Basic plastic surgery techniques and principles: Using local anaesthetics
In the third part of our series, Ben Taylor and Ardeshir Bayat explain local anaesthetics. Which anaesthetic should you use and why? And what are the risks?
Local anaesthetics, when used correctly, enable doctors to do many surgical procedures. However, these drugs can harm patients if care is not taken. When giving local anaesthetics for basic surgery: how, where, which, how much, and what if it all goes wrong?
Local anaesthetics stop the propagation of impulses along nerves by blocking fast sodium channels which are voltage gated.1 To block a channel, the drug must penetrate the cell membrane and act on the channel from the inside.2 Drugs that do this can partition themselves between lipids and water.3 Partitioning is pH dependent and does not occur so readily in acidic conditions in which anaesthetics are less potent.
The potency of local anaesthetics in blocking neurones applies to other excitable cells. Neurones in the brain and conduction pathways in the heart are affected in the same way as peripheral nerves if enough of the drug enters the bloodstream.4 Absorption