Intercostal nerve blockade for evaluation of local anaesthetic agents.

Bilateral intercostal nerve block provides the opportunity to subject as many as 16 separate peripheral nerves in a single subject to known or unknown local anaesthetic agents in a variety of concentrations, volumes, and additives. It permits the observation of local (e.g., neuritis), clinical (e.g., onset and duration), and systemic (e.g., toxicity and blood concentration) effects of these variables. In double-blind studies, bilateral intercostal nerve block allows the use of each side of the trunk for comparison of two experimental drugs, a new drug against a standard, or two new drugs. Subtle differences in clinical properties as well as simultaneous blood concentrations may be detected in these studies. The advantages of this technique in evaluating local anaesthetic agents are primarily the use of a single subject as his own control while studying may separate peripheral nerves. This aids appreciably in limiting the variable of age, temperature, and perfusion, as well as techniques of administration and evaluation. The constancy of the anatomy of the intercostal nerve provides a highly reliable and reproducible block technique.