What are two factors that influence the effectiveness of local anesthesia?

The effectiveness of local anesthesia is significantly influenced by tissue pH and the presence of infection. Local anesthetics typically function by binding to sodium channels, preventing the generation and conduction of nerve impulses. The pH of the tissue plays a crucial role in this process; anesthetics are more effective in environments where the pH is closer to neutral. When tissues are inflamed or infected, the pH tends to be lower (more acidic), which can lead to more ionization of the anesthetic. This ionization prevents the drug from penetrating nerve membranes effectively, resulting in decreased anesthetic efficacy.

Furthermore, the presence of infection can increase vascularity in the area, leading to higher systemic absorption and potentially reducing the local concentration of the anesthetic agent. This makes it more challenging to achieve the desired level of anesthesia in infected tissues compared to healthy tissues. Thus, both tissue pH and the presence of infection are critical factors that directly affect how well local anesthesia will work for a patient.