Does radial or median nerve blocks affect the area and blood flow of radial artery?

Abstract

BACKGROUND AND AIMS\nRadial artery is a common site of cannulation in acute care setting. There are conflicting reports as to which nerve, radial or median or both supplies the radial artery. We did this prospective study in patients undergoing minor procedures under peripheral nerve blocks to ascertain which nerve block, radial or median increases the cross sectional area and blood flow in the radial artery.\n\n\nMETHODS\nNinety ASA I/II patients undergoing upper limb minor surgeries under various blocks (radial or median or radial\u2009+\u2009median nerve) were enrolled in this study. Patients in group R were those who received Ultrasound-guided (USG) radial nerve block, group M median nerve block while group MR received both the nerve blocks. The primary objective was to assess the increase in cross sectional area (CSA) of radial artery in the groups after the block. Secondary objectives included assessment of time average maximum velocity (TAMAX) and blood volume (BV) after the block.\n\n\nRESULTS\nThe CSA, TAMAX and BV of radial artery increased in all the three groups. Within each group the difference between the preblock and postblock parameters were highly significant. However, the differences are greater in groups M and M\u2009+\u2009R than in group R; (P\u2009<\u20090.001.) CONCLUSION: Ultrasound-guided median nerve block causes arterial vasodilation, and an increase in radial artery blood flow velocity. There was no added benefit of radial block along with median block in increasing the blood flow further.