Regional anesthesia technique in the form of supraclavicular block is widely used to provide analgesia during intraoperative and postoperative period in patients undergoing upper limb surgeries. It avoids the unwanted effect of drugs used during general anesthesia (Murphy 2000), reduces the use of opioids, hospital stay, as well as cost and results in better patient satisfaction (Shrestha et al. 2003). Postoperative pain is an unpleasant outcome in any surgical operation and it may delay the functional recovery of the patients (Gan 2017).
Supraclavicular brachial plexus block is widely used in our institute for arm, forearm and hand surgeries because of simple, safe, and effective technique for upper limb surgery. Perineural dexamethasone provided early onset of block with longer duration of analgesia (Golwala et al. 2009). In another study, it was found to reduce overall pain scores and analgesic requirements with preoperative use of oral as well as IV dexamethasone (Elhakim et al. 2003).
Dexamethasone sodium phosphate is water soluble, so safe for parenteral use. Dexamethasone, synthetic glucocorticoids has a potent anti-inflammatory and immunosuppressant property (Barnes 1998). Analgesic mechanism of dexamethasone may be due to inhibition of synthesis of cyclooxygenase and lipo-oxygenase in peripheral tissues and central nervous system, thus reducing prostaglandin production, plays a main role for pain and inflammation (Hong et al. 2010). In addition, dexamethasone decreases bradykinin also responsible for pain in the inflamed tissues and operated area. According to other theory, analgesic property of dexamethasone may be alteration in the function of potassium channels in the excitable cells by blocking transmission of nociceptive myelinated type C fibers and suppressing ectopic neuronal discharge (Johansson et al. 1990).
Pathak et al. (Pathak et al. 2012) and Shreshtha et al. (Shrestha et al. 2003) had used 8 mg of perineural dexamethasone and found prolongation of the duration of analgesia. Similarly, some studies had reported that intravenous dexamethasone also increases the duration of analgesia in supraclavicular block (Dhanger et al. 2016; Saba and Bhalotra 2020).
Some authors had observed equally prolonged duration of analgesia with 8 mg of perineural and intravenous dexamethasone (Mathew et al. 2019; Aliste et al. 2017; Abdallah et al. 2015).
There is controversy about the dose and route of dexamethasone. Perineural dexamethasone may be more prone for peripheral neurotoxicity in vitro studies (Williams et al. 2011). However, in some studies perineural dexamethasone has been used without any neurotoxicity (Pathak et al. 2012; Shrestha et al. 2003). Single dose of intravenous dexamethasone is widely used for prophylaxis to prevent nausea and vomiting without any systemic toxicity (Elhakim et al. 2003).
In a study, single dose of 10 mg of intravenous dexamethasone has been found effective to prolong the duration of analgesia of supraclavicular block without any systemic toxicity (Saba and Bhalotra 2020).
Hence in our study, we used dose of 8 mg of intravenous dexamethasone along with supraclavicular block. In our study, we found statistically significant difference in onset of sensory block and motor block in group D (8.68 ± 1.81, 11.12 ± 1.58) min and in group C (11.0 ± 2.34, 13.2 ± 1.65) min (P < 0.05). However, Mathew et al. (Mathew et al. 2019) found that patients receiving 8 mg perineural dexamethasone with 25 ml of 0.5% bupivacaine had faster onset of sensory and motor blockade than in patients receiving 8 mg of intravenous dexamethasone with 25 ml of 0.5% bupivacaine in supraclavicular block.
In our study, we also compared the total duration of sensory and motor block in both the groups. The duration of sensory block in group D 843.6 ± 62.56 min was longer as compared to 281.28 ± 22.42 min in group C (P < 0.0001). The motor block in group D was 576.8 ± 70.40 min as compared to 204.2 ± 12.96 min in group C which was also highly significant (P < 0.0001).
Dhanger et al. (Dhanger et al. 2016) had used 2 mg of intravenous dexamethasone with 25 ml of 0.5% bupivacaine and had showed that the mean duration of motor block in group D was 6.12 ± 0.48 h to 4.33 ± 0.47 h in group C (P < 0.05). Godbole et al. (Godbole et al. xxxx) used 0.05 mg/kg of perineural and intravenous dexamethasone with mixture of local anesthetic agents and reported the total duration of motor block was significantly prolonged in BD group 12 ± 2.11 h as compared to BI group 7.17 ± 0.95 h (P < 0.001).
In our study, the duration of motor block was 9–10 h in group D with mixture of local anesthetic agents which was prolonged than other study. Both low (2–4 mg) and high doses (8–10 mg) of intravenous dexamethasone used with local anesthetic agents provided longer duration of motor block.
Mathew et al. (Mathew et al. 2019) found that the duration of analgesia in group DP was 817.2 ± 88.011 min to 858.00 ± 86.168 in group DI and difference was found statistically not significant with a P = 0.104. Similarly Abdallah et al. (Abdallah et al. 2015) and Desmet et al. (Desmet et al. 2013) found comparable results with 8 mg and 10 mg dexamethasone by IV and perineural route in supraclavicular block in terms of prolong duration of analgesia. However in our study, the duration of analgesia in group D was 895.6 ± 43.98 min and 324.4 ± 27.36 min in group C. This difference was found to be statistically significant (P < 0.001).
However, Godbole et al. (Godbole et al. 2019) suggested that low-dose perinueral dexamethasone, when used in supraclavicular block significantly, provides longer duration of analgesia as against IV dexamethasone after supraclavicular block.
Meta-analysis done by Bei et al. (Bei et al. 2021) of twelve RCTs with 1345 patients concluded that perineural dexamethasone is better to IV dexamethasone for prolonging the duration of analgesia, sensory block and motor block. In a meta-analysis done by Baeriswyl et al. (Baeriswyl et al. 2017) in approximately 900 patients, it was concluded that when perineural dexamethasone added with bupivacaine but not with ropivacaine mildly prolong the duration of analgesia as compared to intravenous dexamethasone, without affecting other secondary pain related outcomes.
Abdallah et al. (Abdallah et al. 2015) had not observed steroid induced hyperglycemia but found prolong duration of analgesia up to 25 h with 8 mg IV dexamethasone along with long-acting local anesthetic agents in supraclavicular block. Desmet et al. (Desmet et al. 2013) had noticed prolonged duration of analgesia up to 21 h in supraclavicular block with 10 mg IV dexamethasone and association of more incidence of hyperglycemia.
In our study, we found that 8 mg IV dexamethasone with mixture of local anesthetic agents in supraclavicular block prolongs the duration of analgesia up to 15 h respectively but did not notice steroid induced hyperglycemia.