 Of 573 patients, 48% were discharged in less than 2 hours, 23% in 2–4 hours and 29% in >4 hours.94 patients who were held in the emergency department (ED) or admitted required a critical intervention, including supplemental oxygen for hypoxia (74), repeat naloxone (52), antibiotics administered intravenously (IV) (14), assisted ventilations (13), fluid bolus for hypotension (12), charcoal for associated life-threatening overdose (6), IV inotropic agents (2), antiarrhythmics for sustained tachycardia >130 beats/min (1), and administration of bicarbonate for arterial [HCO3] <5 or venous CO2 <5 (1)".This study concluded that emergency physicians can clinically identify patients at risk of deterioration after naloxone reversal of suspected opioid overdose.