Volatile Capture Technologies

1. The Council noted that the evidence on VCTs is rapidly evolving with further studies underway which would inform the relative capture rates of the technologies in clinical practice. The Council is aware of the work being undertaken by VCT manufacturers to establish a process for recycling volatile anaesthetic gases in the UK, and to obtain regulatory approval for the process. For these reasons, the evidence and use case surrounding VCTs may need to be revisited.
2. The Council discussed the need for high quality life-cycle assessments, which systematically assess the relative environmental impact associated with all stages of the life cycle of VCTs. Life-cycle analyses should take into account the direct effects of VCT manufacture and use, alongside any indirect effects most relevant to the delivery and provision of healthcare. When comparing the environmental impact of alternative anaesthetic strategies (for example, TIVA) the direct and indirect environmental impact of the alternatives should be subject to the same level of assessment.
3. The Council reiterated that factors beyond the environmental impact of volatile anaesthetic gases and VCTs need to be considered when determining the value of VCTs in clinical practice. The impact of anaesthesia strategy on patient care remains a vital determinant of value, as does the cost and cost effectiveness of the technology.
4. The Council heard from two consultant anaesthetists. The first summarised the published views of several climate experts, that the impact of volatile anaesthetic gases on climate change has been overstated. The consultant anaesthetist highlighted literature which documents this view (a summary is included in our evidence review). While volatile anaesthetic gases are greenhouse gases, they are not said to ‘force the climate’ because of their short atmospheric lifespans and overall low quantities within the atmosphere. The anaesthetist stressed their view of the need to ensure that approaches to protecting the climate did not inadvertently cause more environmental damage. In other words, we should be mindful not to introduce new technologies – with their own carbon impact – if they are not sufficiently offsetting environmental impact elsewhere.
5. The second anaesthetic expert highlighted that VCT technologies, and the evidence informing their use, are rapidly evolving. The expert noted that our recommendations may need revisiting in light of any new and compelling evidence. They acknowledged that while the contribution of volatile anaesthetic gases to climate change may have been overstated, there were other factors to take into consideration when weighing up the relative environment impact of VCTs. For example, optimising anaesthesia protocols may improve the capture efficiency of VCTs; the recycling of the gases and the associated reduction of virgin gas manufacture could result in improved environmental 
   benefits for VCTs; and because hospital anaesthetic gas scavenging systems (AGSSs) require energy to run, the opportunity to use VCT systems that do not rely on a hospital AGSS could potentially boost their relative environmental benefit.
6. The Council recognised the challenges for decision makers in assessing environmental impact alongside more usual domains of value such as effectiveness, safety and cost 
   effectiveness. The Council agreed that the low quality and quantity of evidence for VCTs across all domains of value was the determining factor in informing their recommendations, but in doing so highlighted the need for improved and standardised methodologies for weighing up environmental impact alongside other domains of value.
7. The Council noted that ongoing comprehensive data collection and auditing of anaesthetic practice in NHSScotland will be important in informing future life-cycle 
   assessments and subsequent decision making. 

1. The two VCT systems currently available for use in NHSScotland are CONTRAfluranTM (manufactured by ZEOSYS), and SID-Dock (manufactured by SageTech Medical). We identified four studies that evaluated how well VCTs work in capturing volatile anaesthetic gases. All studies were small and preliminary in design and were described in letters that had been submitted to journals.
   ◼ Two UK-based bench studies (that is, studies that did not involve patients) both reported that the SID-Dock system captured approximately 95% of available volatile anaesthetic gases. 
   ◼ Two studies were conducted with patients. One, conducted in Germany (n=80), evaluated CONTRAfluranTM and reported a capture efficiency of 25%. The other, conducted in the UK (n=50), evaluated SID-Dock and reported a capture efficiency of 51%. 
2. SageTech Medical submitted an unpublished life-cycle assessment for our consideration. Their analysis suggested that the use of the SID-Dock system could reduce the total carbon impact from volatile gas emissions from a hospital by 57%. The model assumes that implementation of the VCT system would allow volatile gases to be recycled. At this moment, there is no established process for recycling volatile anaesthetic gases in the UK, nor is there regulatory approval for the reuse of recycled gases. This limits the applicability of the model to NHSScotland.
3. A small study (n=32) conducted within NHS Lothian reported that staff attitudes towards use of the CONTRAfluranTM system were favourable overall. The majority of respondents said that they found the technology easy to use and that it did not significantly increase workload.
4. No economic evaluations of VCTs were identified. We were not able to obtain the information required to develop our own economic model (for example, technology costs were not available) and so it was not possible for us to assess the cost effectiveness of VCTs compared with current practice from the perspective of NHSScotland.
5. Reducing the environmental impact of the volatile anaesthetic gases (desflurane, isoflurane and sevoflurane) is a key priority for Scottish Government. Various measures have already been taken across NHSScotland, most importantly the decommissioning of desflurane in March 2023. Desflurane is reported to be the most polluting of the three 
   volatile anaesthetic gases.
6. Total intravenous anaesthesia (TIVA) has been highlighted as a way to reduce the amount of volatile anaesthetic gases that are used. It cannot be assumed that TIVA is the ‘greener’ option and TIVA should be subject to the same level of environmental scrutiny as volatile anaesthetic gases. In preparing this report, we asked our peer reviewers (mostly anaesthetists) the extent to which they felt TIVA could replace volatile anaesthetic gases. While several respondents agreed that the use of TIVA would probably increase over coming years, no one felt that it could (or should) be used in all general anaesthesia cases.
7. Before measures are taken to capture, recycle and reuse volatile anaesthetic gases, the topic experts we consulted highlighted the importance of reducing the volume of gases 
   that are used in the first place, for example, by enabling the use of low fresh gas flows.
8. The existing evidence is not sufficient to support the purchase and installation of VCTs in NHSScotland. Important uncertainties remain around:
   ◼ the capture efficiencies of VCTs in real-life settings
   ◼ whether VCTs offer net environmental benefits over and above the mitigation measures already implemented to reduce release of volatile anaesthetic gases into the atmosphere (for example, the decommissioning of desflurane)
   ◼ possible changes in the types of anaesthesia that are administered in NHSScotland, in particular whether TIVA is going to be used more widely
   ◼ how TIVA compares with volatile anaesthetic gases in terms of environmental impact and patient outcomes
   ◼ the extent to which volatile anaesthetic gases contribute to climate change at the concentrations used currently
   ◼ the process for recycling the volatile gases, and whether this will be regulated and implementable in NHSScotland.

What were we asked to look at?
The Scottish Government’s Health Infrastructure Division asked SHTG to independently evaluate the use of VCTs in anaesthetic rooms and operating theatres. The intended purpose of VCTs is to reduce anaesthetic volatile gas emissions (greenhouse gases) entering the atmosphere and contributing to global warming and climate change.

 
Why is this important?
The gases that are used for anaesthetics and pain relief are greenhouse gases, and include the volatile gases desflurane, sevoflurane and isoflurane. Volatile gases are defined as those that evaporate readily at normal temperatures. Reducing the environmental impact of anaesthetic gases has been highlighted by the Scottish Government as a key priority.

Desflurane, isoflurane and sevoflurane are reported as having 100-year time horizon global warming potentials (GWP100) that are respectively 2,540, 510 and 130 times more potent than carbon 
dioxide. Some climate experts suggest these figures are misleading, and that the impact of these gases on climate change is insignificant because the lifetimes of the gases are too short and the concentrations are too low to have a meaningful environmental impact. In NHSScotland an 82% reduction in volatile gas emissions was achieved over the period of 2018/19 to 2021/22 as a result of 
various mitigation measures (for example, low flow anaesthetic techniques and switching from desflurane to sevoflurane). An impartial assessment of VCTs was requested to establish whether the purchasing, installation and maintenance of VCTs offers good value for money and whether they provide net environmental benefit.