Monitors to Improve Indoor Carbon Dioxide Concentrations in the Hospital: Background, Rationale and Protocol for a Randomized, Sham-controlled, Cross-Over, Open Label Trial

ABSTRACT Coronavirus disease 2019 (COVID-19) has caused considerably morbidity and mortality worldwide, mainly among older adults. Hospital outbreaks contribute to the burden of this disease, despite optimal hand hygiene and personal protective equipment such as masks and face shields. Ventilation with fresh outdoor air has emerged as an important strategy to reduce indoor aerosol transmission of COVID-19. Carbon dioxide (CO 2 ) monitors are increasingly advocated to facilitate ventilation in schools, long-term care facilities, offices and public buildings. Moreover, several health authorities have issued guidelines for target CO 2 values in work as well as clinical environments. Given that modern hospitals have superior indoor air quality control systems, it remains however unknown whether feedback from CO 2 monitors is needed and/or effective to improve ventilation further. Here, we describe the rationale and protocol for a randomized, sham-controlled, crossover, open label trial of CO 2 monitors in double-bed hospital rooms in two acute geriatric wards. Based on pilot data, Aranet4 Home ® monitors will be used to alert nurses and other staff to raised indoor CO 2 concentrations. Practical limitations in implementing CO 2 monitors are discussed, and will be surveyed among staff as additional study outcomes. The Monitors to Improve Indoor Carbon Dioxide (CO 2 ) Concentrations in the Hospital (MICH) trial is registered at ClinicalTrials.gov, identifier: NCT04770597 .