Intravenous dexmedetomidine and low-dose ketamine are both effective and safe in lowering occurrence and severity of shivering during cesarean section under spinal anesthesia. Dexmedetomidine, however, is more effective than ketamine