Electrical Stimulation for Erector Spinae Plane Catheter Insertion

The erector spinae plane (ESP) block has been studied for analgesia in shoulder surgery as a phrenic nerve-sparing alternative. However, successful ESP catheter placement appears multifactorial, with failure mechanisms including lamination, plane collapse, or catheter overcoiling. Electrical stimulation (ES) is a common technique used in regional anesthesia to detect possible intraneural placement. ES of the erector spinae muscle complex may objectively guide proper interfascial catheter placement and improve local anesthetic spread. The primary goal of this study is to establish if ESP catheter placement with the addition of ES to ultrasound (US) guidance facilitates accurate catheter placement. This study will further characterize postoperative analgesia and the incidence of brachial plexus stimulation for patients who receive ES-assisted ESP catheter placement.

Electrical stimulation will be used to confirm needle and catheter placement within the interfascial plane between the erector spinae muscle and thoracic transverse process.

Ultrasound guidance will be used to visualize needle and catheter placement within the interfascial plane between the erector spinae muscle and thoracic transverse process.

Successful erector spinae plane needle and catheter insertion means that the needle/catheter is deep to the myofascia of the erector spinae muscle complex and superficial to the intertransverse ligaments / transverse process. Thus, any stimulation of the catheter after its placement in the erector spinae muscle complex seen under ultrasound or perceived by the patient will be documented as catheter placement failure. No visualized or perceived stimulation of the erector spinae muscle complex will be documented as catheter placement success.

Time for catheter placement will begin when the US probe first touches the patient and end when the inner stimulating catheter hub meets the skin. If no visual identification of the target erector spinae plane (US) and no evoked motor respoinse (US+ES) is achieved within 10 minutes, the placement will be considered a failure, and the primary end point will be recorded as 10 minutes. If a catheter cannot be placed per protocol within 20 minutes, the placement will be considered a failure, and the primary endpoint will be recorded as 20 minutes. In such cases, the subject will have a catheter placement attempt using the alternative method. Subjects who do not have a catheter placed as per their randomized group protocol will be removed from further study.

As soon as the patient is able to respond verbally in the PACU, the subject will be asked to rate their pain on an 11-point numeric rating scale (NRS, 0 being no pain and 10 being worst possible pain)

We will administer cold spray (name, manufacturer location) 3 cm lateral to the spinous process from C1 to T12, and document the highest and lowest dermatomal levels of when the patient detects a difference in temperature sensation compared to the contralateral side.

Incidence of brachial plexus or intercostal stimulation via stimulating catheter before local anesthetic bolus

Prior to local anesthetic bolus, any perceived stimulation of an intercostal muscle or in the distribution of the brachial plexus on the operative side, including but not limited to twitching of or warmth of skin overlying the deltoid, biceps, triceps, supraspinatus, infraspinatus, pectoralis major/minor, and teres major/minor, will be documented.

Incidence of brachial plexus or intercostal stimulation via stimulating catheter after local anesthetic bolus

30 minutes after local anesthetic bolus, any perceived stimulation of an intercostal muscle or in the distribution of the brachial plexus on the operative side, including but not limited to twitching of or warmth of skin overlying the deltoid, biceps, triceps, supraspinatus, infraspinatus, pectoralis major/minor, and teres major/minor, will be documented.

The subject's total opioid administration in the PACU will be documented and converted to oral morphine milliequivalents (MME).

The subject's total opioid administration on POD1 will be documented and converted to oral morphine milliequivalents (MME).

The subject's total opioid administration on POD2 will be documented and converted to oral morphine milliequivalents (MME).

The subject's total opioid administration on POD3 will be documented and converted to oral morphine milliequivalents (MME).

The subject's average postoperative pain score ratings will be calculated on POD 1. Pain scored on an 11-point numeric rating scale (NRS, 0 being no pain and 10 being worst possible pain)

The subject's average postoperative pain score ratings will be calculated on POD 2 Pain scored on an 11-point numeric rating scale (NRS, 0 being no pain and 10 being worst possible pain)

The subject's average postoperative pain score ratings will be calculated on POD 3 Pain scored on an 11-point numeric rating scale (NRS, 0 being no pain and 10 being worst possible pain)

Inclusion Criteria: elective total or total reverse shoulder arthroplasty Exclusion Criteria: inability to provide consent history of active opioid use emergency procedures shoulder arthroscopy partial shoulder replacement shoulder resurfacing any revision shoulder surgery any indwelling deep brain stimulator, pacemaker, and/or other neurostimulators