Neutropenia Potentially Associated With Remifentanil Administered for Respiratory Drive Suppression: A Case Report

Remifentanil-related neutropenia (< 500/μL) has not been previously described. We encountered it in an 81-year-old man after aortic surgery complicated by acute respiratory distress syndrome. While receiving remifentanil at 0.04-0.08 μg/kg/min to suppress excessive respiratory effort in the intensive care unit, his neutrophil count plummeted from 20,690/μL to 2400/μL. Suspect drugs were stopped and granulocyte colony-stimulating factor given, yet neutropenia persisted until remifentanil was withdrawn, after which neutrophils recovered. When respiratory status deteriorated, remifentanil was restarted, and neutropenia promptly recurred. The temporal relationship, dechallenge, and rechallenge strongly implicate remifentanil as the cause of this rare adverse reaction. This case highlights the need for vigilance regarding hematologic toxicity with any medication, even those without prior reports, and underscores the importance of prompt review and withdrawal of potential offending agents when severe neutropenia develops.