This one is for @drsamko, thanks to his tweet yesterday.
The most recent of 19 articles in pubmed for the search "sodium polystyrene sulfonate lithium", a retrospective cohort review looking at the use of SPS in the treatment of lithium toxicity. Given that lithium and potassium are similarly charged cations, multiple animal studies evaluated its use in lithium overdose, but only case reports in humans. These authors reviewed 9 years of cases at their institutions, two hospitals in Montreal, Canada, for the effect on lithium serum half-life between patients prescribed SPS vs. patients who were not prescribed SPS.
They only looked at chronic overdoses admitted for management - 90 patients, 72 chronic, 48 had data points to properly evaluate the half-life. 36 received "standard treatment" and 12 were prescribed SPS. The authors don't well-describe the standard treatment group, and don't indicate whether any received hemodialysis - but I get the impression the treatment for chronic toxicity only employs HD on rare occasions of renal failure. Of the 12 that received SPS, most simply received IV hydration and observation in addition to SPS - and one received hemodialysis due to renal failure. Half-life of lithium in the controls was 43 hours compared to 20.5 hours in the SPS-receiving group.
SPS isn't totally benign - there was mild hypokalemia in half their treatment population - and in rare cases it causes intestinal necrosis. And, considering chronic lithium toxicity generally has a benign course, you could go either way. You can certainly argue that decreased hospital length-of-stay is a significant financial and health benefit and justify giving it, though, so it's worth knowing about.
"Successful treatment of lithium toxicity with sodium polystyrene sulfonate: a retrospective cohort study"