Some regional nerve blocks may not achieve their primary goal for a variety of reasons.

Definition: The block is partially or completely insufficient to be the sole surgical anesthetic.


Consequence - additional intervention to provide anesthesia:

(1) local supplementation in the surgical field

(2) increased sedation

(3) conversion to general anesthesia


In addition, there is increased morbidity associated with longer operative times, longer recovery time and additional drug exposures.


Failure during surgery needs to be distinguished from postoperative failure of the regional block since the solution and consequences differ.


Risk factors:

(1) higher ASA physical status

(2) female sex

(3) substance use disorder

(4) obesity

(5) failure to use ultrasound or nerve stimulator guidance

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