Naloxone use by Aotearoa New Zealand emergency medical services, 2017-2021.

Objective: Emergency medical services (EMS) use of naloxone in the prehospital setting is indicated in patients who have significantly impaired breathing or level of consciousness when opioid intoxication is suspected. The present study characterised naloxone use in a nationwide sample of Aotearoa New Zealand road EMS patients to establish a baseline for surveillance of any changes in the future.

Methods: A retrospective analysis of rates of patients with naloxone administrations was conducted using Hato Hone St John (2017-2021) and Wellington Free Ambulance (2018-2021) electronic patient report form datasets. Patient demographics, presenting complaints, naloxone dosing, and initial and last vital sign clinical observations were described.

Results: There were 2018 patients with an equal proportion of males and females, and patient median age was 47 years. There were between 8.0 (in 2018) and 9.0 (in 2020) naloxone administrations per 100 000 population-years, or approximately one administration per day for the whole country of 5 million people. Poisoning by unknown agent(s) was the most common presenting complaint (61%). The median dose of naloxone per patient was 0.4 mg; 85% was administered intravenously. The median observed change in Glasgow Coma Scale score was +1, and respiratory rate increased by +2 breaths/min.

Conclusions: A national rate of EMS naloxone patients was established; measured clinical effects of naloxone were modest, suggesting many patients had reasons other than opioid toxicity contributing to their symptoms. Naloxone administration rates provide indirect surveillance information about suspected harmful opioid exposures but need to be interpreted with care.