ABSTRACT
There is, however, one important exception to this-high concentrations of N2O. At inspired concentrations greater than 20%, the rate of rise at which the alveolar concentration (FA) approaches the inspired concentration (FI) is greater the higher the inspired concentration. In other words, the time taken for the alveolar concentration to reach 50% of the inspired value (50% FA/FI) will be less with 70% N2O than with 20% N2O. This is a phenomenon known as the concentration effect and is shown in Figure 33.13.
