The investigators are studying a type of technology that is already used called surface electromyography (EMG). This measures and records electrical activity using sensor stickers in a non-invasive way. The purpose of this study is to use a prototype/test surface EMG machine to measure how well regional anesthesia (nerve block) is working. This device is non-invasive and being used for research use as an unapproved medical device. The information may teach us how to give nerve blocks more safely and effectively.

Study participation: Subjects having surgery will have the surface EMG sensor stickers placed on their arms or legs before surgery. These will stay on during surgery and for part of recovery.

Study visits: The study will consist of 1 visit that starts in the pre-operative area, through the surgery, and for part of recovery time after surgery.

This study aims to investigate how non-invasive, non-significant risk EMG monitoring can be used intraoperatively to objectively characterize peripheral nerve blockade (upper or lower extremity) in pediatric, adolescent, and young adult patients undergoing surgery. We also aim to quantify the impact of sevoflurane (general anesthesia) on basal muscle tone based on EMG changes.

Hypothesis: EMG monitoring can be utilized to objectively measure neuraxial blockade, including onset, resolution, density, and dermatomal level.

Inclusion Criteria:

• Patients ≤ 21 years of age
• Patient presenting for a surgical procedure in which GA and a peripheral regional block will be used

Exclusion Criteria:

• Patients > 21 years of age
• Parent / patient refusal
• Premature infants; neuromuscular disease; systemic infection; hemodynamic instability; coagulation disorder; degenerative CNS abnormality that precludes regional anesthesia; and local anesthetic allergy; pregnant women.