How should this large double-blind, randomized, noninferiority trial comparing IM (IntraMuscular) midazolam (Versed) with IV (IntraVenous) lorazepam (Ativan) affect the way we treat patients with seizures?
21.3% of patients had their seizures stop before they could be given IV lorazepam, while none of the IM midazolam patients had seizures stop before being given medication.
Does that provide a bias toward improved outcomes with IM midazolam?
The primary outcome was termination of seizures before arrival in the emergency department without the need for the paramedics to provide rescue therapy.
Seizures were absent without rescue therapy on arrival in the emergency department in 329 of 448 subjects assigned to active treatment with intramuscular midazolam (73.4%) and in 282 of 445 assigned to active treatment with intravenous lorazepam (63.4%) (difference, 10 percentage points; 95% confidence interval [CI], 4.0 to 16.1; P<0.001 for noninferiority and P<0.001 for superiority) (Fig. 2).
The patients who had seizures stop without any lorazepam are included in those considered successfully treated.
This is appropriate, since we can expect a similar rate of spontaneous resolution among the patients receiving IM midazolam. The only difference is that those patients will have received the midazolam so quickly that the seizure will not yet have stopped.
Status epilepticus was terminated by the time of arrival at the emergency department in 59.1 percent of patients given lorazepam, 42.6 percent of patients given diazepam, and 21.1 percent of patients given placebo (P=0.001)
Is this a reason to avoid/delay administration of IM midazolam?
The greater risk appears to be to the patients with continuing seizures. The primary benefit of IM midazolam is the rapid administration.
There is no evidence of any harm to the patients who would have their seizures stop without midazolam. There is evidence of harm from delaying/avoiding treatment. Most seizures will stop prior to the arrival of EMS. Delays in treatment should probably only be for those known to have self-limiting seizures and EMS is at the patient’s side in less than 5 minutes.
An out-of-hospital complication (hypotension, cardiac dysrhythmia, or respiratory intervention) occurred in 7 (10.6 percent) of the patients treated with lorazepam, 7 (10.3 percent) of the patients treated with diazepam, and 16 (22.5 percent) of the patients given placebo (P=0.08). The most common complication was a change in respiratory status requiring ventilation assistance by bag valve-mask or an attempt at intubation (7 patients given lorazepam, 6 given diazepam, and 11 given placebo).
Those who did not receive benzodiazepines did not do as well as those who did receive benzodiazepines – this includes the most worrisome side effect of benzodiazepines – respiratory compromise. We are not improving outcomes by delaying care or by using low doses.
Among subjects admitted to the hospital, the lengths of stay in the intensive care unit and in the hospital did not differ significantly between the groups, but the proportion of subjects admitted was significantly lower (and the proportion discharged from the emergency department was significantly higher) in the intramuscular group than in the intravenous group (P=0.01).
If there is no IV already in place, is there much reason to not use IM midazolam for active seizures?
Our data are consistent with the finding that endotracheal intubation is more commonly a sequela of continued seizures than it is an adverse effect of sedation from benzodiazepines.11 
High dose benzodiazepines appear to be more likely to prevent intubation, than to result in intubation. This is something that many medical directors do not seem to have considered.
 Intramuscular versus intravenous therapy for prehospital status epilepticus.
Silbergleit R, Durkalski V, Lowenstein D, Conwit R, Pancioli A, Palesch Y, Barsan W; NETT Investigators.
N Engl J Med. 2012 Feb 16;366(7):591-600.
PMID: 22335736 [PubMed - in process]
 A comparison of lorazepam, diazepam, and placebo for the treatment of out-of-hospital status epilepticus.
Alldredge BK, Gelb AM, Isaacs SM, Corry MD, Allen F, Ulrich S, Gottwald MD, O’Neil N, Neuhaus JM, Segal MR, Lowenstein DH.
N Engl J Med. 2001 Aug 30;345(9):631-7. Erratum in: N Engl J Med 2001 Dec 20;345(25):1860.
PMID: 11547716 [PubMed - indexed for MEDLINE]