Ketamine for Preventing Post-Spinal Hypotension in Orthopedic Surgery

Patients receive crystalloid preloading of 15ml/kg (Ringer's lactate) +the sub-anesthetic dose of ketamine of 0.5 mg/kg IV added to the first bottle of ringer for blinding over 20 min before the spinal injection.

Patients receive a crystalloid preloading of 15 ml/kg (Ringer's lactate)+ 0.5 mg/kg IV of Normal Saline added to the first bottle of ringer for blinding, over 20 min before the spinal injection.