Premedication

Abstract

The aims of premedication are anxiolysis, analgesia, anti-emesis and to reduce perioperative risk to the patient (e.g. with antihypertensives, antacids and antisialogogues). Many factors have contributed to the decline in premedicant prescription, including changes in anaesthetic agents and short postoperative stays. As well as considering premedication as part of the preoperative visit, the anaesthetist should review the patient’s current medications and decide which drugs should be continued during the perioperative period. In general, most drugs are given on the morning of surgery, but there are important exceptions, some of which may require discontinuation before hospital admission (e.g. clopidogrel). Insulin and steroids may need parenteral supplementation. Anxiolytics are less commonly prescribed than other premedications but are useful for some cases. Benzodiazepines are the most frequently used anxiolytic agents. Analgesics are sometimes prescribed, especially in the day-surgery setting, since paracetamol and non-steroidal anti-inflammatory drugs reduce perioperative opioid requirements. Caution must be taken when considering the use of cyclo-oxygenase-2 inhibitors, because of their association with increased risk of myocardial infarction and stroke. Topical analgesics are used in children to lessen the pain of cannulation. Anti-emetics, though commonly given at induction, can be prescribed as a premedicant. Consideration should also be given to the perioperative use of β-adrenoreceptor antagonists for patients undergoing major surgery. Antacids (e.g. H₂-receptor antagonists and proton-pump inhibitors) should be prescribed for patients at risk from aspiration of gastric contents. Antisialogogues are rarely needed but may be indicated for awake fibre-optic intubation.