Factors Associated with Treatment Failure in Patients with Acute Exacerbation of COPD Admitted to the Emergency Department Observation Unit

Figure 1

Study flow diagram. Abbreviations: AECOPD, acute exacerbation of chronic obstructive pulmonary disease; ED, emergency department; EDOU, emergency department observation unit; EDOULOS, emergency department observation unit length of stay; ICU, intensive care unit. Patients who received either invasive or noninvasive mechanical ventilation or both and then needed ward admissions, ICU admission, or were referred to other hospitals.