Continuous neostigmine infusion versus bolus neostigmine in refractory Ogilvie syndrome

Acute colonic pseduo-obstruction (ACPO), or Ogilvie syndrome, is a syndrome of colonic obstructive symptoms and dilatation in the confirmed absence of mechanical obstruction. It carries a high mortality, which increases with the duration of the disease. Because the pathophysiology is thought to involve an excess of sympathetic activation with parasympathetic inhibition, the acetylcholinesterase inhibitor neostigmine has replaced surgical management as the primary mode of therapy. The optimal dose, rate, and frequency of neostigmine administration remain largely unexplored. Our patient had ACPO that was refractory to traditional bolus dosing of neostigmine. A continuous infusion of 0.4 mg/h (5 mg neostigmine in 50 mL of 0.9% normal sline) was therefore started in an intensive care setting. Bowel sounds returned and 8 hours later he passed stool and flatus. Though the infusion was discontinued, the bowel sounds remained persistent and complete resolution of pseduo-obstruction occurred. The likely mechanism of a superior response to continuous infusion is probably related to the short mean half-life (1 hour) of neostigmine. A continuous infusion would likely lead to prolonged period of sustained and subdued peristalsis resulting in the resolution of nonobstructive ileus that is otherwise refractory to bolus doses of neostigmine. Continuous neostigmine infusion may thus be tried in ACPO patients who are refractory to bolus doses of neostigmine.