Potentially explosive colonic concentrations of hydrogen after bowel preparation with mannitol

Hydrogen (H2) concentrations were measured in undiluted samples of intracolonic gas and in expired air in twenty patients undergoing colonoscopy after preparation with either mannitol or castor oil. Potentially explosive intracolonic H2 concentrations were present in six out of ten patients given mannitol, but in none given castor oil. This has important implications for colonoscopic, as well as for surgical, electrosurgery. H2 concentrations in expired air sampled preoperatively did not identify patients with potentially explosive intracolonic hydrogen levels.