How do you manage patients with a diagnosis of AIDP who do not respond to initial IVIg?

I disagree. Using PLEX right after IVIG means you've just removed a lot of the latter from circulation.

It's a retrospective study, but this demonstrated a lack of benefit from additional PLEX. If anything it was just more expensive and patients were hospitalized for longer.

Oczko-Walker et al., PMID 21386771

When we are talking about "a diagnosis of AIDP", are we talking about the broader spectrum of GBS or implying that their NCS/EMG only showed acquired demyelinating features but no evidence of axon loss? If there is axon loss, which is commonly seen, response will probably not be immediate/rapid.

I guess this gets at what "respond to" means. Most patients with GBS reach a clinical nadir at 2 weeks and some may seem as if they worsen ove...

I think we all agree on PLEX as the proper management in this case.

Important point: this is why deciding from the beginning what to use as first-line treatment is influenced by how impaired the patient's functions are. In patients who are "crashing" with issues of breathing and autonomic problems, the best treatment in my opinion is PLEX. These patients should be closely monitored in an ICU or a step down ICU with frequent VC checks. In my opinion, there is no room for IVIg here. If the patient is functioning fine in these parameters and able to eat and breathe then IVIg is a good choice with close monitoring clinically. I don't think I ever had to go from IVIg to PLEX in acute settings (luck!). I may have to repeat the course in 10 days minimum time, if needed.