Postoperative pain is a major determinant of recovery after lower abdominal surgery. Inadequately controlled pain can increase sympathetic activity, restrict deep breathing and mobilization, and delay functional recovery. Contemporary perioperative pain management emphasizes multimodal, procedure-specific analgesia and balancing analgesic efficacy against adverse effects.¹⁰,¹²,¹⁵,¹⁶,¹⁷ Aim and objectives The aim was to compare epidural and intravenous tramadol for postoperative pain relief in adults undergoing lower abdominal surgery. The objectives were to compare onset and duration of analgesia, analgesic quality, rescue analgesic requirement, hemodynamic and respiratory effects, adverse events, patient satisfaction, time to first ambulation, and hospital stay.

Study design and setting: This randomized comparative study was conducted in the Department of Anaesthesiology, Raipur Institute of Medical Sciences (RIMS), Raipur, Chhattisgarh, India, over an 18-month period after institutional ethics approval. The exact study dates and ethics approval number were not reported in the supplied manuscript and should be inserted from the approved protocol before submission. Participants: Adults aged 18–60 years with ASA physical status I or II undergoing lower abdominal surgery and providing informed consent were eligible. Exclusion criteria were age outside the specified range, ASA III–IV status, refusal to participate, coagulation defects, severe hemorrhage or shock, local infection, drug allergy, and antipsychotic medication use. The supplied manuscript should be cross-checked against the original ethics protocol to ensure that these criteria are reproduced verbatim. Randomization and interventions: The thesis states that computer-generated randomization was used and that 110 participants were analyzed, with 55 in each group. The IV group received an initial tramadol dose of 1 mg/kg followed by 100 mg diluted in 100 mL normal saline. The epidural group received 50 mg tramadol diluted to 10 mL with normal saline through an epidural catheter placed at L2–L3 or L3–L4. The exact timing and infusion rate of the IV 100-mg dose, the timing of epidural administration, and the use of any background multimodal analgesics should be confirmed from the original protocol. Outcome measures: The primary outcomes were postoperative analgesic effect assessed using VAS/VRS and duration of analgesia, defined in the source manuscript as the interval from drug administration to rescue analgesia. Secondary outcomes included onset of analgesia, heart rate, blood pressure/mean arterial pressure, respiratory rate, SpO₂, sedation, nausea/vomiting, pruritus, hypotension, rescue analgesic requirement, satisfaction, ambulation, and hospital stay. The precise rule for participants who did not require rescue analgesia during follow-up should be stated in the final statistical analysis. Statistical analysis: The source thesis reports analysis using SPSS, independent-samples t-tests for continuous variables, and chi-square tests for categorical variables, with p<0.05 considered statistically significant. Continuous data are presented as mean±SD and categorical data as frequency/percentage. Because this is a randomized comparative study, the final submission should also report the randomization process, participant flow, missing data, and analysis population in accordance with CONSORT principles. Ethical approval and written informed consent were obtained according to the source manuscript

A total of 110 participants were analyzed, with 55 in each group. Baseline characteristics were comparable: mean age was 43.1±8.4 years in the epidural group and 43.9±8.1 years in the IV group (p=0.67), and mean body weight was 64.5±6.7 versus 63.9±6.4 kg (p=0.58). Sex distribution was also comparable (p=0.69). Surgical categories included hysterectomy, hernia repair, appendectomy, and other lower abdominal procedures, with no reported difference between groups (p=0.92). Baseline heart rate, systolic and diastolic blood pressure, and SpO₂ were also reported as comparable. Epidural tramadol produced a faster onset of analgesia (7.9±2.6 vs 11.2±3.1 min; p<0.001), with 40.0% achieving relief within 5 minutes compared with 18.2% after IV treatment. Duration of analgesia was 6.9±1.4 versus 4.2±1.2 hours (p<0.001). Good-to-complete VRS relief was reported in 83.7% versus 56.4% (p<0.01). Early sedation was greater after epidural administration at 30 minutes and 1–2 hours but reportedly converged by 4 hours. Heart rate and MAP showed transient early between-group differences, without reported clinically important bradycardia, persistent hypotension, or respiratory depression. Nausea/vomiting occurred in 16.3% versus 32.7% (p=0.04). Pruritus (3.6% vs 9.1%; p=0.23) and hypotension (7.3% vs 3.6%; p=0.40) did not differ significantly. Rescue analgesia was required by 21.8% versus 54.5% (p<0.001), with reported mean rescue dose of 65±15 versus 95±20 mg (p<0.001). Patient satisfaction was 4.3±0.6 versus 3.7±0.7 (p=0.02). First ambulation occurred at 5.8±1.2 versus 7.1±1.5 hours (p<0.001), and hospital stay was 4.6±0.9 versus 5.3±1.1 days (p=0.001). Table 1. Baseline demographic and surgical characteristics. Variable Epidural (n=55) IV (n=55) p Age, years 43.1±8.4 43.9±8.1 0.67 Male 28 (50.9%) 30 (54.5%) 0.69 Weight, kg 64.5±6.7 63.9±6.4 0.58 Hysterectomy 17 (30.9%) 16 (29.1%) 0.92 Hernia repair 15 (27.3%) 16 (29.1%) Appendectomy 13 (23.6%) 12 (21.8%) Other lower abdominal 10 (18.2%) 11 (20.0%) Table 2. Principal analgesic and recovery outcomes. Outcome Epidural IV p Onset of analgesia, min 7.9±2.6 11.2±3.1 <0.001 Duration, h 6.9±1.4 4.2±1.2 <0.001 Good/complete VRS relief 83.7% 56.4% <0.01 Rescue analgesia required 21.8% 54.5% <0.001 Mean rescue dose, mg 65±15 95±20 <0.001 Satisfaction /5 4.3±0.6 3.7±0.7 0.02 First ambulation, h 5.8±1.2 7.1±1.5 <0.001 Hospital stay, days 4.6±0.9 5.3±1.1 0.001 Table 3. Adverse effects and safety outcomes. Adverse event Epidural IV p Nausea/vomiting 16.3% 32.7% 0.04 Pruritus 3.6% 9.1% 0.23 Hypotension 7.3% 3.6% 0.40 Respiratory depression 0 0 — Data are presented as mean±SD or n (%). p values are those reported in the source thesis. The surgical-category p value refers to the overall comparison; individual procedure rows do not have separate p values.

The principal finding was that the epidural tramadol regimen was associated with a faster onset and longer duration of postoperative analgesia than the tested IV regimen. The faster onset is notable because systemic administration might intuitively be expected to act rapidly; however, onset is influenced by timing of assessment, dose, route-specific pharmacokinetics, catheter position, and perioperative co-analgesia. It should therefore be interpreted as a study-specific finding rather than a universal pharmacologic rule. The longer duration is biologically plausible and is directionally consistent with earlier clinical studies of epidural tramadol. Current perioperative guidance emphasizes multimodal analgesia and regional techniques where appropriate, but does not establish epidural tramadol as universally preferable to other regional or systemic strategies. Delilkan and Vijayan reported dose-related differences in analgesic interval after epidural tramadol in abdominal surgery, with longer intervals at higher doses.¹ A pharmacokinetic pilot study also demonstrated systemic absorption after epidural administration, emphasizing that epidural tramadol is not confined to the neuraxial compartment.⁸ Pharmacology and route considerations Tramadol is a centrally acting analgesic with weak μ-opioid receptor agonism and inhibition of norepinephrine and serotonin reuptake. Its active metabolite, O-desmethyltramadol, contributes to μ-opioid activity, while CYP2D6 genetic variability can influence response. The IV route produces systemic exposure, whereas epidural administration introduces drug into the neuraxial space with subsequent systemic absorption. The clinical effect of epidural tramadol therefore depends on dose, catheter position, timing, spinal anatomy, and co-administered agents. Published studies have reported useful postoperative analgesia after epidural tramadol, but the magnitude and duration of benefit vary across protocols.¹–⁵,⁸ Analgesic outcomes The 2.7-hour difference in mean time to rescue analgesia is one of the clinically relevant findings. Time to rescue reflects analgesic effect as well as surgical pain intensity and individual pain thresholds, but it is a practical patient-centered endpoint. The lower rescue requirement in the epidural group is consistent with the longer analgesic interval. Good-to-complete VRS relief was also more frequent in the epidural group (83.7% vs 56.4%). Earlier reports support the feasibility of epidural tramadol for postoperative analgesia, although direct numerical comparison is limited by differences in dose, co-administered local anesthetics, surgical populations, and outcome definitions.¹–⁵ The present study is particularly relevant because it directly compares an epidural regimen with an IV regimen. Hemodynamic and respiratory interpretation The transient early reduction in heart rate and MAP after epidural administration warrants interpretation as a measurable physiological effect rather than automatically as an adverse event. At 30 minutes, heart rate was 79.1±7.2 versus 84.3±8.5 beats/min and MAP was 89.3±6.7 versus 95.6±6.2 mmHg in the epidural and IV groups, respectively. The source manuscript reports no clinically important bradycardia and no vasopressor requirement. Respiratory rate remained stable and no respiratory depression was reported. However, the absence of respiratory events in 110 relatively healthy ASA I–II participants does not establish zero risk, particularly in older, medically complex, or opioid-naïve populations. The transient increase in sedation score should likewise be interpreted alongside respiratory monitoring and clinical responsiveness. Strengths and limitations Strengths included randomized allocation, equal group size, standardized study interventions, and assessment of multiple patient-centered outcomes. Important limitations include the single-center design, modest sample size, restriction to ASA I–II patients, heterogeneity of lower abdominal procedures, unclear blinding in the supplied thesis, short follow-up, and the absence of a clearly reported CONSORT participant-flow diagram. The two regimens were also not milligram-equivalent, so the study evaluates the tested route-specific regimens rather than isolating route as the sole causal difference. In addition, the supplied manuscript does not provide a full longitudinal VAS dataset, detailed missing-data handling, or adjusted analyses. The definition and denominator used for the reported mean rescue dose should be clarified before submission.

In this randomized comparative study of adults undergoing lower abdominal surgery, the tested epidural tramadol regimen was associated with faster onset, longer duration, and better reported quality of postoperative analgesia than the tested IV regimen. It was also associated with lower rescue analgesic use, less nausea/vomiting, earlier ambulation, shorter hospitalization, and higher patient satisfaction. Hemodynamic changes were transient, and no respiratory depression was reported. These findings support further evaluation of epidural tramadol as one component of multimodal postoperative analgesia, while recognizing that the study compared unequal route-specific dosing regimens and was conducted in a single center with a relatively small, selected population.

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