A comparative study to evaluate the postoperative analgesic efficacy of erector spinae plane block versus thoracic paravertebral block in patients following modified radical mastectomy

INTRODUCTION

 Breast cancer is the most common female cancer worldwide and in Indian females the age adjusted rate is as high as 25.8 per 100,000 women.1 Surgeries of the breast are among the most common operative procedures.2-6Modified radical mastectomy (MRM) is a procedure in which the entire breast is removed, including the skin, areola and nipple, and most axillary lymph nodes; the pectoralis major is spared 7

Patients who undergo breast surgery experience significant acute pain which may increase the perioperative morbidity and delay in discharge from hospital.8,9Various regional anesthesia techniques have been described for the management of postoperative pain following breast surgeries like thoracic paravertebral block, intercostals block, epidural administration and erector spinae plane block.10

In breast surgery the paravertebral block is the “gold standardâ€.10This block is currently considered a fairly safe and effective therapy11, however, is associated with some minor and major complications like inadvertent vascular puncture (6.8%); hypotension (4.0%); haematoma (2.4%); pain at site of skin puncture (1.3%); signs of epidural or intrathecal spread (1.0%); pleural puncture (0.8%); pneumothorax (0.5%). 12

Erector spinae plane block (ESP) is a technique recently described by Forero et al, in September 2016.[13]The easy, fast and safe execution of erector spinae plane blockwith no reported complications till datemakes it a promising technique in the context of surgical pain during MRM13,14.It was found that by performing this block before anesthesia induction, an opioid sparing effect is achieved and an effective post-operative analgesia is recorded from the patients15.

JUSTIFICATION

There is limited literature on comparison of efficacy of postoperative analgesia between   erector spinae plane block and thoracic paravertebral block in women undergoing modified radical mastectomy. No studies have been done on so far on Indian population. Hence, the present study is designed to compare efficacy of postoperative analgesia either with erector spinae plane block or thoracic paravertebral block following MRM.

RESEARCH QUESTION

Which block produces better post-operative analgesia, erector spinae plane block or thoracic paravertebral block in patient undergoing modified radical mastectomy?

   HYPOTHESIS

Erector spinae plane block provides equivalent post-operative analgesia as compared to thoracic paravertebral block in patients undergoing modified radical mastectomy.

  AIMS AND OBJECTIVES

 PRIMARY OBJECTIVE:

To compare post-operative analgesia in patients who received erector spinae plane block and thoracic paravertebral block at 24 hrs.

 SECONDARY OBJECTIVE:

 1.     To assess the location of postoperative pain.

2.     To assess the total amount of analgesic consumed within 24 hour post-operatively.

3.     To assess complications related to catheter, redness or hematoma at the site of injection.

     MATERIALS AND METHODS

 TYPE OF STUDY:

A Comparative Study

STUDY PERIOD:

july 2019 to june 2020

 PLACE OF STUDY:

Department of Anesthesiology, Lady Hardinge Medical, College, and Associated Hospitals, New Delhi.

 STUDY POPULATION:

Adult female patient aged 18-70 years posted for elective Modified Radical Mastectomy under general anaesthesia at LHMC & Associated Hospital, New Delhi.

 SAMPLE SIZE:

As per available records, approximately 80 cases of breast cancer are being operated each year.  Therefore, a minimum sample size of 60 (30 in each group) is hereby proposed for the study. All efforts will be made to enroll all cases after considering the inclusion and exclusion criteria.

 INCLUSION CRITERIA:

Adult female patient aged 18-70 years posted for elective modified radical mastectomy under general anaesthesia.

                                  EXCLUSION CRITERIA:

1.     Patients with obvious anatomical anomalies [lordosis, scoliosis and kyphosis]

2.     Infection at the local site of injection

3.     Deranged coagulation profile

  METHODOLOGY

 Careful pre-anaesthetic clinical examination will be performed and written informed consent will be taken from the patient. All patients will be explained NRS (numerical rating scale) preoperatively (0=No pain, 10=Severe pain). The patients will be allocated to either Group E (erector spinae plane block) or Group P (thoracic paravertebral block) on the basis of computer generated random table. Blinding will be done by selection of sealed envelope by the patient.

Routine standard monitoring will be applied to the patient and an 18-gauge intravenous line will be taken on the contralateral arm. The blocks in both the groups will be conducted before induction of general anaesthesia. The patient will be placed in sitting position.

In group E,under all aseptic precautions, a high/low frequency linear array ultrasound transducer will be placed in a longitudinal direction 2.5cm lateral to the T5 spinous process side. And just above the hyperechoic transverse process shadow, three muscles will be identified as follows: trapezius, rhomboid major, and erector spinae. An 18 gauge Tuohy needle will be inserted towards the transverse process in a cephalad-to-caudad direction and the tip is advanced so as to lie between the fascia of erector spinae muscles and the transverse process. The correct placement of the needle tip will be identified by visible linear spread of the fluid below the erector spinae muscles upon injection of Normal Saline solution. This will be followed by an injection of 20ml of 0.25% of Bupivacaine and catheter is introduced 3cm inside the space.

In group P, under strict aseptic precautions, a sagittal scan of the paravertebral region at T5 level using high/low frequency ultrasound-guided technique will be performed to delineate the underlying paravertebral anatomy (transverse process, costo transverse ligament and pleura) with the transducer tilted slightly obliquely. An 18-gauge Tuohy needle will be inserted in the plane of the ultrasound beam and advanced under ultrasound guidance to the TPVS (thoracic paravertebral space). The correct position of the needle will be confirmed by injecting saline in the paravertebral space. This will be followed by injection of 20 ml of 0.25% Bupivacaine and a catheter is introduced 3cm into the space.

Following the placement of block, General anaesthesia will be induced with Intravenous(iv) propofol at 1-2 mg/kg and fentanyl at 2 mcg/kg and maintained on nitrous oxide 60% with oxygen 40% (1:2) and sevoflurane at a concentration of 1-2%. Intra operative vital monitoring will be done and any increase in heart rate more than 20% will be managed by treatment with injection of 0.5mcg fentanyl.

Subsequent top up of 14ml 0.125% Bupivacaine will be given in both the groups at every 90 minutes till the end of surgery. Injection Paracetamol at a dose of 15mg/kg will be given 15 minutes before the end of surgery intravenously and will be repeated 6 hourly till 24hrs postoperative period. At the end of surgery, a continuous infusion pump of 0.25% Bupivacaine at a rate of 8ml/hr will be started and continued for 24hrs.

 The following parameters will be assessed:

 1.       During immediate post-operative period, patients will be asked whether they have complained of pain or not.

2.       If yes, the site of pain at which quadrant will be asked, and the intensity and severity of pain will be quantified by NRS (numerical rating scale) at 0, 4, 8, 12 and 24 hrs.

3.        NRS score will be preoperatively explained to the patient so that post-operative assessment will be effective.

4.       Injection Tramadol 1mg/kg will be given intravenously whenever the NRS score > 4, and the total number of doses within 24hrs will be calculated.

5.       At the end of 48hrs, catheter will be removed and local site will be inspected for any signs complications related to catheter, redness or haematoma.

                      OUTCOME MEASURES

PRIMARY OUTCOME      : Mean  NRS score at  24 hrs post operatively for pain assessment in both the groups, group E (erector spinae plane block) and group P ( thoracic paravertebral block).

 SECONDARY OUTCOME:

1.     Site of pain as reported by the patients according to quadrants of the breast postoperatively.

2.     Total amount of analgesic consumed within 24hour postoperatively by the patients.

3.      Post-operative complications (catheter related complications, redness or hematoma at the site of injection) at 24hrs.

           STATISTICAL ANALYSIS

 Â·       Statistical package for social sciences (SPSS) version 16.0 will be used for analysis.

 Â·       The quantitative variables expressed as frequencies/percentages and compared using Chi-square test or mann whitney test.

 Â·       The quantitative variables will be expressed as Mean±SD and evaluated using ANOVA and/or unpaired t-test.

 Â·       A p-value <0.05 will be assumed statistically significant.

                                   ETHICAL ISSUES

·       The studies will be done after approval from the Institutional Ethical Committee.

·       Written informed consent will be taken from all participants/caregivers of the study.

·       Both the techniques are safe and effective.

·       Priority will be given to patient management and appropriate treatment and referrals shall be made.

·       All informations shall be kept confidential.

·       Subjects shall have the right to withdraw any time which will have no bearing on the treatment.