Group A ~ (n = 30 )   Patients will receive 3ml of Isobaric Levobupivacaine 0.5% + Dexmedetomidine 5 μg (0.5ml) – diluted with NS.

Group B ~ (n = 30 )   Patients will receive 3ml of Isobaric Levobupivacaine 0.5% +   Fentanyl 25 μg (0.5ml)

METHODS

After obtaining approval from Institutional Human Ethics Committee and written informed consent, patients undergoing surgeries under subarachnoid block in Chettinad Hospital and Research Institute, Kelambakkam, Chennai . Patients meeting the selection criterion will be included in the study. They will receive either 3 ml of Isobaric Inj. Levobupivacaine 0.5% + Inj. Dexmedetomidine 0.5 ml(5µg) in Group A (n = 30 ) –diluted with NS or 3ml of Isobaric Inj. Levobupivacaine 0.5% + Inj. Fentanyl 0.5 ml(25µg) in       Group B (n = 30 ).

All the patients will undergo routine pre-operative assessment in the pre-anesthetic assessment clinic. All Patients will be advised to stay nil per oral, 8 hours for solid diet & 4 hours for oral clear fluids prior to surgery. They will also be explained about the advantages & disadvantages of Spinal Anaesthesia.

All the patients will receive Tab. Ranitidine 150mg HS and 6AM in the morning of surgery. On the day of surgery, the patient will be shifted from the ward to a room near the operation theater prior to surgery. An IV access with 18G size IV cannula will be secured. All patients will be preloaded with 10-15 ml/kg of Ringer lactate 15 minutes before surgery. Establishment of proper standard monitoring systems pulse oximetry, continuous electrocardiography and non-invasive blood pressure monitoring and SpO₂ will be done and baseline variable values will be noted before the procedure.

Sitting position is recommended for all patients included in this study. Under all aseptic precautions L3-L4 inter-space will be infiltrated with 2ml of 2% Inj. Lignocaine. Study drug will be prepared by the person not involved in the study. The subarachnoid space will be entered at L3-L4 inter-space via the midline approach using 26-Gauge quincke spinal needle. The correct needle placement will be identified by free flow of cerebrospinal fluid and 3.5 ml of study drug will be injected by the anesthesiologist.

The patient will be placed in supine position immediately, the time of which was recorded as “ZERO”.  The onset of sensory and motor blockade will be assessed at baseline (ZERO) and 3 min interval up to 15 min, thereafter 5 mins interval up to 30 minutes.

Sensory Block:

The level of sensory block will be assessed by loss of pinprick sensation. S1, L3, T12, T10, T8, T6 or Higher T4 dermatomes will be checked bilaterally. C5-C6 will be used as baseline point for normal sensation. Sensory onset will be taken as loss of pin prick sensation with 23G needle at T10 level. The test will be performed every 3 minutes till 15 mins and thereafter every 5 mins up to 30 minutes. 

The duration of sensory blockade will be defined as the interval from intrathecal administration of drug to the point of complete resolution of the sensory block (Time of regression of Sensory Block to T10 Level). Two segment regression of the block, highest sensory level, and time taken to reach the highest sensory level will be noted. 

Motor block:

 Modified bromage scale will be used to assess the motor block bilaterally

             Motor onset after intrathecal administration of drug will be taken as achievement of modified modified bromage score 2 and will be considered full after modified bromage score reached grade 4. The duration of motor blockade will be defined as the interval from intrathecal administration of drug to return of modified bromage score to One.

Vital Signs and Side Effects:

Patient’s HR, NIBP, SPO2 will be monitored at 3 min interval up to 15 minutes then every 5 minutes up to 60 minutes then every 10 minutes till end of the procedure. Throughout the procedure, patient will receive 6 liters of oxygen per minute through facemask.

Hypotension: Decrease in systolic blood pressure less than 90 mmHg or more than 30 mmHg decrease from the baseline will be considered as Hypotension. It will be managed by incremental doses of 6mg of intravenous ephedrine.

Bradycardia: Heart rate less than 60/min will be considered as Bradycardia and will be managed by incremental doses of 0.3mg intravenous Atropine.

Respiratory Depression: Respiratory rate less than 8/min and/or Spo2 less than 90% will be considered as Respiratory Depression.

The time for request of first rescue analgesia will be noted from the time of administration of spinal anaesthesia to complain of pain VAS score >/= 3. In case of pain        Inj. Tramadol 50mg will be given intravenously and Inj. Ondansetron 4mg in cases experiencing nausea and vomiting.

            Postoperatively patients will also be monitored for changes in vital parameters, nausea, vomiting, shivering. Urinary retention will be monitored postoperatively and catheterization will be planned in patients with prolonged retention more than 6 hours.