Hematologic effects of nitrous oxide in surgical patients.

Nitrous oxide can cause hematologic abnormalities, including death, if it is administered for several days. However, the adverse hematologic effects of its use for surgical anesthesia are unclear. Accordingly, we have studied the hematologic responses of patients undergoing procedures involving hematologic stress or prolonged anesthesia with and without nitrous oxide. We measured red cell count, hemoglobin concentration, mean red cell volume, reticulocyte count, platelet count, mean platelet volume, blood leukocyte level, and leukocyte differential in patients undergoing total hip arthroplasty or removal of an acoustic neuroma. Nitrous oxide did not affect the production of red blood cells or platelets. Nitrous oxide treatment was associated with an increase in postoperative leukocyte levels that was modestly but significantly smaller than that found in patients not given nitrous oxide. There was no evidence that this small decrease in maximal leukocytosis adversely affected clinical outcome.