ANANDIE VAN DEN BERG
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Blog #9

17 Mar 2021, 12:52 Publicly Viewable
  1. Myelinated and unmyelinated fibers:
    1. Unmyelinated fibers and smaller myelinated fibers are blocked more efficiently by local anesthetics than larger myelinated fibers. Thus, unmyelinated fibers are very sensitive to the effects of local anesthetics.
    2. When A-type fibers are blocked, proprioception, touch, pressure and motor fibers are influenced. These are the last type of fibers to be blocked by local anesthetics, thus the fibers are not that sensitive to local anesthetics.
  2. Local anesthetics affect the cardiovascular tissue by causing cardiac depression. It also affects the central nervous system by producing lightheadedness, visual and auditory disturbances.
  3. A local anesthetic is chosen on the type of procedure that is being done, the type of tissue that the local anesthetic must be used on and also the duration of the numbing effect that is needed in that tissue.
  4. CO2 buffers the local anesthetic. This then reduces the pain of injection and a faster onset of local anesthetics is achieved. This will also raise the effective concentration of the nonionized form of the local anesthetic, for only the nonionized form can cross the plasma membrane to have an effect, and thus the onset time of the regional block will be shortened.
  5. Local anesthetics used for surface anesthesia include: oxybuprocaine, benzocaine and cocaine.