Modification of the physiological disturbances produced by whole gut irrigation by preliminary mannitol administration.

In a prospective non-randomized study of 42 patients it was found that the oral administration of 50 g of mannitol 2 h before whole bowel irrigation (WBI) improved the success rate of the bowel preparation and reduced the time required for the WBI. Mannitol is an osmotic cathartic, and it reduced fluid absorption from a mean value of 2.7 l in patients who had WBI alone to a mean of 1.2 l in those who received mannitol beforehand. Sodium absorption was also significantly reduced.