In-line neb was up to recently our only option, we have since changed that to an MDI administered through a port on the circuit. I don't know how much would actually be delivered to the target tissues, I have no way of measuring that. As I believe someone mentioned earlier in the thread, Heliox would assist in delivering medication to the more distal airways, however pre-hospitally, the world I live in this in not an option. My plan would be to deliver this patient in better shape than I found him to a facility equipped to manage the patient better than I.
Do you feel an in-line nebulizer would do more harm than good in a very tight asthma pt? I know anecdotally that in-line nebulized albuterol has improved compliance in similar patients in my experience in the past, although other medications were also in use.
We now us MDIs on our vent patients as there is a concern with the extra flow. Also, when running a low rate, you can time the delivery with the ventilation where otherwise the nebulized med might just be lost in the circuit. There are numerous studies now on the particle depostition of both delivery methods at this has been extensively researched over the past 30+ years and now re-researched with the HFA MDIs.
I have used a self inflating BVM to bag in a nebulized med but there I do have control over the timing and the BVM is not a continuous flow.
Heliox would be the best choice initially in the ED and/or ICU to deliver meds and attempt ventilation. But I believe I did mention the drawbacks to its use on a truck even for CCT/IFT.