The Effect of Adding Morphine as an Adjuvant to Local Anesthetic in Erector Spinae Plane Block on Management of Acute Post Mastectomy Pain : A Randomized Controlled Trial

Breast cancer is the most common cancer in women requiring surgery . Breast surgeries is one of the most common type of surgery performed worldwide . Of these patients 30% to 50% will report moderate to severe acute pain. Pain if underestimated and untreated will affect patient's recovery , hemostasis, and lead to delayed discharge from PACU and increase length of hospital stay.Variety of local and regional anesthetic procedures which include local anesthetic infiltration , field block , intercostal nerve block , brachial plexus block and thoracic epidural anesthesia for breast surgery have considard as well established option to provide analgesia ,reduce post operative pain score , reduce opioid requirement , decrease post operative nausea and vomiting ,decrease pulmonary complication and duration of stay in PACU and specific to breast surgery there is also some evidence that regional anesthesia may help attenuate the surgical stress response and indirectly contribute to tumor inhibition by reducing opioid usage which has been implicated in immunosuppression and cancer progression. Pectoralis nerve block , serratus anterior nerve block and paravertebral nerve block are used for breast surgery analgesia . pectoralis nerve block and paravertebral block entrenched in clinical practice , and both of these techniques are shown to be effective as analgesic after breast surgery . However these techniques have many drawbacks . For example after performing the pectoralis nerve block the spread of the local anesthetic may interfere with surgical field . Paravertebral block can cause pneumothorax and epidural or intra thecal injection of the local anesthetic. Erector spinae plane block (ESPB) is a relatively new technique that was first described by Forero et Al in 2016 , they found that administration of local anesthetic below the erector spinae muscle produce extensive sensory block over the ipsilateral thorax . Forero et Al proposed that the injected local anesthetic spread anteriorly through the costo transverse foramen to its site of action at the origin of dorsal and ventral rami .Various adjuvants such as morphine , clonidine ,fentanyl, dexamethasone ,epinephrine ,and dexemedetomidine have been used with local anesthetic for improving and prolonging the postoperative analgesia with encouraging result . Morphine is a potent opioid analgesic widely used for treatment of severe pain. sedation scales assess the level of consciousness through behavioral observation and/ or stimulation of the patient. Ramsay sedation scale classifies level of awareness into six categories, this scale has multiple advantages :it is reproducible ,easy executed and has good applicability. This has made the scale the most widely used to assess level of sedation .Several rating scales have been developed to measure quality of recovery after surgery and anaesthesia, but the most extensively used after surgery is the QoR-40 scale,a40-item questionnaire that provide a global score and subscore across five dimension :patient support, comfort, emotion, physical independence, and pain.