Background: Absorption of large quantities of iodine, as induced by the use of topical antimicrobial povidone-iodine in burn-injured patients, may cause metabolic and electrolyte abnormalities as well as renal failure. To diminish iodine levels, haemodialysis was previously reported to be a suitable therapy. We therefore studied the kinetics of iodine in order to define the most optimal dialysis strategy.
Methods: Two patients with elevated iodine levels (93.6 and 81.2 mg/L) underwent continuous dialysis with blood flows Q(B) 150 and 120 mL/min. Blood was sampled from the inlet and outlet dialysis line at several time points during a 7-h and 39-h 10-min period, respectively. Samples were analysed for iodine with the inductively coupled plasma mass spectrometry (ICPMS) method. Kinetic analysis was performed using one and two compartmental models, deriving kinetic parameters: plasmatic volume V(1), extraplasmatic volume V(2) and intercompartmental clearance K(12). The calibrated kinetic model of Patient 2 was further used to simulate different dialysis strategies: 12-h per day with Q(B) 240, 6-h per day with Q(B) 480 and 240, and 12-h every 2 days with Q(B) 240. For each strategy, the mean average plasmatic and extraplasmatic concentration (TAC(p) and TAC(ep)) was calculated during 48 h.
Results: Iodine seemed to follow one compartmental kinetics when serum sample collections were limited to the first 7 h of dialysis (Patient 1), but iodine appeared to be distributed in two volumes (V(1)=19.4 L, V(2)=38.0 L and K(12)=55 mL/min) when a longer observation period was taken into account (Patient 2). The simulations disclosed that 12-h dialysis per day with Q(B) 240 or continuous dialysis with Q(B) 120 resulted in the lowest TAC(p) (18.2 and 19.0 microg/L) and TAC(ep) (34.4 and 36.1 microg/L).
Conclusion: In patients with elevated iodine levels, especially when associated with renal failure, haemodialysis with a minimum 12-h duration with sufficient blood flow should be the first choice to remove iodine.