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.
Who can participate
Age range
18 Years
Sex
ALL
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion criteria
. Ability to provide written informed consent
. Ability and willingness to comply with the study procedures and duration requirements
. ASA physical status 1 or 2
. Age ≥ 18 years
. Weight \> 60kg
Exclusion criteria
. BMI \> 40kg.m-2
. Use of analgesics within 24 hours before the procedure
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1This trial is in Phase 2 and hasn't started recruiting yet — what does that mean for how much is already known about the safety and effectiveness of the rectus sheath block technique being studied here?
2The trial seems focused on measuring nerve and sensation changes like temperature and touch discrimination rather than directly comparing pain relief outcomes — how would participating help my actual pain management after surgery, and would I still receive standard pain control?
3Since this study involves mapping where the nerve block affects sensation on the skin, what does that procedure actually involve, and are there any risks or discomforts beyond what I'd experience with normal postoperative care?
4Given that this trial isn't recruiting yet, is it worth waiting for it to open, or would standard pain management approaches after my surgery be a more practical path right now?
5Could you help me understand whether the type of surgery I'm having is the kind this rectus sheath study is designed for, and whether my situation would even make me a candidate worth discussing with the research team once it opens?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.