European Journal of Cardiovascular Medicine

Supraclavicular brachial plexus block is a widely used regional anesthesia technique for upper limb surgeries due to its effectiveness and safety¹. The addition of adjuvants to local anesthetics has become a common practice to enhance the quality and duration of the block, reduce postoperative pain, and minimize the need for supplemental analgesia^2,3. Among various adjuvants, corticosteroids, particularly dexamethasone, have gained attention due to their potent anti-inflammatory and analgesic properties⁴.

Dexamethasone, a synthetic corticosteroid, has been shown to improve the quality of regional anesthesia by prolonging the duration of both sensory and motor blocks. It achieves this by inhibiting prostaglandin production and suppressing inflammatory responses, which contribute to pain and tissue edema⁵. Previous studies have demonstrated that the addition of dexamethasone to local anesthetics can reduce the incidence of postoperative pain, nausea, and vomiting, while enhancing the overall efficacy of the block^6,7.

However, the optimal dosage of dexamethasone as an adjuvant in brachial plexus block remains a subject of debate. While several studies have used varying doses, there is limited evidence comparing the effects of different doses of dexamethasone in supraclavicular brachial plexus block for upper limb orthopedic surgeries. Therefore, this study aims to compare the efficacy of two doses of dexamethasone—4 mg and 8 mg—when used as adjuvants to 0.25% bupivacaine in supraclavicular brachial plexus block, focusing on their effects on the onset and duration of block, postoperative analgesia, and incidence of side effects.

Study Design and Setting:
This was a prospective, randomized, controlled trial conducted at Government Medical College , Ananthapuramu, from January 2020 to December 2020. The study aimed to compare the efficacy of 4 mg and 8 mg dexamethasone as adjuvants to 0.25% bupivacaine in supraclavicular brachial plexus block for upper limb orthopedic surgeries.

Study Population:
The study included 60 adult patients (aged 18-65 years) who were scheduled for elective upper limb orthopedic surgeries under supraclavicular brachial plexus block. Patients were excluded if they had a history of allergy to local anesthetics or corticosteroids, had a pre-existing neurological disorder, or were pregnant or breastfeeding.

Randomization and Group Allocation:
Patients were randomly allocated into two groups using a computer-generated random number sequence:

Group A (Bupivacaine + 4 mg Dexamethasone): 30 patients received 4 mg dexamethasone with 0.25% bupivacaine.

Group B (Bupivacaine + 8 mg Dexamethasone): 30 patients received 8 mg dexamethasone with 0.25% bupivacaine.

Intervention:
All patients received a supraclavicular brachial plexus block performed by an experienced anesthesiologist. The block was achieved by using a single injection technique with a 22-gauge needle, injecting a total volume of 30 ml of the local anesthetic solution, consisting of 0.25% bupivacaine (27.5 ml) and either 4 mg (Group A) or 8 mg (Group B) dexamethasone (2.5 ml).

Outcome Measures:
The primary outcomes were:

Onset time of sensory and motor blocks, defined as the time from the injection of the anesthetic to the complete loss of sensation and motor function, respectively.

Duration of sensory and motor blocks, defined as the time from the onset of the block to the complete return of sensation and motor function.

Secondary outcomes included:

Duration of postoperative analgesia, measured from the time of the block until the first request for analgesia.

Incidence of postoperative nausea and vomiting, recorded as the percentage of patients experiencing nausea and/or vomiting during the first 24 hours after surgery.

Gastrointestinal side effects, including any symptoms like bloating, indigestion, or abdominal discomfort.

Analgesic requirement, defined as the percentage of patients needing additional analgesics (pentazocine) during the postoperative period.

Statistical Analysis:
Data were analyzed using SPSS version 20.0. Continuous variables were expressed as mean ± standard deviation, and categorical variables were expressed as percentages. Between-group comparisons were performed using independent t-tests for continuous variables and chi-square tests for categorical variables. A p-value of less than 0.05 was considered statistically significant.

Ethical Approval:
The study was approved by the Institutional Ethical Committee, and written informed consent was obtained from all participants before enrollment.

The results of the study comparing the efficacy of 4 mg and 8 mg dexamethasone as adjuvants to 0.25% bupivacaine in supraclavicular brachial plexus block for upper limb orthopedic surgeries are summarized below.

The onset times for sensory and motor blocks were significantly faster in Group B (Bupivacaine + 8 mg Dexamethasone) compared to Group A (Bupivacaine + 4 mg Dexamethasone). The onset of sensory block in Group B was 4.2 ± 0.6 minutes, while in Group A, it was 5.4 ± 0.7 minutes (p < 0.05). Similarly, the onset of motor block in Group B was 4.2 ± 0.6 minutes, whereas Group A had a time of 5.4 ± 0.7 minutes (p < 0.05) (Table 1).

Table 1: Onset and Duration of Block

Regarding the duration of the blocks, Group B showed a significantly longer duration of both sensory and motor blocks. The duration of sensory block in Group B was 225.4 ± 12.3 minutes, significantly longer than the 190.3 ± 11.2 minutes in Group A (p < 0.01). Similarly, the motor block duration in Group B was 180.1 ± 10.6 minutes, compared to 155.2 ± 9.7 minutes in Group A (p < 0.01) (Table 1).

Postoperative analgesia was also significantly prolonged in Group B. The duration of postoperative analgesia in Group B was 650.4 ± 43.5 minutes, compared to 543.6 ± 35.2 minutes in Group A (p < 0.01) (Table 2). Additionally, the incidence of postoperative nausea and vomiting was lower in Group B (8%) compared to Group A (16%), with a significant difference between the two groups (p < 0.05) (Table 2).

Table 2: Postoperative Analgesia and Nausea

In terms of gastrointestinal side effects, Group B experienced fewer side effects, with only 4% of patients reporting them, compared to 12% in Group A (p < 0.05) (Table 3). Furthermore, the need for additional analgesia in the form of pentazocine was lower in Group B, with 10% of patients requiring it, compared to 18% in Group A (p < 0.05) (Table 3).

Table 3: Gastrointestinal Side Effects and Analgesic Requirement

The aim of this study was to evaluate the efficacy of two different doses of dexamethasone (4 mg and 8 mg) as adjuvants to 0.25% bupivacaine in supraclavicular brachial plexus block for upper limb orthopedic surgeries. The results demonstrated significant differences in the onset and duration of the block, postoperative analgesia, and side effects between the two groups, supporting the hypothesis that increasing the dose of dexamethasone improves the clinical outcomes of the block.

Onset of Block: The onset of both sensory and motor blocks was significantly faster in the 8 mg dexamethasone group (Group B) compared to the 4 mg group (Group A), with a p-value of less than 0.05. This is consistent with previous studies that have shown that the addition of corticosteroids to local anesthetics accelerates the onset of block, likely due to their anti-inflammatory properties that reduce tissue edema and inflammation around the nerve, thus enhancing conduction block (8, 9). Dexamethasone may facilitate faster neural blockade by decreasing the surrounding inflammatory response, thereby aiding in quicker conduction (8, 9).

Duration of Block: The duration of both sensory and motor blocks was significantly prolonged in Group B. The sensory block in Group B lasted approximately 225 minutes, compared to 190 minutes in Group A (p < 0.01), and the motor block lasted 180 minutes in Group B compared to 155 minutes in Group A (p < 0.01). These findings align with existing literature, where the use of dexamethasone has been shown to extend the duration of regional anesthesia. Dexamethasone likely prolongs the block by decreasing inflammatory mediators and by stabilizing the neuronal cell membrane, which enhances the duration of the block (10, 11).

Postoperative Analgesia: The duration of postoperative analgesia was significantly longer in Group B, with patients in Group B experiencing approximately 650 minutes of pain relief compared to 543 minutes in Group A (p < 0.01). This prolonged analgesic effect can be attributed to the potent anti-inflammatory properties of dexamethasone, which reduce postoperative pain by limiting the inflammatory response at the surgical site and surrounding the nerve (9, 11). Similar findings have been reported in studies evaluating corticosteroids as adjuvants in regional anesthesia, reinforcing the beneficial impact of dexamethasone on analgesic duration (10, 12).

Side Effects: The incidence of postoperative nausea and vomiting was significantly lower in Group B (8%) compared to Group A (16%) (p < 0.05). This suggests that the higher dose of dexamethasone may have a beneficial effect in reducing nausea and vomiting, common side effects associated with regional anesthesia and opioid usage (11). Furthermore, Group B also experienced fewer gastrointestinal side effects, with 4% of patients reporting issues compared to 12% in Group A (p < 0.05). This reduction in side effects further supports the safety profile of using higher doses of dexamethasone as an adjuvant (9, 10).

Analgesic Requirements: In addition to improved analgesia, Group B patients had a lower requirement for supplemental analgesics. Only 10% of patients in Group B required pentazocine for additional pain relief compared to 18% in Group A (p < 0.05). This reduction in analgesic consumption reflects the superior and longer-lasting pain relief provided by the higher dose of dexamethasone (9, 12). The prolonged analgesic effect of the higher dose of dexamethasone significantly reduces the need for additional opioid analgesics, highlighting its efficiency as an adjuvant in supraclavicular brachial plexus block (11).

Limitations and Future Directions: While this study provides valuable insights into the use of dexamethasone as an adjuvant in supraclavicular brachial plexus block, it has some limitations. The study was conducted at a single center with a relatively small sample size, which may affect the generalizability of the results. Future studies with larger sample sizes and multicenter trials are recommended to confirm these findings. Additionally, the long-term effects of dexamethasone, including any potential risks of prolonged corticosteroid use, were not evaluated in this study. Future research should also explore the optimal dose of dexamethasone to balance efficacy and safety.

The addition of 8 mg dexamethasone to 0.25% bupivacaine in supraclavicular brachial plexus block provides faster onset, prolonged duration of block, extended postoperative analgesia, and fewer side effects compared to the 4 mg dexamethasone dose. This study suggests that higher doses of dexamethasone can enhance the overall efficacy of regional anesthesia, making it a promising strategy for improving the quality of postoperative pain management in upper limb orthopedic surgeries.

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