Abstract ID: A19

Abstract Title: Does General Anesthesia or Deep Sedation Increase the Risk of Nerve Injury Associated with Peripheral Nerve Blocks?

Authors: Ajakwe R¹, Reyes E², Thomas K³, Admir H⁴
St. Lukes-Roosevelt Hospital New York NY USA¹, St. Lukes-Roosevelt Hospital New York NY USA², St. Lukes-Roosevelt Hospital New York NY USA³, St. Lukes-Roosevelt Hospital New York NY USA⁴
Poster Type: Poster

ABSTRACT BODY

INTRODUCTION
It is controversial whether administration of peripheral nerve blocks (PNBs) carries with it a higher risk of nerve injury in an anesthetized patient versus an awake patient. This is because the premise for performing PNBs only in awake patients is based on the assumption that an awake patient provides information (e.g., pain on injection) that will prevent intraneural injection and therefore avoid nerve injury. We reviewed the available literature that supports or refutes the practice of administering PNBs in anesthetized patients.
METHODS
The relevant clinical literature search for this review was conducted using the nationwide MEDLINE and OVID medical online databases. Specific key words that were searched include “regional anesthesia”, “nerve block”, “complications”, “nerve injury”. In the search and selection process, we tried to use the “best evidence” in the form of prospective, randomized clinical trials (RCT)[1]. However, because few such studies were found, we also included observational studies and case reports[2]. Neuraxial anesthesia related injuries and injuries to the spinal cord were excluded in this analysis.
RESULTS
The literature search identified 16 articles that met our search criteria: two prospective studies, one closed claims study and 13 case reports, Table 1. There were 50 reports of nerve injuries related to the PNBs; peripheral nerve stimulator (PNS) was used in 21 of all the cases. With the exception of one case, all cases of reported nerve injuries were in awake patients (defined as GA or deep sedation during block placement). A total of 13 patients (26%) reported pain during needle placement or local anesthetic injection. In the 21 patients who had PNBs by PNS technique only 4 (19%) reported pain during needle placement or local anesthetic injection, Table 2. Permanent nerve injury (injury lasting longer than 6 months) was reported in 67% of injured patients. In at least 3 patients, the information on pain on injection/insertion was used by anesthesiologists to either reposition the needle or abort the injection of local anesthetic; regardless, the three patients went on to develop nerve injury.
DISCUSSION
Nearly all reported injuries after PNBs occurred in awake and not in anesthetized patients. Contrary to the common belief, only few patients who developed injury had pain or paresthesia on needle insertion or local anesthetic injection. Moreover, neurologic injury could not be prevented even when pain on injection led to discontinuation of injection. Although avoidance of deep sedation and GA before PNBs has been suggested to decrease the risk of peripheral nerve injury with PNBs, the reviewed literature suggest there is no evidence that such practice decreases the risk of nerve injury. Instead, future efforts should be directed toward developing more objective nerve localization and injection monitoring techniques to more reliably detect and prevent intraneural injection.

References
1. Haynes RB, Wilczynski N: Developing optimal search strategies for detecting clinically sound studies in Medline. J Am Med Inform Assoc 1994;1:447-58
2. Pronovost PJ, Berenholtz SM: Evidence- based medicine in anesthesiology. Anesth Analg 2001;92:787-94

ATTACHED FILES

A19_Table1 awake vs asleep.doc

A19_Table 2 Awake vs. asleep.doc

Reg Anesth Pain Med 2005; 30(3):A19