Desflurane - balancing the environmental costs and cognitive benefits. A reply

A randomised controlled trial comparing quality of recovery between desflurane and isoflurane inhalation anaesthesia in patients undergoing ophthalmological surgery at a tertiary hospital in South Africa (DIQoR trial)

Background

The patient's experience of their postoperative recovery is an important perioperative outcome, with the 15-item quality of recovery scale (QoR-15) recommended as a standardised outcomes measure. Desflurane has a faster emergence from anaesthesia compared with other volatile anaesthetics, but it is uncertain whether this translates to better subjective quality of recovery. The hypothesis for this study is that patients receiving desflurane for maintenance of anaesthesia would have better postoperative quality of recovery than patients receiving isoflurane.

Methods

Male and female adult patients undergoing ophthalmological surgery under general anaesthesia were randomly allocated to receive desflurane or isoflurane for maintenance of anaesthesia. The primary outcome was to compare postoperative QoR-15 scores. Secondary outcomes included comparing preoperative QoR-15 scores, volatile agent consumption, and time spent in the recovery room.

Results

Data from 164 patients were analysed (80 desflurane, 84 isoflurane). Median (Q1, Q3) postoperative QoR-15 scores were not significantly different (desflurane: 145 [141, 148], isoflurane: 144 [139, 147], 95% confidence interval 0-3, P=0.176, minimal clinically important difference=8). Median (Q1, Q3) volatile agent consumption was 15.4 (12.5, 19.3) ml hr-1 in the desflurane group, and 7.4 (5.9, 9.7) ml hr-1 in the isoflurane group. Median (Q1, Q3) time spent in the recovery room was significantly shorter in the desflurane group (desflurane: 18 [13, 23]; isoflurane: 25 [19, 32], 95% confidence interval -10 to 5, P<0.001).

Conclusions

This study found no difference in quality of recovery between patients who received desflurane or isoflurane for maintenance of general anaesthesia during ophthalmological surgery. A shorter time in the recovery room was not associated with improved QoR-15 scores.

Clinical trial registration

NCT04188314.

Greenhouse gas reduction in anaesthesia practice: a departmental environmental strategy

Sustainability interventions were implemented at the Royal Brisbane and Women’s Hospital (RBWH) following identification of inhaled anaesthetic gases as a target for reducing medical carbon emissions. This quality improvement study assessed and evaluated the impact of sustainability interventions on the environmental and financial cost of inhaled anaesthetic gas use in order to guide future initiatives and research in reducing carbon emissions from healthcare practice.

Ethical exemption was granted from the RBWH Research Ethics Committee (EX/2021/QRBW/76078). Usage (bottles) and expenditure for desflurane and sevoflurane from January 2016 to December 2021 were obtained. Global warming potential and carbon dioxide equivalent (CO₂e) were used to report environmental impact of volatile agents. Methods to estimate this were performed in Excel based on Campbell and Pierce methodology. An Environmental Protection Agency greenhouse gas equivalency calculator was used to convert CO₂e to equivalent petrol carbon emissions and kilometres travelled by a typical passenger vehicle.

The total number of bottles of sevoflurane and desflurane purchased between January 2016 and December 2021 decreased by 34.76% from 1991 to 1299. The number of desflurane bottles purchased decreased by 95.63% from 800 to 35 bottles. The number of sevoflurane bottles purchased increased by 6.13% from 1191 bottles to 1264 bottles. This was achieved by implementing quality improvement interventions such as staff education of desflurane-sparing practices, distribution of posters and progressive removal of desflurane from operating theatres. Total carbon emission from volatile anaesthetics equalled 2326 tonnes CO₂e. Combined desflurane and sevoflurane emissions decreased by 87.88%. In 2016, desflurane made up 92.39% of the annual CO₂e, which steadily decreased to 33.36% in 2021. Combined sevoflurane and desflurane usage costs decreased by 58.33%.

Substantial reductions in carbon emissions from volatile anaesthetics demonstrate the significant degree to which environmentally sustainable practices have been implemented. Applying desflurane-sparing practice can heavily limit anaesthetic drug expenditure and contribution to environmental waste. This is important given the global health sector’s challenge to optimise patient outcomes in the face of global climate change crisis.