Spinal anesthesia is the most widely employed procedure for lower limb orthopedic operations, as it is very cost-effective and simple to apply. These advantages could be restricted because presently existing local anesthetic drugs had relatively short length of action. (1) Spinal anesthesia with 0.5% heavy bupivacaine (hyperbaric) is a common technique, still there was burden of its short duration of action. To overcome this issue, there was a continuous search for an ideal adjuvant.(2) Adjuvants were mostly added to local anesthetic drugs to increase their effectiveness, speedy onset, increase the period of the block, and reduce the local anesthetics dosage, thus reduction their adverse effects.(3) Such adjuvants had been beneficial in extension of analgesia along with initiation of movement though their related side effects.(4)

Administration of opioids intrathecal such as fentanyl, morphine, and buprenorphine, allowed decreasing dose of the local anesthetic drug, augment analgesic effectiveness, and reduce probable toxicity and cardiovascular adverse consequences of local anesthetics. (5, 2) Nevertheless, adverse effects such as possibly disastrous delayed respiratory depression, urinary retention, nausea, pruritus, vomiting, and constipation had provoked further study to investigate non opioid analgesic drugs with less troublesome drawbacks. (6,2,7,8) Dexmedetomidine is a novel central alpha2-agonist that was approved by the FDA in 1999. It had sedation, anxiolytic, analgesic, and sympatholytic effect that depress cardiovascular reflexes in perioperative interval. (2) Thus, this study had been conducted for assessment of the effectiveness of addition 4 µg Dexmedetomidine to hyperbaric Bupivacaine intrathecally in lower limb orthopaedic surgeries.

Aim This clinical comparative study aimed to evaluate the hemodynamic stability and onset and duration of motor block of using intrathecal dexmedetomidine and fentanyl as an adjuvant to heavy bupivacaine in lower limb orthopaedic surgeries.

Patients and Methods After approval of medical institutional ethical committee, 40 patients of American Society of Anaesthesiologists (ASA) physical status 1or 2, aged between 20-60 years had been incorporated in this prospective randomized controlled study.

Inclusion Criteria

1. The patient aged range from 20 to 60 years 2. ASA 1 and 2 3. Patient prepared for elective lower limb orthopaedic surgeries. 4. Height 150-180 cm. 5. Weight 50-70 kg. 6- Either sex male or female. Exclusion Criteria

1. Patient refusal.
2. Patient had absolute contraindication to spinal anaesthesia.
3. Patients with neurological disorders, pregnancy, local infection at the site of injection.
4. Patients suffering from dysrhythmia or heart block.
5. Patients with ASA 3 or more. An informed written consent had been taken from all the contributors. Patients had been divided into the following groups using randomizer software. Group D: patients received 3 mL volume of 0.5% hyperbaric bupivacaine and 4 µg dexmedetomidine in 0.5 mL of normal saline intrathecal (dexmedetomidine 100 µg/mL diluted in 12.5 ml preservative-free normal saline, 0.5 ml had been withdrawn).

Group F: patients received 3 mL volume of 0.5% hyperbaric bupivacaine with 25 µg fentanyl (0.5 mL) intrathecal.

In preoperative room area: clinical history and examination had been evaluated, and then non-invasive blood pressure and heart rate had been measured and recorded as baseline values.

Anesthetic technique

• Patients would be moved to operation table, 18G IV access was inserted and secured.
• Preloading began15minutes before spinal anaesthesia administration with ringer lactated 20ml /kg.
• Intraoperative monitoring involved NIBP, pulse rate, ECG, SPO2.
• Patients were divided randomly into two groups by using randomizer software.
• Baseline vital signs had been measured. Under strict aseptic technique, after the local infiltration with 2% lignocaine, lumbar puncture was done using 25 G Quincke spinal needle, at L 3 - L 4 space after free flow of csf was verified. Instantly after spinal injection, the patient was placed in a supine position with a cushion supporting shoulders and head. O2 (4-6L/min) had been provided throughout face mask.

The following parameters had been measured: Intraoperatively non-invasive mean blood pressure and heart rate had been documented, every 15 min for first 30minutes then every 30 min till the end of the surgery. onset time of bromage 3 motor block had been recorded (Onset of the motor block; period between the ending of intrathecal drug injection and entire motor paralysis) Duration of motor block had been evaluated by the time taken to return from complete Bromage motor block (bromage 3) to scale 0.

Motor block was evaluated with Modified Bromage scale (6) Bromage 0: The patient could move the hip, knee, and ankle. Bromage 1: The patient could move the hip but had ability to move the knee and ankle.

Bromage 2: The patient could move the hip and knee but had ability to move the ankle.

Bromage 3: The patient could not move the hip, knee, and ankle.

Complications would be noted Intraoperative:

nausea, vomiting, pruritis. Hypotension (> 20% fall of baseline blood pressure or systolic blood pressure of <100mmHg.) had been treated with bolus dose of 6 mg ephedrine IV Bradycardia (pulse rate < 60 bpm), had been treated with 0.3- 0.6 mg atropine IV Incidence of respiratory depression defined as respiratory rate less than 9 /min and SpO2 less than 90% on room air, would be noted, it had been treated with Oxygen (2 L/min), administered via a mask.

Inclusion Criteria:

1. The patient aged range from 20 to 60 years
2. ASA 1 and 2
3. Patient prepared for elective lower limb orthopaedic surgeries.
4. Height 150-180 cm.
5. Weight 50-70 kg. 6- Either sex male or female.

Exclusion Criteria:

- 1- Patient refusal. 2- Patient had absolute contraindication to spinal anaesthesia. 3-Patients with neurological disorders, pregnancy, local infection at the site of injection.

4- Patients suffering from dysrhythmia or heart block. 5- Patients with ASA 3 or more.