Intrathecal MoRphine Versus Transabdominal Plane Block (TAP) Block for AnalGesic Management in Elective Caesarean Section

Intrathecal MoRphine Versus Transabdominal Plane Block (TAP) Block for AnalGesic Management in Elective Caesarean Section Performed Under Neuraxial Anesthesia. A Monocentric Pilot Randomized Controlled Trial

The goal of this randomized controlled clinical trial is to determine if low-dose intrathecal morphine is superior to a Transversus Abdominis Plane (TAP) block with ropivacaine and clonidine for postoperative analgesia in women aged 18 years or older undergoing elective cesarean section under neuraxial anesthesia.

The main questions it aims to answer are:

• Is intrathecal morphine more effective than TAP block in reducing postoperative somatic pain at rest?
• Does intrathecal morphine differ from TAP block in terms of adverse events, pain during mobilization, visceral pain, rescue analgesic use, maternal satisfaction, and newborn wellbeing?

Researchers will compare the intrathecal morphine (ITM) group to the TAP block (TB) group to see if ITM provides superior analgesia and improved secondary outcomes.

Participants will:

• Undergo spinal anesthesia with hyperbaric bupivacaine and sufentanil
• add 30 μg intrathecal morphine (only ITM group)
• receive bilateral ultrasound-guided TAP block with 20 ml ropivacaine 0.25% and 75 μg clonidine per side (only TB group)
• receive standardized postoperative analgesia with paracetamol, ibuprofen, and tramadol as needed
• be monitored postoperatively for pain (somatic and visceral, at rest and with movement), adverse events, mobilization, maternal satisfaction, and newborn outcomes at regular intervals for 24 hours

This is a single-center, pilot, single-blind trial involving 100 participants (50 per group).

It is a monocentric randomized single-blind controlled pilot trial, wherein the patient and the biostatistics will be unaware about assigned treatment group, whereas the study investigators and site staff will be aware of the treatment group.

The trial consists in two treatment arms:

• Transabdominal Plane Block (TAP) block with ropivacaine and clonidine performed at the end of surgery (this will be performed in the operating room, behind a drape, so that the patient is unaware of the study arm)
• Addition of low doses of morphine to the other drugs administered during the performance of spinal anaesthesia Women aged 18 years and older, with indication for elective caesarean section, gestational age 34 weeks and older, admitted to the Giannina Gaslini Institute will participate in this study.

After an adequate anamnesis, the confirmation of the presence of all the inclusion criteria and the absence of the exclusion criteria and the acquisition of the informed consent, the subjects will be assigned to the treatment arm with a computer-generated random number sequence. The investigator/designated study personnel will administer the treatment as per the randomization codes.

Clinical and instrumental parameters (such as pain, vital signs, the possible occurrence of symptoms such as nausea, vomiting, itching) will then be evaluated during the caesarean section and at 12, 18, 24 hours on the day of the caesarean section (possibly at 6 a.m. on the following day in the case of a caesarean section after 12 noon) and 24 hours after the operation, and the use of analgesics as needed in the case of uncontrolled pain (previously prescribed by the anaesthetist). The baby's well-being will be assessed at birth and, 24 hours after the operation, a questionnaire will be submitted to the patient, to assess her satisfaction.

The study intervention will be performed in the operating room of Departmental Unit of Obstetrics and Gyne-cology of IRCSS Giannina Gaslini Institute. The follow up will be performed in the inpatient ward of the same Departmental Unit.

For the purpose of this trial, the end of study (EOS) is defined as the last visit of last patient.

A total number of 100 participants, a sample size of 50 per group, will be recruited during the study.

Inclusion Criteria:

• Planned for elective Cesarean Section (CS)
• Scheduled for spinal anesthesia
• Gestational age > 34 weeks
• Age 18 years or above
• Ability to read and understand the information sheet and to sign and date the consent form

Exclusion Criteria:

• American Society of Anesthesiologists (ASA) classification >2
• Body Mass Index (BMI) ≥ 40 kg/m2
• Weight < 50 kg
• Height < 150 cm or ≥ 180 cm
• Complicated Pregnancy (abnormal placentation, preeclampsia or others)
• Women with opioid use disorder
• Contraindication to spinal anesthesia (clotting disorder, local infection, spinal malformation, elevated intracranial pressure)
• Contraindication to Transabdominal Plane Block (TAP) block (skin infection, abdominal wall muscle defects)
• Allergy/contraindication to any medication used in the study
• Previous median abdominal incision
• Emergency or unplanned CS