Certified Nurses Operating Room (CNOR) Practice Exam

The presence of tinnitus and a metallic taste in the mouth are classic symptoms associated with local anesthetic toxicity. These signs often indicate that the local anesthetic has entered the systemic circulation, leading to central nervous system (CNS) stimulation. Tinnitus, or ringing in the ears, can occur due to the effects of the drug on the auditory pathways in the CNS. The metallic taste may arise from the alteration of sensory perception and can also indicate systemic absorption of the anesthetic.

While the other symptoms listed can be associated with various medical conditions or reactions, they are not specific indicators of local anesthetic toxicity. Dizziness and headaches, blurred vision and fatigue, as well as nausea and vomiting can occur in a range of situations, including anxiety, dehydration, or other medical conditions, but they do not directly relate to the effects of local anesthetics in the same way that tinnitus and metallic taste do. Therefore, the connection of tinnitus and metallic taste uniquely identifies the risk of toxicity from local anesthetics.