What symptom indicates the initial stages of local anesthetic overdose?

The initial stages of local anesthetic overdose are characterized by symptoms that reflect central nervous system (CNS) excitability. Confusion is a symptom that indicates this excitability. When local anesthetics enter the systemic circulation in higher-than-therapeutic doses, they can affect the CNS, leading to both excitatory and depressive effects. Initially, patients may experience confusion or altered mental status as the CNS becomes over-stimulated.

As the overdose progresses, more severe symptoms can occur, such as drowsiness, which signifies a shift towards CNS depression. However, confusion is typically observed before drowsiness sets in, making it a key indicator of the early stages of an overdose. Events such as seizures and cardiac arrest are associated with more advanced stages of toxicity and typically do not present at the onset. Thus, confusion is the initial symptom that practitioners should monitor closely to gauge the risk of overdose.