Dexmedetomidina para el escalofrío intraoperatorio en el parto por cesárea electiva programada

Potential subjects will consist of parturients who present for scheduled elective cesarean deliveries. Patients will be recruited and consented for the study pre-operatively and if they display Grade 3 or 4 shivering at the time of delivery then they will be enrolled in the study. Doses of dexmedetomidine will be selected according to a sequential up-and-down method, using a biased coin design to find the estimated dose at which 90% of patients would have desired effect - cessation of shivering within 5 minutes of medication administration. An anesthesia physician not involved in patient care or assessment will prepare the dexmedetomidine for intravenous use. Anesthesia will be initiated with spinal anesthesia with our institution's typical dosing of 1.6 mL 0.75% bupivacaine with dextrose, 15 mcg fentanyl, and 150 mcg morphine.

Shivering will be graded using a five-point scale as outlined by Crossley and Mahajan. Members of the anesthesia team caring for women in the study will be educated on the grading scales.

• Grade 0: no shivering;
• Grade 1: one or more of the following: piloerection, peripheral vasoconstriction, peripheral cyanosis, but without visible muscle activity; Grade 2: visible muscle activity confined to one muscle group;
• Grade 3: visible muscle activity in more than one muscle group;
• Grade 4: gross muscle activity involving the whole body