Lean Thinking in emergency departments: a critical review.

Emergency departments (EDs) face problems with crowding, delays, cost containment, and patient safety. To address these and other problems, EDs increasingly implement an approach called Lean thinking. This study critically reviewed 18 articles describing the implementation of Lean in 15 EDs in the United States, Australia, and Canada. An analytic framework based on human factors engineering and occupational research generated 6 core questions about the effects of Lean on ED work structures and processes, patient care, and employees, as well as the factors on which Lean's success is contingent. The review revealed numerous ED process changes, often involving separate patient streams, accompanied by structural changes such as new technologies, communication systems, staffing changes, and the reorganization of physical space. Patient care usually improved after implementation of Lean, with many EDs reporting decreases in length of stay, waiting times, and proportion of patients leaving the ED without being seen. Few null or negative patient care effects were reported, and studies typically did not report patient quality or safety outcomes beyond patient satisfaction. The effects of Lean on employees were rarely discussed or measured systematically, but there were some indications of positive effects on employees and organizational culture. Success factors included employee involvement, management support, and preparedness for change. Despite some methodological, practical, and theoretic concerns, Lean appears to offer significant improvement opportunities. Many questions remain about Lean's effects on patient health and employees and how Lean can be best implemented in health care.