Magnesium ions and barium coating of colonic mucosa: Is it a simple question of viscosity?

The aim of the present study was to verify whether magnesium-induced increa se of barium coating of the colonic mucosa is specifically due to the incre ase of barium suspension viscosity, One hundred sixty-one patients schedule d for double-contrast barium enema (DCBE) were randomised in one group of 2 3 patients (control group, CG), and three groups of 23 pairs (G1, G2 and G3 ), i.e. 138 patients. The DCBE was performed with standard technique using a barium suspension with dynamic viscosity of 280 cPs (CG), or with viscosi ty increased to 320 cPs (G1), 2500 cPs (G2) or 3200 cPs (G3), by extemporan eous addition of MgSO4 1, 2 or 3 g in one member of the pair, Na2SO4 1, 4.2 or 8 g in the other one. Three radiologists evaluated on an ordinal scale mucosal coating and free fluid. In all magnesium subgroups barium coating w as better than in CG (p < 0.008), the highest value being obtained in G2. N o difference was observed as regards free fluid. Inside paired groups, muco sal coating was more effective in magnesium than in sodium members (p < 0.0 002). Viscosity of barium suspension being equal inside each group, this ef fect must be attributed to magnesium-specific interactions with additives o f the barium suspension inducing events other than viscosity changes.