SAP Block to Reduce Post Mastectomy Pain

The Serratus anterior Plane (SAP) Block has proven to be an effective component of multimodal analgesic regimens for a variety of thoracic procedures. It is designed to block primarily the thoracic intercostal nerves and to provide complete analgesia of the lateral part of the thorax and it may be a viable alternative to paravertebral blockade and thoracic epidural analgesia and may be associated with fewer side effects. It's straight forward to perform, with high success rate and minimal incidence of complications.

It was reported prolonged numbness over the area supplied by the lateral cutaneous branches of the T2-T9 spinal nerves using only 0.4 ml.kg-10.125% levobupivacaine. This is remarkable, because alternative techniques such as intercostal, interpleural and thoracic paravertebral block require relatively high concentrations and volumes of local anesthetics to produce similarly prolonged, multi-dermatomal thoracic analgesia.The duration of Serratus plane block is limited to the effect of administered local anesthetics (LAs). However, recently adjuvants such as epinephrine, ketamine and clonidine are added to LA solution in concentrations advocated for other peripheral blocks to prolong the effect of block with promising results.

Evidence supporting the presence of N-methyl-D-aspartate (NMDA) receptors in skin and muscles have led to the use of magnesium sulphate (MgSO4) (NMDA antagonist) via different routes for brachial plexus block and via neuraxial route. Until date, no study has been done to evaluate the role of MgSO4 as an adjuvant in SAP block. Therefore, the investigators intended this study to evaluate the role of MgSO4 as an adjuvant to bupivacaine in ultrasound (USG)-guided SAP block for postoperative analgesia in patients scheduled for modified radical mastectomy.

While the key requirement for successful regional anesthetic blocks is ensuring optimal distribution of local anesthetic around nerve structures, ultrasound guidance enables the anesthetist to secure an accurate needle position and to monitor the distribution of the local anesthetic in real time.

Inclusion criteria

• Adult, female patients, ASA physical status I, II, and III aged older than 18 years scheduled for modified radical mastectomy surgery under general anesthesia.

Exclusion criteria

Any known allergies to the study drugs. Anatomical abnormalities or infections in the serratus region. Bleeding disorders e.g. thrombocytopenia, high INR, high PT in chronic liver or impaired kidney). Patients on chronic pain medications or regularly receiving analgesics. Pregnant or breast feeding patients. Body Mass Index (BMI) more than 35.