This prospective single-blind randomized controlled study on 50 patients between 18 and 65 years, both sexes, with ASA I-II and undergoing elective lumbar spine surgical procedures. They were equally divided into two groups: Group Erector Spinae Plane Block (ESPB) (Study): (number = 25) received Erector Spinae Plane Block (20 ml bupivacaine 0.25%) combined with general anesthesia. Group General Anesthesia (GA) (Control): (number = 25) received conventional general anesthesia.

In both groups, on arrival to the operation room, a multi-channel monitor will be attached to the patient to display continuous electrocardiogram (ECG) monitoring, heart rate (HR), non-invasive blood pressure, pulse oximeter, temperature probe, capnogram, and anesthetic gas analysis. An intravenous line will be secured, then lactated Ringer's solution will be started at 5 ml/kg/h. Ten minutes before induction of anesthesia, all patients will be premedicated with intravenous midazolam 0.02 mg/kg. Patients will be preoxygenated with 100% oxygen for 3 minutes. In both groups, induction of anesthesia will be carried out by intravenous administration of fentanyl 1 µg/kg, lidocaine 1.5 mg/kg, and propofol 2 mg/kg. After loss of verbal communication, 0.5 mg/kg atracurium will be administered. Intermittent positive pressure ventilation will be adjusted to maintain an end-tidal carbon dioxide partial pressure between 30 and 35 mmHg. Anesthesia will be maintained with 1-2% isoflurane, 0.1 mg/kg atracurium bolus doses will be administered every 20 minutes, and 0.5 µg/kg fentanyl will be administered every 30 minutes.

In the Erector Spinae Plane block (ESPB) group, after prone positioning and before surgery, Erector Spinae Plane Block will be performed bilaterally using a low-frequency curved ultrasound transducer placed in a longitudinal orientation 3 cm lateral to the spinous process one vertebral level above a predetermined marked surgical incision. An 8-cm 22-gauge block needle will be inserted in a cephalad to caudad direction until the tip lies in the interfascial plane below the erector spinae muscle; the block will be performed by injection of 20 ml of 0.25% bupivacaine. In both groups, fentanyl 1 µg/kg as rescue analgesia will be given based on hemodynamic parameters.

If the mean arterial blood pressure (MAP) has fallen below 65 mmHg, 5 mg of ephedrine will be administered, and an intravenous bolus of 0.5 mg of atropine will be administered in case of bradycardia if the heart rate ≤50 bpm. The blood pressure will return to the baseline value before surgical field closure. Then at the end of surgery, the isoflurane vaporizer will be turned off, and the muscle relaxant will be reversed with neostigmine 0.04 mg/kg and atropine 0.02 mg/kg. The endotracheal tube will be removed after the patient regains consciousness and full muscle power, breathes spontaneously, and responds to verbal commands. Isoflurane consumption was measured at the end of surgery.

Postoperative pain management:

A standardized analgesic regimen will be prescribed in the postoperative period. All patients will receive 1 gm of paracetamol every 6 h. If the numeric rating scale (NRS) is more than 3, intravenous morphine 3mg will be administered by an investigator blinded to group assignment.

Clinical evaluation:

Total intravenous drug administration at the post-anesthesia care unit (PACU) and over the 48 hours was recorded. Opioid-related adverse events arising from the analgesic protocol will be systematically assessed at the PACU and surgical ward. The presence of nausea, vomiting, respiratory depression, pruritus, urinary retention requiring evacuation, allergy, and hallucinations will be recorded as binary (yes/no). Arterial oxygen saturation (pulse oximetry), heart and respiratory rates, and blood pressure will also be recorded every 6 hours.

The Ramsay Sedation Scale will be assessed postoperatively. The Ramsay sedation scale comprises two clearly defined groups of scores: those of 1, 2, and 3 are given in assessing degrees of wakefulness, and those of 4, 5, and 6 are given in assessing degrees of sleep. The six levels of the Ramsay sedation scale allow for visual assessments of sedation in patients who are responsive to such assessments

Inclusion Criteria:

1. Patients aged from 18 and 65 years, both sexes
2. The American Society of Anesthesiology (ASA) physical status I-II
3. Scheduled for elective lumbar spine surgical procedures

Exclusion Criteria:

1. Coagulation disorders
2. BMI > 30 or < 18 kg/m2
3. Patients with surgical site infection
4. Known sensitivity or contraindication to local anesthetics
5. History of psychological disorders
6. Patients with unstable spine integrity like fractures or scoliosis
7. Hypertensive, cardiac, and diabetic patients,
8. Known alcohol or substance abuse within the last 6 months and Daily opioid intake