الفهرس 
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Abstract
Successful interscalene brachial plexus block relies on proper techniques of nerve localization, needle placement, concentration and volume of local anesthetic used. One of the most important benefits of real-time ultrasound imaging during peripheral nerve blockade is allowing the operator to distribute LA uniformly around the target nerve. This may reduce the amount of LA required to successfully block the nerves so, reduce the risk of systemic LA toxicity and other complications.
Increasing the duration of local anesthetic action is often desirable because it prolongs surgical anesthesia and analgesia. Investigators have tried mixing local anesthetics with adjuvant drugs in an attempt to prolong analgesia from nerve blocks. Steroids have powerful anti-inflammatory as well as analgesic property. Perineural injection of steroids is reported to influence post-operative analgesia. Also dexmedetomidine which is an agonist of α2 adrenergic receptors reduces the onset time and improves the duration of sensory and motor blocks.
This study compared between low dose, high dose dexamethasone and dexmedetomidine during interscalene brachial plexus block for shoulder arthroscopic surgery. We made a comparison between four groups each group twinty patients scheduled for elective shoulder arthroscopy under ultrasound interscalene block. group C anesthetized by injecting 35ml levobupivacaine +2ml normal saline. group L anesthetized by injecting 35ml levobupivacaine +4mg dexamethasone +1ml normal saline. group H anesthetized by injecting 35ml levobupivacaine +8mg dexamethasone. group D anesthetized by injecting 35 ml levobupivacaine +100ugm dexmedetomidine+1ml normal saline. Ultrasound-guided interscalene brachial plexus block was done using linear ultrasound probe by in-plane technique to visualize the roots of brachial plexus. All groups were assessed for efficacy of the block by assessing sensory and motor block onset and duration and the quality and duration of postoperative analgesia.
All groups were observed and assessed for incidence of adverse effects (pneumothorax, Horner’s syndrome, hematoma, vascular injury, hoarseness, seizures, systemic toxicity and central neuroaxial blockade). Statistical comparison of continuous variables was analyzed using Shapiro test, ANOVA, Kruskall Wallis test and chi-square test. Statistical significance was assumed at P < 0.05.
Addition of dexamethasone and dexmedetomidine for interscalene block decreased the onset time of sensory and motor block by statistically significant values. The duration of sensory and motor blocks were also prolonged when compared to the control group. These effects were more prominent in group H and D.
There were also better quality of postoperative analgesia with lower levels of visual analogue scale and lower analgesic consumption in dexamethasone and dexmedetomidine group than control group. Also stress response measured by blood cortisol showed significant reduction in H and D than C.
Dexmedetomidine 100ug is as effective as Dexamethasone 8mg and better than dexamethasone 4mg as adjuvants with local anesthetic in interscalene brachial plexus block during shoulder arthroscopy with a significant reduction in intraoperative HR and MAP in dexmedetomidine than dexamethasone.