Complication during ultrasound-guided regional block: accidental intravascular injection of local anesthetic.

ULTRASOUND-GUIDED regional blocks are becoming increasingly popular among anesthesiologists. The ultrasonographic image allows real time visualization of anatomical structures, the progression of the needle, and the spread of the injected local anesthetic (LA). The visualization capabilities of ultrasound guidance (USG) are thought to increase the safety of regional blocks when compared with a landmark-guided approach, possibly reducing the risks associated with paresthesia, as well as the frequency of intraneural or intravascular injection of LA drugs. The additional information provided by USG, coupled with the anatomical modifications resulting from the pressure exerted by the ultrasound probe, may also add to or alter the clinical presentation of these adverse events. We present a case of accidental intravascular injection of LA during axillary block, which occurred despite the use of USG. This case demonstrates that although proper use of USG may increase safety compared with landmark-guided peripheral blocks, the risks associated with injection of large amounts of LA are not entirely abolished. The use of USG does not obviate the need for standard safety measures and may alter the effectiveness of traditional signs of intravascular injection.