double blind randomized controlled trial will be conducted on upper abdominal cancer surgery cases to study the effect of Adding Magnesium Sulphate as Adjuvant to Bupivacaine in Ultrasound Guided External Oblique Intercostal Plane Block in Upper Abdominal Cancer Surgery

Despite advances in the field of medical and radiation oncology, surgical resection is a crucial intervention and remains the mainstay of gold standard treatment. Upper abdominal incisions such as the oblique subcostal laparotomy are a cause of severe pain and can lead to significant respiratory impairment . Numerous studies have demonstrated that when enhanced recovery procedures (ERPs) are used, hospital length of stay, time to return to normal function, postoperative ileus duration, thromboembolic complications, morbidity, and all of these factors are all reduced. Traditionally, epidural analgesia has been the cornerstone of pain control in such surgeries. However, it has limitations, including potential complications and contraindications in certain patients.

The innervation of the upper abdominal wall originates from the T6th and T10th intercostal nerves and requires effective blocking of these nerves to achieve analgesic and anesthetic efficacy. For upper abdominal surgeries, the ideal regional anesthesia technique should target both the anterior and lateral cutaneous branches of the intercostal nerves from T6 to T10. Hesham Elsharkawy et al demonstrated the potential mechanism of the external oblique intercostal fascial plane block (EOIB) in a cadaver study in which both lateral and anterior branches of the intercostal nerves T7-T10 were stained. Patients to whom this block was applied exhibited consistent dermatomal sensory blockade between T6-T10 in the anterior axillary line and T6-T9 in the midline. It has been shown that this block can be used in the clinical setting for upper abdominal wall analgesia. The external oblique intercostal (EOI) block has shown promising results in covering the anterior and lateral upper abdominal wall. It's simple, effective, and convenient block, particularly in the context of morbid obesity.

The external oblique intercostal block offers effective pain relief for the upper abdomen without the systemic effects of sympathetic blockade and without impairing motor or bladder function. It ensure optimal pain management, promote early postoperative mobilization, and support functional recovery.

Magnesium is a calcium blocker and an NMDA receptor antagonist. Research has demonstrated that magnesium sulfate [MgSO4] has an analgesic effect by blocking N-methyl-D-aspartate [NMDA] receptors and associated calcium channels, thereby preventing central sensitization that arises due to peripheral nociceptive stimulation. Magnesium may influence the central nervous system's (CNS) ability to transmit nociceptive signals and pain sensation in the central nervous system (CNS) by inhibiting N-methyl-D-aspartate (NMDA) receptor and calcium channels. It was used recently as a powerful analgesic adjuvant resulting in reduced postoperative opioid consumption.

Inclusion Criteria:

• a. Age >18 years old b. Both sex c. Patients who were in risk-scoring groups I-III of the American Society of Anesthesiologists (ASA)

Exclusion Criteria:

• c. Patients' refusal, d. History of allergy to any of the study medications e. Any contraindications to regional anesthesia. f. Patients with anatomical abnormalities. g. Patients have hemodynamic instability. h. Patients with local infection, and suspected intra-abdominal sepsis.

An independent anesthesiologist randomly using computer-generated random numbers divided the patients into 2 groups :(Group 1 and Group 2). Each group will include 34 patients. We discreetly placed the randomization results in envelopes until the end of the study. The researchers who were responsible for postoperative follow-up and data processing were blinded to the group allocation during the whole study period. All patients were also blinded to the group allocation