Figure 5-13 The volume of a pneumothorax created by air injection is affected little when oxygen subsequently is breathed (lower two curves). However, if 75% nitrous oxide is breathed, the volume doubles in 10 minutes and triples in 0.5 hour (upper three curves). (Adapted from Eger EI II, Saidman LJ: Hazards of nitrous oxide anesthesia in bowel obstruction and pneumothorax. Anesthesiology 26:61–66, 1965.)