A Prospective Randomised Controlled trial comparing efficacy of Free hand Landmark guided versus Ultrasound guided Bilateral Erector Spinae Plane Block in lumbar 2-3 level spine surgeries

BACKGROUND:

Spine surgeries are known to cause severe postoperative pain , which may last for at least 3 days.1 Inadequate analgesia delays recovery and discharge of patients, and increases the man power and cost burden on the hospital. It is a common knowledge that moderate to severe postoperative pain influences more than half of the patients following spine surgery. The insufficient control of postoperative pain would delay early mobilization and rehabilitation, worsen the patients outcome, and promote the development of persistent postoperative pain and be associated with prolonged use of opioids often also after discharge.

In the recent years, the Erector spinae-plane block(ESPB) has been adopted in various centres as a part of the Multimodal analgesic regimen. This technique has been shown to anaesthetize both ventral and dorsal rami of spinal nerves, thus useful in the treatment of postoperative and neuropathic pain2,3,4 . There have been various meta analysis conducted which have concluded that for the management of postoperative pain in spine surgery, preoperative ESPB is a good choice, as it was found to reduce the post operative pain scores and the cumulative opioid consumption 24 hour after surgery5.

However all these studies have conducted ESPB with the help of Ultrasound guidance. But in an Indian setup it is important to consider various factors such as economic resources, availability of the ultrasound machine, availability of experienced anaesthesiologists, availability of ancillary pain services to name a few.

PURPOSE- For this reason, we would like to conduct a Randomised controlled trial , wherein the efficacy of Erector Spinae Plane Block (ESPB) given by an experienced spine surgeon using their anatomical landmark technique will be compared with Ultrasound guided (USG) ESPB given by an experienced Anaesthesiologist,  as a part of our Multimodal Analgesic regimen in open 2-3 Level lumbar spine surgeries .

 Type of Study : Randomised Controlled Trail

 Aims & objectives: To compare the efficacy of Ultrasound guided bilateral ESPB and Landmark assisted ESPB as a part of Multi Modal Analgesic regimen in 2-3 level open lumbar spine surgeries Justification for study: To help determine whether Landmark assisted ESPB can be as effective as Ultrasound guided ESPB.

Objectives of study:

1.   To compare the effect of ESPB using two different techniques on post operative VAS scores .

2.   To calculate and compare the total dose of opioids used in the intraoperative period and post op recovery.

3.   To evaluate the time to mobilization, time to discharge, overall patient satisfaction and Quality of Recovery.

 Departments involved : Spine Anaesthesiology and Spine Surgery

Study period : After IEC approval – for a duration of 1 year

 Sample size :  Assuming the difference between the average VAS scores for the two groups as 0.5 with a standard deviation of 0.9, the number of patients required for each group is calculated as 58, with 90% power and 5% level of significance. Considering a dropout rate of 10%, the final sample size per group is 65. So total 130 patients will be included.  Inclusion and exclusion crteria :

a) Inclusion criteria :

1.   Patients undergoing two to three level Lumbar spine surgeries

2.   Between the age group 18-65 years

3.   ASA (American Society of Anaesthesiologists ) status of 1, 2.

Exclusion Criteria:

1.   Clinically serious cardiovascular disease

2.   History of allergy to Local Anaesthetics

3.   BMI >30 kg/m2.

4.   Infection at site of procedure.

5.   Inability to use VAS (Visual Analogue Scale).

6.   Those with Bleeding disorders

b) Biological materials required (type - blood, tissue etc and quantity) : NIL

c) Statistical methods :

Statistical analysis will be performed on SPSS software Version 20.0 (IBM Corp., Armonk, New York, USA). The distribution of variables will be evaluated for normality using the Kolmogorov-Smirnov and histogram tests. Descriptive data will be expressed as mean standard deviation. Categorical variables will be analyzed using the chi square test. Normally, distributed data comprising continuous variables will be analyzed using the Student t test. Otherwise, the Mann Whitney U test will be used. P < 0.05 will be considered statistically significant.

 Detailed description of procedure:

After obtaining approval by the Institutional Ethics Committee and registering this trial with the Clinical Trials Registry - India (CTRI), the patients will be enrolled to this study. During Pre anaesthestic evaluation written informed consent will be obtained from every patient and we will  assess their Preoperative Visual Analogue Scale(VAS) scores. They will also be taught how to use the Patient Controlled Analgesia Pumps(PCAP) .

Randomisation and blinding:

Random numbers will be generated by a statistician using the SAS statistical package version 9.3 (SAS Institute, Cary, NC, USA) in a 1:1 ratio with a block size of 4. The generated random numbers will be sealed in sequentially numbered opaque envelopes and kept by a study coordinator. On the day of surgery, the envelopes will be opened in the operating room after general anesthesia according to the recruitment sequence. Patients will be randomized to receive either ESP block which will be performed by an experienced anesthesiologist and spine surgeon before surgery. Anesthesiologists and surgeons will be aware of the study intervention. However, all patients,investigators in charge of postoperative following-ups and other healthcare team members will be masked to group assignments.

On the day of the surgery, all of the patients will receive orally,500mg(<50kg) or 1g(>50KG) Tab Paracetamol and 2.5mg/kg of Tab Pregabalin 2 hours prior to surgery. They will be shifted into the operating room where standard ASA monitors will be applied (electrocardiography, non invasive blood pressure monitor, and pulse oximetry). A balanced intravenous crystalloid solution (lactated Ringer’s solution) will be  administered (2 ml/kg/hr). Before induction, IV Ondansetron 4mg, IV Pantoprazole 40 mg will given. Anaesthetic induction will be performed while providing 100% oxygen (10 L/min). IV Lidocaine bolus of 1.5 mg/kg will be administered . All patients will receive pre emptive analgesia with fentanyl (2mcg/kg), followed by hypnotic dose of IV Propofol (1.5–2 mg/kg) and Rocuronium (0.6-1.2mg/kg) for intubation. After endotracheal intubation,  patient will be positioned prone with optimal padding of pressure points. Patients will be maintained with TIVA propofol .Entropy will be used to maintain depth of anaesthesia between 40-60.

Once patient is in the prone position the ESPB will be performed.

Landmark Guided Bilateral ESPB(GROUP A)

Under aseptic precautions , an experienced spine surgeon will administer ESPB at the level of L1 using their anatomical knowledge and judgement .A total volume of 40 ml of 0.3% Ropivacaine with 20 ml on each side, will be administered for the lumbar ESPB. The needle of choice to administer the block will be purely the surgeons decision.

 Ultrasound-Guided Bi-Lateral ESPB(GROUP B)

Under aseptic precautions a low-frequency curvilinear probe will be placed 4-5 lateral to the L1 spinous process longitudinally. After visualizing the trapezius, rhomboid major, erector spinae muscles, and transverse processes, an in-plane approach will be adopted. An 9 cm, 23-gauge spinal needle (attached to a 50cm extension tubing , connected to a syringe containing the drug) will be inserted in the cephalad-to-caudad direction ,deep to the erector spinae muscle. After negative aspiration is confirmed a total volume of 40 ml of 0.3% Ropivacaine with 20 ml on each side, will be administered for the lumbar ESPB.

 Both group patients will receive the following TIVA regimen-IV propofol (50–150 μg/kg/hr), titrated to maintain entropy 40-60 and IV Fentanyl (0.5mcg/kg/hr). Infusions will be stopped once skin suturing commences.

IV dexamethasone (8 mg) and IV Paracetamol 1g will be given intra operatively

Inhaled halogenated agents (sevoflurane) will be permitted, up to 0.5 minimum alveolar concentration (MAC), as needed and will also be tapered and stopped before extubation. Mechanical ventilation will be achieved with 1:1 mixture of oxygen:air (FiO2 50%) with a tidal volume of 6–8 ml/kg and respiratory rate of 12- 14 titrated to an end-tidal carbon dioxide between 30–35 mm Hg. Convective warming devices will be used to maintain normothermia . Need based fluid management will be carried out using dynamic indicators such as systolic pressure variability(SPV).  Invasive Hemodynamic monitoring will be done as per patient requirements. Entropy and Neuromuscular monitoring with Train of Four (TOF) and Post Tetanic Count( PTC) will be done throughout the surgery. In all patients, more than 20% elevation in mean arterial pressure and/or heart rate 15% above baseline (or higher), Surgical Pleth Index (SPI) more than 50, will be treated with additional bolus doses of Fentanyl(0.5 mcg/kg) and/or propofol (up to a 50-mg) boluses, and/ or by increasing the MAC of inhaled anaesthetics. These will be recorded. Post surgery, once patient is made supine, residual neuromuscular blockade will be reversed with IV Sugammadex 2mg/kg as per TOF count. Time to awakening after switching off propofol will be recorded in both the groups. Intraoperative incidence of hypotension and bradycardia will be recorded.

All procedures will be performed by a single surgeon and his team . All procedures will be provided anaesthesia by the same two Spine Anaesthesiologists.

In the PACU (Postoperative Anaesthesia Care Unit)all patients will receive IV Ketorolac 30 mg in 100 ml NS and IV Paracetamol 15mg/kg 6th hourly. Patient Controlled Analgesic devices will be started for both groups. They will be set to a concentration of 20mcg/mL, 20mcg bolus dose on demand with a lockout interval of 15 minutes, without basal infusion. This will be maintained for 16 hours after starting the infusion.  In addition, as per patient demand IV Tramadol 0.5mg/kg in 100 ml NS will be given for Rescue analgesia and time to request will be recorded. In the PACU we will assess the Visual Analogue scores( VAS) for pain for all patients  at following time intervals- 30 minutes,1 hour,  2nd hr,4th hr,8th hr, 12th  hr and 16th hr post shifting to the PACU.

Their Hemodynamics will also be continuously monitored.

Incidence of PONV will be recorded in both groups.

Post operatively , NPO will be maintained  for 6 hours, following which patient will be restarted gradually on oral feeds with sips of water/juice.

Time to first mobilisation soon after surgery under guidance of a physical therapist will be recorded and patients will be discharged home early, as soon as the following conditions are true: 1) pain optimally controlled by oral analgesics, 2) no complication (e.g., incidental durotomy) that would require prolonged hospital stay, and 3) ability to climb stairs. Post discharge, patients will have a dedicated support line provided by the Spine care team; Surgical consultation will be routinely undertaken at 7th day Post operatively, during which Satisfaction Scores and Quality of Recovery will be recorded. These scores will also be recorded 1 month post surgery.