Effect of intratracheal lignocaine, halothane and thiopentone on changes in plasma beta-endorphin immunoreactivity in response to tracheal intubation.

Alterations in the concentration of plasma beta-endorphin immunoreactivity (beta-EPir), in response to the stress of tracheal intubation, were measured in 48 women during halothane anaesthesia. The increase in plasma beta-EPir in response to tracheal intubation could be prevented by topical analgesia (4% lignocaine 2 ml) to the trachea, a deeper level of halothane anaesthesia (1.5%) and an increased dose of thiopentone (10 mg kg-1). It was concluded that a low plasma beta-EPir value is a sign of stress-free anaesthesia and that measurements of plasma beta-EPir may be useful in determining the degree of stress present during various anaesthetic procedures.