Reducing the environmental impact of mask inductions in children
A quality improvement report
Submitted December 2023 by Dr Tracy Jackson
Read by 187 Journal Watch subscribers
The environmental impact of anaesthetic gases are of increasing concern. In Australia and New Zealand, children are traditionally induced by gas induction with high flow nitrous/oxygen and sevoflurane. High fresh gas flows (FGFs) are traditionally used to speed up induction, although once the circuit is primed FGFs above minute ventilation do not change speed of induction. The Society of Paediatric Anesthesia recommends 0.15/min/kg as the minimum safe and effective FGF during induction i.e . 3L/min for a 20kg child. Many anaesthetists routinely run 6-10L/min regardless of the child’s weight.
The authors instituted 4 interventions with the aim to decrease nitrous oxide usage from 80% to 20% and reduce maximum FGF from a baseline of 0.53L/min/kg. Interventions included – a lecture on environmental impact of anaesthetia from a visiting professor, survey of nitrous oxide usage with repeat education, visual reminders of recommended minimum FGF rates, FGF rates as screen saver on anaesthesia work stations.
The authors analysed 33 285 anaesthesia records over a 20 month period. Emergency surgery, planned IV induction and ASA 3 patients were excluded. A subset of patients undergoing insertion myringotomy tubes were analysed for speed and quality of induction and mask acceptance.
Results: Nitrous usage dropped from 75% to 25% following intervention 1 &2 with a slow decrease to 15% by the end of the study. Maximum FGF decreased by 30% over the study with the greatest change in smaller patients. Induction times increased initially but returned to baseline after a few months. Induction behaviour scores and mask acceptance was unchanged.
Education if followed up with visual reminders can be a powerful tool to change behaviour. The authors note that the visiting speaker was invited due to a general interest in the department to improve environmental practices, therefore there primed for change. The avoidance of nitrous and “low flow” gas inductions did not change the speed and quality of the induction. This has been supported in other studies (Singh, 2019).
All patients over 12 months were offered a midazolam premed. There was no data as to the number which received a premed. This may influence the quality of induction and mask acceptance and not reflect standard practice in Australia and New Zealand.
As a throwaway line in the discussion the authors note the issues with piped nitrous. Multiple studies both in Australia/Nz and worldwide have found 80-90% of nitrous is lost to leaks before even reaching a patient. Therefore decreasing nitrous usage without decommissioning pipeline supply is not likely to make a huge difference. That said, reducing nitrous usage from standard to occasional practice can allow for easy the change to cylinder supply.