Autonomic Neural Field Block for Visceral Pain in Minimally Invasive Left-Sided Colectomy (ANfiELD)

January 10, 2026 updated by: Antonio Caycedo, MD

Autonomic Neural Field Block for Visceral Pain Control in Minimally Invasive Left-Sided Colorectal Resections

Effective postoperative pain control is a core component of enhanced recovery after surgery (ERAS) pathways in colorectal surgery; however, postoperative pain following minimally invasive left-sided colectomy remains a persistent clinical challenge. Standard multimodal analgesic strategies primarily target somatic pain pathways and may inadequately address visceral postoperative pain, which is mediated through autonomic afferent neural pathways. Residual visceral pain is associated with increased opioid consumption, postoperative nausea and vomiting, delayed recovery, and prolonged length of stay.

This prospective, multicenter observational registry evaluates the feasibility and real-world outcomes of an intraoperative autonomic neural field block targeting the superior hypogastric and inferior mesenteric plexuses during minimally invasive left-sided colectomy. The technique is performed under direct visualization as an adjunct to standard ERAS-based analgesic care. The primary outcome is postoperative opioid consumption within the first 24 hours after surgery. Secondary outcomes include opioid use through 48 hours, postoperative nausea and vomiting, antiemetic use, pain scores, length of stay, and readiness for discharge. Data from this registry will inform future comparative studies and help define the role of autonomic neural modulation in perioperative pain management for colorectal surgery.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Background and Rationale

Effective postoperative pain control is a cornerstone of enhanced recovery after surgery (ERAS) pathways in colorectal surgery. Adequate analgesia facilitates early mobilization, pulmonary hygiene, gastrointestinal recovery, and timely hospital discharge. Despite widespread adoption of ERAS protocols and multimodal, opioid-sparing analgesic strategies, postoperative pain following left-sided colectomy remains a clinically relevant and persistent challenge. A substantial proportion of patients continue to experience moderate to severe pain in the early postoperative period, which may contribute to increased opioid consumption, postoperative nausea and vomiting (PONV), delayed functional recovery, and prolonged length of stay.

Current perioperative analgesic approaches in colorectal surgery predominantly address somatic pain pathways. These strategies include non-opioid analgesics, opioid-based regimens, local anesthetic infiltration, neuraxial techniques, and transversus abdominis plane (TAP) blocks. While effective in reducing abdominal wall and incisional pain, these modalities do not specifically target visceral postoperative pain, which is mediated through autonomic afferent neural pathways. Visceral pain arises from bowel distension, traction, ischemia, and inflammatory processes affecting the colon and mesentery and is transmitted primarily via sympathetic and parasympathetic fibers. This component of postoperative pain is qualitatively distinct, often diffuse and poorly localized, and frequently associated with nausea, ileus, and other autonomic symptoms.

Neuraxial techniques may provide effective visceral analgesia but are invasive, resource-intensive, and associated with potential adverse effects such as hypotension and urinary retention. As a result, many contemporary ERAS pathways have moved away from routine neuraxial analgesia, creating an unmet need for effective, targeted visceral pain control that is compatible with minimally invasive surgical workflows and ERAS principles.

Targeted modulation of autonomic neural pathways involved in visceral afferent transmission represents a potential strategy to address this gap. The superior hypogastric plexus and inferior mesenteric plexus play central roles in transmitting visceral sensory input from the left colon and rectum and are anatomically consistent structures routinely encountered during left-sided colorectal resection. Intraoperative autonomic neural field block targeting these plexuses may offer a mechanistically distinct approach to perioperative analgesia that complements existing somatic-focused techniques.

Description of the Intervention

The autonomic neural field block is performed intraoperatively during elective minimally invasive (laparoscopic or robotic) left-sided colonic or rectal resection with primary anastomosis constructed above the peritoneal reflection. Following establishment of pneumoperitoneum and trocar placement according to surgeon preference, standard minimally invasive dissection is carried out.

Dissection exposes the inferior mesenteric plexus in proximity to the origin of the inferior mesenteric artery and the superior hypogastric plexus at the level of the sacral promontory. These anatomic landmarks are routinely visualized during left-sided colorectal surgery and do not require additional dissection beyond standard operative technique.

An insulin needle connected to an anesthesia extension set is introduced through a 10-12 mm auxiliary port and attached to a syringe containing a diluted local anesthetic solution. All air is purged from the system prior to injection. Each plexus is infiltrated with approximately 5-7 mL of local anesthetic solution, administered incrementally in 1 mL aliquots. Aspiration is performed prior to each injection to confirm the absence of intravascular placement, and adequate tissue infiltration is confirmed visually. The surgical procedure then proceeds according to standard operative practice. When an extraction incision is used, any remaining local anesthetic solution may be infiltrated into the incision prior to closure.

Perioperative Analgesic Management

The autonomic neural field block is intended to complement, rather than replace, established multimodal perioperative analgesic strategies. Additional analgesic interventions, including TAP blocks, non-opioid medications, and opioid administration, are performed according to institutional ERAS protocols and surgeon or anesthesiologist discretion. This pragmatic approach allows evaluation of autonomic neural blockade within real-world clinical environments and across varying perioperative practices.

Study Design and Registry Framework

This study is a prospective, multicenter observational registry designed to systematically collect perioperative analgesic and recovery outcomes in patients undergoing minimally invasive left-sided colectomy who receive an intraoperative autonomic neural field block. The registry is descriptive and hypothesis-generating and does not mandate a comparator group. Use of additional analgesic modalities, including TAP block, is recorded but not standardized.

Participating centers collect perioperative data using standardized case report forms. Data capture includes patient demographics, operative details, analgesic interventions, and postoperative recovery metrics. The registry is designed to facilitate assessment of feasibility, reproducibility, and variability of outcomes across institutions and practice settings.

Outcome Measures

The primary outcome is postoperative opioid consumption, expressed as morphine milligram equivalents (MME), during the first 24 hours following surgery. Secondary outcomes include cumulative opioid consumption during the first 48 postoperative hours, intraoperative analgesic requirements, incidence of postoperative nausea and vomiting, antiemetic use, length of hospital stay, and readiness for discharge based on ERAS-aligned criteria. Patient-reported pain outcomes are collected during hospitalization and through the first postoperative week after discharge.

Safety and Feasibility

Feasibility outcomes include the ability to perform the autonomic neural field block under direct visualization without deviation from standard operative technique or prolongation of operative time. Adverse events potentially related to the intervention, including bleeding, vascular injury, or hemodynamic instability temporally associated with the block, are recorded. The registry does not alter routine postoperative monitoring or follow-up.

Data Analysis and Future Directions

Data from this registry will be summarized using descriptive statistics. The registry is not powered to assess comparative efficacy but is intended to generate preliminary data regarding analgesic patterns, recovery trajectories, and variability across centers. These findings will inform the design of future comparative or randomized studies, refine patient selection, and help define the role of autonomic neural modulation within ERAS-aligned perioperative pain management strategies for colorectal surgery.

Study Type

Observational

Enrollment (Estimated)

400

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

The study population includes adult patients undergoing elective minimally invasive (laparoscopic or robotic) left-sided colonic or rectal resection with primary anastomosis constructed above the peritoneal reflection. Eligible patients receive an intraoperative autonomic neural field block targeting the superior hypogastric and/or inferior mesenteric plexuses under direct visualization as part of routine operative care. Perioperative management follows institutional standardized analgesic pathways, such as enhanced recovery after surgery (ERAS) protocols, with postoperative opioid administration documented in the medical record. Patients undergoing emergency surgery, procedures without primary anastomosis, low pelvic or extraperitoneal anastomoses, planned open surgery, or those with contraindications to local anesthetics are excluded.

Description

Inclusion Criteria:

  • Age ≥ 18 years.
  • Scheduled for elective minimally invasive (laparoscopic or robotic) left-sided colonic or rectal resection with primary anastomosis constructed above the peritoneal reflection (e.g., sigmoid colectomy, left colectomy, anterior resection/rectosigmoid resection with intraperitoneal anastomosis).
  • Planned intraoperative administration of autonomic neural field block targeting the superior hypogastric plexus and/or inferior mesenteric plexus, performed under direct visualization, as part of routine operative workflow.
  • Managed perioperatively under an institutional standard analgesic pathway (e.g., ERAS or equivalent), with postoperative opioid administration recorded in the medical record.
  • Ability to provide informed consent

Exclusion Criteria:

  • Emergency/urgent colorectal surgery (e.g., perforation, uncontrolled bleeding, toxic megacolon, obstructing cancer requiring urgent operation).
  • Planned open left-sided colectomy/rectal resection (minimally invasive approach not intended).
  • Procedures in which no primary anastomosis is created (e.g., Hartmann's procedure, end colostomy, permanent diversion without anastomosis).
  • Planned low pelvic/extra-peritoneal anastomosis (e.g., low anterior resection with anastomosis at or below the peritoneal reflection) or planned handsewn coloanal anastomosis.
  • Known allergy or contraindication to the local anesthetic agents used for the block (or inability to receive local anesthetic for clinical reasons).
  • Inability to reliably capture outcome data for the primary endpoint (e.g., anticipated transfer to another facility within 24 hours post-op, incomplete medication administration records).
  • Pregnancy
  • Prisoners or other protected populations where participation is restricted
  • Chronic opioid therapy at baseline defined as daily opioid use for > 30 days preoperatively, or baseline opioid dose > 30 MME/day
  • Planned use of neuraxial analgesia (epidural/spinal) intended for postoperative analgesia

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Autonomic Neural Field Block Cohort
This cohort includes adult patients undergoing elective minimally invasive (laparoscopic or robotic) left-sided colonic or rectal resection with primary anastomosis who receive an intraoperative autonomic neural field block targeting the superior hypogastric and inferior mesenteric plexuses. The autonomic neural field block is performed under direct visualization as an adjunct to standard perioperative care within established enhanced recovery after surgery (ERAS) pathways. Use of additional analgesic modalities, including transversus abdominis plane blocks, non-opioid analgesics, and opioids, is permitted according to institutional practice and is recorded as part of routine perioperative management.
Procedure: Autonomic Neural Field Block
An intraoperative autonomic neural field block targeting the superior hypogastric and inferior mesenteric plexuses is performed under direct visualization during elective minimally invasive left-sided colorectal resection. The block is administered using incremental injections of diluted local anesthetic as an adjunct to standard perioperative analgesic care within established enhanced recovery after surgery (ERAS) pathways.
Other Names:
  • Neural blockade

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Opiod consumption
Time Frame: 24 hours
Total opioid consumption during the first 24 hours following surgery, converted to morphine milligram equivalents (MME), based on all opioid medications administered during the postoperative period.
24 hours

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative opioid consumption (48 hours)
Time Frame: 48 hours
Total cumulative opioid consumption during the first 48 hours following surgery, converted to morphine milligram equivalents (MME), based on all opioid medications administered postoperatively
48 hours
Intraoperative opioid administration
Time Frame: Intraoperative period
Total opioid dose administered intraoperatively, converted to morphine milligram equivalents (MME), as recorded in the anesthesia record.
Intraoperative period
Postoperative nausea and vomiting (PONV)
Time Frame: First 48 hours after surgery
Incidence of postoperative nausea and/or vomiting documented during the postoperative period and/or requirement for antiemetic medication.
First 48 hours after surgery
Antiemetic medication use
Time Frame: First 48 hours after surgery
Administration of any antiemetic medication during the postoperative period, recorded as a binary outcome and by total number of doses administered.
First 48 hours after surgery
Postoperative pain intensity
Time Frame: Postoperative days 0-7
Patient-reported pain intensity measured using a standardized numeric rating scale (0-10) at predefined postoperative time points.
Postoperative days 0-7

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Antonio Caycedo, MD

Investigators

  • Principal Investigator: Antonio Caycedo, MD, MSc, Orlando Health Colon & Rectal Institute

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

January 20, 2026

Primary Completion (Estimated)

July 20, 2026

Study Completion (Estimated)

September 1, 2026

Study Registration Dates

First Submitted

January 10, 2026

First Submitted That Met QC Criteria

January 10, 2026

First Posted (Actual)

January 20, 2026

Study Record Updates

Last Update Posted (Actual)

January 20, 2026

Last Update Submitted That Met QC Criteria

January 10, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2365950-1

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Sharing Time Frame

at 3,6 moths and after final results prior to any publication submission

IPD Sharing Access Criteria

Reasonable request

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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