Comparison of Neostigmine Dosing Order Sets for Colonic Pseudo-Obstruction

Introduction: Colonic pseudo-obstruction (Ogilvie’s syndrome) can be an acutely critical finding that necessitates intervention, whether medical or procedural, with the goal of preventing further decompensation and potential for perforation. Treatment is typically medical management with neostigmine or decompressive colonoscopy, or both. Neostigmine itself poses the risk of bradycardia with administration and warrants ICU admission for monitoring. Within our health-system, two dosing strategies exist, 2 mg IV piggyback over 30 minutes (IVPB), or 0.4mg/hour continuous infusion (CI). Neither dosing strategy has been compared to the other, and it remains unclear if one is more effective or safe than the alternative.


Methods: A retrospective cohort study was performed to evaluate order set utilization of each dosing strategy from May 2024 to May 2025. The primary outcome was the administration of antidote therapy for bradycardia. Secondary outcomes included total dose exposure and need for repeated administration. Patients were excluded if they received both dosing strategies within an index admission.


Results: Of 305 patients in the study period, 123 were excluded due to receiving both strategies, leaving 100 who received CI compared to 82 receiving IVPB. Most patients were admitted to the CVICU (70.9%), with the next most common ICU service as mixed medical/surgical (16.5%). Gastroenterology was consulted for 37.9%, with 13.7% receiving a decompressive colonoscopy. The mean maximal colonic dilation was 9.34 +- 2.83 cm. Alternative bowel regimens were trialed in 170 (93.4%) of patients. The median total dose of neostigmine was 9.6 mg in the CI arm compared to 2mg in the IVPB arm. Use of antidote therapy was rare, with only one patient receiving atropine in the CI arm, and new inotropic therapy was initiated in eight patients (8%) in the CI arm compared to one (1.2%) patient in the IVPB arm. Repeated doses were administered in 73 patients, distributed evenly between groups.


Conclusions: The CI strategy exposed patients to significantly more drug and required more antidote administration, predominantly via new inotropic support compared to IVPB.