The use of nitrous oxide can expand gas bubbles in the bloodstream and result in a threefold increase in the air volume that is introduced into the circulation. This phenomenon is critical in cases where venous air embolism is a concern, particularly in neurosurgery and cardiopulmonary surgeries.
The expansion of these bubbles caused by nitrous oxide can increase the risk of obstruction of coronary or pulmonary arteries, leading to cardiovascular collapse. For this reason, it is often recommended to discontinue nitrous oxide in the anesthetic mixture at least ten minutes before any intravenous injection of air or contrast media that may carry the risk of air embolism.
A detailed study found that even very small emboli could prove fatal if nitrous oxide is used. In one case, a small embolus that impacted the coronary arteries expanded due to nitrous oxide, resulting in the patient’s death. Therefore, it is strongly advised to avoid nitrous oxide in patients at high risk for air embolism or, if necessary, to limit its concentration to no more than 50%.
