AbstractAimTo evaluate the impact of locally adapted targeted implementation interventions on bronchiolitis management through reduction in ineffective investigation and therapies within emergency departments.MethodsA multi‐centred, quality improvement study in four different grades of hospitals in Western Australia that provide paediatric emergency and inpatient care. All hospitals incorporated an adapted implementation intervention package for infants under 1 year with bronchiolitis. The proportion whose care complied with guideline recommendations to not receive investigations and therapies of minimal benefit were compared to pre‐intervention care in a previous bronchiolitis season.ResultsA total of 457 infants in 2019 (pre‐intervention) and 443 in 2021 (post‐intervention) were included, with mean age of 5.6 months (SD 3.2, 2019; SD 3.0, 2021). In 2019, compliance was 78.1% versus 85.6% in 2021, RD 7.4 (95% CI −0.6; 15.5). The strongest evidence was reduced salbutamol use (compliance improvement: 88.6% to 95.7%, RD 7.1 95% CI (1.7; 12.4)). Hospitals initially at <80% compliance demonstrated greatest improvements (Hospital 2: 95 (78.5%) to 108 (90.8%) RD 12.2 95% CI (3.3; 21.2); Hospital 3: 67 (62.6%) to 63 (76.8%) RD 14.2 95% CI (1.3; 27.2)).ConclusionTargeted site‐adapted implementation interventions resulted in improvement in compliance with guideline recommendations, particularly for those hospitals with initial low compliance. Maximising benefits through guidance on how to adapt and effectively use interventions will enhance sustainable practice change.