How would you approach managing severe, functionally disabling steroid induced edema that is refractory to treatment with chlorthalidone or bumetanide?

This is a difficult issue - I'm assuming the patient is unable to taper steroids at this time. The edema results from the mineralocorticoid activity of the steroid, so attempting to change to a low or negligible mineralocorticoid corticosteroid may be helpful if possible - dexamethasone, betamethasone, methylprednisolone or triamcinolone. Decreasing sodium levels (<2 g/day) may also be helpful depending on the clinical scenario. Spironolactone or eplerenone are mineralocorticoid receptor antagonists and may be useful if the patient is able to tolerate these medications. If the patient is hospitalized, a nephrologist may also be able to help manage the fluid balance in this challenging clinical context.