We do not expect people to be deeply moved by what is not unusual.G. Eliot, Middlemarch 18712
There are certain clinical challenges that we meet only occasionally in anaesthetic practice. They may be difficult to manage: more conscious effort is required and one needs to refer to a readily available text. Endocrine disorders fall into this category. Some are not uncommon in the general population such as insulin-dependent diabetes mellitus or thyroid disease, but others occur much less frequently, such as carcinoid syndrome or Cushings disease.
Anaesthesia for patients with endocrine disorders was the subject of a symposium held by The Royal College of Anaesthetists in London in March 1999. It has also, on at least two occasions, been the subject of one of the popular symposia held at the Association of Anaesthetists of Great Britain and Ireland headquarters in Bedford Square, London. We thought it appropriate to invite selected speakers from these symposia to submit didactic reviews for publication on their area of interest. We have added to these topics for completeness, with reviews of the anaesthetic aspects of such rare metabolic disorders as porphyria by international experts on the subject,1 and an update on malignant hyperthermia.2 We have also considered related topics such as the stress response to surgery3 and the perioperative challenges of the morbidly obese patient.4
Understanding the endocrine response to anaesthesia and surgery is fundamental to successful management of all patients undergoing a major operation. Desborough describes this rapidly developing area succinctly and with considerable clarity.3 Our knowledge of cytokines and other acute phase proteins which trigger the stress response is increasing rapidly and anaesthetists need to be regularly updated on this topic. Anaesthetists dread the management of a morbidly obese patient presenting for major surgery. Will the patient fit on the operating table; will they breathe adequately postoperatively; and who will manage their inevitable postoperative problems? These points are addressed by Adams and Murphy,4 who instil us with the confidence to face this particular challenge in the future.
Most anaesthetists in adult practice will occasionally have to manage patients presenting for thyroid surgery. Always a potentially challenging area because of the risk of a difficult intubation, anaesthetic techniques for management of the airway in the presence of an enlarged thyroid gland have developed alongside fibreoptic intubation and the increasing range of airways and laryngoscopes that have become available. These are discussed in detail by Farling.5 Similar anaesthetic techniques are required for parathyroid surgery, yet the hormonal and biochemical problems which these patients present are very different. Knowledge of the physiology of calcium regulation has increased significantly. It is a complex area, often unfamiliar to anaesthetists, which is ably described by Mihai and Farndon.6 The anaesthetic problems which may be encountered in patients with hyperparathyroidism are also detailed.
Perhaps the endocrine disorder that all anaesthetists consider to be the greatest challenge is phaeochromocytoma, often known as the great mimic. Such patients can present unexpectedly during anaesthesia, or for planned surgical excision. Thorough preoperative preparation is pivotal to successful intraoperative management. This challenge is detailed by Prys-Roberts,7 together with an account of his extensive experience in the management of these patients over many years.
Anaesthesia for patients with pituitary disease is a highly specialized area. Even within a neurosurgical unit, only a few practitioners will have extensive experience of it. Smith and Hirsch have addressed the anatomy and pathophysiology of the pituitary gland, as well as the preoperative preparation and intraoperative management of these patients.8 Acromegalic patients are rare, but they may present on any operating list (possibly undiagnosed), and an anaesthetist must be able to manage them appropriately.
Every trained anaesthetist should also be able to manage patients competently with any form of diabetes mellitus. Much is now known about the actions of insulin in health and disease. The historical background to this knowledge is interesting; it is described in a logical manner by Sonksen and Sonksen.9 What goes wrong in diabetes is explained; the metabolic sequelae must be understood for appropriate management of these complex patients in the accident and emergency department, the operating theatre or the intensive care unit. Perioperative management of diabetic patients is often suboptimal: this is inexcusable. McAnulty, Robertshaw and Hall10 provide a systematic and clear approach to the anaesthetic management of these patients which, if followed, should avoid many of the postoperative problems which diabetics unnecessarily develop (when their care is only being supervised by inexperienced, non-anaesthetic trainee doctors and a paucity of nurses).
Perhaps the most esoteric of endocrine tumours are those found in the gastrointestinal tract. Many anaesthetists will never encounter patients with such tumours of the pancreas as gastrinomas, glucagonomas or somatostatinomas in a lifetime of clinical practice. But they may be presented with patients with multiple endocrine neoplasia including, for instance, carcinoma of the thyroid gland, which can also involve the gut. Diagnosis can often be elusive in these patients and expert anaesthetic knowledge in this area is rare. Holdcroft provides it in a wide-ranging review of hormones and the gut.11
Drugs used in anaesthesia may, albeit rarely, produce an atypical response which is potentially fatal. The classic example is malignant hyperthermia.2 The neuroleptic malignant syndrome (NMS) is an altered response to neuroleptic drugs. It most commonly presents in psychiatric patients, to intensivists rather than anaesthetists. But a relationship has been suggested between NMS and malignant hyperthermia and this topic is discussed by Adnet and colleagues.12 The adverse metabolic effects of recreational drugs are poorly detected and treated. They are primarily managed in accident and emergency departments, but may present to intensivists and anaesthetists. Their complexities are well described by Henry.13
We hope that you will find this postgraduate issue interesting and useful. We think it will help all of us to practice anaesthesia more effectively and appropriately in the next millennium, even in patients with exceptionally challenging or unusual endocrine disease.
P. M. Hopkins
Academic Unit of Anaesthesia
St James University Hospital
Leeds LS9 7TF
J. M. Hunter
Department of Anaesthesia
University of Liverpool
Duncan Building, Daulby Street
Liverpool L69 3GA
References
1 James MFM, Hift RJ. Porphyrias. Br J Anaesth 2000; 85: 14353
2 Hopkins PM. Malignant hyperthermia: advances in clinical management and diagnosis. Br J Anaesth 2000; 85: 11828
3 Desborough JP. The stress response to trauma and surgery. Br J Anaesth 2000; 85: 10917
4 Adams JP, Murphy PG. Obesity in anaesthesia and intensive care. Br J Anaesth 2000; 85: 91108
5 Farling PA. Thyroid disease. Br J Anaesth 2000; 85: 1528
6 Mihai R, Farndon JR. Parathyroid disease and calcium metabolism. Br J Anaesth 2000; 85: 2943
7 Prys-Roberts C. Phaeochromocytomarecent progress in its management. Br J Anaesth 2000; 85: 4457
8 Smith M, Hirsch NP. Pituitary disease and anaesthesia. Br J Anaesth 2000; 85: 314
9 Sonksen P, Sonksen J. Insulinunderstanding its action in health and disease. Br J Anaesth 2000; 85: 6979
10 McAnulty GR, Robertshaw HJ, Hall GM. Anaesthetic management of patients with diabetes mellitus. Br J Anaesth 2000; 85: 8090
11 Holdcroft A. Hormones and the gut. Br J Anaesth 2000; 85: 5868
12 Adnet P, Lestavel P, Krivosic- Horber R. Neuroleptic malignant syndrome. Br J Anaesth 2000; 85: 12935
13 Henry J. Metabolic consequences of drug misuse. Br J Anaesth 2000; 85: 13642