Erector Spinae Plane Block vs Erector Spinae Plane Block With Serratus Anterior Plane Block in Thoracic Surgery

Once consented, the patient will be randomized by computer generated random number to one of the two treatment groups.

Blinding Plan: At the acute pain management office, one member of the research team will be responsible for providing the anesthesiologist in charge of performing the block with a sealed envelope. Each envelope will be labeled with a number corresponding to a matching number labeled on each patient binder. This envelope will contain the randomized block to be administered - ESP with SAP or ESP with SAP normal saline. Once the anesthesiologist knows which block combination to administer, he/she will reseal the envelope and return it to the research team member. This process allows only the anesthesiologist performing the block to have knowledge of the block being administered, keeping both the patients and research team members blinded. The envelopes and binders will be kept by the principle investigator in a safe place and only reopened to be analyzed at the end of the study.

All study procedures will take place in the preoperative patient room in DAS prior to surgery, as is standard practice in this institution. The consent process will take place prior to performing any research procedures.

If randomized to the ESP block with SAP normal saline, an anesthesiologist on the Acute Interventional Perioperative Pain Service (AIPPS) will administer the block with this approach: Prior to initiating the block procedure and receiving any sedative medications, patient will be asked to give 3 maximum efforts using the incentive spirometer by first taking a maximum breath in and blowing out forcefully and completely into the incentive spirometer device. Average of these three efforts will be recorded as the patient's incentive spirometer effort baseline. Patient will be positioned in seated position with side to be blocked marked. T5 spinous process will be identified by palpating starting with C7 and continuing caudad. C7 is the most prominent spinous process anatomically. T5 spinous process will be marked with a marking pen. Block area will be cleaned using 2% Chlorhexidine solution. Entire block procedure is performed under strict aseptic technique. Ultrasound probe covered in sterile probe cover will be placed at the T5 spinous process in a cephalad to caudad orientation and moved lateral until the T5 transverse process is identified. 1-2ml of 1% lidocaine will be administered just above the ultrasound probe for local skin infiltration. An 18 gauge Touhy needle will then be inserted in plane in a cephalad to caudad direction under ultrasound visualization until the tip of the needle touches the T5 transverse process. The T5 transverse process is the anatomical target for this block. 20ml of 0.375% bupivacaine will then be injected using slow fractionated injection, aspirating every 5ml to ensure needle tip is not intravascular. Local anesthetic spread in the appropriate plane will be confirmed with ultrasound. Once injection is complete, a 20 gauge non-stimulating catheter will be inserted through the Touhy needle. Catheter tip placement will be confirmed with ultrasound.

SAP Approach with normal saline - Patient will be placed in a lateral position with the side to be blocked facing up. After disinfecting the block area with 2% Chlorhexidine solution and under strict aseptic technique the ultrasound probe will be placed over the midclavicular region of the thorax in a sagittal plane. Ribs will be counted inferiorly and laterally starting with the 2nd rib, until 5th rib is identified in midaxillary line. At this level the 3 appropriate muscle layers overlying the 5th rib are easily identifiable. Latissimus dorsi M. is superficial and posterior, teres major m. is superior, and serratus m. is deep and inferior. Skin at the block site will be infiltrated with 1-2ml of 1% lidocaine, and a 20 gauge Touhy needle will be introduced in plane under ultrasound visualization in a superoanterior to posteroinferior direction just above the Serratus m. At this point 20ml Normal Saline will be injected using slow fractionated injection, aspirating every 5ml to ensure needle tip is not intravascular. Injectate spread in the appropriate plane will be confirmed with ultrasound. Total procedure time for both injections is expected to take 30 minutes from start to finish.

If randomized to the ESP+SAP block, an anesthesiologist on the Acute Interventional Perioperative Pain Service (AIPPS) will administer the block with this approach: Incentive spirometer effort as described above. ESP performed as described above. SAP block: Patient will be placed in a lateral position with the side to be blocked facing up. After disinfecting the block area with 2% Chlorhexidine solution and under strict aseptic technique the ultrasound probe will be placed over the midclavicular region of the thorax in a sagittal plane. Ribs will be counted inferiorly and laterally starting with the 2nd rib, until 5th rib is identified in midaxillary line. At this level the 3 appropriate muscle layers overlying the 5th rib are easily identifiable. Latissimus dorsi M. is superficial and posterior, teres major m. is superior, and serratus m. is deep and inferior. Skin at the block site will be infiltrated with 1-2ml of 1% lidocaine, and a 20 gauge Touhy needle will be introduced in plane under ultrasound visualization in a superio-anterior to posterio-inferior direction just above the Serratus m. At this point 20ml 0.375% Bupivacaine will be injected using slow fractionated injection, aspirating every 5ml to ensure needle tip is not intravascular. Local anesthetic spread in the appropriate plane will be confirmed with ultrasound. Total procedure time for both injections is expected to take 30 minutes from start to finish.

For ESP block and SAP with normal saline, the local anesthetic used will be 20ml 0.375% bupivacaine for ESP block. ESP block group will also receive SAP block with 20ml Normal Saline. For ESP + SAP block group, the local anesthetic used will be 20ml 0.375% Bupivacaine for ESP block. Local anesthetic used for SAP block will be 20ml 0.375% Bupivacaine.

Anesthetic Management: Both treatment groups will receive the standard anesthetic technique and multimodal analgesic technique including preoperative Gabapentin 300mg PO and Acetaminophen 1000mg PO, intraoperative IV propofol infusion-based general anesthetic combined with sub-anesthetic dose IV ketamine infusion, IV dexmedetomidine infusion, IV acetaminophen, and strict avoidance of intraoperative opioids. Post-operative pain management will also follow standard protocol, using IV hydromorphone (0.2 mg) and PO oxycodone (5-10 mg) on request by patient for moderate to severe pain (NRS >5), IV ketamine infusion 5mg/hr for 48 hours, scheduled acetaminophen 1000mg IV for 24hours.

For study participants, the investigator placing the block will record in the narrative that "this patient is a study participant and received Paravertebral block with ESP approach and SAP block". By documenting the blocks in this way, the research team member collecting the data and the nurses documenting the pain scores will be blinded to whether patient received ESP block with 0.375% Bupivacaine + SAP block with normal saline, or ESP block with 0.375% Bupivacaine + SAP block with 0.375% Bupivacaine.

After surgery, the patient will be followed by the blinded research team for incidence of adverse events, as well as the collection of the primary and secondary outcome measures. These include total narcotic medication consumption, reported as total Morphine equivalent in 24 hours after surgery as primary outcome measures. Secondary outcome measures include pain scores at 6, 12, and 24 hours after surgery, total dose of local anesthetic administered at 12 hours and 24 hours after surgery - reported in (mg), percent change from baseline using incentive spirometer at 6 and 24 hours after block performance, total hospital length of stay - from admission to discharge, and incidence of adverse effects - nausea and vomiting requiring treatment, hypotension, and bradycardia or tachycardia. Pain assessment will be done by nurses in the PACU and on the floor using Numeric Pain Rating Scale, with 0 meaning no pain and 10 meaning worst possible pain. Narcotic medication consumption, pain scores, local anesthetic medication consumption, incentive spirometer values, and adverse effects will be recorded on worksheets included in patient research folders, with each study participant having their own research folder identified only by randomly assigned patient study number. Both nursing staff and research staff (study coordinators) collecting data will remain blinded to whether patient received ESP block with 0.375% Bupivacaine + SAP block with normal saline, or ESP block with 0.375% Bupivacaine + AP block with 0.375% Bupivacaine. Only nurses and study coordinators, not acute pain physicians, will record this data.

Patients in both study groups will receive a nerve block, either ESP alone or ESP \& SAP. Both ESP and SAP nerve blocks have an identical side effect profile, and adverse events resulting from administration of either of these blocks would be treated in an identical manner. In light of this, we do not anticipate implementing emergency unblinding of patients. However, in the case of adverse event/s occurring, emergency unblinding procedures will be the following. The principle investigator or co-investigators will be contacted and provided the patient unique study ID number, which will be used to access the master list, which includes patient study ID and the type of block received. The patient will be treated for adverse events pertaining to receiving a nerve block and/or other medications mentioned as part of the research protocol. The patient will then be removed from the study, and no further data collection will occur.