ANAESTHETIC GASES
professionals, who are regularly exposed to the gas in the work environment. In most countries nitrous oxide programmes have exposure limits for healthcare professionals. Known as threshold limits, they stipulate how much exhaled gas staff are allowed to be exposed to. These also apply in the UK, meaning that, alongside a high room air exchange rate, inhaled and exhaled gas from patients should be controlled in a closed system. Therefore, exhaled gas should be captured by an exhalation hose, and moved away from where it may affect staff. This process of collection and removal is called scavenging.
Although the effects of exposure to nitrous oxide are still uncertain, and the literature is inconclusive, the effects can vary from headache, to dizziness, to loss of concentration and focus on the treatment of patients.5
These possible
effects are not in the best interests of either the professional or the patient, who expects total focus on the procedure. In Scandinavia, closed systems for delivering nitrous oxide gas mixes to patients are used routinely to capture and destroy the gas locally, making it a ‘win-win’ situation for everyone concerned and the environment.
Nitrous oxide uses in Scandinavia The use of closed delivery systems and the threshold limits for staff exposure are governed by national guidelines across Scandinavia. Hospitals have technicians and work environment specialists that make sure that guidelines are correct and followed. Medical equipment is used for inhalation and exhalation, and gases captured via pipeline systems, which are designed by hospital gas system contractors. The exhaled gas from patients goes to a gas outlet in the treatment room, and from here a gas evacuation pipeline transports it to a mechanical services room. Hospitals will have a central destruction unit in place, as there are many rooms that support the nitrous oxide programme. In the same hospital there may be a paediatric and an emergency department supporting patients with nitrous oxide. In this case, there is no gas evacuating pipeline. The amount of nitrous oxide used is small by both volume and frequency, so here hospitals would use the mobile destruction unit.
In Sweden, all hospitals with a nitrous oxide programme are aware of the solutions for capturing and destroying it. Given that even a small volume of nitrous oxide leads to a very high CO2
emission
value, failure to install the solution would result in a heavy local carbon dioxide footprint. For example, the University Hospital Rigshospitalet in Copenhagen calculated that nitrous oxide use for its maternity department in 2018 was
82 Health Estate Journal October 2021
Malene Hegenberger, a Danish midwife, works daily with nitrous oxide to support her patients.
4,514 kilograms. Determining the CO2 equivalency by multiplying by 298 means that the department alone emitted the equivalent of 1,345,172 tons of carbon dioxide.
Compelling environmental case The environmental case is compelling. By installing a central destruction unit connected to the gas evacuation system, 99% of these CO2
from the hospital’s nitrous oxide programme. Compared with other possible CO2
emissions solutions, this
technology requires a relatively small investment, but delivers a huge beneficial impact on the hospital’s total carbon footprint.
Sweden came to this conclusion in 2011, after installing central destruction units in 12 different hospitals. The ‘Destruction of Medical N2
O in Sweden’ report6
compared both lifecycle assessment and lifecycle cost for this technology with other methods of reducing the CO2 footprint in healthcare settings. The conclusion was that destruction was a good and competitive investment, and that the collection of exhaled gas for destruction supported efforts to reduce the negative effect on occupational health. Since then, as the energy consumption required for destruction technology has decreased, the investment is even more attractive today.
Taking a green leaf out of Scandinavia’s book
Optimising the running and maintenance of hospitals and other healthcare facilities and the delivery of clinical care is at the heart of the NHS mission, and a major focus of sustainability, with interventions already being implemented across NHS
A mobile destruction unit is deployed in settings where there are no gas evacuation pipelines – such as emergency departments, and in clinical spaces used for orthopaedics, endoscopy, paediatrics, and ambulatory care.
estates and facilities. With the nitrous oxide evolution beginning to take shape in the UK, there is now an opportunity to take this a step further – and progress is already being made across the UK. The destruction programme developed by Medclair in Sweden is now being trialled in hospitals in Manchester, Newcastle, and
emissions are removed
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