After obtaining approval from the Institutional Ethics Committee, patients meeting the inclusion criteria and providing informed consent for participation will be enrolled in the study. Randomization will be done using sealed opaque envelopes, maintaining a one-to-one ratio for equal distribution across the study. The envelopes will be sealed and stored until a patient arrives in the pre-anesthetic holding area. At that point, the attending anesthesiologist will open the envelope and proceed according to the group assigned to the patient. The attending anesthesiologist will not be involved in data collection.

Upon arrival in the operating room, patients will be connected to American Society of Anesthesiologists standard monitors such as a non-invasive blood pressure cuff, a three-lead electrocardiogram, and a pulse oximeter. Baseline vital readings will be recorded before proceeding with anesthesia. An intravenous line using an 18-gauge cannula in both upper limbs with 100-centimeter extension lines and a three-way stopcock will be inserted, and Ringer’s lactate will be started. Following this, ondansetron four milligrams intravenously will be administered.

Patients allocated to Group M will receive intrathecal morphine at a dose of two micrograms per kilogram of body weight, with a maximum dose of 200 micrograms. Patients will be positioned in a sitting position, and under strict aseptic precautions, the lumbar region will be prepared using chlorhexidine. The L3-L4 or L4-L5 intervertebral space will be identified by palpation. Local anesthesia with two percent lignocaine will be administered at the puncture site, followed by the insertion of a 25-gauge Quincke needle.

For Group M, preservative-free morphine at 15 milligrams per milliliter is initially diluted with sterile saline to 1.5 milligrams per milliliter using a ten-milliliter syringe. One milliliter of this solution is further diluted to 150 micrograms per milliliter in another ten-milliliter syringe. The first syringe is removed to prevent confusion. The required dose of two micrograms per kilogram, with a maximum of 200 micrograms, is extracted and further diluted to two milliliters with saline for administration.

After the procedure, patients will be positioned appropriately for the induction of general anesthesia. Following adequate preoxygenation, all patients will receive premedication with midazolam 0.03 milligrams per kilogram, glycopyrrolate 0.01 milligrams per kilogram, and ondansetron 0.15 milligrams per kilogram. Induction of general anesthesia will be achieved using fentanyl two micrograms per kilogram and a titrated dose of propofol two milligrams per kilogram until the loss of verbal contact. Neuromuscular blockade will be achieved using atracurium at a dose of 0.5 milligrams per kilogram administered after induction and maintained intraoperatively with a continuous infusion of atracurium at 0.5 milligrams per kilogram per hour via an infusion pump. Intraoperative monitoring will include standard parameters along with a skin temperature probe to monitor core temperature. Anesthesia will be maintained using isoflurane, titrated to achieve a minimum alveolar concentration of 1.1 to 1.2, delivered in a fifty percent oxygen-in-air mixture. All patients will receive intravenous dexamethasone four milligrams following induction.

Patients allocated to Group C, following the induction of general anesthesia, will have neuromuscular blockade facilitated with atracurium at a dose of 0.5 milligrams per kilogram, and it will be maintained intraoperatively with a continuous infusion at 0.5 milligrams per kilogram per hour. Patients allocated to Group C will then receive a continuous infusion of fentanyl at 0.5 micrograms per kilogram per hour via an infusion pump throughout the intraoperative period to ensure consistent analgesia.

After induction, the surgical team will install and operate the Da Vinci Surgical System following the manufacturer’s guidelines. Continuous intraoperative monitoring will be conducted to ensure patient stability. Intraoperative vital recordings will be done at baseline, carbon dioxide insufflation, retrieval of the specimen, and the end of surgery. Intraoperative monitoring includes heart rate, blood pressure, oxygen saturation, end-tidal carbon dioxide, and temperature. The surgical duration, episodes of hypotension defined as mean arterial pressure below 65 millimeters of mercury, use of rescue ephedrine dose, fentanyl dose, hourly fluid intake, and total blood loss will be recorded.

Rescue opioids will be administered to Group M if the mean arterial pressure increases by more than twenty percent from baseline. In such cases, patients in Group M will receive intravenous fentanyl boluses at a dose of 0.5 micrograms per kilogram as needed.

Before the introduction of the robotic arm, port sites will be infiltrated with 0.25 percent bupivacaine. Prior to wound closure, all patients will receive paracetamol one gram intravenously and local infiltration of 0.25 percent bupivacaine at the port site incisions. At the conclusion of the procedure, neuromuscular blockade will be reversed using neostigmine 0.05 milligrams per kilogram and glycopyrrolate 0.01 milligrams per kilogram. Extubation will be performed once the patient is fully awake and meets all extubation criteria. Any failure of extubation will be documented and managed according to institutional protocol.

Postoperatively, patients will be transferred to the post-anesthesia care unit where the Numeric Rating Scale score will be recorded at rest and during movement. Group C will be initiated on intravenous patient-controlled analgesia with a continuous infusion of twenty micrograms, patient-controlled boluses of twenty micrograms upon request, and a twenty-minute lockout period.

During the first twenty-four hours postoperatively, continuous monitoring will include electrocardiogram, oxygen saturation, level of consciousness, and respiratory rate and depth to ensure early detection of complications. Cumulative opioid consumption will be assessed at twelve and twenty-four hours postoperatively. Postoperative assessments will be conducted at zero hours in the post-anesthesia care unit and subsequently at three, six, twelve, and twenty-four hours. Rescue opioid usage will be monitored throughout the first twenty-four hours.

As part of a multimodal pain management strategy, all patients will receive intravenous paracetamol one gram every eight hours. Breakthrough pain defined as a Numeric Rating Scale greater than four will be managed with either fentanyl 0.5 micrograms per kilogram intravenously or tramadol fifty milligrams intravenously, at the discretion of the physician. Nonsteroidal anti-inflammatory drugs will be avoided.

Pain severity will be assessed using the eleven-point Numeric Rating Scale. A structured proforma will be used to evaluate potential complications related to intrathecal morphine and spinal anesthesia, including respiratory rate less than eight, respiratory depth, oxygen saturation below ninety-two percent, level of consciousness, post-dural puncture headache, pruritus, nausea, and vomiting. All data will be systematically recorded and compiled into a spreadsheet for statistical analysis.