Comparison of two ultrasound guided nerve blocks in patients undergoing breast surgery: effects on post-surgery pain.

In the operation theatre of Safdarjung Hospital, new delhi, general anesthesia will be induced with midazolam 1mg, fentanyl 1.5 mcg/kg, propofol 1- 2 mg/kg and vecuronium bromide 0.1 mg/kg and trachea of the patient will be intubated, Patient will be given either ultrasound guided paravertebral block (n=25) or ultrasound guided serratus anterior plane block (n=25) with 20 ml of 0.5% bupivacaine by a staff anesthesiologist with experience of both the blocks ( more than 50 each). 1. Group SAB:--- Ultrasound guided serratus anterior plane block- This block will be given in supine position. Linear transducer (8-13Mhz) probe of ultrasound machine (Sonosite M-Turbo, Sonosite Inc., USA) will be placed in mid-clavicular region of thoracic cage in the sagittal plane. The latissimus dorsi, teres major and serratus anterior muscles will be identified between 4th and 5th rib. The fascial plane between serratus anterior muscle and latissimus dorsi muscle will be identified. 20 G sonosonic needle will be introduced in-plane with respect to ultrasound probe from superio-anterior to posterio-inferior direction. Under continuous ultrasound guidance, 20ml of 0.5% bupivacaine will be injected superior to the serratus anterior muscle. Group PVB: Ultra sound guided paravertebral block--- This block will be given in the lateral position. The transducer (linear, 38mm, high frequency 8-13MHz) probe of ultrasound machine (Sonosite M-Turbo, Sonosite Inc., USA) will be placed parallel to the spine, above the transverse process of T4 vertebrae and T5 vertebrae. The thoracic paravertebral space will be identified as a wedge shaped hypoechoic space between internal intercostal membrane and pleura. 20 G sonosonic needle will be inserted in an out of plane approach and advanced under ultrasound guidance until the tip penetrates internal intercostal membrane. Hydro-dissection will be used to locate the tip of needle. 20ml of 0.5% bupivacaine will be injected and movement of pleura downwards will be used as confirmation of block. Anesthesia will be maintained with O2/ N2O/ 0.8-1% Isoflurane. At the end of surgery, . Neostigmine 50 mcg/kg and glycopyrrolate 10 mcg/kg will be given I.V. and trachea extubated. Patient is shifted to PACU for intensive monitoring of vitals.A resident blinded to block will assess the pain relief and adverse effects at regular intervals for next 72 hrs.