This study will be conducted at Ain Shams University Hospital in Operating Theatre after ethical committe approval number (MS 32/ 2020). It is a prospective randomized controlled study will be done on patients undergoing lower abdominal and lower limb surgeries under spinal anethesia,Eligible patients will be randomized by computer system to one of two groups, either intravenous dexamethazzoe 8 mg with intrathecal heavy bupivacaine 0.5% or intrathecal 4mg dexamethazone with intrathecal heavy bupivacaine 0.5%. .

Patients will be randomly divided into two equal groups: Group 1: patients receive intrathecal 3 ml bupivacaine 0. 5% +1 ml normal saline + intravenous 8 mg dexamethazone in 10 ml saline. Group 2: patients receive intrathecal 3 ml bupivacaine 0. 5% + 4 mg (1 ml) dexamethazone + intravenous 10 ml normal saline. Upon patients' arrival into the operating room, peripheral oxygen saturation (SPO2), ECG, pulse rate (PR), and systolic and diastolic blood pressures will be monitored one of the researchers and recorded every 5 minutes till the end of surgery. In a sitting position and with antiseptic techniques, 25 G Quincke needle was inserted intrathecally at L3-L4 or L4-L5 interspace through midline approach. The study drugs were given by an anesthesiologist not not aware of the type of medications injected. Subsequently, the patients were put in the supine position, and given oxygen 3 L/minutes by nasal prongs.

Inclusion Criteria:

• Patients ASA I or II undergoing lower limb surgeries under spinal anesthesia
• Patients ASAI or II undergoing lower abdominal surgeries under spinal anesthesia.

Exclusion Criteria:

• Emergency surgeries.
• Patients with uncompensated heart diseases.
• Patients with coagulopathy.
• Presence of infection at site of injection of spinal anesthesia.

double (participant and outcome assessor)