Correlation between measured (NOMEAS) and calculated (NOCALC) inspiratory tracheal concentrations of NO during continuous administration. The x-axis represents the inspiratory tracheal concentrations of NO measured by fast-response chemiluminescence apparatus. The difference between the measured and calculated inspiratory tracheal concentrations is represented on the y-axis. The dark line in the center represents the mean error. The dotted lines on either side represent the precision (± 2 SD). Calculated inspiratory tracheal NO concentrations underestimate the actual inspiratory tracheal NO concentrations delivered to the patient. Published with permission .