Clinical and economic factors that are important to consider when selecting anaesthesia for day-case surgery can differ from those for inpatient anaesthesia. Patients undergoing day-case surgery tend to be healthier and have shorter durations of surgery. They expect less anxiety before surgery, amnesia for the surgical experience, a rapid return to normal (normal mentation with minimal pain and nausea) after surgery, and lower expenses. However, the latter 2 expectations can conflict; older generic drugs have lower acquisition costs but often impose longer recovery times. Longer recovery periods can increase costs by prolonging the time to discharge from labour-intensive areas such as the operating suite or the post-anaesthesia recovery unit. The challenge for today's anaesthetist is to use newer drugs judiciously to minimise their expense without compromising the rate or quality of recovery. Several approaches can secure these aims. Most apply the least anaesthetic needed. 'Least anaesthetic' may mean the particular form of anaesthetic (e.g. local infiltration with monitored anaesthesia care versus a general anaesthetic), or may mean the delivery of the smallest effective dose, perhaps guided by anaesthetic monitors such as end-tidal analysers or the bispectral index. For patients requiring general anaesthesia, a combination of several drugs usually secures the closest approach to the ideal. Drug combinations used usually include a short-acting properative anxiolytic (e.g. midazolam), intravenous propofol (a short-acting potent anxiolytic and amnestic agent) for induction of anaesthesia (and sometimes for maintenance) and primary maintenance of anaesthesia with inhaled nitrous oxide combined with a poorly soluble (low solubility produces rapid recovery; the least soluble is desflurane) potent inhaled anaesthetic delivered at a low inflow rate (to minimise cost). Although old, nitrous oxide is inexpensive and has favourable pharmacokinetic and cardiovascular advantages; however, it is limited in its anaesthetic/amnestic potency, and has the capacity to increase nausea. In children, induction of anaesthesia is often accomplished with sevoflurane rather than desflurane; although sevoflurane is modestly more soluble than desflurane, it is non-pungent whereas desflurane is pungent. Moderate- or short-acting opioids (fentanyl is popular) or nonsteroidal anti-inflammatory agents (especially ketorolac), or local anaesthetics are added to secure analgesia during and after surgery. Similarly, when needed, moderate- or short-acting muscle relaxants are selected. Before the end of anaesthesia, an intravenous antiemetic may be given. With this drug combination, patients usually awaken within minutes after anaesthesia and can often move themselves to the vehicle for transport to the recovery unit. These combinations of anaesthetics and techniques minimise use of expensive drugs while expediting recovery (again minimising cost) with minimal or no compromise in the quality of recovery.
