Over the many years of nitrous oxide use, there has been concern about the effects of nitrous oxide on the hematologic, neurologic, cardiac, reproductive, and immunologic systems. Nitrous oxide has been associated with decreased proliferation of mononuclear cells and neutrophil chemotaxis, megaloblastic anemia, anemia, thrombocytopenia, subacute combined neurodegeneration of the spinal cord, polyneuropathy, myocardial ischemia, increased spontaneous abortions, reduced fertility and birth defects, and impaired wound healing.27,39–42 More recently, nitrous oxide-induced neurotoxicity has been implicated in the development of long-lasting cognitive deficits when administered to patients of extremes of age.43