Comment on: The financial and environmental impact of purchased anaesthetic agents in an Australian tertiary hospital

We read with interest the paper by Davies et al. ¹ We have observed a similar trend in anaesthetic purchasing and use in Sir Charles Gairdner Hospital, a tertiary hospital located in Perth, Western Australia. Propofol total intravenous anaesthesia (TIVA) is now the most common anaesthetic at our hospital. We write to share the results of a survey of consultant anaesthetists in our department which sought to identify the reasons behind the shift in preferred anaesthetic technique.

To investigate the current trends in anaesthetic technique we audited 665 anaesthetic charts retrospectively to see if patients received volatile anaesthesia or TIVA. We reviewed all anaesthetic charts from 7 consecutive days in each of the years 2016, 2020 and 2022. The proportion of general anaesthetics that involved TIVA were 37%, 66% and 74%, respectively. Purchasing data for our institution mirrored this trend. The average amount of sevoflurane purchased was 64.3 bottles/month in 2017 and 37.4 bottles/month in 2022. The average amount of propofol purchased was 54.1 litres/month in 2017 and 113.6 litres/month in 2022. Desflurane purchasing by our institution ceased in 2020.

We sent a survey to all consultant anaesthetists in the department using Survey Monkey (https://www.surveymonkey.com) in March 2023, with an 89% response rate (quality improvement activity registration number 49784). Those surveyed were first asked which maintenance anaesthesia technique they use for most cases, irrespective of anaesthesia subspecialty practice. Forty-two of 61 respondents (69%) reported they use TIVA for most cases and 19 of 61 (31%) reported they use volatiles for most cases. Those who prefer TIVA reported using volatiles for 21% of cases on average, while those who prefer volatiles reported using TIVA for 23% of cases on average.

Using branched questions, we asked why anaesthetists preferred one or other technique and why they switched to their non-preferred technique. The commonest three responses for each group are shown in Table 1.

Table 1.

Most common three responses as to why anaesthetists preferred TIVA or volatile anaesthesia and why they switched to their non-preferred technique.

TIVA enthusiasts (n = 42, 69%)
Why TIVA?		Why switch to volatile?
How the patient is at the time of wakeup (quality of wake-up)	33/42	High complexity of case: using volatile frees up attention, time and mental focus to identify and manage surgical mishaps or support patient physiology	17/42
2. Low rates of postoperative nausea and vomiting	29/42	2. Teaching trainees how to administer volatile anaesthesia safely	15/42
3. Environmental considerations	20/42	3. Poorly controlled asthma	13/42
Volatile enthusiasts (n = 19, 31%)
Why volatile?		Why switch to TIVA?
Predictable quick wake-up time with low flows	15/19	History of postoperative nausea and vomiting	16/19
2. Reduced risk awareness under anaesthesia	14/19	2. Administering sedation without a secured airway	15/19
3. Because it is easy to administer it frees up attention, time and mental focus to identify and manage surgical mishaps or support patient physiology, complete documentation, rest	9/19	3. Neurosurgery/spinal surgery	10/19

TIVA: total intravenous anaesthesia.

The survey responses indicate the dominant reason why TIVA is chosen by TIVA enthusiasts is to optimise patient recovery by improving quality of wake-up and to reduce nausea and vomiting. Environmental considerations were given as a reason for using TIVA by 20 of the 41 TIVA enthusiasts.

Both volatile and TIVA enthusiasts identified that they choose volatile anaesthesia because it frees up attention, time and mental focus to manage surgical mishaps and support patient physiology. This may be relevant for complex patients, high risk surgery, critically unwell patients and high turnover lists.