The carbon footprint of metered dose inhalers (MDI) used by inpatients at a large metropolitan hospital for asthma and COPD is the equivalent of providing electricity to 50 homes for a year, a study shows.
Considering there are effective yet more environmentally friendly alternatives to MDIs, the finding is just one example of the contribution of the healthcare sector to greenhouse gas emissions and the opportunity to make significant change.
The study, published in the Internal Medicine Journal [link here], said Australia could follow the example of international colleagues such as the British Thoracic Society and Canadian Thoracic Society in making recommendations to prioritise use of dry powder inhalers (DPIs) and soft mist inhalers (SMIs) over MDIs
“Although the efficacy of the inhaler type is of paramount importance and may be determined by individual patient factors, it is clear that preferential use of DPIs over pMDIs in appropriately selected patients would significantly reduce the carbon footprint related to inhaler use,” the Australian investigators said.
The study involved a retrospective pharmacy-based database search of all inpatient inhaler dispensing from 1 July 2022 to 30 June 2023 across all hospital units at The Royal Melbourne Hospital.
It quantified use by inhaler type and calculated the carbon footprint for the entire life cycle of the inhalers by type, and their relative contribution to total emissions.
Of the 9,246 inhalers dispensed during the study period, 79% were MDIs which accounted for almost all (98.81%) of the total inhaler carbon footprint.
“Salbutamol MDI (51%), ipratropium MDI (12.5%) and budesonide/formoterol MDIs (8%) were the most frequently dispensed inhalers, accounting for 71.5% of total inhalers dispensed,” the study said.
“Tiotropium respimat (406 inhalers) and budesonide-formoterol DPI (379 inhalers) were the most frequently dispensed SMI/DPIs but accounted for only 4.39% and 4.01% of dispensed inhalers respectively.”
About half of the inhalers were dispensed in the general and respiratory medicine wards and the ED.
Sustainable switch
The investigators, including Associate Professor Megan Rees, said switching to more sustainable inhalers had occurred in countries such as Sweden where “…MDIs account for approximately only 13% of inhalers without compromising asthma and COPD outcomes.”
They noted that switching all inhalers from pMDIs to DPIs and SMIs may not always be the optimal prescribing practice for individual hospitalised patients.
“For example, DPI use may not be appropriate for patients in the intensive care or post-operative setting as they may be unable to generate sufficient inspiratory flow rates because of critical illness or sedation.”
However they said the environmental impact of inhaler choice should be considered in decision-making around prescribing as the environment was an important issue for both health professionals and patients.
“Our respiratory department has worked closely with the emergency department in implementing policy that emphasises environmental considerations in inhaler decision-making pathways,” they said.
“An important component of this has been promoting maintenance and reliever therapy for patients presenting with asthma, through DPI wherever possible, which reduces the need for short-acting beta-2 agonist inhalers and are typically used as pMDIs, while also improving asthma control.”
They said other plans to encourage change included integrating decision support into inhaler prescribing in the electronic medical charts, and updating hospital-based guidelines regarding the management of respiratory conditions that require inhaler therapy, “…to raise awareness of DPI and SMI inhalers as equally effective and more environmentally friendly alternatives to MDIs.”