The purpose of this study is to investigate the use of the erector spinae (ESP) block in reducing the morphine milligram equivalent (MME) consumption post percutaneous nephrolithotomy. Objectives:

1. - Determine if there is a significant effect on post percutaneous nephrolithotomy MME consumption with the usage of an ESP block vs. saline control.
2. - Determine if there is a significant effect on reported pain levels with the use of an ESP block vs. saline control in post percutaneous nephrolithotomies.

This is a double-blind, randomized control trial involving 128 subjects undergoing an elective percutaneous nephrolithotomy. All subjects who meet all inclusion and exclusion criteria will be equally randomized on the day of the procedure by operating room pharmacy into either the ESP block or the control block. An interim analysis at the sample size required for a large effect size (n = 52, with n = 26 in each treatment arm) will be performed. In order to blind the anesthesiologist performing the block, the control arm will be equally randomized by the pharmacist at the time of distributing the pre-filled syringes for the ESP block procedure. Randomization will occur with the use of a random number generator with 1:1 ESP:Control allocation ratio.

Subjects will be followed at Pre-op and the 24-h, 48-h, 7 days and 30 days post operatively to assess the quality of recovery utilizing the Quality of Recovery-15 (QoR-15) questionnaire, VAS pain scale, and opioid consumption. Intraoperative MMEs, PACU MMEs, total MME's, FLACC scores at 30 minutes/1 hour VAS scores at 1 hour/2 hours/6 hours/24 hours, PACU LOS, hospital LOS, time to first flatus will be documented in patient chart, reviewed by study personnel and uploaded into a password protected database on the UTMCK server.

All aspects of the study and consent forms will be IRB approved prior to implementation. Potential candidates will be selected for consent based on chart review and surgery scheduling.

• The Surgeon will initially approach potential subjects and provide them with a copy of the consent form to take home and read prior to pre-anesthesia testing.
• At the subject's pre-anesthesia testing appointment, the research staff will explain the risks and benefits of the study, answer any questions, and obtain consent to participate.
• The Biostatistician will randomize the subjects with a random number generator. Once randomized, a blinded package labeled "ESP" or "Control" will be delivered to the regional anesthesia team containing the following:

ESP

Active group:

1. One 30mL syringe containing 29mL of 0.5% ropivacaine and 4mg of dexamethasone- labeled "ESP Block"
2. One 30mL syringe containing 30mL of preservative free normal saline- labeled "wound infiltration" Sham group

1. One 30mL syringe containing 30mL of 0.5% ropivacaine- labeled "wound infiltration" 2. One 30mL syringe containing 30mL of preservative free normal saline- labeled "ESP Block"

• The pharmacist will create a table pre-populated with the randomization assignments with space to fill out patient information and medication information on the day of surgery. This chart will be in paper form and kept in a research binder in the OR pharmacy. When a patient is consented for the RCT, the treatment group will be chosen based on the numbers assigned a priori. Each qualifying patient will be documented on the subsequent row in the table, maintaining the original order of randomization as dictated by the statistician. Based on the assignment, the pharmacy technician will be instructed as to which products to make in the sterile hood. The pharmacist will verify that the products were made appropriately and will label the syringes according to assignment.
• Operating room pharmacy will hand the anesthesiologist a blinded package with one prefilled syringe for the regional block that will either contain 30mL of 0.5% ropivacaine with 4mg of dexamethasone or preservative free normal saline.
• The regional anesthesiologist will perform the ESP block using standard protocols and procedures.
• Age, BMI, duration of operation, EBL, intraoperative MMEs, PACU MMEs, 48 hours post-operative MMEs, total MME's, FLACC scores at 30 minutes/1 hour VAS scores at 1 hour/2 hours/6 hours/24 hours, PACU LOS, hospital LOS, time to first flatus will be documented in patient chart and reviewed by study personnel.
• QoR-15, MME consumption, and VAS will be assessed at Pre-op, 24-h, 48-h, 7 and 30 days by study staff. Data will be uploaded into a database kept on secured password protected computers on the UTMCK server.
• All patient identifiers will be removed prior to data analysis.

Inclusion Criteria:

• Adults, male and female greater than or equal to 18 years of age and undergoing non-emergent percutaneous nephrolithotomy Monday through Friday between the hours of 6:00AM and 4:00PM.
• Female participants of childbearing potential will be required to provide a negative pregnancy test.
• Ability to understand and teach back consent for the procedure.
• Willingness to sign consent for procedure.
• English speaking.

Exclusion Criteria:

• Emergent surgery status.
• Local infection
• Allergy to local anesthetics.
• Recreational drug use.
• Inability to provide informed consent.
• Pregnancy or breastfeeding.
• History of Guillain-Barre' Syndrome.
• Underlying medical conditions that would post a significant risk to the patient.
• Opioid use >90 days in the year leading up to surgery.