Postoperative Analgesia in Breast Cancer Surgery: Safety and Efficiency of Ultrasound Guided Erector Spinae Plane Block

Breast cancer surgery is one of the most common surgeries, due to the high incidence of breast cancer. Unfortunately, patients experience significant postoperative acute pain, placing them at risk for increased clinical morbidity and the development of disabling chronic pain which may rich up to 55% . The intensity of perioperative pain experienced by the patient is one of the best predictors of chronic pain.

However, postoperative analgesia in breast cancer surgery is difficult due to the extensive nature of the surgery and the complex innervation of the breast.

Several newly described regional anesthesia techniques exist to control perioperative pain, including the Paravertebral block (PVB) which has been proved to be the most effective one. The anatomic proximity of the pleura and central neuraxial system makes it a particularly challenging technique and carrying a risk of pneumothorax.

The Erector Spinae Plane Block (ESPB) is a novel interfascial plane block described by Forero et al in September 2016. Local anesthetic injection is performed beneath the erector spinae muscle. Local anesthetic (LA) expected to achieve paravertebral spread of three vertebral levels cranially and four levels caudally, blocking the dorsal and ventral rami of the spinal nerves.The easy, fast and safe execution of ESPB makes it a promising technique in the context of surgical pain during breast cancer surgery.

There is no sufficient randomized controlled trials that assess the effectiveness of ESPB in controlling post-operative breast surgery pain.

The main purpose of this study is to evaluate the postoperative analgesic effect of Ultrasound-guided ESPB in patients undergoing breast cancer surgery.

It is a prospective double blind trial. Sixty female patient aged between 20-65 years old with American Society of Anesthesiologists (ASA) physical status I-II and scheduled for elective surgery for breast cancer were included in the study. Only unilateral surgical procedures will be included. The patients will be randomized into two groups:

Group B (ESP block): Patients in the experimental arm will receive an ESPB prior to induction of general anesthetic.

Group P: (sham ESP block): Patients allocated to the placebo-control arm will receive a placebo injection of normal saline in almost identical fashion to that of the ESP block.

Intravenous access will be obtained with an 18-gauge intravenous (IV) cannula in the contralateral upper limb of the surgical site and monitors (pulse oximeter, electrocardiography, non-invasive blood pressure (NIBP) will be applied.

All blocks will be performed before induction of general anesthesia.

ESPB technique:

The ESPB will be done in the sitting position using linear ultrasound probe (L10) of MySonoU6 machine. The blocks will be performed at the T4-T5 level of the spine using an in-plane approach. A linear probe will be placed 2-3 cm laterally to the spine using a sagittal approach. Three muscles will be identified superficial to the transverse process shadow as follows: trapezius, rhomboid major, and erector spinae. Local anesthetic (LA) is injected between the erector spinae muscle and transverse process. Following confirmation of the correct position of the needle tip with administration of 0.5-1 ml of the fluid a total of 40 mL of fluid will be injected next. The distribution will be observed in both cranial and caudal directions.

* Group B (ESP block) will receive 150 mg of Ropivacaine : 40cc of Ropivacaine (3.75mg/cc).
* Group P (Sham ESP block) will receive 40 cc of normal saline.

General Anesthesia:

All patients will receive pre-oxygenation with 100% O2 for 3 min. Anesthesia will be induced by using fentanyl 2μg/kg, Propofol 2-3 mg/kg and Atracurium 0.5 mg/kg. During anesthesia maintenance, monitoring will include Pulse Oximetry, an Electrocardiogram, Non-Invasive Blood Pressure (NIBP), end-tidal Carbon Dioxide, End-Tidal Sevoflurane, and Fraction of Inspired Oxygen.

The reinjection of 0.5μg/kg of fentanyl will be given intraoperatively either when heart rate or Non-Invasive Blood Pressure (NIBP) report an increase by more than 20% of the basal records.

Paracetamol 1 g IV and Ketoprofen 100 mg intramuscular (IM) will be administered for postoperative analgesia at the end of surgery. Anesthesia will be discontinued and tracheal extubation will be done once patient fulfilled the extubation criteria. In the recovery room, all patients will be given a patient-controlled analgesia device (PCA) containing morphine 1 mg/ml-1 ,set to deliver a 1 mg bolus dose of morphine, with an 5 min lockout time and 12mg 1 h limit. Postoperative pain will be assessed using a visual analogue scales (VAS) scores ranging from zero (no pain) to 10 (worst imaginable pain). The VAS scores will be recorded at 1,2,4,8 6, 12, 16, 20 and 24 h postoperatively.If VAS scores are superior to 6 the investigators will resort to rescue analgesia as following: If 6\<VAS\<8: paracetamol 1g IV will be administered and if VAS\>8: paracetamol 1g IV associated to ketoprofen100mg IM.

Incidence of nausea and vomiting, and total morphine consumption during the 24-h postoperative period will be recorded.

Eligibility Criteria:
Inclusion Criteria:

* 25-65 years old
* ASA I-II
* Undergoing unilateral breast cancer surgery

Exclusion Criteria:

* obesity (body mass index \>40 kg/m2)
* Preoperative chronic dependence upon opioid and NSAID medications
* History of psychiatric or neurological disease
* Patients with chronic pain syndromes
* allergy to local anaesthetics
* other contraindications to peripheral nerve blocks
* Patients' refusal to participate