PECS I and II blocks are thought to be quite safe because the area of interest is not surrounded by any important neurovascular bundles [2,3]. Kumar [4] investigated the effectiveness of performing a bilateral PECS block with ultrasound guidance in patients undergoing heart surgery via a midline sternotomy. They discovered that this method significantly enhances patient comfort and satisfaction while promoting improved pulmonary recovery. The authors concluded that the PECS block is a simple, safe, and highly effective approach that is appropriate for postoperative cardiac surgery patients within a multimodal analgesia framework, leading to better clinical outcomes. The utilization of ultrasound guidance simplifies the implementation of this block and provides a relatively short learning curve, contributing to its growing acceptance and importance. It is often used as an alternative to thoracic paravertebral block (TPVB) and thoracic epidural block (TEA) [4].

It is evident from the evidence given that early extubation and less perioperative opioid use are beneficial to the patient [4-6]. Effective pain management is crucial for respiratory function and metabolic processes, especially in patients with heart conditions. PECS block offers a major benefit over other regional anesthesia procedures when used in the supine position because it is easy to implement and shouldn't interfere with the operating room's workflow. It also shows great promise as a post-operative analgesic and rescue block for cardiac surgery [4].

The long-acting local anesthetic ropivacaine has a lower affinity for lipids compared to bupivacaine, and this reduced lipophilicity correlates with a diminished likelihood of causing cardiotoxicity and toxicity in the central nervous system [7].

Dexmedetomidine is a powerful and targeted agonist of the α2-adrenoreceptor. It possesses properties that provide pain relief, reduce anxiety, induce sedation and hypnosis, lower the need for anesthesia, and function as a local anesthetic [8]. Dexmedetomidine may improve the efficacy of local anesthetics through various mechanisms. These include its actions within the central nervous system, vasoconstriction facilitated by α-2 adrenergic receptors, diminishing inflammatory responses, directly affecting peripheral nerves, and encouraging activity-dependent hyperpolarization by inhibiting the hyperpolarization-activated cation (Ih) current [9].

When combined with local anesthetics, dexmedetomidine is well tolerated and does not result in neurotoxicity symptoms, based on preclinical and clinical data currently available [10]. This study suggests that the addition of dexmedetomidine to ropivacaine could improve postoperative pain relief from bilateral PECS block in patients who have undergone cardiac surgery via midline sternotomy, while also extending the duration of anesthesia when compared to the administration of ropivacaine on its own.

METHODS

Mohamed Ahmed Hamed, the principal investigator of this prospective randomized clinical study, registered on ClinicalTrials.gov on October 10, 2024, using the NCT06636578 code. See https://clinicaltrials.gov/ct2; Ct2/show/NCT06636578.

The survey took place from October to December 2024. The local ethics committee (R 611) approved the study, and informed consent was obtained from a total of 90 patients who were set to undergo either coronary artery bypass grafting (CABG) or valve surgeries performed through midline sternotomy.

Inclusion criteria

Ages 20-65, elective valve surgery or CABG alone, and an ejection fraction (EF) more than 35%.

Exclusion criteria

Poor left ventricular function is helped by an intra-aortic balloon pump

A myocardial infarction during the previous seven days, combination procedures (such CABG and other heart/vascular treatments)

Emergency surgery or scenarios that need to be redone

The study excluded patients with hemodynamic instability, an infection at the block site, a local anesthetic allergy, mental illness, a prolonged ventilatory course after surgery, renal or hepatic impairment, creatinine >1.5, and other conditions.

Randomization and blinding

A computer-generated random table was used to randomly assign patients in a 1:1 ratio (using the closed envelope approach).

During the double-blind trial, the participant, assessor, and clinical care team were all blinded to the treatment allocation. A centralized web-based randomized approach was used to ensure allocation concealment.

Each patient underwent a conventional preoperative laboratory test and a preoperative clinical assessment. Patients received training on using the VAS prior to surgery. A visual analog scale (VAS), which uses a 10-cm line, is a pain score with "no pain" on the far left and "the most intense pain" on the far right. It is employed to compare pain levels among patients or to record a patient's discomfort.

Each participant underwent the demonized anesthetic treatment. The main objective of this anesthetic strategy was to facilitate a rapid return to consciousness and defensive reflexes while minimizing residual sedative effects, with a key emphasis on enabling early mobilization. Total intravenous anesthesia (TIVA) involves the continuous infusion of rocuronium, midazolam, and fentanyl.

The sternum was closed for 15 min following surgery, and a 1gram intravenous infusion of paracetamol was administered while TIVA was halted.

After dressing, patients were randomly assigned to three groups:

Group (C) control group (n = 30) would only receive fentanyl at 1μg/kg/h, without any regional anesthetic.

For the other two groups, a regional anesthetic was used, and the surgeon gave each patient 20 milliliters of ropivacaine 0.25% to penetrate the skin around the surgical incision site and the mediastinal drains. Additionally, the following bilateral ultrasound-guided PECS block was performed on each patient in these two groups:

Group (R) (n = 30): got 30 ml of 0.25% plain ropivacaine on each side.

The DR group (n = 30) got 30 mL of 0.25% ropivacaine and 0.5 μg/kg dexmedetomidine on each side.

Technique of ultrasound guided PECS block

A linear ultrasonic transducer operating at 12 MHz was utilized to perform a bilateral PECS block after confirming hemodynamic stability, suitable blood gas levels, balanced electrolytes, a normalized active coagulation time (ACT < 120 seconds), and minimal drainage output. The procedure was performed using a 5-cm, 20-gauge needle, ensuring strict adherence to aseptic techniques. The patient was positioned on their back with the arm slightly raised. An ultrasound probe was positioned inferolaterally along the midclavicular line to visualize both the axillary artery and vein, which facilitated the identification of the pectoralis major, pectoralis minor, and serratus anterior muscles at the fourth rib level.

The needle was positioned in line with the ultrasonic probe. A total of 20 milliliters of a local anesthetic solution was injected into the fascial space between the serratus anterior and pectoralis minor muscles. Following this, an extra 10 milliliters of the solution was administered by pulling back the needle to access the fascial plane located between the pectoralis major and minor muscles. The block was carried out in the same manner on both sides. Remember that the total dosage of local anesthetic cannot above the lethal dose of ropivacaine (3 mg/kg). The patients were then intubated and taken to the Surgical ICU (SICU), where they were closely watched until they regained consciousness. A patient was extubated once they satisfied the requirements for extubation:

Following extubation, an intensivist, who had no knowledge of the study groups, utilized the Visual Analog Scale (VAS) to evaluate pain levels both while at rest and during coughing. This evaluation was performed using a scale ranging from 0 to 10, starting at baseline (0 hours) and continuing to be measured at 3, 6, 12, 18, and 24-h intervals. ​For analytical purposes, pain was categorized into three levels: mild (VAS scores from 0 to 4), moderate (VAS scores from 5 to 7), and severe (VAS scores exceeding 8).

The amount of air inhaled, indicated by the number of balls lifted in an incentive spirometer, was evaluated at regular intervals. Each ball signifies a particular volume: one ball equals 600 mL, two balls represent 900 mL, and three balls indicate 1200 mL.

Every 15 min, a dose of 0.5 to 1.0 micrograms per kilogram of fentanyl was administered to manage breakthrough pain, characterized by a resting Visual Analog Scale (VAS) score exceeding 4. The anesthesiologist assessed the extra analgesic required to reduce the VAS score to between 0 and 4.

The duration of mechanical breathing, the total amount of fentanyl given for breakthrough pain, the occurrence of any issues, and the length of the intensive care unit stay were all noted.

Once the patients had completely recuperated and were able to express their thoughts about the events that occurred during the procedure, they were requested to evaluate their satisfaction with the study by reflecting on any negative or undesirable experiences. Their level of satisfaction was measured using a five-point Likert scale: a score of 1 reflects total dissatisfaction, a score of 2 denotes slight satisfaction, a score of 3 signifies moderate satisfaction, a score of 4 indicates high satisfaction, and a score of 5 represents very high satisfaction.

Primary outcome

1. In the initial 24 h post-surgery, pain assessment was conducted utilizing the Visual Analog Scale (VAS). An intensivist, unaware of the participants’ research group assignments, measured pain levels during periods of rest and while coughing at specific time points: immediately after extubation (0 hours) and subsequently at 3, 6, 12, 18, and 24 h. For the purpose of analysis, pain intensity was classified into three categories: mild (VAS scores from 0 to 4), moderate (VAS scores from 5 to 7), and severe (VAS scores exceeding 8).
2. The total amount of opioids used (from hours 1-24 of ICU admission). The quantity of opioids (mostly equivalent doses of fentanyl amp) utilized during the 24 h following ICU admission.

Secondary outcomes

1. How long does mechanical ventilation last?
2. The likelihood of any issues.
3. length of ICU stays.
4. Patient satisfaction levels were evaluated using a five-item Likert scale.

Statistical analysis and sample size estimation:

The sample size was derived from the primary outcome of the study, which is the visual analog pain score observed in the first 24 h. With the assumption of a two-tailed test and a significance level (α) set at 0.05, along with a power of 80% (β = 0.20), the necessary sample size was calculated to identify an effect size (f) of 0.35. This was based on findings from previous studies examining this primary outcome within this context (mean scores of 2.85, 2.5, and 2.4) and a pooled standard deviation of 0.55 [4,14]. The calculation for the sample size was executed using G*power software, version 3.1.9.6, which also factored in an anticipated dropout rate of 5%, leading to a total required sample size of 90 participants, with 30 assigned to each group.

Data was collected and analyzed using SPSS (Version 21). Numerical and categorical data were categorized appropriately. The Shapiro-Wilk test was employed to assess normality; data with non-significant results were reported as means and standard deviations, followed by one-way ANOVA. Conversely, data with significant results were described in terms of median and inter-quartile range, utilizing the Kruskal-Wallis test. Categorical data were presented as frequencies and percentages, with the chi-square test evaluating relationships between qualitative variables. Fisher's Exact test was applied for cell counts below five. A p-value of less than 0.05 was considered statistically significant, maintaining a 95% confidence interval.

RESULTS

Patients in this study were enrolled between October and December Ninety-seven patients were assessed for eligibility. After excluding 7 patients due to refusal to participate or not meeting inclusion criteria, 90 patients were randomly allocated into one of the 3 study groups. 30 patients in each group were finally analyzed (Figure 1).

Patients in either study group did not differ significantly in demographics, baseline ejection fraction, or type of surgical procedure. The data collected from pain scores, opioid consumption, ICU stay duration, inspiratory flow rates, and patient satisfaction demonstrate significant differences between the study groups (Table 1).

As p-values were less than 0.05 at every recorded time, this Table 2 demonstrates that there is statistical significance between the three study groups with regard to visual analog pain scale during rest throughout the postoperative period.

The visual analog pain scale with cough during the postoperative period was statistically significant for all three study groups, as indicated by the table's p-values, which were less than 0.05 at all times (Table 3).

The three study groups' differences in the amount of time and dosage of analgesic needed were statistically significant, as indicated by the p-values in this table being less than 0.05 (Table 4).

This Table 5 shows that there is statistical significance between the three study groups with regard to inspiratory flow rate as assessed by incentive spirometry after extubation during the postoperative period, since p-values were less than 0.05 at every recorded time.

This Table 6 shows that there is statistical significance in the patient satisfaction score between the three study groups because the p-values were less than 0.05.

DISCUSSION

The effectiveness of using dexmedetomidine alongside ropivacaine in ultrasound-guided pectoral nerve block (PECS) for postoperative pain relief in open heart surgery was examined in this prospective randomized study, focusing on pain levels, analgesic requirements, respiratory function, and patient satisfaction. The application of ultrasound-guided PECS block for multimodal analgesia in chest wall surgeries has significantly surged across various medical institutions. While neuraxial techniques are recognized for providing excellent pain relief in non-cardiac thoracic surgeries, they are typically avoided in cardiac operations due to the fact that most cardiac surgery patients are administered heparin during cardiopulmonary bypass. This increases the rare but serious risk of developing epidural hematomas and experiencing postoperative hemodynamic instability. Avoiding neuraxial needling is especially desirable for heart surgery because there aren't many effective regional anesthetic options. Acute postoperative pain, however, can lead to complications that exacerbate pulmonary issues, including hypoxemia, myocardial ischemia, delayed wound healing, extended hospitalization, and decreased respiratory mechanics [4,11].

The pectoral nerve (PECS) block represents an innovative and less invasive approach to regional analgesia, serving as an alternative to thoracic epidural analgesia for patients undergoing thoracic surgeries. The technique was initially introduced by Blanco [1] for ultrasound-guided breast surgery. There are two types of PECS blocks: PECS I and the modified PECS II. PECS I is a simple and reliable superficial block that focuses on the lateral and medial pectoral nerves located in the interfacial plane between the pectoralis major and minor muscles. It can be utilized for breast surgeries as well as other procedures involving the chest wall [1,4,12]. In our open-heart surgery cases, PECS I alone was unable to fully block the operation region, therefore we investigated combining it with PECS II block. PECS II inhibits the thoracodorsal nerve, the long thoracic nerve, and the thoracic intercostal nerves (T2-T6). We used bilateral PECS I and II to cover the surgical site during open heart surgery.

Dexmedetomidine has a higher affinity for the alpha-2 receptor than clonidine, as seen by its α2:α1 activity ratio of 1620:1 (1620:1 for dexmedetomidine, 220:1 for clonidine). Due to its heightened selectivity for the α2 receptor, especially the 2A subtype, administering higher doses can yield effective sedation and pain relief while minimizing the vascular side effects associated with the activation of α1 receptors [13,14]. In regional procedures like caudal, epidural, upper and lower extremity, and transabdominal plane blocks, dexmedetomidine has shown encouraging results without notable adverse effects. The combination of 0.5 μg/kg of dexmedetomidine with bupivacaine in these blocks has led to an extended period of pain relief and reduced morphine consumption [15]. In their study on breast surgery, Kaur [14] utilized dexmedetomidine as a supplement to ropivacaine within a PECS block. The administration of 1μg/kg dexmedetomidine alongside ropivacaine in the PECS block resulted in extended postoperative pain relief and decreased the need for opioids [14].

Hamed MA and colleagues also proposed the administration of dexmedetomidine during the postoperative phase as a supplementary treatment for patients who have undergone open heart surgery with general anesthesia. This approach aims to reduce the reliance on opioids, which have various side effects, and enhance overall patient satisfaction [16].

The PECS block reduced the intensity of the pain on both the static and dynamic visual analog pain measurements. When dexmedetomidine was given to ropivacaine, the PECS block significantly decreased (P < 0.001) at all postoperative times. Bashandy [17] found that patients in the Pecs group reported significantly reduced pain on the visual analog scale during all test periods when they randomly allocated 120 patients to undergo PECS I/II blocks in addition to general anesthesia as contrasted to general anesthesia and no blocks [17]. After surgery, the PECS group's resting VAS scores were considerably lower than the control groups, per Kumar et al. This was evidenced by the fact that the PECS group utilized rescue analgesia less frequently than the control group, which used it more frequently, over the 24-hour postoperative period [4].

In comparison to the other two groups, the group receiving dexmedetomidine required fewer doses of analgesics and experienced a shorter duration of pain relief. This can be explained by how the PECS block operates and how dexmedetomidine enhances the effects of local anesthetics. These findings are consistent with those from a study by Eldeen et al., which focused on conservative breast cancer surgery. Their research revealed that patients receiving the PECS block required significantly less fentanyl in the first 24 hours after surgery compared to those who received a thoracic epidural, and they also experienced a notably longer period of postoperative pain relief [18]. In their research on surgical procedures for breast cancer, Thomas et al. discovered that the PECS group experienced a notably extended average duration of pain relief and a reduced total requirement for analgesics during the initial 24 hours when compared to the saline group (27.17 ± 18.08 min) (P < 0.002) [19].

According to Kumar [4], the PECS group outperformed the control group in terms of peak inspiratory flow rates at 0, 3, 6, 12, 18, and 24 h (P < 0.05), which is consistent with our findings. On incentive spirometry, patients in the PECS group showed noticeably higher inspiratory flow rates than those in the control group, indicating better pulmonary rehabilitation. This was because the patients in this group had far less postoperative discomfort, even when coughing, which made it easier for them to expel secretions. Because of improved pain management, individuals in the PECS group may have required fewer opioids during the postoperative phase, resulting in a quicker recovery and rehabilitation [4].

Compared to patients in the other two groups, those who underwent PECS block with dexmedetomidine experienced better analgesia, which facilitated a quicker extubation and a noticeably shorter ventilator duration (P < 0.001). With a P value < 0.0001, Kumar et al. found comparable outcomes and approximate timings for the PECS block (108.5 ± 24.34 min) and placebo (206.3 ± 47.05) [4].

Multimodal analgesia, which integrates various strategies such as regional anesthesia, may help to decrease both opioid usage and the adverse effects associated with opioids, and it could also lead to shorter stays in intensive care units and hospitals. According to Kamal [20], the average length of ICU stay for patients in the PECS block group was considerably shorter than that of the control group, with a P-value of less than 0.05. Specifically, the PECS block group had an average stay of 52 hours (95% CI 43.522-62.378), compared to 80.40 hours (95% CI 64.310-96.490) for the control group. These findings align with the results seen in the current study [20].

Zafar [21] performed PECS II for cardiac implantable electronic devices and showed great patient satisfaction (81.7%) [21]. Our findings align with the study by Salem et al., which compared pectoral nerve block (PECS) and thoracic paravertebral block (TPVB) as supplementary techniques to general anesthesia during simple mastectomy. The results indicated that the satisfaction score for the PECS group was substantially greater, measuring 2.66, compared to the TPVB group’s score of 2.26 [22].

Compared to no regional therapy, PECS block improves postoperative nausea and vomiting and offers analgesia. The likelihood of experiencing nausea and vomiting after surgery decreased from 30.8% (95% Confidence Interval: 25.7%, 36.3%) to 18.7% (95% Confidence Interval: 14.4%, 23.5%; p = 0.01), according to Grape et al.'s thorough review and meta-analysis [23]. The PECS group reported less pain and used less opioids and analgesics that induce nausea and vomiting during the postoperative phase, which may account for this relevance to our current investigation [23].

At elevated doses, dexmedetomidine can lead to bradycardia and hypotension alongside its sedative and anxiolytic properties. In the present study, participants who received dexmedetomidine showed a greater occurrence of bradycardia compared to the other two groups. This observation is consistent with the research by Kaur [14], who analyzed the effects of adding dexmedetomidine to ropivacaine in a PECS block during breast surgery. Their findings revealed that, following 20 minutes of induction, the heart rate in the group treated with dexmedetomidine and ropivacaine was significantly lower than in the group that only received ropivacaine. While none of the patients required active treatment for this condition, the effects persisted for two hours post-surgery [14]. Blood pressure exhibited a biphasic response that depended on the dosage when dexmedetomidine was given. In low doses, it decreases vascular resistance, heart rate, and blood pressure predominantly through its impact on α2 receptors. Conversely, when administered rapidly or in large doses, its α2 selectivity is diminished, leading to a reduction in heart rate and an increase in blood pressure. Nonetheless, this response gradually normalizes over time.

The clinical trial participants were entirely Egyptian, which limited the data's generalizability to other racial groups and is one of the study's shortcomings. We were unable to investigate the effect of PECS block on persistent postsurgical pain because to the small sample size, restricted follow-up, and need to add 10% to the sample size estimations to account for projected dropouts. Furthermore, we did not monitor the patients' postoperative sedation and anxiolysis levels.

CONCLUSION

Combining ropivacaine and dexmedetomidine during the PECS block effectively reduced pain intensity on both the static and dynamic visual analog pain measures. It dramatically reduced the time and analgesics required to address postoperative pain in heart surgery patients.

ACKNOWLEDGMENT

Not applicable.

AUTHORS' CONTRIBUTIONS

Data collection: MAH, MME, WST, ASG

Data analysis: MAH, YSM, ISA, OSF, AAL

Writing: MAH, YSM, MME, AMA, AAM, DLA

Revising: MAH, RAA, MAS, MMS, MHR

Study design: MAH, RAA, MAS, IEE

Patient recruitment: MAH

All authors contributed equally to this work.

Corresponding author and the guarantor: MAH

FUNDING

The authors declare no sources of support for this manuscript.

AVAILABILITY OF DATA AND MATERIALS

The datasets used and analyzed during the current investigation are accessible from the corresponding author on reasonable request.

DECLARATIONS

Ethics approval and consent to participate:

Fayoum University Hospital's ethical review board authorized the study design (R 611) prior to the study's commencement date in accordance with the applicable standards and laws. All patients provided written informed consent.

Consent for publication: Not Applicable”.

Competing interests: The authors have declared no conflicts of interest.

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  Table 1
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  Table 2
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  Table 5
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  Table 6