Prevention of Shivering Associated With Spinal Anesthesia

Inclusion Criteria: \- BMI 20-30 Scheduled patients for knee arthroscopy under spinal anesthesia. American Society of Anesthesiologists (ASA) physical status: I and II Exclusion Criteria: * Patient refusal Aged less than 18 years or lesser than 150 cm in height Pregnant woman Allergy to the studied drugs. Patients with contraindications to spinal anesthesia. Patients with advanced decompensated cardiac, respiratory,renal or hepatic diseases, ASA III-IV Coagulopathy or thrombocytopenia CNS diseases as epilepsy, stroke or psychiatric illness.