The measurement of human plasma catecholamines by high performance liquid chromatography and electrochemical detection, and the study of sympathoadrenal responses during the induction of anaesthesia prior to surgery.

A major part of this study details the technical procedures required to separate the catecholamines from their biological matrix as efficiently as possible, to detect them, and to quantify them accurately. The method is subsequently validated in detail, and reference ranges established from a small normal population. An attempt was also made to estimate the platelet catecholamine content: this was not successful, but is included here for the light it sheds on the technical problems encountered.Plasma catecholamines were measured using these methods in three different clinical situations: in patients suspected of harbouring a phaeochromocytoma, and in two separate groups of patients undergoing induction of anaesthesia prior to surgery. Because of the individual nature of these studies, the layout of this thesis is unusual: the three clinical studies are presented in their entirety in three separate chapters. Each is introduced with a background to the study and a presentation of the hypothesis being tested, and a full discussion of the results and conclusions will be found at the end of each of chapters 8, 9 and 10. In chapter 9 the catecholamine responses during induction of anaesthesia and skin incision were studied in patients undergoing coronary artery bypass grafting, either for the first time or as a review of previous grafts. In chapter 10, the catecholamine responses during the induction of anaesthesia were compared in neurosurgical patients with the use of either intravenous magnesium sulphate or intravenous alfentanil. In all of these groups of either intravenous magnesium sulphate or intravenous alfentail. In all of these groups of patients the catecholamine responses, and haemodynamic responses were found to be surprisingly small, quite unlike the marked response to intubation reported by other groups in the past, and the conclusion is drawn that this is probably a reflection of efficient, modern anaesthetic practice.