What is the global impact of anaesthesia?
This is uncertain. Discussion usually centres on the environmental impact of anaesthetic gasses and inhalational agents (see below) and disregards the contributions made by equipment and drug manufacture/transport (procurement accounting for approximately 60% of NHS carbon emissions), patient and staff transport (~22%), building energy use (~18%) and waste disposal (~2300 kg anaesthetic waste/theatre/year). Given that anaesthesia is administered by ~15,000 anaesthetists for ~450,000 surgical procedures annually in the UK (~200 million anaesthetics worldwide), it might be expected that the global impact of anaesthesia is not insignificant.
What about anaesthetic waste?
Each operating theatre produces approximately 2300kg of anaesthetic waste and 230kg of sharps waste a year, which is invariably incinerated (at ~£750 per tonne). However, ~40% of anaesthetic waste could be reclassified as domestic waste (disposed of for ~£80 per tonne) or be recycled (potentially earning income of ~£15 per tonne). Furthermore, ~40% of sharps waste comprises inappropriately disposed of packaging, metals, plastic etc. Decreasing solid waste in anaesthetic practice is hampered by convenience, technology, lack of knowledge and statutory regulation. Several strategies (the ‘5R’ approach) may be employed to decrease waste:
REDUCE – a key factor is to reduce the amount of waste produced in the first instance, by for instance, decreasing (double, triple or more) packaging;
REUSE – more controversially, concerns about sterility demand new solutions rather than continued utilization of single-use equipment;
RECYCLE – although there is a carbon cost involved in recycling, non-clinical waste, given the amount of anaesthetic waste produced, there is potential for environmental and financial benefit;
RETHINK – for example, redesigning the layout of anaesthetic rooms to encourage de facto waste segregation;
RESEARCH – for example, into new methods of packaging and cold sterilisation.
How do I go about solid waste streaming?
Decreasing solid waste disposal in anaesthesia is not straightforward. There is little in the way of accessible knowledge on the subject, and a general (understandable) attitude from hospitals concerned by the possibility of inappropriately disposing of clinical waste, contrary to the Environmental Protection Act and the Control of Substances Hazardous to Health regulations, amongst other legislation. Waste streaming into hazardous and non-hazardous waste is possible at the point of waste creation (in this case the anaesthetic room, during unpackaging), but endorsement is required from several agencies, including theatre managers, estates managers, risk managers, hospital lawyers and clinical staff.
Anaesthetists have to take responsibility for initiating and continuing waste streaming methods, which may involve acting as guarantors for the contents of disposed waste. Audit and pre-planning are important in this instance, and can reassure the Trust about safety concerns, whilst emphasising the environmental and financial benefits of correct segregation.
Should I use nitrous oxide?
Similarly to Inhalational anaesthetic agents (IAAs), nitrous oxide is a potent greenhouse gas. Although its GWP20 is less than half that of the least polluting IAA (sevoflurane), at 290, nitrous has a much greater atmospheric longevity (114 years), resulting in a GWP100 greater than sevoflurane, at 300. In addition, as a carrier gas it is usually administered in a high fractional concentration, accounting for an estimated 99.5%+ of the climate impact potential of anaesthetic gasses/IAAs (Axelson). Medical nitrous oxide accounts for approximately 1% of atmospheric nitrous oxide, or 0.07% of all global warming factors. Given that nitrous oxide also appears to worsen cardiovascular outcomes after anaesthesia, the continued use of nitrous oxide is increasingly difficult to justify.