Comparison of intertransverse plane block vs erector spinae plane block for postoperative analgesia in patients undergoing thoracic spine surgery: double-blind, prospective, randomised controlled trial

Spine surgeries are generally associated with significant perioperative pain. Various nerve blocks like thoracic paravertebral block and erector spinae plane block have been suggested for managing postoperative pain in patients undergoing thoracic spine surgery. The TPVB is advocated as the first choice regional anaesthetic technique for thoracic surgeries. However, this advanced block technique involves the needle tip penetrating the superior costotransverse ligament, placing it in close proximity to the pleura and thereby carrying a risk of pneumothorax. The ESP block is less invasive with an easily identifiable landmark that makes it a potentially safe alternative to TPVB for thoracic spine surgeries.

Intertransverse process block has been recently identified as a modification of the TPVB for postoperative analgesia. It has shown better analgesia for thoracoscopic surgeries, lumbar decompression and large breast cancer operations than ESP block. ITP block is a collective name for several reported block techniques, including the midpoint transverse process to pleura block, multiple injection costotransverse block, subtransverse process interligamentary block and costotransverse foramen block. The mechanism of action is related to the potential spread of local anaesthetic in the paravertebral space through the superior costotransverse ligament.

No study has till date assessed the effect of ITP block on postoperative recovery characteristics in patients undergoing thoracic spine surgery.

We hypothesize that the ITP block will provide better postoperative pain relief compared with ESP block for thoracic spine surgeries.

Objective

Aim

To assess the differences in postoperative analgesic effects between Intertransverse process block and Erector Spinae Plane Block under ultrasound guidance in patients undergoing thoracic spine surgery.

Primary objective

The median difference in the visual analogue scale scores between the ITP block and the ESP block groups on movement 6 hours postoperatively in patients undergoing thoracic spine surgery.

Secondary objective

The average number of blocked dermatomes along the anterior axillary line midclavicular line and scapular line at 6 and 24 hours postoperatively.

The time to first use of rescue analgesic and the amount of non steroidal anti inflammatory drugs and opioid use.

Description of trial design

Trial design

Prospective double blind parallel controlled randomised single centre clinical trial.

Unit of randomisation is individual participant.

Allocation ratio is 1 ratio 1.

Trial setting This will be a single centre study to be conducted in Neurosurgery OT under the Department of Anaesthesiology Dr Ram Manohar Lohia Institute of Medical Sciences Lucknow Uttar Pradesh. Written informed consent will be taken from patients.

Study duration 12 months for data collection 2 months for data analysis and 2 months for writing the manuscript total 16 months.

Sample size assessment

This study is a randomised controlled trial with the experimental group receiving ITP block and the control group receiving ESP block. The primary outcome is the median difference in the visual analogue scale scores between the ITP block and the ESP block groups on movement 6 hours postoperatively in patients undergoing thoracic spine surgery.

Assuming that the intertransverse block compared to the ESP block will result in 10 mm lower VAS on movement at 6 hours after surgery at 90 percent power and at 5 percent significance level and at the 10 mm standard deviation of VAS 22 patients per group will be required. Taking attrition rate to be 10 percent a total of 46 patients will be required for the study. To facilitate block randomisation the study ultimately plans to recruit 48 patients.

Randomisation and blinding

A total of 48 cases will be randomised using statistical product and service solution SPSS version 26 employing a block randomisation method with a block length of 4. The 48 subjects will be divided into 12 blocks and the two trial groups will be represented by A and B. In advance each block will have different arrangements of A and B corresponding to a number. Subsequently a set of random numbers will be generated in SPSS and the arrangement of the blocks will be determined according to the order of these random numbers. Subjects will be assigned their corresponding blocks and group conditions based on the order of enrolment with their final group assignment represented solely by A or B. The final group distribution will be 24 cases in the ITP block group and 24 cases in the ESP block group.

All random number generation and subject enrolment will be managed by a nurse who will not participate in the subsequent trial processes. This nurse will be unaware of the specific groups represented by A and B. After generating the corresponding group assignments the nurse will place the group information A or B into an opaque sealed envelope. All sealed envelopes will be stored in a locked cabinet and opened by the attending anaesthesiologist on the day of surgery before the block procedure. The attending anaesthesiologist is informed and understands what A or B corresponds to in actual groups and will then perform the corresponding block procedure. This anaesthesiologist will not be involved in the study group allocation or subsequent data analysis. All other personnel involved in the study such as surgeons outcome assessors and data analysts will remain blinded to the subjects allocation.

Sampling technique

Patients planned to undergo thoracic spine surgery will be screened for eligibility during the pre anaesthetic checkup visit which will be done 2 days before the scheduled surgery. The pre anaesthetic checkup will be conducted as per institutional practice and written informed consent will be taken from eligible patients.

The envelopes will be opened on the day of surgery when the patient is shifted to the operating room table. The two study groups will be

Group one ITP block group

Group two ESP block group

Masking

Both the anaesthesiologist providing anaesthesia management and the researcher who will follow up after the operation will be blinded.

Intervention description

Each enrolled patient will undergo standard monitoring and bispectral index monitoring. Anaesthesia induction involves pre oxygenation followed by intravenous administration of propofol 2 mg per kg fentanyl 2 microgram per kg and vecuronium 0.1 mg per kg. All patients will undergo intubation with a wire reinforced endotracheal tube. After the patient is placed in prone position the chief anaesthesiologist will open the envelope and perform the appropriate nerve block according to group assignment.

ITPB group

Twenty millilitres of 0.125 percent bupivacaine will be injected after confirming correct needle placement under ultrasound guidance.

ESPB group

Twenty millilitres of 0.125 percent bupivacaine will be injected deep to the erector spinae muscle under ultrasound guidance after confirmation of correct needle placement.

Anaesthesia maintenance will be achieved with fentanyl 0.5 to 1 microgram per kg per hour vecuronium 0.04 mg per kg per hour and sevoflurane 1.8 percent. Unless contraindicated all patients will receive intravenous ondansetron 4 mg dexamethasone 5 mg and paracetamol 1 g approximately 15 minutes before cessation of anaesthesia. BIS will be maintained between 40 and 60 and blood pressure within 20 percent of baseline values.

Data collection

Outcome measures will be assessed at 0 2 6 12 24 and 48 hours postoperatively. Data will be stored in Microsoft Excel and analysed after trial completion.

Primary outcome

VAS on movement at 6 hours postoperatively.

Secondary outcomes

Number of blocked dermatomes at 6 and 24 hours.

Time to first rescue analgesic.

Total NSAID and opioid consumption.

Rescue analgesia

If VAS score is 40 mm or more additional NSAIDs will be administered. If pain persists opioids such as fentanyl or tramadol will be given.

Inclusion criteria

Patients aged 20 to 70 years with American Society of Anesthesiologists physical status 1 to 3 scheduled for thoracic spine surgery.

Exclusion criteria

Age less than 20 or more than 70 years allergy to local anaesthetics BMI more than 30 kg per meter square coagulopathy daily opioid use mental or neurological disorders allergy to analgesics communication disorders previous thoracic spine surgery.

All patients will be operated on by the same neurosurgeon.