Objectives The presence of critically ill patients may impact care for other ED patients. We sought to evaluate whether the presence of a critically ill child was associated with the time to (1) receipt of the first medication among other patients, and (2) administration of diagnosis-specific medications.

Methods We performed a retrospective cohort study of all paediatric ED visits over 3 years. Patients were exposed if they arrived during the first hour of a critically ill patient's care. The primary outcome was the time from arrival to first medication administration. Secondary outcomes were time to corticosteroids in asthma and time to antibiotics for fever/neutropenia. We modelled times to medication using median regression, adjusting for demographics, arrival time and weekday, and census (number of patients in the ED).

Results We analysed 170 112 visits. Median times to first medication for those exposed to 0, 1 and >1 simultaneous critically ill patients were 90 min (IQR 54–146), 96 min (IQR 58–157) and 113 min (IQR 72–166), respectively (p<0.001). The increase in time to corticosteroids among exposed patients versus unexposed was 6 min (IQR 2–14, p=0.11) and in time to antibiotic for fever/neutropenia was −4 min (IQR −4 to −11, p=0.13). Modelled time to first medication increased 3.1 min (95% CI 0.5 to 5.7) among all exposed patients (p=0.02). Time to first medication increased 15.3 min (95% CI 14.7 to 15.9) for each 10 patient increase in census.

Conclusions The presence of critically ill patients was associated with a delay in medication administration to others. Census independently predicted medication delays.