PLEX is, in severe cases, first line including respiratory distress requiring support, and/or rapid paralysis, and/or severe autonomic dysfunction. I may follow that with IVIg depending on the case. The milder presentations, IVIg first line. 

In general, combination therapy with IVIG and PLEX has not been shown to be effective (but does increase cost, hospital stay, and complications). The sequence of PLEX after IVIG is particularly problematic since the pharesis removes the circulating IVIG that you previously infused. Similarly, recent...

Pretty much never...

Agree that PLEX after IVIg is not supported by evidence and can be counterproductive. I would sooner give a second round of IVIg, though this is a difficult decision to make based simply on early response. Our data on the effectiveness of IVIg measure delayed outcomes (less time on vent, sooner ambu...