A Comparison the effects of lidocaine - dexamethasone with Lidocaine -epinephrine intrathecal on quality of sensory block

INTERVENTION: Intervention 1: Intrathecal injection of 75 mg lidocaine and 1 cc normal saline. Intervention 2: Intrathecal injection of 75mg lidocaine and 100 microgram epinephrine. Intervention 3: Intrathecal injection of 75 lidocaine and 4mg dexamethasone. Intrathecal injection of 75 mg lidocaine and 1 cc normal saline. Intrathecal injection of 75 lidocaine and 4mg dexamethasone Intrathecal injection of 75mg lidocaine and 100 microgram epinephrine Treatment ‐ Drugs CONDITION: Other complications of Anesthesia during pregnancy. ; Other complications of anaesthesia during pregnancy Other complications of anaesthesia during pregnancy PRIMARY OUTCOME: Onset of sensory block. Timepoint: Time from intrathecal injection to highst sensory level. Method of measurement: Pin prik test with needle. The duration of sensory block. Timepoint: Every 15 minutes until 4 dermatom regretion. Method of measurement: Pin prik test with needle. SECONDARY OUTCOME: Blood pressure. Timepoint: Every 3 min to end of surgery. Method of measurement: Manometer. Hear rate. Timepoint: Every 5 min to recovery. Method of measurement: ECG. Nausea. Timepoint: During delivery to24 hours. Method of measurement: Questioning from patient(having or not). Pain. Timepoint: Recovery room to 24 hours. Method of measurement: Visual analog scale. Vomiting. Timepoint: During delivery to 24 hours. Method of measurement: Questiening from patient. INCLUSION CRITERIA: INCLUSION CRITERIA: elective cesarean section in pregnant women 18‐35 years ,ASA ClassI, II ,elective cesarean section Exclusion criteria from the study: patients with a history of alergy, psychiatric disorder, chronic pain, those taking corticosteroids , alcohol and drug dependence , emergency cesarean