A randomized double blinded comparative interventional study to assess the post operative analgesic effect of Magnesium sulphate versus Dexamethasone as adjuvants to Bupivacaine in ultrasound guided Transversus Abdominis Plane Block in open unilateral hernia surgeries

Inguinal hernia is one of the most commonly performed surgical procedures which is associated with moderate to severe intensity of pain that is at its most extreme in the first 24 hours post surgery. Inadequate pain relief in these patients can lead to delayed recovery extended duration of hospital stays and also lead to persistent pain after surgery

Abdominal field blocks and costo iliac block have been used in anaesthesia for surgery involving the anterior abdominal wall for severe decades through innervation of the anterior abdominal wall arises from the spinal nerves T7 to L1. The aim of TAP block is to deposit  local anaesthetic in the plane between  internal oblique and Transversus abdominis muscle. By blocking  these nerves, the innervation to abdominal skin, muscles and parietal peritoneum can be interrupted. The somatic component is blocked and aids in decreased consumption of opioid in 24 hours after surgery as opioid causes nausea, constipation and urinary retention as well as negative consequences such as respiratory depression, hormonal , sedation and post operative ileus. Various adjuvants have been used with local anaesthetics to improve the quality and duration like Dexamethasone, magnesium sulphate, adenosine and buprenorphine ,dexmedetomidine in TAP block to prolong the analgesic action in lower abdomen

Bupivacaine is a long acting aminoamide local anaesthetic agent. Chemically Bupivacaine is a racemic  mixture  of levo  and dextro  isomers. It blocks impulse conduction in nerve fibres via reversible of sodium influx and it has more action on A and C fibres which are meant for pain transmission

Magnesium sulphate is a N methyl D aspartate  antagonist. It  acts by non competitive antagonism blocks the voltage dependent ion channel . It blocks calcium influx which inhibits central sensitisation and decrease pre existing pain hypersensitivity and provides better post operative analgesia

Dexamethasone is a long acting glucocorticoid . It inhibits potassium conductance by binding to receptors which decrease the activity of nociceptive Cfibres and prolong the duration of  analgesia through anti inflammatory effects and local vasoconstrictive action