Question

What is the effect of lidocaine on CBF (Cerebral Blood Flow) and CMR (Cerebral Metabolic Rate)?

1) Increases CBF and decreases CMR
2) Decreases CBF and increases CMR
3) Increases both CBF and CMR
4) Decreases both CBF and CMR

Answer 1

Lidocaine decreases both Cerebral Blood Flow (CBF) and Cerebral Metabolic Rate (CMR) by preventing sodium ions from moving across neuronal membranes, which inhibits action potentials and transmission of pain signals.

Step-by-step explanation:

The effect of lidocaine on Cerebral Blood Flow (CBF) and Cerebral Metabolic Rate (CMR) is that it decreases both CBF and CMR. Blocking sodium channels in neurons prevents action potentials from propagating, leading to decreased neuronal activity. This reduction in neural activity subsequently leads to a decreased demand for oxygen and glucose, thus reducing the cerebral metabolic rate. Since the metabolic needs of the brain dictate CBF to a significant extent, the reduction in CMR leads to a lower CBF as a secondary effect.

Lidocaine acts as an effective local anesthetic because it inhibits sodium ion movement across neuronal membranes. By blocking voltage-gated sodium channels, lidocaine prevents the initiation and propagation of action potentials, which are necessary for the transmission of nerve impulses that signal pain.