The effect of sepsis and short-term exposure to nitrous oxide on the bone marrow and the metabolism of vitamin B 12 and folate
It is recognised that prolonged anaesthesia with nitrous oxide (N20) induces megaloblastic anaemia by oxidising vitamin B12 To determine whether sepsis aggravates the effect of H20 on haemopoiesis 5 patients with severe sepsis, who required surgery and were exposed to short-term (45 - 105 minutes) N20 anaesthesia, were studied. Hone had evidence of pre-operative vitamin B12 or folate deficiency. The effect of the combination of N20 anaesthesia and sepsis on DNA synthesis in bone marrow cells was assessed morphologically, and by the deoxyuridine suppression test. In 3 patients exposed to the longest duration (75 - 105 minutes) of N20, addition of folinic acid and vitamin B12 partially improved the utilisation of deoxyuridine in vitro. No patient had evidence of megaloblastic haemopoiesis as judged by bone marrow morphology. It is concluded that prolonged N20 anaesthesia in patients with severe sepsis may adversely affect DNA synthesis. Although this effect did not manifest as overt megaloblastic erythropoiesis, it may be prudent to avoid N20 in such patients.