[Side effects of nitrous oxide (author's transl)].

When nitrous oxide is breathed the alvolar partial pressure will cause it to diffuse into the blood, tissues and gas-containing spaces within the body until equilibrium is reached. At the same time nitrogen will be excreted from tissues and blood to alveolar gas. There is a 35 fold difference in the blood-gas partition coefficient between nitrous oxide (0.47) and nitrogen (0.013). For every molecule of nitrogen that is removed from the aircontaining space in the body, 35 molecules of nitrous oxide are transferred from the blood to the air space. This differential solubility of nitrogen and nitrous oxide results either in an increase in the volume of the gas space if the space is compliant (gastrointestinal tract, pneumothorax, air embolus, cuff of the endotracheal tube), or in an increase in the pressure if the space is non-compliant (pneumencephalography, middle ear, sinus). The clinical significance of these side effects of nitrous oxide and experimental studies are discussed.