European Journal of Cardiovascular Medicine

Pain relief remains a fundamental objective of medical and surgical care, with anaesthetic techniques playing a crucial role in modern surgery. Epidural anaesthesia, by blocking afferent pain impulses and efferent reflexes, offers significant benefits including effective analgesia, controlled hemodynamics, and improved postoperative comfort [1,2].

Inguinal hernia repair, accounting for approximately 12.5% of all surgical corrections in men, can be performed under spinal, epidural, general, or local anaesthesia [3]. While conventional epidural dosages (≥15 mL) are effective, they often lead to adverse hemodynamic changes such as decreased cardiac output and systemic vascular resistance [4,5]. These effects are particularly concerning in elderly patients who commonly present with inguinal hernias.

Segmental epidural anaesthesia, which involves limiting the block to only the dermatomes involved in the surgical field (T8–T12), has been suggested as a safer alternative with reduced drug requirements, minimal hemodynamic changes, and fewer complications [6]. This study aimed to evaluate the safety, efficacy, and analgesic quality of low-dose (5–6 mL) 0.5% Bupivacaine in segmental epidural anaesthesia for inguinal hernia repair.

Study Design and Setting: A prospective clinical study was carried out in the Department of Anaesthesiology, Malla Reddy Hospital, MRIMS, Hyderabad, from January 2020 to September 2021.

Study Population: A total of 60 patients, aged 18–70 years, classified as ASA I or II, scheduled for elective inguinal hernia repair, were enrolled.

Inclusion Criteria:

• Age 18–70 years.
• ASA I and II status.
• Controlled hypertension (BP <140/90 mmHg).
• Controlled diabetes mellitus (FBS <160 mg/dL).
• BMI <30.

Exclusion Criteria:

• Allergy to local anaesthetics.
• Spinal deformities or infections.
• ASA III or IV status.
• Uncontrolled systemic diseases, ischemic heart disease, epilepsy, renal disorders, or history of adverse reactions to anaesthesia.

Procedure:

• Patients were pre-medicated with Tab. Alprazolam 0.5 mg and Tab. Pantoprazole 40 mg the night before surgery.
• Baseline vitals were recorded, and an IV line was established with a preload of 500 mL Ringer Lactate.
• The L1–L2 epidural space was identified under aseptic precautions using an 18G Tuohy needle, and an epidural catheter was inserted.
• 5–6 mL of 0.5% Bupivacaine was slowly administered to achieve a sensory block of T12–L2 dermatomes.
• Incremental doses (1 mL) were given if the block was inadequate.

Monitoring and Data Collection:

• Hemodynamic parameters (heart rate, systolic and diastolic BP) were recorded every minute for the first 5 minutes and every 5 minutes thereafter until surgery completion.
• Onset and duration of analgesia were measured by loss and return of pinprick sensation.
• Motor block was assessed using the Bromage scale.
• Pain scores were evaluated using the Visual Analogue Scale (VAS).
• Any adverse effects were documented.

Statistical Analysis: Descriptive statistics (mean ± SD) were used for continuous variables. Categorical variables were expressed as numbers and percentages. Chi-square tests were applied where appropriate, and a p-value <0.05 was considered statistically significant. Data were analyzed using SPSS version 16.

A total of 60 patients undergoing elective inguinal hernia repair under segmental epidural anaesthesia were included in the study. The demographic characteristics, volume of drug required, onset and duration of analgesia, quality of block, sensory levels, hemodynamic parameters, and complications were analyzed. The results demonstrated that low-dose 0.5% Bupivacaine provided effective analgesia with minimal side effects and stable hemodynamics.

Table 1: Volume of Bupivacaine Used

The volume of 0.5% Bupivacaine required ranged from 5 to 9 ml, with 51.6% of patients achieving effective analgesia with 5 ml. The mean volume used was 6 ml.

Table 2: Quality of Analgesia

Most patients (56.7%) reported excellent analgesia, while 3.3% experienced poor block and required conversion to general anaesthesia.

Table 3: Duration of Analgesia

The mean duration of analgesia was 162.25 minutes, with the highest proportion of patients (25%) experiencing analgesia for 141–150 minutes.

Table 4: Association Between Age and Volume of Drug Used

Patients older than 45 years required less drug volume (5–6 ml), indicating higher sensitivity to Bupivacaine.

Table 5: Sensory Level of Analgesia (Pre-operative)

T10 was the most frequent level achieved (36.6%) and provided adequate coverage for hernia repair.

Table 6: Sensory Level of Analgesia (Post-operative)

Postoperative sensory block levels were consistent with intraoperative requirements, with T10 being most common (38.3%).

Table 7: Side Effects

No major complications were observed. Minor side effects like sweating (8.3%) and shivering (5%) were self-limiting.

Table 8: Analgesia and Relaxation Success Rate

The overall success rate was 96.6%, demonstrating the reliability of segmental epidural anaesthesia for this procedure.

Table 9: Mean Heart Rate Changes

Heart rate remained stable with no episodes of significant bradycardia.

Table 10: Mean Blood Pressure Changes

Both systolic and diastolic pressures remained within normal limits, with no significant hypotension observed.

Table 11: Summary of Results by Age Groups

Patients in the younger age group (18–30 years) required higher drug volumes and had longer onset times, while those aged 41–50 years had the longest duration of analgesia.

This study was conducted on 60 patients undergoing elective inguinal hernia repair to evaluate the safety and efficacy of low-dose segmental epidural anaesthesia using 0.5% Bupivacaine. The mean age of the study population was 40.23 years, with a predominance of males (93%). Indirect inguinal hernia was more common than direct hernia, which is consistent with the known higher incidence of indirect hernias in males [1].

The mean volume of Bupivacaine required to achieve adequate segmental blockade was 6 ml, with 85% of patients aged over 45 years requiring only 5–6 ml. This observation aligns with findings by Dr. Rao and Dr. Phani Thota, who reported that segmental dose requirements decrease with age due to anatomical changes like narrowing of intervertebral foraminae and reduced epidural space compliance [8]. Younger patients often required higher volumes (7–9 ml), likely due to greater epidural space patency and drug spread limitations [9].

In this study, the mean onset time of analgesia was 7.8 minutes, and the mean duration was 162.25 minutes (range 120–240 minutes). Hollman et al. reported a similar duration of approximately 150 minutes with 0.5% Bupivacaine [10], and Prys-Roberts et al. noted that a 5 ml bolus typically maintains analgesia for 3–4 hours [11]. These findings confirm that the low-dose technique provides sufficient surgical analgesia without prolonging recovery.

The preoperative block level predominantly reached T10 (36.6%), which is ideal for inguinal hernia repair [6]. The quality of analgesia was excellent or good in 85% of cases, demonstrating the adequacy of the technique. Similar high success rates with segmental epidural anaesthesia have been documented by Peutrell and Hughes in paediatric hernia repairs [12].

Hemodynamic parameters, including heart rate and blood pressure, remained stable throughout the procedure, with no significant hypotension or bradycardia. Earlier studies by Odom and Guiterrez reported less hypotension with epidural block compared to spinal anaesthesia due to slower onset and restricted sympathetic blockade [13]. The minimal drug volume used in this study likely contributed to the absence of significant hemodynamic changes.

Minor complications were observed in only 10 patients (16.6%), with sweating and shivering being the most common. Inadvertent dural puncture occurred in 2 cases (3.3%), consistent with reported rates in lumbar epidurals [13]. No major complications such as respiratory depression or toxic drug reactions were encountered.

The success rate of 96.6% in this study is comparable to earlier work by Cedric Prys-Roberts and Andrew Black, who found that correct segmental placement of a 5 ml dose of 0.5% Bupivacaine resulted in effective anaesthesia in over 90% of lower abdominal surgeries [11]. Additionally, the limited spread of anaesthesia and reduced drug requirement support previous findings that segmental epidural techniques reduce complications and provide targeted analgesia [10, 14].

Segmental epidural anaesthesia using low-dose (5–6 ml) 0.5% Bupivacaine proved to be a safe, effective, and reliable technique for inguinal hernia repair. The onset of analgesia was rapid, the duration was adequate for surgery, and the quality of analgesia was excellent or good in the majority of patients (85%). Hemodynamic parameters remained stable throughout the procedure, with minimal side effects and no major complications. The study demonstrates that segmental epidural anaesthesia not only minimizes drug requirements and reduces the risk of systemic toxicity but also provides precise dermatomal coverage, making it particularly advantageous for elderly patients and those with comorbid conditions. Given its high success rate (96.6%) and favorable safety profile, segmental epidural anaesthesia can be considered a preferred alternative to conventional spinal or general anaesthesia for inguinal hernia repair.

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