A prospective double-blinded randomized controlled study to determine efficacy of ephedrine in preserving core temperature in patients under neuraxial spinal anesthesia for knee and ankle arthroscopic surgery.

To determine the effect of ephedrine on preserving core temperature (tympanic) when given at finishing of local anesthetic administration for spinal neuraxial anesthesia comparing to normal saline (120 minutes period)

Inclusion Criteria:

• Patient undergoing knee or ankle arthroscopic surgery under spinal block at department of orthopaedic Ramathibodi Hospital
• BMI 17-30 kg/m2
• ASA physical status 1-3
• Age 18-70
• Last oral intake more than 6 hours (2 hours for water)
• Consent form acquired

Exclusion Criteria:

• Patient who are contraindicated for spinal block
• Anesthesia level higher than T4 or lower than T10
• Tympanic temperature more than 37.5 or less than 35.5 degrees Celsius
• Otitis or other ear infection
• Patients who receive alpha adrenergic blocker or beta adrenergic blocker
• Initial blood pressure presenting in operating theater 140 90 mmHg repeat after rest 5 minutes
• Patient refusal