Analgesic Equivalence of NSAIDs and Tramadol in Acute Postoperative Pain Following Minimally Invasive Surgery

ISSSTE Hospital Regional "Gral. Ignacio Zaragoza"30 enrolled

Overview

This pilot randomised controlled trial compared the analgesic equivalence of three intravenous premedication regimens - tramadol 150 mg, ketorolac 60 mg, and diclofenac 150 mg - in adult patients undergoing elective minimally invasive surgery under balanced general anaesthesia. The primary outcome was postoperative pain intensity measured using the Numerical Rating Scale (NRS 0-10) at recovery room arrival and at 30, 60, and 90 minutes thereafter.

Acute postoperative pain remains inadequately managed in a substantial proportion of surgical patients, with particular challenges in resource-limited settings where access to potent opioids is restricted. Cross-class equianalgesic data comparing NSAIDs with weak opioids are scarce. This single-centre, double-blind, parallel-group pilot RCT was conducted at Hospital Regional "General Ignacio Zaragoza," ISSSTE, Mexico City. Thirty adult patients (ASA I-II, age 18-55 years, BMI 18.5-34.99 kg/m²) scheduled for elective laparoscopic surgery were randomised equally to receive tramadol 150 mg IV, ketorolac 60 mg IV, or diclofenac 150 mg IV, administered 45 minutes before skin incision. All patients received standardised balanced general anaesthesia. Pain was assessed using the NRS and Verbal Rating Scale (VRS) at five time points. Rescue analgesia (morphine 3 mg IV) was available on request. The trial was initially registered with the ISSSTE institutional research registry (RPI #403-2024).

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Postoperative Pain

Interventions

TramadolDRUG

Tramadol 150 mg IV, single dose, administered in 100 mL 0.9% saline 45 minutes before skin incision.

KetorolacDRUG

Ketorolac 60 mg IV, single dose, administered in 100 mL 0.9% saline 45 minutes before skin incision.

DiclofenacDRUG

Diclofenac 150 mg IV, single dose, administered in 100 mL 0.9% saline 45 minutes before skin incision.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 55 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Age 18-55 years * ASA physical status I or II * Body mass index 18.5-34.99 kg/m² * Scheduled for elective minimally invasive surgery under balanced general anaesthesia * Pre-surgical pain NRS = 0 and VRS = "absence" at baseline assessment Exclusion Criteria: * Pregnancy * Known hypersensitivity to any study drug (tramadol, ketorolac, or diclofenac) * Pre-existing acute pain with NRS ≥ 4 or VRS ≥ "moderate" before surgery * Chronic pain with current analgesic use * Withdrawal of consent before premedication administration * Surgical duration exceeding 180 minutes * Conversion from laparoscopic to open surgical approach * Hypersensitivity reaction during study drug administration * Haemodynamic shock of any aetiology during the perioperative period * Requirement for postoperative mechanical ventilation due to anaesthetic-surgical complications

Outcomes

Primary Outcomes

Postoperative pain intensity

Pain intensity assessed using the Numerical Rating Scale (NRS, 0-10; 0 = no pain, 10 = worst imaginable pain). Between-group comparisons performed at each time point using Kruskal-Wallis tests with Dunn post-hoc correction.

Time frame: At recovery room arrival (Time_0), and at 30 (Time_1), 60 (Time_2), and 90 (Time_3) minutes after recovery room arrival.

Secondary Outcomes

Categorical pain intensity by Verbal Rating Scale (VRS)

Pain category assessed using a four-point Verbal Rating Scale (0 = absence, 1 = low, 2 = moderate, 3 = severe). Between-group differences assessed using Pearson's chi-squared test with Cramér's V as effect size.

Time frame: At recovery room arrival (Time_0), and at 30 (Time_1), 60 (Time_2), and 90 (Time_3) minutes after recovery room arrival.

Rescue morphine consumption

Number of rescue analgesic doses and total morphine consumed (mg IV) per group. Rescue analgesia (morphine 3 mg IV) was administered on patient request or clinical indication.

Time frame: At 30 (Time_1), 60 (Time_2), and 90 (Time_3) minutes after recovery room arrival.

Incidence of hypersensitivity reactions

Hypersensitivity reactions of any grade classified according to Müller criteria (Grade I-IV). Managed per institutional protocol (hydrocortisone 100 mg IV; adrenaline 0.5 mg IM for anaphylaxis).

Time frame: Throughout the 90-minute observation period