Minimum Effective Volume of A Combination of Ropivacaine and Dexmedetomidine for Supraclavicular Brachial Plexus Block Using Ultrasound and Nerve Stimulator Guided Technique for War Wounded Soldiers in the Covid Era

Background: Our objective was to find out the effective volume required in supraclavicular block to achieve effective surgical anaesthesia for upper limb surgeries in war wounded soldiers in India, when ropivicaine and dexmedetomidine are used in combination and the procedure is performed under ultrasound guidance and nerve stimulator confirmation.

Methods: Study done at a tertiary trauma military hospital in India. USG guided and nerve stimulator confirmed supraclavicular blocks were perfomed starting with initial volume of 30ml of solution containing ropivacaine (0.75%) plus dexmedetomidine 0.5mcg/ml which was subsequently varied by 3 ml according to the response of the previous patients (step-up, step-down technique). Based on this, effective volume 50% (EV 50) of the drug combination would be determined.

Results: Minimum Effective Volume in 50% individuals (MEV 50) for a combination of 0.75% ropivacaine and 0.5mcg/ml of dexmedetomidine for ultrasound and nerve stimulator guided brachial plexus block via supraclavicular approach is 11.30ml. Minimum Effective Volume in 90% individuals (MEV 90) for a combination of 0.75% ropivacaine and 0.5mcg/ml of dexmedetomidine for ultrasound and nerve stimulator guided brachial plexus block via supraclavicular approach is 20.48ml. Duration of block – 7.81 hrs (average), 8 hrs (median)

Conclusions: USG guided and nerve stimulator confirmed supraclavicular brachial plexus block has the advantange of being able to give lesser amount of drug solution and also increase the safety margin of the procedure. During the COVID times, the availability of drugs are restricted. Aerosol dispersion during intubation can also be avoided.

Keywords: Regional Anaesthesia, Ropivacaine, Dexmed, War wounded.