Incidence of and indications for conversion of cervical plexus block to general anesthesia in patients undergoing carotid surgery: a single center experience

Abstract

Aim: He aim of this paper was to investigate the incidence of and the indications for conversion to general anesthesia (GA) in a large single-center series of patients undergoing carotid surgery under cervical plexus block (CPB).

Methods: With IRB approval we retrospectively analyzed the medical records of all patients who underwent carotid surgery under CPB from November 2007 to October 2010. Cervical plexus was blocked at both the superficial and deep levels. An intraluminal shunt was inserted in patients who demonstrated signs of inadequate cerebral perfusion upon carotid clamping (CC). Propofol was given to patients reporting pain or discomfort throughout the procedure. The primary outcomes were the number and percentage of conversions to GA as well as the indications for this intervention. The secondary outcome was the incidence of partial cervical block failure, defined as the need for supplemental propofol administration for pain relief during surgery.

Results: In total, 1464 carotid surgical procedures were performed under CPB in 1305 consecutive patients during the investigated period. Conversion to GA was required in 17 (1.2%) patients. The most common reason for conversion to GA was persisting neurological deterioration upon CC and intraluminal shunt insertion, which was recorded in 8/17 (47.1%) procedures. Other indications to convert were systemic toxicity of local anesthetics, pain, general discomfort and restlessness during surgery, and acute myocardial infarction.

Conclusion: Cervical plexus block for carotid surgery is associated with a low rate of conversions to GA. Neurological deterioration upon carotid clamping and local anesthetic toxicity are identified as the most common indications for such intervention.