Patients will be randomly allocated by sealed, opaque envelopes- which will not be opened until patient consent has been obtained into one of the two groups according to a computer generated sequence of random numbers.

Group A: Patients in Group A (n=40) will receive 8 mg (2 ml Dexamethasone + 8ml NS= 10 ml total) Dexamethasone intravenously.

Group B: Patients in Group B (n=40) will receive 10 ml Normal saline intravenously. 

Drugs used in the study will be prepared by an investigator not involved with patient enrollment or data collection.

All the patients will be positioned by a trained assistant in sitting position. Under all aseptic precautions, 25 G Quincke’s spinal needle will be inserted intrathecally at L4-L5 or L3-L4 intervertebral space. Intrathecal positioning will be confirmed by observation of clear cerebrospinal fluid return through the needle. 10 mg (2 ml) of 0.5% Hyperbaric Bupivacaine will be injected intrathecally. At the end of intrathecal injection, patient will be positioned supine for surgery. O2 will be administered to the patient via facemask at a flow rate of 4-6 L/min. The level of the sensory and motor blockade will then be evaluated by a blinded investigator every 2 minutes for the first 10 minutes, then every 5 minutes for the next 20 minutes followed by 15 min interval till the regression of sensory block to L1 and restoration of motor power to Bromage score II. Sensory blockade will be evaluated with a blunt 22 G hypodermic needle while motor blockade will be evaluated using Bromage Score. After completion of surgery patient will be continuously monitored in post-operative area for regression of sensory blockade to L1 and return of Bromage score to II. If desired level of spinal block is not achieved, it will be considered as failure of technique, and surgery will then be conducted under general anaesthesia.

Following observations will be recorded during the study

1.Demographic characteristics such as age (years), height (cm), weight (kg) of all the patients will be recorded. 

2.Sensory block will be assessed by a sterile blunt 22 G hypodermic needle.

2.1 Onset of sensory blockade : The time between intrathecal injection of local anaesthetic and T6 or higher dermatome blockade as determined by 22 G blunt hypodermic needle tip will be taken as onset of sensory block.

2.2 Peak sensory level attained: Maximum height of the sensory blockade attained at 20 minutes will be recorded as peak sensory level. 

2.3 Duration of stable sensory block: The time of regression of sensory blockade from the peak sensory level attained at 20 minutes to L1 dermatome will be recorded as duration of stable sensory block. 

3. Motor block will be assessed using Bromage Score.

3.1 Onset of motor blockade: Time between the intrathecal injection of local anesthetic to Bromage score of III or higher will be taken as onset of motor blockade.

3.2 Peak motor blockade attained: Maximum degree of motor blockade at 20 min will be recorded as peak motor blockade.

3.3 Duration of motor block: The time of regression of motor block from peak motor blockade to Bromage score of II will be defined as the duration of motor block.

4.Intraoperative haemodynamic parameters: Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP) and heart rate (HR) will be recorded immediately after spinal anesthesia and then every 5 minutes till the regression of sensory block to L1 and motor block to Bromage score of II. Any episode of hypotension (fall in MAP >20 percent of the baseline), bradycardia (heart rate < 60 beats /min) will be recorded and managed as per standard protocol 

5.Duration of post-operative analgesia: Time from the intrathecal injection to the time of the first complaint of pain will be recorded as duration of analgesia. Rescue analgesia will be given with paracetamol 1 gm iv. Time of administration of rescue analgesia will be recorded