Perfusion index versus conventional method for determining success of Ultrasound guided supraclavicular brachial plexus block


Introduction

Supraclavicular nerve block is a popular approach for anaesthesia for upper limb surgeries. Conventional methods for evaluation of block success are time consuming and need patient cooperation.

 Aim

The aim of this study is to evaluate whether the perfusion index (PI) can be used to predict and provide a cut-off value for ultrasound-guided supraclavicular nerve block success.

 Primary objective

To compare the conventional method with perfusion index

Secondary objective

To predict the cut off value for perfusion index

Inclusion  criteria

Patients aged between 18 and 60 yr who were to undergo elective upper limb orthopaedic procedures under ultrasound-guided supraclavicular nerve block.

Exclusion criteria were Allergy to drug,Infection,Coagulopathy

 Methodology

Prospective observational study Sample  size 100 patients

The supraclavicular nerve block has to be done under usg guidance of a linear transducer over the supraclavicular fossa in the coronal oblique plane immediately superior to the midclavicular point.Patient in semi-sitting position, with the head of the patient turned away from the side to be blocked.

 A 22-gauge insulated block needle is in-plane (lateral to medial) to the ultrasound probe. The brachialplexus  will be identified as a compact group of nerves, hypo-echoic, round or oval, located lateral and superficial to the pulsatile subclavian artery and superior to the first rib. A volume of 20ml of localanaesthetic(bupivacaine 0.5%, 10ml and lidocaine 2%, 10 ml) is  injected under vision strictly perineural to surround all the nerve cords.

 The limb is evaluated for block success every 3 min for the sensory block and every 5 min for the motor block. Sensory function is assessed using pinprick in the dermatomal areas supplied by the four main nerves (median nerve, radial nerve, ulnar nerve, and musculocutaneous nerve). Motor block assessed by the ability to flex the elbow and the hand against gravity.

 The supraclavicular nerve block is considered successful with regard to neurologicalexaminationwhen brachial plexus dermatomes (C5–T1) were completely blocked.

 The PI  is measured using pulse oximetry applied on the index finger. The PI will be recorded at baseline and at 10, 20, and 30 min after local anaesthetic injection in both the blocked limb and the contralateral unblocked limb using two separate oximeters. The PI ratio is  calculated as the ratio between the PI at 10 min after injection and the baseline PI. In every patient, a comparison between the blocked and unblocked limb is  performed.

 Expected outcome

PI when compared to compared to conventional may provide better block success