Adequate analgesic regimen is one of the most important key elements of Enhanced recovery after surgery (ERAS) protocols. The cornerstone of analgesia is multimodal analgesia combining local anesthetic (LA) techniques and trying to avoid parenteral opioids and their side effects. Subcostal approach to Anterior quadratus lumborum block (SAQLB), compared to other variants of quadratus lumborum blocks (QLBs), was associated with wider and longer sensory blockade, and provided somatic as well as visceral analgesia of the abdomen. The newly emerging, relatively easy erector spinae plane block (ESPB) provided excellent analgesia across a variety of surgical procedures and reduced opioid consumption. This motivated us to do this study to assess and compare the analgesic efficacy of ESPB versus SAQLB following laparoscopic cholecystectomy.

Site of the Study: Zagazig university surgical hospitals.

Type of the Study: Prospective randomized double-blinded clinical trial.

Sample Size:

The sample size is calculated to be 27 for each group, assuming that the mean ± standard deviation of 24 hrs postoperative total opioid consumption among group of patients undergoing ESBP technique versus control group is 130 ± 88 and 201 ± 78, respectively. Assuming that US-guided SAQLB will be similar to ESBP technique in 24 hrs postoperative total opioid consumption. with confidence level of 95% and power of test 80%, with 10% drop out.

Withdrawal Criteria:

The patient has the right to withdraw from the study at any time without any negative consequences on medical or surgical treatment plan.

Randomization:

Computer-generated randomization numbers will be used to randomly assign patients into 3 groups using sealed opaque envelopes that will be randomly selected by each patient and contained a group number in which the patient was enrolled. Once enrolled in the study, patients will be randomly assigned into 3 groups;

Group I (ESP Group): will receive US-guided erector spinae plane block (ESPB). Group II (AQL Group): will receive US-guided subcostal anterior quadratus lumborum block (SAQLB).

Group III (Control Group): will receive intravenous (IV) multimodal analgesia only.

Clinician performing the blocks and patients will not be blinded, but investigators evaluating the outcomes will be blinded to the randomization to keep the data analysis unbiased.

Type of the Study: Prospective randomized double-blinded clinical trial.

Steps of Performance:

A. Intraoperative Management:

Preoperative Assessment:

All patients will be assessed by careful history taking, clinical examination and laboratory investigations. Laboratory work needed included; Complete blood count (CBC), biochemistry and coagulation profile. Other investigations (e.g., electrocardiography [ECG], echocardiography, and chest x-ray) will be done according to the patient's medical condition.

Preoperative Preparation:

The day before surgery, the purpose of this study, benefits from the block and possible complications that may occur will be explained clearly to the patient. After that, informed written consent will be obtained from him. Standard fasting guidelines will be also explained to the patients, i.e., no solid foods for 6 - 8 hrs (depending on fat content of the food) and no clear liquids for 2 hrs. Also, for aspiration prophylaxis, all patients will be instructed to take Erythromycin tablet 250 mg with Ranitidine tablet 150 mg, with 10 ml of water 2 hrs before procedure.

Premedication:

On arrival to the operating room, and after ensuring of working 18 gauge IV line, midazolam (2 mg) will be given IV for anxiolysis, then IV fluid drip will be started.

B. Intraoperative Management:

Intraoperative Monitoring:

Monitoring will be applied and maintained throughout the procedure, including 5- lead electrocardiogram (ECG), non-invasive arterial blood pressure, pulse oximeter, and capnography.

Hemodynamic parameters including heart rate (HR) and mean arterial blood pressure (MAP), will be recorded after receiving sedation (baseline data) and intraoperative immediately after induction, then every 5 minutes for 15 minutes, then every 15 minutes afterwards till the end of surgery.

General Anesthesia:

1. Induction and Intubation:

   Pre-oxygenation; will be done by asking the patient to take 8 vital capacity breaths of 100% O2 over one min. via a tightly fitting face-mask. Intravenous induction will be done using Fentanyl (1 µg/kg), Propofol (2 mg/kg) and Cis-atracurium (0.15 mg/kg). Mask ventilation will be done with 100% O2 for 3 min. until complete muscle paralysis. Endotracheal tube of suitable size will be used for tracheal intubation.

2. Immediately after Induction: Dexamethasone 8 mg IV will be given to all patients for prevention of postoperative nausea and vomiting (PONV).

3. Maintenance:

Anesthesia will be maintained with oxygen and 1.5% isoflurane. Additional doses of cis-atracurium (0.04 mg/kg) will be given when needed, guided by nerve stimulator. Volume-controlled mechanical ventilation will be used to maintain end-tidal carbon dioxide of 35-40 mmHg. Ventilator settings will be tidal volume 8 ml/kg and respiratory rate 10-15/min.

IV Fentanyl (0.5 - 1 mic/kg) will be given if MAP or HR increased 20% above baseline.

30 min. before the end of surgery, all patients will receive a combination of IV multimodal analgesia for postoperative pain control in the form of Acetaminophen (15 mg/kg), Ketorolac (0.5 mg/kg) and Nalbuphine (0.1 mg/kg).

Block Technique:

At the end of the surgical procedure, while patients are still under general anesthesia, the patient's envelope which contains the number of group will be opened and it will be recorded in the data collection sheet as a number of group because the data collector will be blind to the intervention which will be done to the patient, only the anesthetist knows each number will be referring to which intervention.

I) Group I (ESP Group): will receive US-guided ESPB. II) Group II (AQL Group): will receive US-guided SAQLB. III) Group III (Control Group): will receive IV multimodal analgesia only. Block techniques will be performed under complete aseptic precautions.

Time of Performing the Block:

It will be recorded and defined as the time from placement of US probe on the patient's skin till the end of local anesthetic (LA) injection. It represents the time needed for adequate ultrasonic visualization, needle introduction and drug injection. The time for skin preparation, draping, and probe sheathing will not be included.

Recovery from General Anesthesia:

After completion of blockade, isoflurane will be discontinued, residual neuromuscular blockade will be antagonized using neostigmine (0.05 mg/kg) and atropine (0.02 mg/kg) administered IV, and the patient will be extubated.

Block Assessment:

After recovery from general anesthesia, sensory blockade will be confirmed on both sides at the level of T6 dermatomal level (at the level of the xiphoid process) 30 min. after LA injection at PACU by pin prick using Hollmen scale for sensory block, as follows; 1 = Normal sensation of pinprick, 2 = Pin prick felt as sharp pointed but weaker when compared with unblocked area, 3 = Pin prick felt as touch with blunt object, 4 = No perception of pin prick. Cases of failed block, who would have Hollmen sensory scale of 1 , will be excluded from the study.

C. Postoperative Management:

Multimodal Analgesia:

Postoperative pain in the post-anesthesia care unit (PACU) and on the ward will be treated with a combination of IV multimodal analgesia in the form of Acetaminophen (15 mg/kg 4/day) and Ketorolac (0.5 mg/kg 3/day) using a fixed scheme. In addition, Nalpuphine, as 3 mg IV bolus at each dose, will be given when Numerical Rating Scale (NRS) ≥ 3. VAS will be assessed 5 - 10 min. after each opioid dose to assess the need for additional opioid doses.

Measured Parameters:

1. Time of Performing the Block.

2. Postoperative Hemodynamics; including; heart rate (HR), mean arterial blood pressure (MAP), respiratory rate (RR), and oxygen saturation (SpO2) will be recorded immediately postoperative, then every hour for the first 4 hrs, and then every 4 hrs till the end of the first 24 hrs postoperative.

3. Postoperative Pain;

   A. Patients will be instructed how to represent their level of pain using NRS 0 to 10, 0 indicated no pain, and 10 indicated the most intense pain. Taking the procedures of laparoscopic cholecystectomy (LC) into account, pain assessment was performed in four domains: pain when coughing, pain at rest, incision pain and visceral pain. Specific questions were used respectively:

   "What is NRS pain scores when you cough?" "What is your NRS pain scores when you lay down in a quiet situation?" "What is your NRS pain scores on the incision site?" "What is your NRS pain scores about dull pain inside the abdomen?" NRS will be recorded by the data collector who will be blind to the intervention done to the patient. Pain assessment will be done 30 min. postoperative, then at 2, 4, 6, 8, 12, 18 and 24 hrs postoperative.

   B. Shoulder pain (SP) will be assessed using a 3 point scale (0 = none, 1 = mild and 2 = severe) at the same time points.

4. Time of Postoperative First Opioid Analgesic Request.

5. Total Opioid Consumption in the First 24 hrs Postoperative.

6. Time To Recovery Of Intestinal Function; defined as time from recovery to first flatus.

7. Time To First Ambulation; defined as time from T0 until the subject was able to stand up and walk without support.

8. Patient Satisfaction; will be also considered and recorded at the end of the first 24 hrs postoperative using a 5-point scale of "completely dissatisfied" to "completely satisfied" as follows; 1 = Completely dissatisfied, 2 = Dissatisfied, 3 = Neither satisfied, nor dissatisfied, 4 = Satisfied, 5 = Completely satisfied.

Complications:

1. Pain:

2. Undesirable Effects of Opioid Usage; A. Sedation: will be measured using Pasero opioid-induced sedation scale (POSS); S; Sleep, easy to arouse, 1; Awake and alert, 2; Slightly drowsy, easily aroused, 3; Frequently drowsy, arousable, drifts off to sleep during conversation, 4; Somnolent, minimal or no response to verbal and physical stimulation.

   B. Respiratory Depression: defined as decreased respiratory rate (RR) < 8-10 breaths/minute or decreased oxygen saturation (SpO2) < 90%.

   Naloxone will be administered in case of excessive sedation and/or respiratory depression. Times of excessive sedation or respiratory depression, and total requirements of naloxone reversal in the first 24 hrs postoperative will be recorded.

   C. Postoperative Nausea and Vomiting (PONV): will be measured using a categorical scoring system; 0 = none, 1 = mild, 2 = moderate, 3 = severe. Detection of nausea will be occurred when nausea score > 0 at any time point postoperatively. Ondansetron (4 mg) will be administered IV in case of nausea and/or vomiting. Frequency of PONV and total requirements of ondansetron in the first 24 hrs postoperative will be recorded.

3. Technical Complications; Include visceral injury, hematoma formation, lower extremity weakness and local anesthetic systemic toxicity (LAST).

Inclusion Criteria:

1. Age 18 - 60 years, of both sexes.
2. ASA class II - III.
3. Scheduled to undergo laparoscopic cholecystectomy under general anesthesia.
4. Body mass index (BMI) ≥ 30 kg/m².

Exclusion Criteria:

1. Age < 18 or > 60 years. 2. ASA IV patients. 4. Intraoperative conversion to open surgery. 5. Contraindications of regional anesthesia, e.g., allergy to local anesthetics, coagulopathy or infection at the site of injection.

6. Uncooperative patients or psychiatric disorders. 7. Spinal deformity or previous spine surgery. 8. Chronic use of analgesics or drug dependence. chronic pain characterized by opioid use for > 30 consecutive days within the 3 preoperative months at a dose equivalent to at least 15 mg of morphine.

Computer-generated randomization numbers will be used to randomly assign patients into 3 groups using sealed opaque envelopes that will be randomly selected by each patient and contained a group number in which the patient was enrolled. Once enrolled in the study, patients will be randomly assigned into 3 groups;

Group I (ESP Group): will receive US-guided ESPB. Group II (AQL Group): will receive US-guided AQLB. Group III (Control Group): will receive IV multimodal analgesia only.

Both patients and data collector responsible for assessing outcomes will be blinded to group assignment (double-blinded clinical trial).