Acute postoperative pain begins with surgical trauma and ends with tissue healing. Post operative pain if not adequately managed leads to untoward events such as pain, reduced organ function and prolonged hospital stay. A greater emphasis is now being laid on the management of post operative pain relief. Following surgical procedures, the nociceptive signals increase the autonomic reflexes, metabolic and endocrine responses, thereby causing a delay in the restoration of body functions. Hence, appropriate management of post operative pain is necessary. The most commonly used pharmacological agents are opioids and non-steroidal anti-inflammatory drugs (NSAIDs). There are a number of side effects associated with the use of opioids namely nausea, vomiting, respiratory depression and sedation. NSAIDs, on the other hand, are associated with decreased hemostasis, gastrointestinal bleeding and renal dysfunction. Due to these adverse events, regional anaesthetic techniques are being increasingly used. It helps to reduce the consumption of such analgesic medications and their associated adverse events.

In upper limb surgery pain relief is the major concern for the anesthesiologist. In published literature, high opioid consumption has been observed in surgeries for fracture of humerus during intra and post operative period.3 Intravenous (IV) opioid through patient controlled analgesia is associated with side effects but its use with peripheral nerve blocks have shown to provide better outcome in terms of pain relief and patient satisfaction.  Recently, use of ultrasound guidance for peripheral nerve blocks has reduced the complication rate leading to decreased hospital stay and reduced cost.

The role of sympathetic nervous system has been established in chronic pain states like complex regional pain syndrome (CRPS). Mc Donell et al demonstrated the role sympathetic nervous system in a case series of four patients undergoing operative treatment for humeral fractures. Stellate ganglion block (SGB) with local anaesthetic was given to patients preoperatively and effective post operative analgesia up to 48 hours was reported. In patients undergoing upperlimb surgeries, Kumar et al conducted the first randomised controlled trial to evaluate the role of pre operative SGB on post operative analgesia. In the lignocaine group the mean hourly tramadol consumption was significantly reduced as compared to the saline group. The study of Kumar et al demonstrated a postoperative tramadol sparing effect following pre operative SGB in patients undergoing upper limb orthopaedic surgery under general anaesthesia.

Stellate ganglion block has an established role in upper limb surgeries now. At times when the access to medical care is limited maximum reporting of pain was made. The role of adjuvants to peripheral nerve blocks which increase the duration of analgesia and reduce requirement of analgesics has also been described in the literature. 

Corticosteroids are widely used in peripheral nerve blocks for acute pain control and injected in the epidural space to treat radicular pain.⁷ Dexamethasone, a high potency, long acting corticosteroid commonly used to treat post operative nausea, vomiting and pain, and is considered a good candidate to augment block duration. Dexamethasone prolongs peripheral nerve block when added to short acting local anaesthetics. Intravenous dexamethasone has been shown to attenuate the post operative need for analgesics in different clinical settings, including after orofacial, general, urological and orthopedic surgeries.

So far, no study had compared tramadol sparing effect of addition of dexamethasone to lignocaine during preoperative SGB or IV with control in upper limb surgeries. Therefore the present study was planned to evaluate the tramadol sparing effect of addition of dexamethasone to lignocaine during preoperative SGB in upper limb surgeries. 

As per pilot cases conducted for tramadol sparing effect of preoperative SGB for postoperative pain relief in patients undergoing upper limb surgeries the mean tramadol consumption was 130 mg with standard deviation of 24.To estimate a difference of consumption of 20% tramadol our sample size came out to be 16 patients per group, with a power of 80% and confidence interval of 95%.Considering a dropout rate of 20% the sample size came out to be in 19 patients per group.

The present study was a prospective, randomised, double blind, placebo controlled clinical trial which was started after approval from the institute ethics committee (EC/2016/0070) dated 5.12.2016 and registration with Clinical trial registry of India (CTRI/2017/02/007851). The study evaluated the tramadol sparing effect of dexamethasone as an adjuvant to lignocaine in pre operative SGB in patients undergoing upper limb surgeries.

Fifty seven patients (19 per group) of ASA grade I-II, aged 18-60 years of either sex having BMI 18-30 kg.m^-2 scheduled to undergo upper limb orthopaedic surgery under general anaesthesia were enrolled in the study after taking written informed consent.

A preoperative SGB was given in all the patients. Using a para-tracheal out of plane technique (between thyroid gland and common carotid artery), a blunt regional anaesthesia needle (22G, 50mm Stimuplex A; BBraun, Melsung, Germany) was advanced after retracting the carotid artery laterally and directing towards the longus colli muscle. Following which 4 ml of study drug per group allocation was given sub fascially.

SGB_Dex (n = 19) received preoperative ultrasound guided SGB with 4 ml of a solution (3 ml 2% lignocaine + 1 ml dexamethasone (4mg) = final volume of 4 ml) and 15 ml of normal saline by IV route.

SGB_C (n = 19) received preoperative ultrasound guided SGB with 4 ml of a solution (3 ml 2% lignocaine + 1 ml normal saline = final volume of 4 ml) and 15 ml of normal saline by IV route.

SGB_IV (n = 19) received preoperative ultrasound guided SGB with 4 ml of a solution (3 ml 2% lignocaine + 1 ml normal saline = final volume of 4 ml) and 1 ml dexamethasone (4mg) diluted in 15 ml of normal saline by IV route.

The primary outcome of the study was total tramadol consumption at the end of 48 h post operatively. All the patients were observed for any inadvertent motor or sensory blockade, change in VAS score, temperature change, features of Horner’s syndrome - ipsilateral ptosis, miosis and chemosis at intervals of 5 min each up to 15 mins after SGB placement. Following SGB patients received a standard technique of general anaesthesia. Post operatively each patient received multi modal analgesia with IV paracetamol 1gm, diclofenac 75 mg and tramadol PCA. All patients were monitored postoperatively for MAP, PR, RR, VAS at rest, VAS on movement and tramadol consumption at the following time interval - 0, 2, 4, 6, 8, 12, 24, 36 and 48 h. Nausea and vomiting and side effects like shivering, pruritus were also noted during the study period. Patient satisfaction score was taken at 24 and 48 h. Observations were analysed statistically and the following inferences were drawn.

·         The total tramadol consumption at 0, 6 and at the end of 48 h was significantly reduced (p value 0.029, 0.008 and 0.003 respectively) in the SGB_Dex group as compared to SGB_C group. The total tramadol consumption at the end of 48 h was significantly reduced in SGB_Dex group as compared to SGB_IV group (p value 0.003).

·         No patient in SGB_DEX required tramadol PCA after 4 h post operatively. In SGB_C, no patient required tramadol PCA after 12 h post operatively and in SGB_IV, no patient required tramadol PCA after 8 h post operatively.

·         The postoperative VAS at rest was significantly reduced at 0, 2, 6, 12, 36 and 48 h (p values = 0.014, 0.013, 0.018, 0.023, 0.017 and 0.005 respectively) in the SGB_Dex as compared to the SGB_C group and the postoperative VAS at rest was significantly reduced at 2 h in the SGB_Dex group as compared to the SGB_IV group ( p value 0.006).

·         The postoperative VAS on movement was significantly reduced at 0, 2, 6, 12, 24 and 48 h (p values = 0.040, 0.022, 0.050, 0.043, 0.005 and 0.034 respectively) in the SGB_Dex group as compared to the SGB_C group.

·         The hemodynamic parameters were within normal physiological range for most of the time intervals in all the three groups.

·         Only three patients reported transient nausea and none of the patients reported      vomiting, pruritus or shivering.

·         Patients reported superior patient satisfaction score at 24 and 48 h (p values = 0.002 and 0.004 respectively) in SGB_Dex as compared to the SGB_C and SGB_IV.

·         No serious adverse effects were reported in any patient during the entire study period.

CONCLUSION

Perineural dexamethasone with lignocaine in SGB significantly reduced tramadol consumption at 48 h post operatively as compared to IV dexamethasone and control group.