- Background The realization of the potential benefits of health information exchange systems (HIEs) for emergency departments (EDs) depends on the way these systems are actually used. The attributes of volume of information and duration of information processing are important for the study of HIE use patterns in the ED, as cognitive load and time constraints may result in a trade-off between these attributes. Experts and non-experts often use different problem-solving strategies, which may be consequential for their system use patterns. Little previous research focuses on the trade-off between volume and duration of system use or on the factors that affect it, including user expertise. Objectives This study aims at exploring the trade-off of volume and duration of use, examining whether this relationship differs between experts and non-experts, and identifying factors that are associated with use patterns characterized by volume and duration. Methods The research objectives are pursued in the context of critically-ill patients, treated at a busy ED in the period 2010–2012. The primary source of internal and external data is an HIE linked to 14 hospitals, over 1300 clinics, and other clinical facilities. We define four use profiles based on the attributes of duration and volume: quick and basic, quick and deep, slow and basic, and slow and deep. The volume and duration of use are computed using HIE log files as the number of screens and the time per screen, respectively. Each session is then classified into a specific profile based on distances from predefined profile centroids. Experts are physicians that are board-certified in emergency medicine. We test the distribution of use profiles and their associations with multiple variables that describe the patient, physician, situation, information available in the HIE system, and use dynamics within the encounter. Results The quick and basic profile is the most prevalent. While available admission summaries are associated with quick and basic use, lab and imaging results are associated with slower or deeper use. Physicians who are the first to use the system or are sole users during an encounter are less inclined to quick and deep use. These effects are intensified for experts. Discussion A trade-off between volume and duration is identified. While system use is overall similar for experts and non-experts, the circumstances in which a certain profile is more likely to be observed vary across these two groups. Information availability and multiple-physician dynamics within the encounter emerge as important for the prediction of use profiles. The findings of this study provide implications for the design, implementation, and research of HIE use.