REctus Sheath Trial (REST)

Duke University

Status and phase: Begins enrollment in 2 months; Phase 2

Conditions: Postoperative Pain, Acute; Acute Pain

Treatments: Drug: 1.0% lidocaine with epinephrine (1:100,000)

Study type: Interventional

Funder types: Other

Identifiers

NCT07068243

Pro00118293

Details and patient eligibility

About

Regional anesthesia techniques (or nerve blocks) are used to provide sensory blockade over the abdominal wall. The most established technique is thoracic epidural. This provides bilateral spread but is also associated with neuraxial complications, which has led to a decrease in clinical usage. The rectus sheath block (RSB) is an established regional anesthesia technique used to provide somatic analgesia to the midline anterior abdominal wall by depositing local anesthetic in the posterior rectus sheath, thereby targeting the terminal anterior branches of the lower thoracic intercostal nerves. The conventional approach involves placing the ultrasound (US) probe transversely across the rectus abdominis muscle and advancing the needle in-plane either lateral-to-medial or medial-to-lateral. While this technique achieves spread within the sheath, the cephalocaudal distribution of local anesthetic may be suboptimal, potentially limiting the extent of dermatomal coverage. A longitudinal probe orientation, with needle insertion from cephalad to caudad, may theoretically facilitate a more extensive cranio-caudal spread by aligning the injection axis with the anatomical fascial plane of the posterior rectus sheath. However, the relative efficacy of these two approaches has not been investigated in a controlled, comparative setting. Thus, this randomized, single-blinded trial aims to evaluate the dermatomal sensory distribution and ultrasound-assessed local anesthetic spread achieved by the transverse versus longitudinal in-plane approaches to ultrasound-guided RSB in healthy adult volunteers. To compare the dermatomal sensory block distribution, investigators will use dermatomal mapping with pinprick, and cold.

Full description

A total of 14-18 adult volunteers will be included. Each participant will receive bilateral rectus sheath blocks at a standardized supraumbilical level. The side receiving the transverse approach (US probe perpendicular to muscle fibers; needle in-plane lateral-to-medial) and the side receiving the longitudinal approach (US probe parallel to muscle fibers; needle in-plane cephalad-to-caudad) will be randomized. The blocks will be performed with a standardized volume and concentration of local anesthetic, under real-time US guidance by the same experienced anesthesiologist. The research team member assessing the block will be blinded. Immediately after injection of each block, US imaging will be used to assess and measure the length and pattern of spread within the posterior rectus sheath. At baseline and at 60 minutes post-block, dermatomal sensory mapping will be performed using standardized cold and pinprick stimuli over the anterior abdominal wall.

Enrollment: 25 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

1. Ability to provide written informed consent
2. Ability and willingness to comply with the study procedures and duration requirements
3. ASA physical status 1 or 2
4. Age ≥ 18 years
5. Weight > 60kg

Exclusion criteria

1. BMI > 40kg.m-2
2. Use of analgesics within 24 hours before the procedure
3. History of abdominal trauma or surgery
4. Abdominal deformities or abnormalities that may prevent proper block performance
5. Abdominal tattoos in the supraumbilical area
6. Systemic neuromuscular disease
7. Contraindications to regional anesthesia (e.g., infection, allergy)
8. Structures are unable to be visualized by ultrasound
9. Pregnancy
10. Other known health conditions that would affect the participant's ability to successfully complete the study

Trial design

Primary purpose: Other

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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25 participants in 2 patient groups

Transverse Approach to the Rectus Sheath Block

Active Comparator group

Description:

In the transverse approach, the US probe will be positioned perpendicular to the he rectus abdominis muscle's fibers, and the needle will be inserted in-plane from lateral to medial.

Treatment:

Drug: 1.0% lidocaine with epinephrine (1:100,000)

Longitudinal Approach to the Rectus Sheath Block

Experimental group

Description:

In contrast, the longitudinal approach will involve aligning the probe parallel to the rectus muscle fibers, with the needle advanced in-plane from cephalad to caudad.

Treatment:

Drug: 1.0% lidocaine with epinephrine (1:100,000)