How does the sensitivity for blockade by a LA compare regarding the following types of fibres:

(a) myelinated fibres with unmyelinated fibres; and

(b) pressure/touch nerves with the dorsal nerves that transmit pain impulses?

1. Unmyelinated fibres and smaller myelinated fibres are easier to block than larger myelinated fibres, thus they are more sensitive to the effects of local anaethetics.
2. When type A fibres are blocked it influences the proprioception, touch, pressure, muscles, pain, and temperature functions. This fibre has high frequency pain transmission; thus blockade will be done with lower concentration of local anesthetic. And does not appear to have high sensitivity for local anesthetics.

Make a list of the effects of LA on other tissues.

CVS: cardiac depression

CNS: sedation, lightheadedness, visual and auditory disturbances, restlessness, and CNS depression.

Skeletal muscle: it has a weak blocking action thus no clinical applications.

 What is the basis for the selection of a LA?

it is chosen by the type of procedure that is done, the target tissue it is must be used for and the duration of the numbering effect.

Why are LA solutions sometimes saturated with CO₂?

It buffers the local anesthetics. Reduces the pain of injection and thus a faster onset is achieved. It also raises the effective concentration of nonionized form of the local anesthetic, onset of regional block is shortened.

Which of the LA are typically used for surface anaesthesia?

Oxybuprocaine, benzocaine and cocaine