Ultrasound guided erector spinae plain block combined with general anaesthesia versus conventional general anaesthesia in lumbar spine surgery, it's hypothesized that combined regional anaesthesia with general anaesthesia in lumbar spine surgery may reduce the anaesthetic requirements, aid in controlled hypotension and improve the perioperative pain management.

Primary outcomes:

• Anaesthetic requirements: based on entropy monitoring(state and response entropy monitoring and the difference as a measure for adequacy of analgesia) and haemodynamic parameters ( heart rate and mean arterial blood pressure) at the following time intervals: before induction, after induction, after giving either ESP block or multimodal analgesia and starting surgical stimulus, at 30 min intervals, at end of anaesthesia, at eye opening.

Secondary outcomes:

• Stress response measurement based on serum cortisol and blood glucose levels
• Controlled hypotensive anaesthesia: various drugs required and doses given
• Intraoperative and postoperative analgesia.
• Postanaesthesia care unit data concerning recovery.

Inclusion Criteria:

patients undergoing lumbar spine surgery

Exclusion Criteria:

• Coagulation disorders.
• BMI > 30 or < 18.5.
• Patients with surgical site infection.
• Patients with unstable spine integrity like fractures or scoliosis.
• Hypertensive ,cardiac and diabetic patients.

After May 2020

Anaesthetic requirements, Haemodynamic parameters, entropy monitoring, perioperative pain evaluation

closed envelope method