Anticholinergic syndrome precipitated by opioid reversal

NaIoxone is an opioid antagonist used for the reversal of life-threatening opioid overdose. Because naloxone is believed to have few side effects, it is often given liberally even in the absence of absolute indications. The relative safety of prehospital naloxone administration has been rep0rted.l We report two patients in whom the prehospital administration of naloxone unmasked anticholinergic poisoning. PREHOSPITAL CARE Patient 1 was a 46-year-old man who called EMS with a chief complaint of shortness of breath and headache. On arrival, paramedics found the patient conscious and alert with no signs of respiratory distress. The patient stated that he and his girlfriend had been injecting heroin approximately 30 minutes prior to calling EMS. He reported feeling lightheaded within minutes of injecting the drug, a feeling that was not consistent with his past experiences with heroin. The patient denied chest pain, fever, headache, recent trauma, weakness, or paresthesias prior to the onset of symptoms. He was not taking any prescription or over-the-counter medications, and had no known allergies. His social history included past heroin and alcohol abuse, as well as prior cocaine use. His vital signs were heart rate (HR) 110 beats/min, respiratory rate (RR) 22 breaths/min, blood pressure (BP) 150/110 mm Hg, and oxygen saturation 99% on room air. EKG monitor revealed sinus tachycardia without ectopy. The patient's breath sounds were clear and equal in all fields. The skin was pale and clammy