Evaluating the effectiveness of the maximum permitted dose of midazolam in seizure termination: Insights from New South Wales, Australia

Objective

Out-of-hospital seizures demand rapid management. Midazolam plays a key role in stopping seizures. At times the first dose of midazolam proves insufficient, necessitating additional doses. Within the New South Wales Ambulance (NSWA) service, the upper limit for midazolam administration is set at 15 mg. However, the outcomes and safety of using midazolam at this maximum dosage have not been thoroughly investigated.

Methods

A retrospective analysis of out of hospital electronic health records from New South Wales, Australia, over the year 2022, was conducted. The study manually reviewed cases where adult patients received the maximum dose of midazolam for seizure management by paramedics. It focused on seizure cessation success rates and the incidence of adverse effects to evaluate the clinical implications of high-dose midazolam administration.

Results

Of 818 790 individual attendances by NSWA clinicians, a total of 11 392 (1.4%) adults had seizures noted, of which midazolam was administered in 2565 (22.5%). An algorithm shows that in 2352 (91.7%) instances the midazolam was associated with the apparent termination of seizures. Analysis revealed that 176 (1.5%) proportion of all adult's seizure patients required the maximum dose of midazolam for seizure control. These higher doses successfully terminate seizures in about half of the instances. AEs following the maximum dose of midazolam included hypoxia in 26.7% of patients and respiratory depression in 9.7%, indicating significant side effects at higher dosages.

Conclusion

In New South Wales, Australia, administering the maximum dose of midazolam to seizure patients is rare but proves effective in approximately half of the refractory seizure cases. Therefore, assessing the potential for additional doses of midazolam or the use of a second-line agent is advisable.