Opioid-Free Anesthesia in Colorectal Surgery, 2025 (OFA-CRC-2025)

Postoperative pain management is a critical component of Enhanced Recovery After Surgery (ERAS) pathways, particularly in major abdominal procedures such as laparoscopic colorectal surgery. Traditionally, intraoperative and postoperative analgesia relies heavily on opioid administration. However, opioid use is frequently associated with adverse events-including postoperative nausea and vomiting (PONV), paralytic ileus, respiratory depression, and hyperalgesia-which can delay functional recovery and prolong hospital stays.

Opioid-Free Anesthesia (OFA) is a multimodal analgesic strategy that utilizes non-opioid pharmacological agents to block sympathetic nervous system responses and prevent central sensitization. This study is a prospective, single-blind, randomized controlled trial designed to evaluate the efficacy and safety of an OFA protocol compared to standard Opioid-Based Anesthesia (OBA). The OFA protocol utilizes a customized combination of agents, including Dexmedetomidine, Ketamine, Lidocaine, Magnesium Sulfate, and Dexamethasone.

Eligible adult patients (ASA I-III) scheduled for elective laparoscopic colorectal surgery will be randomized in a 1:1 ratio to either the OFA or OBA group. Standardized clinical pathways will be followed for all patients outside of the specific anesthetic interventions. Data collection will occur from the intraoperative period through 24 hours post-surgery, with continuous follow-up extending until hospital discharge.

By comparing these two approaches, this trial aims to provide robust clinical evidence on whether completely eliminating intraoperative opioids can optimize postoperative pain control, reduce the incidence of classic opioid-related adverse effects, enhance overall patient satisfaction, and accelerate surgical recovery in colorectal patients.

Inclusion criteria

• Adult patients aged 18 to 90 years old of any sex.
• Diagnosed with colorectal cancer (any type and stage).
• Scheduled for elective laparoscopic colorectal surgery in the Lanzarote Health Area.
• Classified as American Society of Anesthesiologists (ASA) physical status I, II, or III.
• Ability to understand the study procedures and signed written informed consent.

Exclusion criteria

• Known allergy or hypersensitivity to any of the study drugs.
• Elevated intraocular pressure or history of intracranial lesions with a risk of elevated intracranial pressure.
• History of traumatic brain injury (TBI) or epileptic seizures.
• Severe psychiatric disease that may interfere with pain evaluation or outcome assessment.
• Hyperthyroidism or currently undergoing thyroid replacement therapy.
• Severe cardiac history, including congestive heart failure, severe coronary artery disease, poorly controlled tachyarrhythmias or bradyarrhythmias, or difficult-to-control arterial hypertension.
• Baseline oxygen saturation (SpO2) < 90% on room air.
• Moderate or severe renal or hepatic insufficiency.
• Pathologies associated with hypersalivation or swallowing difficulties.
• Pregnancy or currently lactating.