D-FAB-POUR Trial: Dexmedetomidine vs Fentanyl as Adjuvants to Bupivacaine on Postoperative Urinary Retention

Not Applicable

Not yet recruiting

• Conditions: Spinal Anesthesia; Postoperative Complications; Bupivacaine; Dexmedetomidine; POUR; Orthopedic Surgery; Fentanyl; Anesthesia, Spinal; Urinary Retention Postoperative

• Registration Number: NCT07117565
• Lead Sponsor: Tribhuvan University Teaching Hospital, Institute Of Medicine.

Brief Summary

This study aims to compare two medications, dexmedetomidine and fentanyl, when used alongside a commonly used spinal anesthetic called bupivacaine in patients undergoing lower limb surgery. The main focus of the study is to see which combination causes fewer problems with urination after surgery - a condition known as postoperative urinary retention (POUR). POUR can lead to discomfort, delayed recovery, and a need for catheterization. Dexmedetomidine is a newer drug that may help reduce this problem compared to fentanyl, which is more commonly used but may increase the risk of urinary retention. This trial will help determine which medication combination provides better pain relief while reducing urinary side effects. The study is being conducted as a randomized, double-blind trial at a hospital in Nepal and will include 190 adult patients.

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Detailed Description

Spinal anaesthesia is a common and effective method used to manage pain during lower limb surgeries. It allows patients to remain awake and comfortable while providing excellent pain control. To make spinal anaesthesia last longer and provide better pain relief, certain medications called adjuvants are added to the main anaesthetic drug, bupivacaine. Two commonly used adjuvants are fentanyl, an opioid, and dexmedetomidine, a medication that works on the body's alpha-2 receptors to provide sedation and pain relief.

However, a known side effect of spinal anaesthesia especially when combined with certain adjuvants is postoperative urinary retention (POUR). This condition occurs when a patient is unable to urinate normally after surgery. POUR can be uncomfortable, may delay recovery, and often requires insertion of a urinary catheter, which can increase the risk of infection and hospital stay.

This clinical trial, called the D-FAB POUR Trial, is designed to find out which of these two adjuvants dexmedetomidine or fentanyl is more likely to cause or prevent POUR when used with bupivacaine in patients undergoing elective lower limb surgery.

The study will involve 190 adult patients. Each participant will receive spinal anaesthesia with bupivacaine and be randomly assigned to also receive either dexmedetomidine or fentanyl. Neither the patients nor the doctors will know which medication is given in a process known as double-blinding to ensure fairness and eliminate bias.

The researchers will monitor the ability of patients to urinate at the third and sixth hours after surgery, using ultrasound to measure bladder volume. If the patient is unable to pass urine and the bladder is overly full, temporary or longer-term catheterisation may be needed. These outcomes will help determine how each drug affects bladder function.

In addition to urinary outcomes, the study will also look at side effects like nausea, vomiting, itching, changes in blood pressure or heart rate, sedation level, and how much extra pain relief the patient needs after surgery.

The goal of this research is to help doctors choose the best adjuvant to use in spinal anaesthesia, one that provides effective pain control without increasing the risk of urinary problems. The findings may lead to improved safety, comfort, and recovery for patients undergoing lower limb operations.

Study Timeline

• Status Verified: 2025-06
• Study First Submitted: 2025-06-30
• Study First Submitted QC: 2025-08-09
• Last Update Submitted: 2025-08-09
• Study First Posted: 2025-08-12
• Last Update Posted: 2025-08-12
• Study Start: 2025-09-15
• Primary Completion: 2026-09-14
• Study Completion: 2026-11-25

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 190

Inclusion Criteria

• Adults aged 18 to 60 years
• Scheduled for elective lower limb surgery under spinal anesthesia
• Classified as American Society of Anesthesiologists (ASA) physical status II or III
• Minimum height of 150 cm (to ensure uniform drug volume)
• Able to understand the study procedures and provide written informed consent (in English or Nepali)

Exclusion Criteria

• Contraindications to spinal anesthesia (e.g., coagulopathy, infection at injection site, hemodynamic instability)
• Known allergy or hypersensitivity to bupivacaine, fentanyl, or dexmedetomidine
• Chronic pain conditions or long-term opioid use
• Neurological, Cardiac, Renal, or uncontrolled diabetic conditions
• Current treatment for prostatic pathology or use of alpha-2 blockers
• Presence of a Foley's catheter preoperatively
• Estimated surgical duration: >2.5 hours
• Inability or unwillingness to provide informed consent

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Incidence of Postoperative Urinary Retention (POUR) at the 3rd Postoperative Hour	3 hours after spinal anesthesia	The primary outcome is the number of participants who are unable to void urine at the 3rd postoperative hour with a urinary bladder (UB) volume of ≥600 mL, confirmed by bladder ultrasound. Participants meeting this criterion will be considered to have postoperative urinary retention and will undergo in-out catheterization.

Secondary Outcome Measures

Name	Time	Method
Requirement of Urinary Catheterization at 6th Postoperative Hour	6 hours after spinal anesthesia	Number of participants unable to void urine by the 6th postoperative hour, requiring insertion of a Foley's catheter.

Trial Locations

Locations (1)

Om Sai Pathibhara Hospital; 🇳🇵 Bhadrapur, Koshi, Nepal