Final answer:
The toxic central nervous system effects of intravascular injection of a large volume of a local anesthetic can include seizures, respiratory depression, hypotension, and loss of consciousness. Respiratory depression is likely to appear first.
Step-by-step explanation:
The toxic central nervous system effects attributed to intravascular injection of a large volume of a local anesthetic can include seizures, respiratory depression, hypotension, and loss of consciousness. Of these effects, respiratory depression would likely appear first. When a large volume of local anesthetic enters the bloodstream, it can depress the respiratory centers in the brain, leading to a decrease in breathing rates and inadequate exchange of oxygen and carbon dioxide.