Go Low Flow
Using low flow anesthesia is another important strategy in reducing the environmental impacts of volatile agents. Although sevoflurane is a relatively sustainable gas, it still has about 130 times the heat-trapping potential as CO2 over a 100-year period. Consequently, finding ways to reduce the total amount of gas used per case can dramatically lower total anesthetic emissions and anesthetic costs.
Low flow anesthesia is most commonly defined as a fresh gas flow (FGF) of ≤1 L/min. Despite early concerns regarding the nephrotoxicity of one of its metabolites (compound A) in rats, studies conducted to date have not shown adverse renal effects from low-flow (0.5–1.0 L/min), long-duration sevoflurane in humans1, and low-flow practice has been used safely in adult and pediatric populations. Physiologically, low flow can preserve body temperature and humidity in the breathing circuit, and can be achieved through manual adjustments or by automated gas control. Check out the resources below to learn more about going low flow and initiatives to encourage this practice.
Citations
Ebert TJ, Schmid PG. Inhaled Anesthetics. In: Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC, eds. Clinical Anesthesia,, Edited by Paul G. Barash. Sixth. Wolters Kluwer; 2009:413-443.
Resources
Time to stop the go slow on low flow. Published in Paediatric Anaesthesia (2019).
doi: 10.1111/pan.13618
This editorial comments on the opportunity to adopt low flow strategies in a pediatric population.
Change of inspired oxygen concentration in low flow anesthesia. Published in Anesthesia and Pain Medicine (2020).
doi: 10.17085/apm.20055
This RCT examines the change in oxygen concentration in low-flow anesthesia using 30 patients in each group. Main findings are that in the low-flow group, patients maintained an inspired oxygen concentration of 35.4±4.0% at 180 min, whereas the inspired oxygen concentration in the high-flow group (4 L/min) was about 44.5±1.0% at 180. Both groups maintained pulse oximeter readings of 99-100%.
Promoting low-flow anaesthesia and volatile anaesthetic agent choice. Published in BMJ Open Quality (2019).
doi:10.1136/bmjoq-2018-000479
This paper describes a quality improvement initiative in London, UK utilizing provider education and a visual 'low flow board' to encourage sustainable practice. Over a period of 6 months, they noted no FGF rates over 2L/min and noted a 18% reduction in bottles compared to the same time in the previous year, despite an increased caseload.
The implementation of low-flow anesthesia at a tertiary pediatric center: A quality improvement initiative. Published in Paediatric Anaesthesia (2020).
doi:10.1111/pan.13994
This quality improvement initiative employed departmental education, updates on the huddle board, and intraoperative confirmation rounds to promote low flow anesthesia with sevoflurane. Bottles of sevoflurane used per month decreased on average by 20% following the intervention.
Low-flow anaesthesia. Published in the British Journal of Anaesthesia Education (2008)
https://doi.org/10.1093/bjaceaccp/mkm052
Low-flow anaesthesia – underused mode towards “sustainable anaesthesia”. Published in the Indian Journal of Anaesthesia (2018).
doi: 10.4103/ija.IJA_413_17
This article provides a review of the history of low-flow anesthesia and provides recommendations for anesthesiologists seeking to implement the technique in their practice.