Rowe analysed the costs of providing anaesthesia using a variety of different techniques in his own day surgery unit in Norfolk and Norwich [2]. His first analysis looked simply at the cost of maintaining anaesthesia in a 70 kg individual using either volatile anaesthesia or propofol infusions. Whilst Rowe analysed a variety of volatile agents we have limited the data reproduced here to those commonly in practice today. He considered maintenance with both high or low fresh gas flows for volatile anaesthesia and high and low infusion rates for TIVA. Using high fresh gas flow or high TIVA infusion rates as might be appropriate for induction of anaesthesia or for short procedures before steady state is achieved, he demonstrated that the hourly cost of TIVA infusions is slightly greater than that of isoflurane or desflurane however 50 % cheaper than using sevoflurane. When low flow rates of volatile agents were considered and compared with a lower maintenance infusion rate for propofol. P, propofol anaesthesia was found to be double the cost of using isoflurane or desflurane but still cheaper than with sevoflurane (Table 33.2). It is of note that when considering day surgery anaesthesia sevoflurane is the volatile agent most commonly used for comparison purposes due to its improved side effect profile compared with the other agents combined with smooth induction and emergence and relatively quick recovery.

In a further audit Rowe analysed the cost of a common procedure (laparoscopic sterilisation) undertaken by five different anaesthetists using different anaesthetic techniques (Table 33.3). Those anaesthetists using TIVA had shorter total procedure times which may reflect a variety of factors including speed of surgeon, theatre team or anaesthetic efficiency. The mean anaesthetic cost did not vary greatly between techniques and was shown to equate to approximately 4 % of the total procedure cost when staffing and disposable costs were taken into account. Interestingly those patients receiving the cheapest anaesthetic incurred the highest total procedure costs! Whilst the costs of all the drugs shown have changed since the time of analysis the comparisons are still we believe noteworthy.

Of particular note is that the most significant change in drugs cost since both the work of Rowe and that of ourselves back in the 1990s is that propofol came off patent which removed the requirement to use the very expensive diprifusor chipped syringes if using the Target Controlled model of delivery.

This is shown very clearly by the step change in propofol costs within the Torbay Day Surgery Unit in July 2007 (Fig. 33.1). Switching to an alternative source of propofol saved £4000/month, whilst new pumps were required their cost of £25,000 was paid for in 6 months by the propofol savings incurred. Rowe republished his data in 2006 [3] considering the use of generic propofol as shown in Table 33.4, he now demonstrates that propofol infusions for maintenance of anaesthesia are more cost effective than either sevoflurane or desflurane.

Choice of drug for induction and maintenance of anaesthesia will also have an impact on the disposables and other equipment used during the conduct of anaesthesia and this needs to be taken into account even in the most simple cost minimisation study of different anaesthetic techniques. Use of volatile anaesthesia requires certain expensive items of equipment to be available. The most obvious of these is an anaesthetic machine with the ability to deliver the anaesthetic vapours to the patient, whilst it would be unusual for most hospitals in the UK not to have anaesthetic machines readily available, this may not be the case for more financial restricted parts or the world. Even within our own hospitals it is not possible to provide an anaesthetic machine in every environment where anaesthesia may be undertaken and the simple drug delivery system of a syringe driver for TIVA administration may be preferable, desirable or the only option available. Choice of volatile anaesthesia also dictates the requirement for a more formal airway, the majority of cases undertaken using volatile anaesthesia employ either an endo-tracheal tube or laryngeal mask. Whilst short cases may be undertaken using a face mask this still requires a formal circuit and filter and commits the anaesthetist to holding the facemask for the duration of anaesthesia. With TIVA the interdependence of airway and anaesthesia delivery is not present, hence the anaesthetist is free to select whichever airway technique is appropriate for that patient. In many cases this may simply be the use of a variable performance (Hudson type) facemask with spontaneous ventilation. This technique eliminates the cost of anaesthetic circuit/filter/face mask/laryngeal mask/endotracheal tube, etc. As this technique of airway management is commonly used in our day surgery unit we have analysed the costs of providing anaesthesia by a variety of techniques and included the costs not only of the drugs but of the associated delivery and airway management equipment required for that technique [4].