Treating an asthma exacerbation with steroids–and the sooner the better–is undisputed. And it makes intuitive sense that higher doses of steroids work better, and that IV steroids work better than PO steroids, right?
Well, the answer’s not so simple.
First of all, I see patients >18 years of age (usually). A lot of the literature on asthma was studied in the pediatric population, so while the results might be generalizable, we don’t know for sure.
Is there a maximum dose for steroids?
No, although this Cochrane review suggests that upwards of 100 mg prednisone daily, you’re probably not getting much benefit. This separate Cochrane review concludes most of the evidence is pretty low-quality, so it’s hard to make a strong recommendation. Side effects such as hyperglycemia and agitation/delirium are dose dependent.
Are IV steroids better than PO steroids?
I’ve heard some people suggest that if someone has “failed” PO steroids, then they should get a trial of IV steroids for at least 48 hours. On the one hand, this seems reasonable, because you want to avoid intubating the patient for worsening respiratory distress. On the other hand, there’s no evidence to support the assertion that IV steroids are better. See this pediatric study or this randomized adult study. This review makes the argument that it can be hard to ascertain the true effect of IV steroids in retrospective studies because (1) there is often no true “control” or “placebo” group (2) more severe asthma attacks are more likely to get IV steroids upfront, so you have a “confounding by severity” problem.
IV steroids make sense as a one-time dose for initial therapy in the ED, or for patients who are too obtunded or can’t take PO for some other reason. Then again, I’ve had a couple of cases where we used IV steroids 4-5 days into someone’s asthma treatment, and they got better. There’s the literature, and then there’s practice.