European Journal of Cardiovascular Medicine

Postoperative pain following cardiac surgery—particularly via median sternotomy—is typically severe and, when inadequately managed, contributes to a cascade of adverse outcomes. These include impaired respiratory mechanics, delayed mobilization, increased risk of atelectasis and pneumonia, heightened sympathetic response, and even cardiovascular instability [1]. Poor pain control is also associated with postoperative delirium, prolonged mechanical ventilation, extended ICU stays, and increased healthcare costs [2].

The current standard for postoperative analgesia in cardiac surgery primarily relies on systemic opioids and NSAIDs. Although opioids are effective, they are often limited by side effects such as respiratory depression, sedation, nausea, ileus, and the potential for opioid-induced hyperalgesia and dependence [3]. NSAIDs carry significant risks in cardiac patients, including bleeding, renal impairment, and impaired wound healing, especially in those receiving anticoagulation or undergoing cardiopulmonary bypass [4].

Regional anaesthetic techniques offer an attractive alternative, especially in patients for whom neuraxial blocks like thoracic epidural analgesia (TEA) are contraindicated due to anticoagulation concerns. TEA, though effective, is associated with rare but serious risks such as epidural hematoma in anticoagulated patients, limiting its widespread use in cardiac surgery [5].

In recent years, the advent of ultrasound-guided fascial plane blocks has revolutionized chest wall analgesia by offering safer and more targeted options. Among these, the pecto-intercostal fascial block (PIFB) has emerged as a particularly promising technique for median sternotomy. By delivering local anaesthetic into the fascial plane between the pectoralis major and the external intercostal muscles, PIFB blocks the anterior branches of thoracic intercostal nerves (T2–T6), providing focused analgesia without the risks associated with neuraxial blocks [6].

A variety of local anaesthetics have been utilized for PIFB, including bupivacaine, a long-acting amide widely used in regional anaesthesia. However, bupivacaine’s racemic formulation carries a known risk of cardiac and central nervous system toxicity. Its S-enantiomer, levobupivacaine, offers a similar pharmacologic profile in terms of potency and duration but with a safer toxicity margin, particularly important in cardiac surgical patients [7].

Despite the growing use of PIFB in cardiac surgery, limited evidence directly compares the clinical performance of bupivacaine and levobupivacaine in this context. This study was therefore undertaken to evaluate and compare the analgesic efficacy, opioid-sparing effect, and recovery profile of bupivacaine versus levobupivacaine when used in ultrasound-guided bilateral PIFB in patients undergoing cardiac surgery via median sternotomy.

Aim and Objectives

Aim

The study was undertaken to compare the efficacy of ultrasound-guided pecto-intercostal fascial block (PIFB) using levobupivacaine versus bupivacaine, both combined with fentanyl, in the management of postoperative pain and recovery outcomes in patients undergoing cardiac surgery via median sternotomy.

Objectives

1. To evaluate and compare postoperative pain control between the two groups using the Visual Analogue Scale (VAS) at multiple time points over the first 24 hours post-extubation.
2. To assess and compare the total opioid (fentanyl) consumption within 24 hours postoperatively as a surrogate for analgesic efficacy.
3. To compare intraoperative hemodynamic stability, including heart rate, systolic and diastolic blood pressure, mean arterial pressure, and oxygen saturation between the two groups.
4. To evaluate recovery outcomes, including:

• Time to tracheal extubation
• Duration of ICU stay
• Total number of ICU days

To observe and compare any adverse events or complications, including hypotension, bradycardia, postoperative nausea and vomiting (PONV), or block-related complications such as hematoma, infection, or local anaesthetic toxicity.

Study Design and Setting

This was a prospective, randomized, double-blind, controlled clinical trial conducted at a tertiary care institute in Mumbai. Institutional Ethics Committee approval was obtained prior to study initiation. All patients provided written informed consent before enrollment.

Participants

A total of 110 adult patients, aged 18 to 70 years, with ASA physical status II–III, scheduled for elective cardiac surgery via median sternotomy under general anaesthesia, were enrolled in the study.

Inclusion Criteria:

·         Age ≥18 years

·         Body weight between 50–100 kg

·         Patients undergoing elective cardiovascular surgery via median sternotomy

·         Written informed consent obtained

Exclusion Criteria:

·         Emergency surgeries

·         Allergy to local anaesthetics or fentanyl

·         BMI >40

·         Left ventricular ejection fraction <25%

·         Systemic or injection-site infections

·         Coagulopathy (INR >1.4, platelets <100,000) or ongoing anticoagulation

·         History of previous sternotomy

·         Pregnancy or breastfeeding

Randomization, Blinding, and Interventions

Patients were randomized into two groups using a computer-generated randomization sequence. Group L (Levobupivacaine group, n = 56) received 20 mL of 0.25% levobupivacaine combined with 25 mcg of fentanyl per side, totalling 40 mL of local anaesthetic and 50 mcg of fentanyl per patient per block. Group B (Bupivacaine group, n = 54) received the same volume and opioid dose, using 0.25% bupivacaine instead of levobupivacaine.

Both patients and data collectors were blinded to group allocation. A third-party anaesthesiologist, not involved in data collection or block administration, prepared all syringes identically to ensure allocation concealment and maintain blinding integrity.

Anaesthesia Protocol

All patients underwent standardized general anaesthesia. Induction included intravenous midazolam (0.05–0.1 mg/kg), fentanyl (2 µg/kg), etomidate (0.3 mg/kg), and vecuronium (0.08–0.1 mg/kg) to facilitate tracheal intubation. Anaesthesia was maintained with sevoflurane in oxygen-air mixture, with intermittent doses of fentanyl and vecuronium as clinically indicated.

Hemodynamic monitoring included continuous electrocardiography (ECG), pulse oximetry (SpO₂), non-invasive and invasive arterial blood pressure monitoring, central venous pressure (CVP), and end-tidal carbon dioxide (EtCO₂) measurement.

 Pecto-Intercostal Fascial Block (PIFB) Technique

Each patient received two ultrasound-guided bilateral PIFBs: the first administered preoperatively and the second postoperatively. The preoperative block was performed after induction of general anaesthesia but prior to the surgical incision. The second block was administered at the conclusion of surgery, immediately before the patient was shifted to the intensive care unit (ICU). This dual-timing strategy was employed to ensure both intraoperative and sustained postoperative analgesia.

Data Collection and Outcome Measures

Primary Outcomes:

·         Postoperative pain scores using the Visual Analogue Scale (VAS, 0–10) at 2, 4, 8, and 16 hours post-extubation

·         Total fentanyl consumption over the first 24 hours

Secondary Outcomes:

·         Time to extubation (in minutes)

·         Duration of ICU stay (in days)

·         Intraoperative hemodynamic parameters: HR, SBP, DBP, MAP, SpO₂

·         Complications: Hypotension, bradycardia, postoperative nausea and vomiting (PONV), and any block-related issues (e.g. hematoma, infection, LAST, pneumothorax)

Statistical Analysis

Data were analyzed using SPSS version 25.0 (IBM Corp., Armonk, NY). Continuous variables were expressed as mean ± standard deviation and compared using the independent-samples t-test. Categorical variables were assessed using the Chi-square test or Fisher’s exact test as appropriate. A P-value < 0.05 was considered statistically significant.

1. Study Population Characteristics

A total of 110 adult patients scheduled for elective cardiac surgery via median sternotomy were enrolled and randomized into two study groups:

• Group L (Levobupivacaine + fentanyl, n = 56)
• Group B (Bupivacaine + fentanyl, n = 54)

Baseline demographic and anthropometric characteristics were statistically comparable between the two groups (Table 1). The mean age of participants was 55.59 ± 21.53 years in Group L and 55.04 ± 11.98 years in Group B. The difference was not statistically significant (P = 0.814; Independent t-test).

Regarding gender distribution, 76.8% (n = 43) of patients in Group L and 83.3% (n = 45) in Group B were male. The remaining were female (23.2% in Group L, 16.7% in Group B), with no significant difference between groups (P = 0.477; Fisher’s exact test).

Anthropometric variables, including weight, height, and body mass index (BMI), were similar between groups. The mean BMI was 24.38 ± 2.49 kg/m² in Group L and 24.56 ± 1.83 kg/m² in Group B, with no statistically significant difference (P = 0.667; Independent t-test). These findings confirm adequate randomization and baseline comparability.

Table 1. Baseline Demographic and Anthropometric Characteristics

                          Note: Values are expressed as mean ± standard deviation or number (percentage), as appropriate.

2. Intraoperative Hemodynamic Parameters

Intraoperative hemodynamic stability was assessed using continuous monitoring of heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and oxygen saturation (SpO₂) throughout the procedure. Comparison between Group L (Levobupivacaine, n = 56) and Group B (Bupivacaine, n = 54) revealed no statistically significant differences in any measured parameter (Table 2).

The mean intraoperative heart rate was 76.45 ± 8.36 beats per minute in Group L and 77.15 ± 7.45 bpm in Group B (P = 0.583; Independent t-test). Similarly, SBP and DBP were comparable between groups, with mean SBP of 120.71 ± 8.89 mm Hg in Group L and 120.87 ± 7.77 mm Hg in Group B (P = 0.924), and DBP of 78.41 ± 6.90 mm Hg vs. 78.87 ± 6.63 mm Hg, respectively (P = 0.743).

Mean arterial pressure (MAP) during surgery also showed no significant difference: 92.43 ± 7.16 mm Hg in Group L and 92.80 ± 6.60 mm Hg in Group B (P = 0.778). Oxygen saturation (SpO₂) remained stable in both groups, with mean intraoperative values of 98.86 ± 0.63% in Group L and 98.83 ± 0.60% in Group B (P = 0.799).

These findings confirm that both analgesic regimens provided equivalent intraoperative cardiovascular stability, with no adverse hemodynamic effects observed.

Table 2. Intraoperative Hemodynamic Parameters

Note: Values are expressed as mean ± standard deviation. SBP = systolic blood pressure; DBP = diastolic blood pressure; MAP = mean arterial pressure; SpO₂ = peripheral oxygen saturation.

3. Operative Parameters

Key intraoperative parameters, including total duration of surgery and cardiopulmonary bypass (CPB) time, were measured in hours and compared across groups. As shown in Table 3, both metrics were statistically similar between the groups.

The mean total duration of surgery was 5.77 ± 1.01 hours in Group L (Levobupivacaine) and 5.80 ± 0.98 hours in Group B (Bupivacaine) (P = 0.851; Independent t-test). Similarly, the mean CPB time was 2.39 ± 0.62 hours in Group L and 2.17 ± 0.43 hours in Group B, with no statistically significant difference (P = 0.051). These results confirm that the choice of local anaesthetic had no impact on operative or perfusion duration during cardiac surgery.

Table 3. Comparison of Operative Parameters between Study Groups

         Note: Values are expressed as mean ± standard deviation.

4. Postoperative Pain and Analgesic Requirement

Postoperative pain was assessed using the Visual Analogue Scale (VAS) at defined intervals: post-extubation, 2 hours, 4 hours, 8 hours, and 16 hours. In addition, cumulative fentanyl consumption and the need for rescue analgesia were recorded over the first 24 hours following surgery.

VAS scores were consistently low in both groups, and no statistically significant differences were observed at any measured time point. At post-extubation, the mean VAS score was 1.98 ± 0.35 in the levobupivacaine group and 1.91 ± 0.40 in the bupivacaine group (P = 0.304; Independent t-test). At 8 hours, both groups reported their highest scores, with values of 3.00 ± 0.00 and 2.98 ± 0.13, respectively (P = 0.311). At all-time intervals, P-values exceeded 0.05, confirming statistical equivalence.

Cumulative fentanyl consumption in the first 24 hours was 161.6 ± 21.3 mcg in the levobupivacaine group and 165.74 ± 27.17 mcg in the bupivacaine group (P = 0.376; Independent t-test), indicating no significant difference in opioid requirement between the two regimens. Notably, none of the patients in either group required rescue analgesia throughout the postoperative period, suggesting adequate pain control in both study arms.

These findings confirm that both levobupivacaine and bupivacaine, when used in ultrasound-guided pecto-intercostal fascial block, provide comparable and effective analgesia following cardiac surgery.

Table 4. Comparison of Postoperative Pain Scores and Opioid Consumption

Note: VAS scores are presented as mean ± SD at each time point. Fentanyl values are cumulative over 24 hours. No rescue analgesia was needed in either group.

5. Recovery Outcomes

Postoperative recovery was evaluated by measuring the time to extubation and the duration of intensive care unit (ICU) stay. These metrics were compared between the two groups to assess any influence of the analgesic regimen on early postoperative recovery. The two groups demonstrated similar recovery profiles in terms of extubation time and ICU stay, as presented in Table 5 and Figure 1 below.

The mean time to extubation was 165.21 ± 42.12 minutes in the levobupivacaine group and 155.46 ± 42.12 minutes in the bupivacaine group. This difference was not statistically significant (P = 0.227; Independent t-test), indicating that the choice of local anaesthetic did not affect the timing of tracheal extubation.

The duration of ICU stay was also comparable. Patients in the levobupivacaine group stayed for an average of 3.20 ± 0.80 days, while those in the bupivacaine group stayed for 3.09 ± 0.73 days. The difference was not statistically significant (P = 0.479; Independent t-test), suggesting similar recovery profiles in both groups.

Table 5. Postoperative Recovery Outcomes

                    Note: Values are expressed as mean ± standard deviation.

6. Complications and Safety Outcomes

Postoperative complications and block-related adverse events were monitored to assess the safety profile of bilateral ultrasound-guided pecto-intercostal fascial block using either levobupivacaine or bupivacaine.

Transient episodes of hypotension were observed in 2 patients (3.6%) in the levobupivacaine group and in 2 patients (3.7%) in the bupivacaine group. Bradycardia occurred in 1 patient (1.8%) in each group. None of these differences were statistically significant (P > 0.999; Fisher’s exact test).

Postoperative nausea and vomiting (PONV) was reported in 3 patients (5.4%) in the levobupivacaine group and in 3 patients (5.6%) in the bupivacaine group (P > 0.999; Fisher’s exact test). No cases of block-related complications such as local anaesthetic systemic toxicity (LAST), hematoma, pneumothorax, or infection were observed in either group.

These results confirm that both levobupivacaine and bupivacaine are safe and well-tolerated for use in pecto-intercostal fascial block in patients undergoing cardiac surgery.

Table 6. Complications and Adverse Events

                 Note: Values are expressed as number (percentage). PONV = postoperative nausea and vomiting.

Pain management following median sternotomy remains a clinical challenge due to the invasive nature of the procedure and the complex innervation of the thoracic wall. Various systemic analgesics and regional techniques have been explored, with variable success and safety profiles. In recent years, fascial plane blocks such as the ultrasound-guided pecto-intercostal fascial block (PIFB) have gained popularity for cardiac surgeries due to their efficacy and lower risk of neural injury. Ultrasound guidance provides the advantage of direct visualization, allowing for precise deposition of the anaesthetic and minimizing the risk of complications such as neurovascular damage [8].

In the present study, we compared the intraoperative hemodynamic stability, postoperative analgesia, recovery metrics, and safety profile of PIFB using either bupivacaine or levobupivacaine in 110 patients undergoing elective cardiac surgery. Levobupivacaine, the S-enantiomer of bupivacaine, is associated with lower cardiotoxicity and neurotoxicity and offers comparable potency, making it a compelling alternative for regional blocks in cardiac surgery [9].

Demographic Comparison

The two groups were demographically similar, with mean ages of 55.04 ± 11.98 years (bupivacaine) and 55.59 ± 21.53 years (levobupivacaine). This is lower than the mean age reported in studies by Khera et al. and Wang et al., which generally included older populations [10,11]. The gender distribution in our study, with a predominance of males in both groups, mirrors trends observed in other investigations, including those by Zhang et al. and Yang Zhang et al. in adult and pediatric populations, respectively [12,13]. The mean BMI was comparable to that seen in Wang et al.’s study [11], though slightly lower than in Khera et al.’s data [10].

Intraoperative Hemodynamic Effects

No significant differences in heart rate, systolic or diastolic blood pressure, mean arterial pressure, or oxygen saturation were observed between the two groups throughout the intraoperative period. This suggests that both agents provide equivalent hemodynamic stability when used in PIFB. Notably, hemodynamic data collected during and shortly after sternotomy showed no exaggerated sympathetic responses, indicating effective preoperative analgesia. To our knowledge, no other studies have specifically reported hemodynamic response immediately post-sternotomy for PIFB, making this a novel observation in our study.

Operative Duration and Bypass Time

The duration of surgery and cardiopulmonary bypass (CPB) time were statistically similar in both groups. In our study, the total duration of surgery was 5.80 ± 0.98 hours in the bupivacaine group and 5.77 ± 1.01 hours in the levobupivacaine group; bypass durations were 2.17 ± 0.43 and 2.39 ± 0.62 hours, respectively. This aligns with findings from Zhang et al. [12], where operative and bypass times were not significantly different between intervention and control groups. Unlike Wang et al. [11], who found reduced surgical times in the PIFB group, our findings reflect the fact that PIFB was administered in both groups, with only the anaesthetic agent differing.

Extubation and Recovery

The mean time to extubation was 165.21 ± 42.12 minutes in the levobupivacaine group and 155.46 ± 42.12 minutes in the bupivacaine group, with no statistically significant difference. Previous studies have shown reduced time to extubation with PIFB compared to control groups [11,12]. However, because both of our groups received PIFB, no between-group differences were expected. Similarly, ICU stays were nearly identical between the groups (3.20 ± 0.80 vs. 3.09 ± 0.73 days), although slightly longer than those reported by Wang et al. and Khera et al. [10,11]. This could be attributed to institutional practices such as prolonged ICU monitoring until drain and arterial line removal due to workforce limitations.

Pain Scores and Opioid Use

Postoperative VAS scores remained low (≤3) in both groups throughout the first 16 hours, with no significant differences. The dual timing of block administration (preoperatively and again post-sternum closure) likely contributed to this sustained analgesic effect. Our results support the findings of Liu et al. [14] and Khera et al. [10], who reported effective pain control with PIFB. Most existing studies compare PIFB to saline or placebo, and find PIFB superior. Our study uniquely compares two local anaesthetic agents and confirms their equivalence in clinical effect. Unlike Wang et al. [11], who found lower dynamic pain scores (e.g., during coughing) in the PIFB group, our data reflected resting scores only.

Notably, no patients in either group required rescue opioids postoperatively, highlighting the efficacy of PIFB. This is consistent with the findings of Zhang et al. [12], where opioid consumption was significantly reduced in the PIFB group compared to placebo. In our study, all patients received IV paracetamol and ketorolac patches postoperatively, which likely supported the analgesic regimen but did not confound the comparison between groups.

Safety Profile and Complications

No significant block-related or systemic complications were observed in either group. Minor occurrences of hypotension, bradycardia, and PONV were similar across both groups and did not require intervention. This aligns with the high safety profile reported by previous authors, including Horlocker et al. [15], Casati and Putzu [9], and Liu et al. [14]. Notably, Wang et al. [11] reported more opioid-related complications in their control group, supporting the role of regional blocks in minimizing adverse effects.

Limitations

This study was conducted at a single centre with a modest sample size, which may limit the generalizability of the findings. The study was not double-blinded, and although analgesic administration protocols were standardized, subjective factors such as pain perception and ICU extubation practices could introduce variability. Additionally, dynamic pain scores (e.g., during coughing or movement) were not recorded, which may have provided further insight into functional analgesia.

Ultrasound-guided bilateral pecto-intercostal fascial block using either bupivacaine or levobupivacaine provided effective and comparable postoperative analgesia, hemodynamic stability, and recovery outcomes in patients undergoing cardiac surgery via median sternotomy. No significant difference was observed in pain scores, opioid consumption, time to extubation, or ICU stay between the two groups. Both agents demonstrated excellent safety profiles. Given its lower cardiotoxicity, levobupivacaine remains a suitable alternative to bupivacaine for PIFB, though their analgesic efficacy appears clinically equivalent in this setting.

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